ZXG10-BSC(V2) Technical Manual

ZXG10 Z T E G S M W L L S Y S T E M

GGSSMM WWLLLL SSYYSSTTEEMM

TTeecchhnniiccaall MMaannuuaall

OOFF

ZZXXGG1100--BBSSCC ((VV22))

SSHHEENNZZHHEENN,, CCHHIINNAA

Technical Manual of ZXG10-BSC (V2)

PAGE: I/III

CONTENTS

1. OVERVIEW ......................................................................................................... 1 1.1 Brief introduction.................................................................................................. 1 1.1.1 Architecture of GSM networks............................................................................. 1 1.1.2 Composition of a BSS system ............................................................................. 2 1.2 System interface protocols .................................................................................. 4 1.2.1 Protocol stack of circuit-type services.................................................................. 4 1.2.2 GPRS protocol stack ........................................................................................... 8 1.3 System networking mode .................................................................................. 10 2. PERFORMANCE AND FEATURES.................................................................. 11 2.1 Service functions ................................................................................................11 2.2 Specifications..................................................................................................... 13 2.3 Physical features ............................................................................................... 15 3. HARDWARE STRUCTURE .............................................................................. 17 3.1 Overview............................................................................................................ 17 3.1.1 Module Structure ............................................................................................... 17 3.1.2 Block Siagram ................................................................................................... 19 3.1.3 Rack Structure ................................................................................................... 22 3.2 System control................................................................................................... 23 3.2.1 Overview of system control module................................................................... 23 3.2.2 Descriptions to Physical structure and functions of main control units .............. 25 3.2.3 MP Circuit .......................................................................................................... 27 3.2.4 COMM ............................................................................................................... 31 3.2.5 MON .................................................................................................................. 36 3.2.6 PEPD................................................................................................................. 37 3.3 Switching network.............................................................................................. 38 3.3.1 Structure and functions of digital switching network .......................................... 38 3.3.2 Basic principle of digital switching ..................................................................... 40 3.3.3 BOSN principle diagram .................................................................................... 41 3.3.4 Digital switching network interface (DSNI)......................................................... 42 3.4 Basic interface: .................................................................................................. 47 3.4.1 Structure and functions of base station interface unit ........................................ 47 3.4.2 Base station interface peripheral processor BIPP ............................................. 49 3.4.3 Digital trunk interface (TIC)................................................................................ 51 3.5 Transcoder and A interface unit ......................................................................... 52 3.5.1 Transcoder and adapter .................................................................................... 53 3.5.2 A interface.......................................................................................................... 56 3.6 SM (sub-multiplexer) unit................................................................................... 57 3.6.1 SMU function descriptions................................................................................. 57 3.6.2 SMU structure.................................................................................................... 59 3.7 Power supply ..................................................................................................... 59 3.7.1 POWP................................................................................................................ 60


PAGE: II/III

3.7.2 POWB................................................................................................................ 61 3.8 Synchronization system..................................................................................... 63 3.8.1 Overview of synchronization system ................................................................. 63 3.8.2 Synchronizing circuit.......................................................................................... 65 3.8.3 Clock output....................................................................................................... 67 3.8.4 Clock synchronization........................................................................................ 68 4. SOFTWARE FUNCTIONAL STRUCTURE....................................................... 70 4.1 Operating & Support Subsystem (OSS) ............................................................ 71 4.1.1 unning support module ...................................................................................... 72 4.1.2 Data link control module .................................................................................... 84 4.1.3 Interface equipment drive module ..................................................................... 86 4.2 Database subsystem (DBS) .............................................................................. 87 4.3 Service processing subsystem (SPS) ............................................................... 89 4.3.1 Message assignment module............................................................................ 90 4.3.2 Traffic process handling module........................................................................ 93 4.3.3 Flow control module .......................................................................................... 95 4.3.4 Ground circuit maintenance module.................................................................. 95 4.4 Operation & Maintenance Sub-system (OMS) .................................................. 96 4.4.1 Fault management............................................................................................. 98 4.4.2 Security management...................................................................................... 101 4.4.3 Performance management .............................................................................. 103 4.4.4 Configuration management ............................................................................. 105 4.4.5 System management functions ....................................................................... 107 5. OMC-R NETWORKING SOLUTIONS ............................................................ 107 5.1 Design Of ZXG10-OMC System...................................................................... 108 5.2 Structure features and configuration of OMC-R .............................................. 109 5.2.1 Architecture features of OMC system.............................................................. 109 5.2.2 OMC-R configurations ......................................................................................110 5.2.3 XG10-OMC concentrated maintenance networking solutions..........................112 5.3.1 X.25 ..................................................................................................................113 5.3.2 PCM-A interface ...............................................................................................113 5.3.3 LAN...................................................................................................................114 5.3.4 Special modes ..................................................................................................114 6. FUNCTION DESCRIPTION ............................................................................ 116 6.1 Basic flow .........................................................................................................116 6.1.1 Allocation flow of access and initialization........................................................116 6.1.2 Paging flow .......................................................................................................117 6.1.3 Management flow of transmitting mode and encrypting mode .........................118 6.1.4 Executing flow of handover ..............................................................................118 6.1.5 Call reestablishment flow..................................................................................119 6.1.6 Channel release flow ....................................................................................... 120 6.1.7 Load management flow ................................................................................... 120 6.1.8 BCCH broadcasting message processing flow ............................................... 120 6.1.9 SACCH message processing flow................................................................... 121


PAGE: III/III

6.2 Handover ......................................................................................................... 121 6.2.1 Overview.......................................................................................................... 121 6.2.2 Handover types and flow of ZXG10-BSC ........................................................ 126 6.2.3 Handover flow.................................................................................................. 129 6.2.4 Handover control parameters .......................................................................... 135 6.3 ZXG10-BSC POWER CONTROL ......................................................................... 141 6.3.1 Overview.......................................................................................................... 141 6.3.2 Power control process ..................................................................................... 143 6.3.3 Rapid power control......................................................................................... 145 7. SYSTEM MECHANICAL STRUCTURE AND CONFIGURATION.................. 147 7.1 Shelf configuration........................................................................................... 148 7.2 Rack configuration........................................................................................... 151 7.2.1 Units excluding sub-multiplexing functions...................................................... 151 7.2.2 Units including submultiplexing functions ........................................................ 156 8. APPENDIX LIST OF BSC ABBREVIATIONS.............................................. 161


PAGE: 1/162

1. Overview

1.1 Brief introduction

BSC is an important component part of a GSM digital mobile communication system, and it is part of the base station system (BSS). It is oriented to the wireless network, for managing radio resources, and supporting the various services of GSM

ZXG10-BSC is based on and designed by complying with the ETSI specifications Phase 2+. It is a multi-module product, and its capacity and processing capability are up to 2048 TRXs. It is characterized by high reliability, high cost performance and perfect functions. Its network platform is completely open, and supports various GSM services. It is obviously more competitive compared with similar equipment currently running on various networks.

1.1.1 Architecture of GSM networks

B S C

B T S

M S C /V L R

S G S N

S M C

H L R

E IR

M S

O th e r P L M NG G S NG G S N

P D N T E

P S T NM S C /V L R

M A P -E

M A P -DU m

A b is

G f

G r

G n G p

G d

G s

G b

G i

A M A P -H

M A P -F

M A P -C

Fig. 1-1 Architecture of GSM mobile communication network

The composition of a GSM digital mobile communication network is as shown in Fig. 1-1.


PAGE: 2/162

The device names in the figure are listed in table 1-1:

Table 1-1 Device names of a GSM communication network

Acronyms Full names BSC Base Station Controller BTS Base Transceiver Station EIR Equipment Identification Register

GGSN Gateway GPRS Support Node GPRS General Packet Radio Service HLR Home Location Register MS Mobile Station

MSC Mobile services Switching Center PSTN Public Switching Telephone Network PDN Public Data Network

PLMN Public Land Mobile Network SGSN Serving GPRS Support Node SMC Short Message Center VLR Visitor Location Register

ZXG10-BSC provides three interfaces in the GSM900/1800 system: Abis interface for connecting BTS, A interface for connecting MSC, and Gb interface for connecting SGSN. It is mainly responsible for implementing radio resources management, base station management and monitoring, power control, cross-cell handover and base station traffic statistics in the system.

1.1.2 Composition of a BSS system

Fig. 1-2 illustrates the structure and devices of a typical ZXG10-BSS. Please pay attention to the various interface relations of BSC.

Abbreviations in the figure are interpreted in Table 1-2.

Table 1-2 Interpretations of abbreviated words

Acronyms Full names TC TransCoder SM SubMultiplexing BIE Base station Interface Equipment

Composition of BSS:

1) Base Transceiver Station (BTS)


PAGE: 3/162

The base transceiver station (BTS), constituting the wireless part in BSS, includes three parts, namely the baseband unit, the carrier frequency unit and the control unit. Furthermore, this station, controlled by the base station controller, serves as the wireless transceiver equipment in a certain cell by implementing the conversion between BSC and wireless channels. In this way, the wireless transmission between BTS and MS via the air interface is achieved and other related control functions are realized simultaneously.

MS

Ater interface

Um interface

BSC

BTS

BIE

Abis interface

TC

A interface

MSC

OMC

Q3 interface

BIE

Abis interface

SM SM

BIE

BTS

BIESGSN

Gb interface

PLMN

PDN

Acon interface

SM SMBIE

Abis interface

BTS

Fig. 1-2 Architecture of ZXG10-BSS

BTS is interconnected with BSC using the Abis interface, with BIE (BS interface equipment) configured at both sides.

2) Base Station Controller (BSC)

Serving as the controlling part in BSS, ZXG10-BSC fulfills the switching function in BSS.

One end of BSC can be connected to multiple BTSs, and another end is connected with MSC and OMC. BSC is oriented to the wireless network, implementing the management of the wireless network, management of radio resources and monitoring and management of radio base stations as well as controlling the establishment and release of wireless connections between MS and BTS. In addition, BSC controls the location, handover and paging of MS; provides speech coding, code conversion


PAGE: 4/162

and rate adaptation; and performs operation and maintenance of BSS

The number of BTSs controlled by BSC in BSS varies with the traffic volume.

3) Transcoder (TC)

The transcoder (TC) mainly performs code conversion between the various types of speech coding employed by the wireless interface in GSM systems (in the following chapters, full rate speech coding will be used as an example for description) and the 64kbit/s A law PCM encoding. Meanwhile, TC also implements the processing of data rate adaptation in circuit-type data services. In a typical application, ZXG10-TC is located between MSC and BSC.

With TC located on the side of MSC, the cost of transmission lines can be reduced by taking full advantage of the low voice encoding transmission rate used in the air interface via the transmission submultiplexer SM and BIE between MSC and BSC as well as between BSC and BTS. If SM is employed between BSC and TC, the interface between the near end and far end (between BSC and TC) is the Ater interface, and the interface between TC and MSC is called A interface.

1.2 System interface protocols

1.2.1 Protocol stack of circuit-type services

CC

MM

RR

LAPDm

MS

RR

LAPDm

Um

LAPD

BTSM

LAPD

Abis

RRBTSM SCCP

MTP3

BSSAP

BTS BSC

MTP2

SCCP

MTP3

BSSAP

MTP2

CC

MM

MSC

ATransport layer

Fig. 1-3 Protocol stack structure of BSC circuit-type services


PAGE: 5/162

In which:

Transport layer: Data transmission function, providing the function of bearing subscriber data over each section along the communication path and providing the approaches for transmitting signaling between entities.

RR: Radio resources management, establishing and releasing the stable connection between MS and MSC in the course of subscriber communication, which is mainly implemented by MS and BSC.

BTSM--BTS management part.

MM: Mobility and security management. If environment changes, MS can select different cells to establish subscriber call process effectively; yet basic infrastructures are needed to manage the location data of subscribers (location updating);

CM:Communication management, establishing, maintaining and releasing connections between subscribers as required. (It is divided into CC-call control, SSM-supplementary service management and SMS-short message service).

In reference to the signaling protocol model in Fig. 1-3, each interface is introduced as follows:

1) The interface between BSC and MSC (A interface)

The A interface complies with the technical specifications 08.xx of ETSI GSM systems.

Layer1: Physical and electrical parameter and channel architecture, defines the physical layer structure of MSC~BSC.

It is realized by employing the first level of the message transfer part (MTP) in the common-channel signaling system No.7 (CSS7). 2Mbit/s PCM digital links are adopted as the transmission link, and its performance complies with GB7611-87 Standards.


PAGE: 6/162

The signaling channel may use certain time slots in the 2Mbit/ link. The TS0 in the 2Mbit/s PCM link is generally used to transmit synchronizing signals between MSC and BSC, so maximally there are 31 time slots for transmitting service signals and signaling signals. In this interface, the service signal is transmitted at the rate of 64kbit/s in A law PCM encoding mode.

Layer2: Network operation program, defines the data link layer and the network layer, namely MTP2 (Q.702-Q.703), MTP3 (Q.704-Q.705) and SCCP (Q.711-Q.714).

Where, MTP2 is a variant of HDLC (high data link control) protocol. The frame structure consists of a flag field, control field, information field, check field and a flag sequence; while MTP3 and SCCP (signal connection control part) chiefly implement such functions as signaling route selection.

Layer3: Application layer, includes BSS application protocol (BSSAP) and BSS operation and maintenance application protocol (BSSOMAP), maintains and manages the resources and the connections in BSS as well as controls both the connection and the disconnection of services.

2) Interface between BSC and BTS (Abis interface)

BSC supports the SITE configuration for two types of base stations: 900MH and 1800MHz. The Abis interface complies with the requirements in 08.5X series of GSM standards.

Layer1: Physical layer, usually adopts the 2Mbit/s PCM link in accordance with the specifications specified in ITU-T G.703 and G.704

Layer2: data link layer employs the LAPD protocol, which is a point-to-multi-point communication protocol and a subset in the Q.921 specifications. Moreover, LAPD also utilizes the frame structure including the flag field, the control field, the information field, the check field and the flag sequence. The flag field includes two parts: service access point identification (SAPI) and terminal equipment identification (TEI), used to


PAGE: 7/162

indicate what service and what entity to access.

Layer3: The upper layer part, mainly transmits the application part of BTS, including the radio link management (RLM) function and the operation and maintenance function (OML)

Over the Abis interface, BSC provides such signaling control information for BTS configuration, BTS monitoring, BTS test and service control. Generally, one LAPD signaling link can be shared by four TRXs, and the link has the flow indication function. Its service interface has eight 16kbps (FR) circuits.

3) The Interface between BSC and TC (the Ater interface)

The Ater interface is a self-defined interface inside the ZXG10-BSS system.

What is transmitted on the Ater interface is similar to what is transmitted on the A interface with the exception of the transmission rate of the traffic channel in two interfaces. To be more exact, the speech signal in the A interface is the 64kbit/s A law PCM encoding signal, while the speech encoding signal on the Ater interface is the same as that on the A interface. CCS7 is the signaling signal transmitted on the Ater interface.

The existence of the Ater interface saves a great number of transmission trunks, hence greatly reducing the cost.

4 Acon interface

Similar to the Ater interface, the Acon interface is also a self-defined interface in ZXG10-BSS (see Fig. 1-2). A large number of transmission trunks can be saved by configuring submultiplexing units between the remote radio management module and system control module of BSC, and the interface between the remote end and near end is named as Acon interface.


PAGE: 8/162

1.2.2 GPRS protocol stack

The GPRS transmission protocol platform is as shown in Fig. 1-4. The transmission mode in each section of the GPRS network is composed respectively of the GTP, LLC and RLC protocols. Different combinations of these three protocols correspond to different QoS levels.

MSMS

UmUm GbGb

BSSBSS SGSNSGSN

IPIP

UDP/UDP/TCPTCP

IP/X.25IP/X.25

GTPGTP

GGSNGGSN

GnGn

L2L2

L1L1

IPIP

L2L2

UDP/UDP/TCPTCP

L1L1

GTPGTP

BSSGPBSSGP

LLCLLC

SNDCPSNDCP

NetworkNetworkServiceServiceL1bisL1bis

RelayRelay

BSSGPBSSGPNetworkNetworkServiceServiceL1bisL1bis

RLCRLC

MACMAC

GSM RFGSM RF

relayrelayRLCRLC

MACMAC

GSM RFGSM RF

LLCLLC

SNDCPSNDCP

IP/X.25IP/X.25

ApplicationApplication

GiGi

Figure 1-4 Architecture of protocol stacks

Each interface is introduced as follows in reference to the signaling protocol model in Fig. 1-4.

1) Interface between BSS and MS (Um interface).

RF part--employs the same transmission mode as that of the voice service.

MAC/RLC--provides the channel for packet data transmission.

MAC enables multiple MSs to share the same transmission media (several physical channels may be included), and provides arbitration, collision detection and recovery functions for simultaneous sending attempts of multiple MSs. MAC also allows a single MS to use multiple


PAGE: 9/162

physical channels in parallel with different time slots.

The RLC protocol supports the data transmission between MS and BSS in both acknowledged mode and unacknowledged mode. It has the backward error correction function, and selectively retransmits incorrect codes.

LLC - It is relatively independent of the RLC protocol, and provides a highly reliable logic link between MS and SGSN for data transmission. The LLC protocol also supports both acknowledged and unacknowledged modes, and the LLC layer supports a variety of QoS time delay levels.

SNDCP--as the transition between the network layer and the link layer, it segments and compresses IP/X.25 subscriber data and then send them to the LLC layer for transmission.

2) Interface between BSS and SGSN (Gb interface).

L1bis--physical transmission layer.

Network Service--this layer is based on frame relay, and is used to transmit upper-layer BSSGP PDU.

BSSGP--On the transmission platform, this protocol is used to provide a connectionless link between BSS and SGSN for unacknowledged data transmission.


PAGE: 10/162

1.3 System networking mode

BSCBSC

SITESITE

SITESITE

SITESITE

BSCBSC

SITESITE

SITESITE

SITESITE

Ring networkingRing networking Star networkingStar networking

BSCBSC SITESITESITESITE SITESITE

Chain networkingChain networking

BSCBSC

SITESITE

SITESITE SITESITE

Tree NetworkingTree NetworkingSITESITE

Fig. 1-5 Networking diagram of the BSC system

In ZXG10-BSC, the networking of BTS sites can be configured according to various practical requirements, supporting star, chain, ring and tree networking modes of BTS.

In the ring networking mode, the two sets of links are respectively for active and standby use, hence improving the reliability of the link. Once a Site or link fails, the lower-rank node will select the other link for data transmission.

In the star networking mode, each SITE is directly connected to BSC. This networking mode is relatively simple, with reliable circuit and convenient maintenance and engineering. It is applicable to areas with dense population.

The chain networking mode can save a great deal of transmission equipment. Since ZXG10-BTS has the bypass direct-connection function--i.e., if the link of any BTS with lower depth is disconnected, the


PAGE: 11/162

BTS with higher depth can be directly connected in cascade, and it is guaranteed that the normal operation of the equipment will not be affected--with high line reliability and applicable to areas in zonal distribution.

The tree networking mode is applicable to districts with relatively large areas and sparse population. This networking mode is relatively more complicated because signals pass too many nodes and the circuit reliability is relatively poor. And the fault from the upper-level SITE may affect the proper running of the lower-level site.So the tree networking mode is not commonly used.

In practical engineering, generally the above several networking modes are used in combination, so as to achieve the best cost performance.

2. Performance and Features

As an important component part of the GSM digital cellular mobile communication system, ZXG10-BSC implements the management of the wireless network, management of radio resources and monitoring and management of radio base stations; controls the establishment and release of wireless connections between MS and BTS. In addition, BSC controls the access, paging and handover of MS; implements speech coding, code conversion and rate adaptation; provides mutual adaptation and interconnection of GPRS services, and performs operation and maintenance of BSS

This system is designed for the GSM900/1800 system, so it should be able to implement control and monitoring to the two types of base stations (900MHz and 1800MHz) specified in the GSM900/1800 specifications. It can be used for hybrid networking, and can cooperate to fulfil the handover process between two cells with different frequencies.

2.1 Service functions

ZXG10-BSC supports the following services:


PAGE: 12/162

a) Speech service

Full-rate speech service (FS)

Enhanced full-rate speech service (EFS)

b) Short-message service (supporting Chinese short messages).

Point-to-point short message service with MS as the terminating party. MT/PP

Point-to-point short message service with MS as the originating party. MO/PP

Cell broadcast service originated from the short-message center.

c) Circuit-type data service (basic service channel)

Full-rate data service and half-rate data service.

Enhanced data service (4.8kbit/s,9.6kbit/s and 14.4kbit/s)

d) GPRS service

Point-to-point interactive telecom service:

Distribution according to the needs of subscribers, e.g., Internet. Database access

Storage and forwarding function as well as information processing function are available for communication from subscriber to subscriber

Conversational service

Bi-directional end-to-end real-time information communication between subscribers (e.g., Internet Telnet services)

Remote action service

Applicable to data processing services with small data size, credit card confirmation, lottery transaction, electronic monitoring, remote checking of meters (water, electricity and gas), and monitoring system, etc.

Point-to-multi-point telecom service:

Broadcast service

Point-to-multi-point uni-directional broadcast services, such as news, weather forecast, service report, and advertisement, etc.

Dispatching service

Point-to-multi-point bi-directional communication service, such as public dispatching service and taxi dispatching, etc.

Conference service

Real-time multi-directional information transmission service among multiple subscribers


PAGE: 13/162

Special services can be provided by combining point-to-multi-point telecom service and point-to-multi-point bearer service.

2.2 Specifications

The main specifications of ZXG10-BSC are as follows:

1. Standard BSCs employ 32K×32K switching matrixes and Pentium 166MMX processors, and provide completely open A interfaces, guaranteeing interworking with equipment from different manufacturers.

2. The system is compatible with ZXG10-BSC, and can manage the hybrid access of all ZXG10-BTS series of products, including ZXG10-BTS, ZXG10-BTS and ZXG10-MB

3. Smooth capacity expansion can be realized by adding modules. The capacity indexes are as follows:

Maximum capacity of A interface: 512 E1 trunks

Maximum capacity of Abis interface: 640 E1 trunks

Maximum capacity of Gb interface: 200Mbit/s

Maximum number of SS7 links: sixteen 64kbit/s links

Maximum number of carrier frequencies: 2048

Maximum number of base stations: 1024

BHCA >800K

Maximum traffic: 9600 Erl

4. The reliability index is the same as that of the switching system, and conforms to the specifications of the Red Book of former Ministry of Post and Telecommunications of China: MTBF≥100,000 hours.


PAGE: 14/162

5. Supports both GSM900 and GSM1800 base stations as well as hybrid base stations,and supports the access of dual-band mobile stations.

6. Supports star networking, chain networking, ring networking and tree networking with BTS;

7. The Abis interface supports variable-rate LAPD communication, and the rate is 16kbit/s~64kbit/s;

8. The A interface provides 4:1 line multiplexing;

9. Hot standby configuration, improving the reliability:

2N redundant configuration mode is employed for all control parts, switching networks, clocks and power supplies, with both units operating independently.

N+1 or N+m backup is employed for each external interface unit;

10. Clock synchronization: master-slave synchronization mode.

11. Supports RF hopping and baseband frequency hopping.

12. Overload and flow control, improving network efficiency.

13. Handover:

Supports a variety of handover modes: synchronous handover, asynchronous handover, pseudo-synchronous handover and pre-synchronous handover;

Supports handover between different frequency bands;

Supports the concentric circle handover algorithm based on the carrier-to-interference ratio, expanding the network capacity, while simultaneously ensuring the speech quality;


PAGE: 15/162

Provides specialized handover algorithm for fast-moving mobile phones in multi-layered networks so as to reduce the call drop rate;

Capable of independently implementing handover based on traffic and automatically equalizing the traffic load in the whole area;

14. Power Control

Supports static (6 steps) and dynamic (15 steps) RF power control of MS specified in the specifications.

Supports fast power control based on receiving quality.;

Supports transmitting power limitation in the course of assignment and handover;

2.3 Physical features

1. Shelf size:

790

319

279.5

Back Aluminum Beam

Front aluminum

beam

Backplane

Guide Rail

Sideboard

25

2. Rack size:


PAGE: 16/162

Height

2200

Length:810

Length:870

Width600

Front door

Sideboard

Stand bar

3. Rack weight:

200Kg(without front, back and side doors or boards);

270Kg(with front, back and side doors or boards);

4. Power Supply

Power voltage: -48VDC;

DC voltage fluctuation range: -40~-57V;

AC voltage fluctuation range: ± 10%;

5. Power consumption: 750W for a single rack in full configuration

6. Environment of equipment room:

Long-term operating condition Short-term operating condition

Ambient temperature 15℃~30℃ 0℃~45℃

Relative humidity 40%~65% 20%~90%


PAGE: 17/162

3. Hardware Structure

3.1 Overview

3.1.1 Module Structure

ZXG10-BSC employs modularized structure, fulfilling the following 7 kinds of functions:

Abis interface function.

Circuit switching function.

Packet switching function.

Land equipment operation and management as well as CCS7 transferring function.

Radio resource management function.

Transcoding and rate adapting function.

Sub-multiplexing function (for the sake of saving transmission equipment)

BSC(V2)provides different function units to perform different functions:

The module that performs the base station interface functions. This function unit is named as BIU (Abis Interface Unit). These units are set in one shelf, and one shelf can provide 256/240 carrier frequency interfaces, and separate service TSs from signaling TSs.

Circuit switching module. This function unit is named as NSU (Net Switching Unit). It provides the ability of clock requirements and 32k×32k 2-bit network switching. It also supports frame consistency.

Packet switching module. This function unit is named as PCU (Packet Switching Unit), realizing GPRS function.


PAGE: 18/162

Land equipment operation and management and the management of CCS7. This function unit is named as SCU (System Control Unit), realizing direct management of BSC land equipment and the transferring of CCS7 signaling, so as to guarantee the consistent work of BSC system.

Radio resource management equipment. This function unit is named as RMU (Radio Management Unit) or RRU (Radio Resource Unit), handling services of 240/256 carrier frequencies.

Transcoder and adapter. This fucntion unit is named as TCU (Transcoder Unit) and AIU (A Interface Unit), realizing transcoding and adapting functions.

Due to the modularized structure, it is possible to make corresponding software or hardware configurations in accordance with different user capacity or the number of sites. Figure 3-1 shows the module structure of this system:

RMM1RMM1

RMM2RMM2

RMM7RMM7

RMM8RMM8

……

……

OMMOMMSCMSCM

Figure 3-1 BSC module structure diagram

� Operation and Maintenance Module (OMM)

Mainly realizes the configuration, management and maintenance of foreground equipment, which are realized through Server.

� System Control Module (SCM)


PAGE: 19/162

It is the core of BSC, which mainly executes the management and maintenance of BSC, and the assignment of CCS7 signaling. It includes

� System Control Unit (SCU);

� Network Switching Unit (NSU);

� Transcoder Unit (TCU)

� A Interface Unit (AIU);

� Abis Interface Unit (BIU);

� Far SubMultiplexing Unit (FSMU) and Near SubMultiplexing Unit

� (SMU)

� Packet Control Unit (PCU);

� ZXG10-BSC(V1.x)Peripheral Processor (PP);

� Radio Management Module (RMM)

Realizes radio resource management, mainly consisting of RMUs (Radio Management Units). 8 RMMs are provided.

3.1.2 Block Diagram

The block diagram of ZXG10-BSC is illustrated as below:


PAGE: 20/162

BIU#11BIU#11

BIU#12BIU#12

RMURMU

NNSSUU

88Mx2Mx2

BIU#81BIU#81

BIU#82BIU#82

RMURMU

FFSSMMUU

NNSSMMUU

TCUTCU AIUAIU

TCUTCU AIUAIU

NNSSMMUU

FFSSMMUU

TCUTCU AIUAIU

TCUTCU AIUAIU

RMMRMM＃＃11

RMMRMM＃＃88

E1E1E1E1

88Mx2Mx2

88Mx2Mx2

88Mx2Mx2

22Mx16Mx16

88Mx2Mx288Mx2Mx2

88Mx2Mx2AbisAbis InterfaceInterface

A InterfaceA Interface

GbGbInterfaceInterface

SCMSCM

22Mx8Mx8

OMMOMM

PCUPCU

BIEBIETCTC

SCUSCU

Figure 3-2 BSC block diagram

TICTICTICTIC

TICTICBOSNBOSN

MPMP

BIPPBIPP #1(2#1(2x8M)x8M)

#2#2BIPPBIPP

#1#1

#2#2

#6#6

TCPPTCPP

TCPPTCPP#1#1

##nn

DRTDRT

DRTDRTDRTDRT

#1#1 #2#2

#8#8

E1x4E1x4

Abis Abis interfaceinterface

MPMPMPMP MTPMTP

GbGb InterfaceInterface

MONMON

PEPDPEPD

SYCKSYCK

TCUTCU

SCUSCU

AIPPAIPP

TICTIC

TICTIC

#1#1

#8#8

E1x4E1x4

NSUNSU

MPMPSSMMEEMM

MPPPMPPP

MPMP

MPMPMPMP LAPDLAPD

MPMPSSMMEEMM


RMU kRMU k

k=<8k=<8n=<15n=<15槨槨

RMU1RMU1

AIUAIUBIUBIU

PCUPCU

DRTDRT DTIDTI

SMBSMB

Figure 3-3 BSC hardware system block diagram

Figure 3-3 shows the block diagram of BSC hardware system (with SMU


PAGE: 21/162

omitted).

The names of boards in the above figure are listed as in table 2-1:

Table 2-1 Abbreviations and meanings of boards

Abbreviations Full names

AIPP A Interface Peripheral Processor

AIU A Interface Unit

BIPP aBis Interface Peripheral Processor

BIU aBis Interface Unit

BOSN Bit_Oriented Switching Network

DRT Dual-Rate Transcoder

FSMU Far SubMultiplexing Unit

LAPD Link Access Procedure on the D channel

Abbreviations Full names

MON MONitor board

MTP Message Transfer Protocol

MP Modular Processor

MPMP /

MPPP

NSMU Near SubMultiplexing Unit

NSU Net Switching Unit

OMM Operating Maintenance Module

PCU Packet Control Unit

PEPD Peripheral Environment & Power Detect board

RMM Radio Management Module

RMU Radio Manage Unit

SCM System Control Module

SCU System Control Unit

SMB Subrate Multiplexing to Bts

SMEM Share MEMory

SYCK SYnchronous ClocK board

TC Transcoder

TCPP TransCoder unit Peripheral Processor

TCU TransCoder Unit

TIC Trunk Interface Circuit


PAGE: 22/162

3.1.3 Rack Structure

BSC system has different kinds of backplanes designed so as to realize various types of functions. There are altogether 6 types of backplanes provided. Through combining the 6 kinds of backplanes in different ways, BSC system functions are realized. Here the six kinds of backplanes are listed:

� Backplane of Control (BCTL);

� Backplane of Net Switching and Clock (BNET);

� Backplane of A Interface and TransCoder (BATC);

� Backplane of Abis Interface Unit (BBIU);

� Backplane of Sub-Multiplexing Unit BSMU;

� Backplane of GPRS (PCU).

Take a configuration of small capacity as an example (single rack):

6 BBIU

5 BCTL-RMU

4 BCTL-SCU

3 BNET

2 BATC

1 BATC

By adding a BCTL-RMU, the capacity is expanded-one SCM module can carry 8 RMMs-at the same time, BBIU and BATC should be added correspondingly.

TC can be configured in multiple ways. It can be placed either at BSC side


PAGE: 23/162

or at MSC side, which determines where to plug BATC.

Detailed BSC hardware configurations will be further described.

Now we give descriptions to BSC working principles.

3.2 System control

3.2.1 Overview of system control module

ZXG10-BSC employs multi-module and de-concentrated structure. Each module is controlled by a set of active/standby MP. Communications between MPs of modules is realized in packet switching mode.

RMM/RMURMM/RMU

BIUBIU

TCUTCU

AIUAIUNSUNSU

PCUPCU

TC1TC1BIEBIE

SCM/SCUSCM/SCU OMMOMM

HDLC linkHDLC link

F/S SMUF/S SMU

Figure 3-4 BSC Communications Management Diagram

SCU serves as the core of BSC. Other units, such as the radio resource management module and all kinds of external function units communicates with SCU either directly or indirectly.

The control inside a module is executed in leveled centralized mode, which is realized through the main control unit of this module and the processor in peripheral processor units. The control function realizes the supervision of all function units and boards that are under this module, and sets up message links between MPs, and provides software operation platform, thus meeting the requirements of all kinds of services.


PAGE: 24/162

M P 0M P 0 M P 1M P 1S M E MS M E M

A T B u sA T B u s

M P M PM P M P P E P DP E P D M O NM O N

AASSBB

4 8 54 8 5

P W RP W R

S Y C KS Y C K

T n T n D R ID R I

M S CM S C

SSMMBB DD

RRTT DD

TTII

BBOOSSNN T C P PT C P P A IP PA IP P

F S P P /F S P P /N S P PN S P P

B IP PB IP P

P W RP W R

S Y C KS Y C K

T ICT IC

4 8 54 8 5

T ICT IC

C O M IC O M I

T ICT IC

4 8 54 8 5

D R TD R T

H D L CH D L C

P C UP C U

M P P PM P P P M T PM T P

H D L CH D L CH D L CH D L C

S C US C U

AASSBB

4 8 54 8 5

N o te 1 : A S B : A sy n c h ro n o u s se r ia l b u sN o te 2 : to b e c o m p a tib le w ith Z X G 1 0 （ V 1 .x） p ro d u c t, a d d L A P D C O M M b o a rd o n ly , w ith o u t h a v in g to c h a n g e o th e r e q u ip m e n t o r so f tw a re .

Figure 3-5 SCU Communication Management Diagram

MP0MP0 MP1MP1SMEMSMEM

ATAT BBusus

MPMPMPMP PEPDPEPD

RMURMU

OMUOMU TRUTRU

LAPDLAPDLAPDLAPD

LAPDLAPD

Figure 3-6 RMU Communication Diagram


PAGE: 25/162

RMU communication management block diagram is shown as below. The main control units in SCM and RMM are respectively SCU and RMU, which are separately set in two shelves, namely, the control shelves. They are respectively named as BCTL-SCU and BCTL-RMU.

The following figure illustrates the block diagram of SCU communication management:

3.2.2 Descriptions to Physical structure and functions of main control units

As stated above, there are two types of system control level: SCU and RMU, consisting of a set of active/standby MP and 14 accessory communication processors (COMM). Structure of a shelf is shown as below:

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

PPOOWWBB

MMPP

MMPP

SSMMEEMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

PPEEPPDD

MMOONN

PPOOWWBB

Figure 3-7 Control level shelf structure diagram

As shown in figure 3-5 and 3-6, 6 types of boards are provided: ①Power board (POWB); ②Share Memory (SMEM); ③Active/standby MPs ④Communication board (COMM) ⑤Monitor board (MON); ⑥ Peripheral Environment & Power Detect Board (PEPD).

COMM mainly realizes the functions of link level and environmental information collection, sharing the load of MP. There are three types (board slots are compatible with each other):

①COMM board: it can handle 32 64kb/s HDLC (high level data link control protocol) channels, as well as LAPD, HDLC and MTP2 channels. If no special note is given, any communication board refers to the COMM board.


PAGE: 26/162

②MON board: because HDLC link is not necessary for communications between some units of small traffic volume and MP, COMM doesn't’ serve to monitor these boards. MON is used to realize communications between these boards and MP. This includes power supply board (POWP and POWB), clock board (CKI and SYCK), and digital switching network drive board. They are connected with MON board by 485 bus. Besides, MON board also monitors the primary power supply of a rack.

③PEPD: it serves to monitor the temperature, humidity, smog and infrared conditions of an equipment room. This is optional.

External communication interface at the control level include 2MHW, RS485bus and 10Base-T interface. Structure of control level is shown as in figure 3-8.

MB MPI

MB MPI

SMEM

COMM COMM PEPD MON

AT bus

AT bus

MP0

MP1BCTL bus 1

4 HWS 8 RS485 buses4 HWS

10Base-T

10Base-T

Infrared frog sensor

Hum

idity sensor

OMC-R

BCTL bus 2

Active/standby sw

itching

Figure 3-8 BSC Control Level Structure Diagram

As shown in the above figure, MP is the core of control level. Serving as one type of accessory processor of MP, COMM handles HDLC, LAPD or MTP2 data link communications (it handles LAPD communications when serving as RMU, and handles MTP communications when serving as SCU); serving as other type of accessory processor of MP, it handles RS485 serial bus communications and provides 2 RS232 serial ports as backup. The bearer for communications with background--Ethernet


PAGE: 27/162

interface is handled directly by MP.

SMEM, COMM, MON and PEPD can realize on-line plugging.

3.2.3 MP Circuit

MP(Module Processor)is the central part of system control level. The system control level has two MPs working in active/standby mode, providing high error allowance ability. Data exchange between MPs is realized through SMEM.

MP realizes the following low-level tasks in ZXG10-BSC:

1. Realizes communications with external interface units assisted by COMM board;

2. Controls the connection of switching network assisted by COMM board;

3. Handles Ethernet interface, and realizes background-foreground communications;

4. Controls active/standby MP switching;

5. Controls the active/standby switching of function units working in active/standby mode.


PAGE: 28/162

3.2.3.1 MP structure and functions

Hard DiskHard Disk

MP Mother BoardMP Mother Board

Bus Controller Bus Controller

Ac/St ControllerAc/St Controller

MP Service FunctionMP Service Function

Ethernet InterfaceEthernet Interface

PowerPower

BCTL busBCTL bus

SRAM busSRAM bus

Ac/St switch signalAc/St switch signal

1010BaseBase--TT

--4848VV

Com

puter Main Board

Com

puter Main Board

Figure 3-9 Basis Structure of MP

MP consists of the industrial computer main board, MP mother board, harddisk and power supply. The computer main board and harddisk employ standard products in the market. CPU is Pentium processor, 166MHz. MP mother board provides backplane bus interfaces, Ethernet interfaces, active/standby status control and other services for MP. It also has control register and data register. The main board functions to set functions or switching status data. They occupy four slots in the control level. Figure 3-9 shows the basic structure:

(1) Control level bus controller(BUSI)

BUSI is the bus interface circuit of MP, which improves the ability of MP in driving the backplane bus. Its functions include:

1) Expanding the management function of memory;

2) Providing bus driving function, to prevent backplane signals from being lost.

3) Providing bus management function: implement parity check for data bus, monitor the bus or disable the bus.


PAGE: 29/162

4) Providing interrupt management function: sending the 14 lines of interrupt signals from COMM(including COMM and MON)and one line of interrupt signal from SMEM to the main board after being concentrated through interrupt manager. The interrupt request from MP board to the main board is cleared by main board, and the interrupt request from COMM and MON is also cleared by main board.

(2) MP active/standby management

The active/standby management determines the active or standby status of two MPs, and controls the active/standby switching. The controlling modes of active/standby switching:

1) Switching by command: MP active/standby switching is executed by OAM personnel at background through giving MP switching command.

2) Switching manually: MP active/standby switching is realized through performing switching actions on MP.

3) Switching during resetting: MP active/standby switching is realized when MP is reset.

4) Switching due to failure: when active MP fails, for instance, Watchdog flows out, MP active/standby management will act in response to the judgement of the failure.

(3) Ethernet interface controller

Provides two 10Base-T interfaces, one for foreground-background communications, and the other for the expansion of control level.

(4) Other services:

1) Set configurations: set node number; enable/disable functions.

2) Import BSC system clock, so as to avoid using the less precise real time clock of MP. MP clock is only used when the system clock fails. The


PAGE: 30/162

4M/8K system clock is provided by SYCK board.

3.2.3.2 SMEM

To realize fast switching of active/standby MP, ZXG10-BSC has a SMEM board designed in the main control unit, which provides active/standby MP with 8K dual port RAM that can be visited at the same time, as well as the shared 2M RAM (SMEM), which serves as message switching channel and data backup for MP. The SMEM also provides one slot of corresponding capacity for parity check, to guarantee data accuracy.

The 2M SMEM can be visited by one MP at one time. The arbitrary mechanism is realized by the hardware of SMEM: only the MP that has obtained SMEM control right is allowed to visit SMEM, and is request to submit the right immediately at the end of visit. When one MP has obtained the control right, and the other intends to visit, “busy” signal will be received, however, the one that has control right is not affected.

The 8K dual port RAM can be visited by both MPs and when two MP visit the same address unit at the same time, the SMEM will arbitrate by using the “busy” signal.

SMEM can have an active/standby MP “mailbox” set through 8K dual port RAM. The time when A sends mails to the “mailbox” of B, B will receives interrupt signals sent from B. After B takes away the mails, the interrupt signals will be reset. For SMEM structure, refer to figure 3-3.

SMEM realizes the control and arbitrary functions by using EPLD. As shown in the following figure, MP0 and MP1 arrive at the dual port RAM via the first grade buffer. The address and control buffer is direct and transparent. Data buffer is controlled by EPLD. MP0 and MP1 can visit it at the same time. The second grade buffer (containing addresses, control and data) serves as the switch for 2M shared RAM. The sequence of switching is controlled by EPLD.


PAGE: 31/162

Dual Dual PPortortRAMRAM EPLDEPLD

DataDataBufferBuffer

22MMRAMRAM

MP0 BusMP0 Bus

MP1 BusMP1 Bus

11 22




Figure 3-10 SMEM basic structure diagram

3.2.4 COMM

The COMM board serves as accessory processor for MP, realizing MP-MP communications, MP-PP communications, the data link layer functions of A interface and Abis interface , corresponding to the correspondent procedure of data link control. COMM is divided into LAPD board (LAPD protocol), MPPP board, MPMP board (HDLC protocol) and CCS7 board (CCS7 MTP protocol), which is on the basis of different software.

MPMP, MPPP and CCS7 board work in active/standby mode or load-sharing mode, thus to improve communication reliability.

If BSC control level is configured with PEPD board, there should be 12 COMMs, and each COMM can handle at most 32 64kb/s channels. The physical level uses 2M HW. Each logical link (channel) can select 1~32 TSs from the 4 HWs led from COMM, with a maximum number of 32.

3.2.4.1 Communication mode of COMM

COMM provides the following communication functions.

(1) The main control unit inside module manages function units that are under this module, realizing the maintenance and operation of each board. COMM serves to realize the functions of data link layer.


PAGE: 32/162

(2) RMM real time communicates with SCM, realizing its service functions. MPMP provides communication ability between MPs. The conditions at physical layer is similar to that described in section(1).

(3)BSC communicates with BTS, realizing the management of BSC over BTS. The communication information from BTS is detached transparently by BIE, and is connected to COMM directly. The conditions at physical layer is similar to that described in section(1).

(4)Because A interface and Abis interface has different protocols, COMM helps MP to realize the conversion between LAPD and MTP protocol. The communication information from BTS is detached transparently by the external interface of BSC, and is connected to COMM directly. The conditions at physical layer is similar to that described in section(1).

1. Communication connections between COMM and PP

PP provides a channel for local board maintenance. The active and standby PP respectively takes a 64kb/s TS as the channel with MP. If it is in SCM, this TS is connected to COMM via PP level DSNI board, and then through the half-fixed connection of switching network, and then via MP level DSIN board. If it is in RMU, the TS provided by PP is transferred to COMM through COMI board. Figure 3-11 shows the communication mode.

PPPP

PPPP

COMMCOMM

COMMCOMM

6464Kb/sKb/s

6464Kb/sKb/s

6464Kb/sKb/s

6464Kb/sKb/s

Figure 3-11 Communication With PP

Here, both PP and COMM works in hot backup mode, providing 1+1 backup, thus realizing reliable communications. Each COMM


PAGE: 33/162

communicates with PP through one 64Kb/s channel.

Since the communications between MSC, BTS and BSC is similar to those of their physical layers, we will not explain them again.

2. Communication connections between COMM and MP

MP0MP0 MP1MP1

Active COMMActive COMM Standby COMMStandby COMM

BCTL Bus 1BCTL Bus 1

BCTL Bus2BCTL Bus2

Figure 3-12 Communication With MP

Connections between COMM and the active/standby MP is realized through the wiring on backplane. The two boards are cross connected through backplane bus. Refer to figure 3-12.

Similarly, the 1+1 backup mode is also provided for the same of ensuring communication reliability.

3. Communication connections between modules

When it is inter-module communications, MPMP employs 256Kb/s channel link, and hot backup mode, shown as in figure 3-13:

MPMPMPMP

MPMPMPMP

512512Kb/sKb/sMPMPMPMP

MPMPMPMP

MPMP

MPMP

MPMP

MPMP512512Kb/sKb/s

Figure 3-13 Communications between modules


PAGE: 34/162

4. Communication connection with T net

A special feature of communications between T net and MP is that the T net connection control is connected with DSN through the two 256kb/s link that is from COMM, and TS control is realized through CPU on T net. Refer to figure 3-14.

BOSNBOSN

BOSNBOSN

256256Kb/sKb/s

256256Kb/sKb/s

256256Kb/sKb/s

256256Kb/sKb/s

COMMCOMM

COMMCOMM

MPMP

MPMP

Figure 3-14 Communications with T net

The four 8Mb/s links HW0~HW3 from BOSN active/standby switching plane are specially used for communications between all kinds of physical entities and MP. In the T net connection, links are fixed, however, they are also connected with other TSs, which is the so-called half-fixed connection.

3.2.4.2 Communication circuit

In COMM, the hardware structures are all the same no matter it is LAPD, or HDLC or MTP that is realized. The realization of specific functions is controlled by the software in single boards. For the basic structure, refer to figure 3-15.


PAGE: 35/162

Chip Selection

Chip Selection

Control

Control

EPLDEPLD

HubHub

Data LayerData LayerProtocolProtocolControlControl

Clock Adjusting & ProcessingClock Adjusting & Processing

44MHZMHZ

88KHZKHZ

DSNIDSNI(DSN)(DSN)

Dual PortDual PortRAMRAM

CPU(386)CPU(386)

Parity Parity CheckCheck

Buffer Buffer MP0MP0

Buffer Buffer MP1MP1

00

33

00

33

22MHWMHW22MHWMHW

22MHWMHW22MHWMHW

1122

1122

Differential

Differential

T/R

T/R

Drive

Drive

IsolationIsolation



Figure 3-15 COMM block diagram

COMM and the active/standby MP are connected through data bus. Because the active/standby MP employs dual bus (ISA) structure, COMM is connected with the active/standby MP via two dual port RAM and through the backplane serial port bus. The active/standby MP place the data to be delivered on the dual port RAM that are connected with their own bus, and the CPU of COMM serves to judge the status of active or standby. The messages from active MP are sent to data level protocol controller, and are sent in the required frame format. At the receiving side, the correct messages checked by data layer protocol are placed on the two dual port RAM, and MP receives the messages. If the information is wrong, MP will wait for re-sending.

Interrupt signals can be sent to each other between COMM and the active/standby MPs. Interrupt is created only if one party writes data to the other party’s mailbox, and it is cleared after the receiving party finishes reading the mail.

CPU(386EX)and data layer protocol controller use a dual port RAM to realize the exchange of control commands and status information, and the


PAGE: 36/162

sending and receiving of data. Concentrator is used to switch the 32 TS on a HW of protocol controller over to the four 2MHWs, and output them differently to meet different requirements. Each COMM can process at most 32 TSs in the four 2MHWs.

COMM uses two pieces of programmable logic devices, creating all logic signals on signal boards.

COMM employs system clock, which is 4M/8K, differently driven, coming from clock board.

3.2.5 MON

MON serves to supervise those boards that are not managed by PP, for instance, the power board, clock board, or switching network driving board, and report the results to MP. There is only one MON, located at slot 26 in control level, providing 10 asynchronous serial ports.

CPUCPU386386

PARITY PARITY CHECKCHECK

DUAL PORTDUAL PORTRAMRAM

BUFFERBUFFER

DUAL PORTDUAL PORTRAMRAM

BUFFER BUFFER

EPLDEPLD

CHIP CHIP SELECTIONSELECTIONCONTROLCONTROL

MEMORYMEMORY

MP0MP0

MP1MP1

MULTIMULTI--PORTPORTCONTROLLERCONTROLLER

485485TRXTRX(8)(8)

232232TRXTRX(2)(2)

Figure 3-16 MON Board Principle Diagram

(1) Eight RS485 interfaces, realizing long distance communications. The asynchronous link of each serial port works in semiduplex mode, and a couple of telecom nodes (boards) can be connected to it, realizing communications in active/standby mode under the control of MON board. MON board initiates to send out query signals, and then the queried board gives response and related data information. MON judges the data sent over, and report to MP if abnormality is discovered.


PAGE: 37/162

(2) Two RS232 buses and a backup bus for later expansion.

MON principle diagram is shown as in figure 3-16.

Data transfer between MON board and active/standby MP is similar to that of COMM board, and interrupt signals can be sent between each other.

Communication process between MON and other boards: CPU sends control information (toll) to each board through 8 serial port controller and 485 transceiver via RS485 bus. The information data from single boards are sent to CPU through 485 transceiver and serial port controller, after creating a pairty check slot, the data are sent to MP.

Each time the serial port controller sends or receives data, it creates an interrupt, informing CPU of the corresponding action.

3.2.6 PEPD

PEPD is an optional board on BSC control level, located at slot 25.

PEPD serves to monitor the environment of BSC equipment room, and report abnormal conditions to MP. Functions in detail:

1) Monitors environment of BSC equipment room: temperature, humidity, smog and infrared.

2) Displays the type of abnormal conditions through indicators, and report them to MP timely.

PEPD structure

Figure 3-17 shows the structure of PEPD.


PAGE: 38/162

MP0MP0

MP1MP1

DualDual--portportRAMRAMBufferBuffer

DualDual--portportRAMRAMBuffer Buffer

Isolate Isolate

TemperatureTemperature& Humidity Sensor& Humidity Sensor

InfraredInfrared& Smoke Sensor& Smoke Sensor

CPUCPU386386

Isolate& Isolate& AAmplifymplify

Figure 3-17 PEPD board block diagram

3.3 Switching network

The switching network is located in SCM module, and a switching network level is composed by switching network units BOSN and clock units SYCK. Figure 3-18 shows the structure of this shelf:

PPOOWWBB

CCKKII

BBOOSSNN

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

PPOOWWBB

SSYYCCKK

SSYYCCKK

BBOOSSNN

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

Figure 3-18 Switching network level structure diagram

In this shelf there are 6 types of boards: ①Power board (POWB); ② clock interface board (CKI) ③ Bit-oriented Switching Network board (BOSN); ④ Digital Switching Network Interface board (DSNI); ⑤

Backplane of Network (BNET); ⑥Synchronous clock (SYCK)

We will now focus on the structure and functions of network switching. The structure of POWB and SYCK, as well as clock system synchronization will be described later.

3.3.1 Structure and functions of digital switching network

A single T 2-bit time division switching network that is free-of-blocking, which is named BOSN (simplified as T net). It works in the “double in and single out”(dual plane)hot backup mode. It has a capacity of 32K×32K basic switching units (2-bit). It employs 8Mbit/s PCM bus.


PAGE: 39/162

Connections of T network is controlled by MP through COMM board (which specially set to be responsible for the communications between MP and PP).

COMM is connected with T network via 2048kb/s PCM link, and the connection messages are sent to COMM from MP. COMM forwards the messages to active/standby switching network via 256kb/s(4×64kb/s)HDLC, so as to guarantee the complete consistence of connections of the active and standby switching network. Refer to figure 3-19.

MPMP COMMCOMM

SWITCH NETWORKSWITCH SWITCH

NETWORKNETWORK

SWITCH NETWORKSWITCH SWITCH

NETWORKNETWORK

256kb/s256kb/s256kb/s256kb/sMPMP COMMCOMM

256kb/s256kb/s256kb/s256kb/s

Figure 3-19 T-net connection control structure

The approximate physical location of BOSN in ZXG10-BSC is shown as in figure 3-20:

B O S NB O S N8 K8 K ×× 8 K8 K

C O M MC O M M(H D L C )(H D L C )

C O M MC O M M(H D L C )(H D L C )

M P 0M P 0 M P 1M P 1

D S N ID S N I(M P )(M P )

4 4 ×× 88 MM 1 6 21 6 2 M M H W sH W s

C O M M (S C M )C O M M (S C M )

D S N ID S N I(P P )(P P )

5 9 5 9 ×× 88 MM5 9 5 9 ×× 88 MM

E x te rn a l In te r fa c eE x te rn a l In te r fa c eU n its o r R M MU n its o r R M M

S C MS C M

22 M H WM H W

Figure 3-20 Physical location of BOSN


PAGE: 40/162

The main functions of DOSN:

Performing the switching connection of voice channels in the BSS system to MSC side.

Semi-permanently connecting the communication time slots in each external interface unit to COMM in the main control unit, to set up communications with MP.Semi-permanently connecting the communication time slots in RMM to COMM in SCM, to set up MP-MP communications.

Since the radio source management service is realized by RMM individually, the communication information of BOSN switching mainly includes such information as MP-PP, MTP, and MP-MP.

Supporting n × 16kb/s TS switching; supporting the consistence of TS switching, and the integrity of the data of certain frame (125 ms)

3.3.2 Basic principle of digital switching

BOSN employs the method of ordered writing and controlled reading, to realize the input/output of information. Here we will brief on the process of this switching mode.

00Voice MemoryVoice Memory

1122

mm

qq

TSmTSm

00

Control MemoryControl Memory

1122

nn

qq

mm

WriteWrite ReadReadClock Clock WriteWrite ReadReadClockClock

Processor ControlProcessor Control

TSnTSn

mm

Corresponding to O

utput TS No.

Corresponding to O

utput TS No.

Figure 3-21 T-net digital switching working principle diagram


PAGE: 41/162

A T-net is generally composed of voice memory and control memory, and serial/parallel, parallel/serial circuits. The voice memory is used to store the information from input line. As for each PCM, a frame of PCM code is stored at one time, therefore, the number of units in voice memory is equal to the number of TS from the input line. The control memory is used to store the addresses of TSs, so as to control the voice memory.

The ordered writing and controlled reading indicates that each piece of digital information of input TS is written into each storage units in the voice memory, and the information is stored in the units in order.

The control memory serves to read out the digital information from voice memory. Figure 3-21 shows the working process.

Controlled by the clock, the parallel PCM code that has been multiplexed through serial/parallel conversion, writes data of one frame into the voice memory. One data TS is stored in one unit.

To switch the input TS m to the output TS n, controlled by the processor, the address of TS m is written into unit n in the memory.

Controlled by the clock, when unit n it visited in order, the content m in this unit will be read as an address in the voice memory, which is then put out.

The capacity of T network is indicated as the number of TS that this network can switch at a time. For instance, if 64HW can switched once, and each HW has 128 TSs, it can be said that the capacity of this switching network is 64×128=8K.

3.3.3 BOSN principle diagram

The hardware structure of BSC BOSN is shown as in figure 3-22.

BOSN mainly includes TS switching network, core CPU, clock processing unit, alarm circuits, active/standby controlling circuits, etc.

Among the 64 HWs from BOSN, 4 are provided for COMM, serving as the


PAGE: 42/162

communication links between peripheral units and MP.

Clock Processing CircuitClock Processing Circuit1616MHZMHZ

88KHZKHZSYCKSYCK

SwitchingSwitchingCircuitCircuit

(32K(32K×× 32K)32K)

EPLDEPLDChip Chip SelectSelect

Control Control CircuitCircuit

AlarmAlarm

CPUCPU Ac/StAc/StSwitchSwitch

HubHub

HDLCHDLCProtocol Protocol ControlControl

SMEMSMEM

FE frame alignmentFE frame alignment

6464

HW0HW0HW1HW1HW2HW2

……

……

HW62HW62HW63HW63

1616MM 88KK44MM 88KKCOMM0COMM0

COMM1COMM1Bus Interface Drive IsolationBus Interface Drive Isolation

Figure 3-22 BOSN structure diagram

3.3.4 Digital switching network interface (DSNI)

DSNI serves to drive the 64 HWs originated from BOSN.

3.3.4.1 Overview of DSNI architecture and function

C on tro l Leve lC on tro l Leve l

S w itc h in gS w itc h in gN e tw o rkN e tw o rk

S M U /T CS M U /T CB as e S ta tionB as e S ta tionIn te rface U n it In te rface U n it

D S N I(M P )D S N I(M P )

D S N I(P P )D S N I(P P )

3 23 2 x2 Mx2 M

44 x8 Mx8 M

5 95 9 x8 Mx8 M


PAGE: 43/162

Fig. 3-23 Physical position of DSNI board

DSNI board in the present system falls into two types:

The MP level interface board: Chiefly performs the conversion between the 8Mb/s flow and the 2Mb/s flow in the message passage from outside communication message to MP level, as well as delivering the clock signal of 4MHz and 8kHz respectively to the communication board.

The MP level interface board: Mainly serves to convert the driving modes of two types of 8MHW, improving anti-interference ability. Meanwhile, it provides 8MHz and 8kHz clock signals for PP and RMM.

The physical position of DSNI board in ZXG10-BSC is shown in Fig. 3-23.

There are 10 boards in DSNI. Of them, two MP-level DSNI boards perform the load share; the other eight PP level DSNI boards work in active/standby multiplexing mode. The connecting relationship between T net HW line and DSNI are illustrated in Table 3-1.

Table 3-1 Connecting relationship between T net HW line and DSNI BOSN DSNI(MP) DSNI(PP) HW1,2 The 1st DSNI HW1,2 / HW3,4 The 2nd DSNI HW3,4 /

HW5~20 / The 3rd, and 4th DSNI HW0~15 HW21~36 / The 6th DSNI HW0~15 HW37~52 / The 7th, 8th DSNI HW0~15 HW53~63 / The 9th, 10th DSNI HW0~15

3.3.4.2 DSNI principle diagram

MP level DSNI and PP level DSNI are differentiated through board jumper. We will introduce their principles diagrams separately.

The MP-level interface board:

The basic architecture of DSNI (MP level) is shown in Fig. 3-24.


PAGE: 44/162

88MHZMHZ

88KHZKHZSYCKSYCK

88MM 88KK

44MM

88KK

CPUCPU

Ac/StAc/StSwitchSwitch

Single EndSingle End

Drive Isolation CircuitDrive Isolation Circuit

COMMCOMM44M,8K(16)M,8K(16)

88M,8K(4)M,8K(4)Clock Clock

ProcessingProcessing

TranscoderTranscoder


88MM 88KK



22x8Mx8M

22x8Mx8M

Slot IdentificationSlot Identification

55

88x2Mx2M

88x2Mx2M

88×× 22MM

88×× 22MM

……

……

……

……

HW0HW0HW1HW1

HW14HW14HW15HW15

RS485RS485 MONMON

22x8Mx8M

Differential driveDifferential drive

Fig. 3-24 Basic architecture of DSNI (MP level)

The presence of MP level digital switching network interface board establishes the communication link between MP and T net. The 2Mb/s differential signal from COMM board and the 8Mb/s single end signal from T net, after the message switching at different rates, transform to the 8Mb/s signal and the 2Mb/s differential signal respectively to be output to T net and COMM board.

Through the DSNI (MP level) clock processing circuit, the system clock from SYCK generates the working frequency that DNSI needs and simultaneously supplies COMM with the 4M/8K clock signal, which is in differential output mode in order to upgrade the stability.

CPU controls the working of the DSNI interface and communicates with MP in 485 bus mode. It constantly supervises the working state of both the transcoder and the clock. If anything is found wrong, it alarms MP and executes instructions that MP sends back. The fault is indicated on the


PAGE: 45/162

panel at the same time.

The PP level interface board:

88MHZMHZ

88KHZKHZ

SYCKSYCK1616MM

88KK

CPUCPU

Ac/StAc/StSwitchSwitch

Single EndSingle End

Drive CircuitDrive Circuit

ExternalExternalInterfaceInterfaceUnitUnit

1616M, 8KM, 8KClock Clock

processingprocessing

1616x8Mx8M

Slot identificationSlot identification

55

……HW14HW14

RS485RS485 MONMON

1616x8Mx8M

HW15HW15

HW0HW0HW1HW1

Differential D

riveD

ifferential Drive

Fig. 3-25 Basic structure of DSNI (PP level)

For the list of jumpers, refer to table 3-2. The presence of MP level digital switching network interface board establishes the communication link between MP and T net. The sixteen 8Mb/s single-end signals from T net and the sixteen 8Mb/s dual-end differential signals from the external interface unit are first transformed correspondingly into 16 dual-end differential signals and 16 single end signals by the driving circuit on the board under discussion. Then they are assigned respectively to the external interface unit and T net. After re-driven and reallocated by the clock processing circuit, the system clock from SYCK is output to each external interface unit.

Table 3-2 Jumper Connecting Table Type of Jumper Board MP level PP level

X3: 1 connects to 2 2 connects to 3 X4A, X4B 1 connects to 2 2 connects to 3


PAGE: 46/162

DNSI working mode

The PP level interface board

The active/standby T nets are interconnected, the PP level DSNI interface board is in active/standby multiplexing mode, too.

To correspond with the location, the active/standby signals in T net are connected to the PP level DSNI interface board directly as is shown in Fig. 3-26.

Active Active TnTn

Standby Standby TnTn

Active DSNIActive DSNI

Standby DSNIStandby DSNI

1616

1616

1616

1616External interface unitExternal interface unit1616

Fig. 3-26 Peripheral physical connection diagram of DSNI (PP level)

In the case of active/standby changeover, the following cases may arise:

In the absence of standby DSNI interface board and in the case of the active/standby T net changeover, DSNI isn’t changed over;

With the standby DSNI interface board, DSNI is changed over correspondingly with the active/standby T nets;

By plugging/unplugging of DSNI, the active/standby DSNI boards automatically change over but T net doesn’t.

Once default is found with DSNI drive board in operation, MP will take no time in forcing the active/standby DSNI boards to changeover. As for the reliability in operation, DSNI supports such functions as manual active/standby changeover and automatic failure changeover, etc.

If the standby DSNI fails, MON can acquire this message and notify MP and lock another DSNI as active board.


PAGE: 47/162

The MP level interface board

The MP level DSNI drive board usually works in load sharing mode and doesn’t change over in normal cases. The peripheral physical connection of DSNI (MP level) is shown in Fig. 3-27.

BOSNBOSN

HW1HW1

HW2HW2

HW3HW3

HW4HW4

DSNIDSNI00

CBLHW0(TS0~TS15)CBLHW0(TS0~TS15)


……

……



cable0#cable0#

cable7#cable7#

DSNIDSNI00



……

……



cable8#cable8#

cable15#cable15#

Fig. 3-27 Peripheral physical connection diagram of DSNI (PP level)

3.4 Basic interface:

3.4.1 Structure and functions of base station interface unit

BIU employs DT interface to realize the physical layer functions of Abis interface. The structure of the shelf is shown as below:

PPOOWWBB

BBIIPPPP

BBIIPPPP

CCOOMMII

CCOOMMII

BBIIPPPP

BBIIPPPP

TTIICC

TTIICC

TTIICC

TTIICC

PPOOWWBB

TTIICC

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

Figure 3-28 BBIU structure diagram

One shelf has two BIUs, and each BIU consists of three boards: ①Abis Interface Peripheral Processor (BIPP); ②Trunk Interface Circuit (TIC) ③ COMM Interface Board (COMI). The physical position of BIU in


PAGE: 48/162

ZXG10-BSC is shown as in figure 3-29:

COMMICOMMI88MM

n<=6n<=6

22×× 88MM 22×× 88MM

22×× 88MM1616×× 22MM

RMURMU

BIUBIUTICTIC

TICTIC

11

nn

BIPP 1 BIPP 1

AbisAbis

BIPP 2 BIPP 2

DSNI DSNI

MPMPSSMMEEMM

MPMP

MPMPMPMP LAPDLAPD

Cascade BIPP Cascade BIPP

Figure 3-29 Physical position of base station interface unit

As shown in the above figure, one BIU includes two BIPP (active/standby), two COMI (active/standby), and 6 TIC. It connects with RMU via 8MHW, forming a RMM.

One BIU has a maximum of 24 E1 interfaces, providing about 128 TRX base station interfaces, among which

BIPP serves as the manager of base station interface unit, and is under the control of SCU through HDLC. It employs active/standby working mode. GPP board is employed in its hardware structure.

TIC realizes the physical layer functions of E1 interface. BIU supports the transmission link backup by configuring redundant trunk interfaces.

COMI: the COMM interface board, realizing the highway connection between BIU and RRU. Among all the serial/parallel connected BIU in


PAGE: 49/162

RMM, only one BIU has a pair a active/standby COMI, while the link of other BIU are collected to this two COMI through physical connections. The HighWay connection between BIU and RRU bears two major channels: MPMP-channel between RRU and SCU; LAPD-channel between RRU and BTS.

3.4.2 Base station interface peripheral processor BIPP

As a multi-module structure system, ZXG10-BSC adds a local centralized management to Abis interface, A interface, TC unit and Gb interface, for the purpose of improving channel utilization ratio and reducing the quantity of MPPP channels, which is the so called PP management.

Clock Processing Circuit Clock Processing Circuit

SwitchingSwitchingCircuitCircuit(4Kx4K)(4Kx4K)

DifferentialDifferentialDriveDrive

IsolationIsolation

CPUCPUAc/StAc/St

SwitchSwitch

DriveDrivecircuitcircuit

88MHZMHZ

88KHZKHZTnTn

Cascade BIPPCascade BIPP

TICTIC、、 COMICOMI

Tn Tn CascadeCascadeBIPPBIPP

COMI(2)COMI(2)TIC (6)TIC (6)Pair (1)Pair (1)

Multiplex/Multiplex/DemultiDemulti--

plexplex

44x8Mx8M

HDLCHDLCProtocol ProcessingProtocol Processing

UnipolarUnipolar

99x8Mx8M

485 485 BusBus

Figure 3-30 BIPP working principle diagram

BIPP: realizes centralized management of Abis interface unit;

AIPP: realizes centralized management of A interface unit;

TCPP: realizes centralized management of TC unit;


PAGE: 50/162

GIPP: realizes centralized management of Gb interface unit;

NSPP/FSPP: realizes centralized management of the local end of sub-multiplexing unit

Each PP board has similar functions, which are realized by one GPP board in terms of hardware. In actual applications, different functions of the 6 kinds of single boards are realized by downloading different programs.

Take BIPP as an example, we introduce the working principle of PP. Refer to figure 3-30.

BOSN mainly includes TS switching network, core CPU, clock processing unit, alarm circuits, active/standby controlling circuits, etc. According to the configuration commands send from MP (SCU), the TS switching circuit is responsible for the connection of service TSs between T network and TIC. The communication TSs are detached transparently, which are sent to CPU. At the same time, it is responsible for the signaling channel connections between COMI/TIC and T network.

CPU is in charge of active/standby switching management, active/standby communications, 485 bus management, and contact with MP. It also has self-test function.

The working principles of other PP is similar to that of BIPP. There is one point to be noted that the “multiplexing/de-multiplexing circuit” illustrated in figure 3-40 can only be realized in TCPP, since BOSN is a 2-bit switching network, and one PCM TS has 4 TCH information. To adjust to the conditions that DRT works with one TCH as a basic unit, the multiplexing/de-multiplexing circuit is set in TCPP.The application of de-multiplexing for up-link channels make it possible for each PCM to have one piece of TCH information, which is sent to DRT. It is the opposite situation for the down-link channel.


PAGE: 51/162

3.4.3 Digital trunk interface (TIC)

The signal transmission between BSC and BTS is realized through TIC, which converts the 8M PCM code flow in BSC into E1/T1 flow for long distance transmission, and interfaces with BTS. The 8M PCM code flow from BTS is converted into 8M PCM flow which is in BSC. Meanwhile, the 485 asynchronous serial port interface is provided, cooperating with GRPP, to form a monitoring loop of point-to-multi-point. TIC is a transmission interface board, whose functions are shown as below:

◆ Transcoder

Signals transmitted outside the exchange are high-density bipolar excess three codes (HDB3) or AMI codes. intra-exchange switching connection uses the non-return zero (NRZ) codes. The digital trunk interface unit converts the incoming HDB3 codes into the NRZ codes, and converts the exchange NRZ codes into the HDB3 codes and transmits them out.

◆ Clock Extraction and Re-timing

It means to extract from the input data flow the clock signals as the base clock for the input data, and use them as the external reference clock source.

◆ Frame alignment

At the receiving end, it obtains the frame alignment signals in the input signals from the input PCM code flow. Then it generates the time slot pulses of all the channels at the receiving end. They shall match with the frame time slot pulses at the sending end starting from TS0 (time slot 0), so that the signal codes sent from all channels at the sending end can be correctly received by all the channels at the receiving end. This is how frame alignment is realized.

◆ Control, detection, and alarming

Control includes commands to initialize interface circuits, to execute the


PAGE: 52/162

maintenance system commands such as resetting and loop testing. Items to be tested include bit error, count of slip code, out of frame, out-of multi-frame, loss of trunk signal and loop test command etc.

Alarm refers to the displaying the fault indication on the unit circuit, which are sent to the local OAM equipment through certain modes and channels. The related alarm information is also sent to the peer office.

For the principle diagram, refer to the following figure:

E1 InterfaceE1 InterfaceUnitUnit

To BIPPTo BIPP

from BIPPfrom BIPP

Alarm IndicationAlarm Indication

88M,8K,2MM,8K,2M

BIPPBIPP

Clock Processing UnitClock Processing Unit88K Squire WaveK Squire Wave

88M/8K ClockM/8K Clock

Isolated Isolated receive receive

CPUCPU

485485

IsolatedIsolatedDriveDrive

E1 Interface E1 Interface Circuit 0Circuit 0

E1 Interface E1 Interface Circuit 1Circuit 1

E1 InterfaceE1 InterfaceCircuit 2Circuit 2

E1 InterfaceE1 InterfaceCircuit 3Circuit 3

Figure 3-31 TIC principle diagram

3.5 Transcoder and A interface unit

The transcoder is the equipment that realizes the transcoding function that is characteristic of mobile communication network in BSC. A interface unit serves to realize the physical layer functions of A interface between BSC and MSC. Figure 3-32 shows the structure:


PAGE: 53/162

PPOOWWBB

DDRRTT

AAIIPPPP

AAIIPPPP

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

PPOOWWBB

TTCCPPPP

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

DDRRTT

DDRRTT

DDRRTT

DDRRTT

DDRRTT

TTIICC

TTIICC

TTCCPPPP

DDRRTT

DDRRTT

Figure 3-32 Structure of BATC

TCU and AIU are set between T network and A interface in serial connection mode. One TCU is in serially connected with one AIU. For its physical structure, refer to figure 3-33.

BOSNBOSNDSNIDSNI

TCPPTCPP

((E)DRTE)DRT

((E)DRTE)DRT

…… AIPPAIPP

TICTIC

TICTIC

……11

mm

m<=8m<=8

11

mm

44xE1xE122x8Mx8M

11x8Mx8M 11x8Mx8M

11x8Mx8MTCUTCU AIUAIU

A InterfaceA Interface Figure 3-33 Physical structure of AIU and TCU

3.5.1 Transcoder and adapter

TCU realizes such functions as transcoding and adapting of BSC.

Transcoding and adapting refers to the conversion of GSM radio interface voice code and the A law PCM voice code of PSTN. It also realizes the rate adapting between the two codes (including the adapting of data services)

TCPP is the manager of TC unit. TCPP itself is controlled by SCU through HDLC channel. The 8MhighWay between TCU and T network serves as the physical bearer of HDLC channel. The active/standby TCPP communicates with SCU through the two load-sharing 64Kbps HDLC. As for the software version of TCPP, download it form MP through HDLC. For its working principle, refer to “Base station interface peripheral processor BIPP”.

The transcoding and adapting function is realized by DRT or EDRT.


PAGE: 54/162

DRT: Dual Rate Transcoder. It realizes transcoder service processing. It handles a maximum of 124 lines of FR services, or 32 lines of EFR services.

EDRT: Enhanced dual rate transcoder. It is the enhanced version of DRT. It handles a maximum of 124 lines of FR services, or 120 lines of EFR services.

The detailed functions are as follows:

(a) TRAU function. Converting the 260bit vocoder block into the 160 8bit A law PCM samples, or vice versa; Framing and synchronizing the vocoder block; Testing voice activation; Modulating the phase of the code block on the down link so as to minimize the time delay; Sending alarm message to BSC through the in-band signaling over BSC; Processing data block in accordance with the protocol standard rate adapting, and re-arrange it according to A interface requirements.


PAGE: 55/162

Clock Receive Clock Receive Processing CircuitProcessing CircuitTnTn/FSMU/FSMU

88MHzMHz

88KHzKHz

HDLC HDLC Protocol Protocol ControllerController

88MM

88KK

Level Conversion CircuitLevel Conversion Circuit

88M(16kb/s)M(16kb/s) 88M(64kb/s)M(64kb/s)

Level conversion&Level conversion&Isolation CircuitIsolation Circuit


Communicate with MPCommunicate with MP

Service ChannelService Channel


EPLDEPLD

HPIHPI

TnTn/FSMU/FSMU11x8Mx8M 11x8Mx8M

AIPPAIPP

88MHzMHz

88KHzKHzTo AIPPTo AIPP

DSNI/SMT2DSNI/SMT211x8Mx8M 11x8Mx8M

AIPPAIPP

Level Level

Conversion&

Conversion&

Isolation Circuit

Isolation Circuit

Message C

hannelM

essage Channel

Digital SignalDigital SignalProcess CircuitProcess Circuit

Service Channel Service Channel Concentrating Circuit Concentrating Circuit

DifferentialDifferentialDriveDrive

DifferentialDifferentialdrivedrive

Differential Differential DriveDrive

Differential Differential DriveDrive

CPU

CPU

Switching Switching CircuitCircuit

Figure 3-34 DRT working principle diagram

(b) Providing physical layer functions for the E1 interface and collecting various alarming signals from the E1 interface too.

(c) Separating signals, CCS7 flowing by transparently, service path passing DSP.

(d) Providing HDLC that is directly connected to MP for operation and maintenance.

Working principle of DRT is shown as in figure 3-34.

DRT board is chiefly composed of circuits as follows: 1) the digital signal processing circuit; 2) the kernel CPU system; 3) the HDLC control circuit;


PAGE: 56/162

4) the clock receiving and processing circuit; 5) the electrical level transfer circuit.

The digital signal processing circuit is responsible for bulks of operation functions so as to execute the inter-conversion between 124 wireless service channels and the ground service channels. As the core of DRT board, this circuit is made up of 8 DSP chips.

In order to adapt to the future improvement of algorithm technology and the perfection of new services, by connecting HPI (Host Port Interface) with CPU, DSP completes the loading of programs, the command configuration and the message interaction, etc.

DRT (EDRT) is managed by active TCPP through point-to-point HDLC link. Each DRT (EDRT) board communicates with active TCPP through two load-sharing 64Kbps HDLC channels. During the active/standby switching of TCPP, the peers of DRT or/and EDRT perform natural switching. Software version of DRT and EDRT can be downloaded from TCPP through HDLC.

3.5.2 A interface

(Refer to figure 3-33)

AIU control is realized by active AIPP. AIPP itself is controlled by SCU through HDLC. The 8MhighWay between TCU and T network serves as the physical bearer of HDLC channel (forwarded through the 8MhighWay between TCPP and AIPP). The active/standby AIPP communicates with SCU through the two load-sharing 64Kbps HDLC. As for the software version of AIPP, download it form MP through HDLC.

Management for other boards of AIU (TIC) is realized by active AIPP through 485 bus. The 485 address of each board (8 digits) equals to its slot number in the shelf (1~27). In the process of BIPP active/standby switching, 485 bus manager also implements corresponding switching. On-line download of TIC software version is not allowed.


PAGE: 57/162

Because the physical layer functions are similar to those of BIU, we will detail them here.

3.6 SM (sub-multiplexer) unit

3.6.1 SMU function descriptions

SMU (Subchannel Multiplexing Unit) serves to realize physical layer functions of BSC internal far interfaces. It is a DT interface. It is so named due to the sub-multiplexing mode it employed in its transmission service channel.

SMU is optional in ZXG10-BSC, which is used only in the conditions that remote module is configured.

SMU is divided into two types: near and far SMU, on the basis of the distance between its location and ZXG10-BSC™ T network, which are respectively called Near SMU (NSMU) and far SMU (FSMU). Refer to figure 3-35.

11

TICTIC 11 TICTIC11

TICTIC 22 TICTIC 22

TICTIC nn TICTIC nn

44×× E1E1

……

……

NSPPNSPP

88MM

TTnn

nn×× 8M8M

88MM

n/2n/2

FSPPFSPP

22×× 88MM

SYCKSYCK

n<=8n<=8Far BIPPFar BIPP

/TCPP/TCPP

Far BIPPFar BIPP/TCPP/TCPP

Fig. 3-35 Sub-multiplexing unit architecture

For the physical position of SMU, refer to figure 3-36.


PAGE: 58/162

TnTnBIU/FarBIU/Far

BIUBIU

SMUSMU TCU/FarTCU/FarSMUSMU

TCUTCU

BIUBIU TCUTCU

Figure 3-36 SMU physical position

SMU is transmitted almost transparently between T network and the peripheral units. Trunk transmission of SMU is executed between NSMU and FSMU. Therefore, the E1 interface of the two corresponds to each other (however, as units, the FSMU and NSMU do not necessarily have to be corresponding to each other).

(1) FSPP and NSPP are respectively the controllers for FSMU and NSMU. Their hardware employs unified PP version GPP, and the functions are realized through backplane configurations and related software.

(2) The design of DT interface TIC should be consistent with both A interface and Abis interface.

(3) FSMU has SYCK configured.

Besides BITS clock, the reference of SYCK varies with the objects connecting with FSMU. If a FSMU is connected with BIU, the clock reference comes from local unit, namely, it is provided by FSPP (which is actually derived from the E1 line of the local unit). If a FSMU is connected with TCU, the reference clock comes from AIU (a maximum of two), namely it is provided by AIPP (which is actually derived from the E1 line of the local unit).


PAGE: 59/162

To reduce cost, it is recommended to make the most use of E1 line during configuration.

3.6.2 SMU structure

There are two types of SMUs: BSMU (F) and BSMU (N);

Structure of BSMU (F) is shown as below:

PPOOWWBB

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

PPOOWWBB

SSYYCCKK

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

SSYYCCKK

FFSSPPPP

FFSSPPPP

CCKKII

Figure 3-37 Structure of BSMU (F)

One FSMU occupies one shelf, and each unit has one CKI, two SYCKs (each for active or standby), two FSPPs (each for active or standby), eight TICs, and each TIC has four E1 interfaces. CKI, SYCK and TIC are managed by FSPP through 485 bus. Users are allowed to add/delete TIC according to actual conditions.

Structure of BSMU (N) is shown as below:

PPOOWWBB

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

PPOOWWBB

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

NNSSPPPP

NNSSPPPP

Figure 3-38 Structure of BSMU (N)

One NSMU occupies one shelf, and each unit has two NSPPs (each for active or standby), eight TICs, and each TIC has four E1 interfaces. TIC is managed by FSPP through 485 bus.

3.7 Power supply

As for the primary DC power, we need the following configuration


PAGE: 60/162

parameters:

(1) The nominal voltage supplied by the power equipment in the equipment room to switching equipment is -48V, with its allowable variation range: -57V~-40V

(2) The index of noise level contained in the power voltage should keep in line with the related international requirements.

(3) The power supply has the functions of over voltage/current protection and indication.

The power modules in ZXG10-BSC provide the secondary power in two types:

Power P-Power distributor;

Power B-Power in rack layers.

3.7.1 POWP

Power Power distributordistributor

ZXG10ZXG10--BSCBSC

RackRack

Fig. 3-39 Physical location of power distributor

POWP,also called power P, is located on the top of a rack. It mainly serves the function of leading the power input (output of the primary power supply) into the rack and then distributing it inside the rack. In addition, it also supplies power directly to ventilating fans. It is equipped with such functions as over-voltage and under-voltage alarming for –48V power and


PAGE: 61/162

lightning protection. Its location in the BSC rack is as shown in Fig. 3-39.

The power is led into the rack through two groups of connecting terminals on the power distributor. In each group, there are three terminals respectively for GND (grounding), GNDP (grounding for protection) and -48V. In operation, both groups of input are suggested being connected, if the condition does not allow it, then one group can do. After passing through a diode (which isolates the two groups of input and performs protection for reversed-polarity connection), the two groups of -48V input are merged into one -48V output, which is output to the left/right bus bars on the rack.

The socket set at the back of the power box leads out -48V power for check. The output/input circuit is as shown in Fig. 3-40. Furthermore, six rack fans powered by the -48V power supply of power P are installed inside the power P box.

--4848V2V2

--4848V1V1

--4848V OutputV Output

Rack Bus BarRack Bus Bar

Isolating Diode Isolating Diode

Isolating DiodeIsolating Diode

PrimaryPrimaryPower Power ModuleModule

POWER PPOWER P

Fig. 3-40 Secondary power distribution layout

3.7.2 POWB

PPOOWWBB

PPOOWWBB

11 33 55 66 88 99 1010 1111 1212 1313 1414 1515 1616 1717 1818 1919 2020 2121 2222 2323 2424 2525 2626 27277722 44

Other Circuit Other Circuit PlugPlug--in Unitsin Units


PAGE: 62/162

Fig. 3-41 Physical location of power board in each shelf

By employing the -48VDC input supplied by power P, POWB (or power B) provides the DC output of +5V(60A), +12V(2A), and -12V(2A), supplying power to the boards in each rack layer such as the BIE layer, the TC layer and the network layer. Two POWBs, closely near to the left/right bus bars of the rack, can be used in parallel in each rack layer for 1+1 backup. The physical location of the power board in each shelf is shown in Fig. 3-41.

Power B is a modular switching power supply system with its major peripheral circuits consisting of the slow start circuit, filter and monitor circuits

1. Basic principles of POWB

The basic principles of POWB are shown in Fig. 3-42.

+12+12V ModuleV Module

FilteringFiltering

+12+12V/2AV/2A

--1212V ModuleV Module

FilteringFiltering

--1212V/2AV/2A

+5+5V ModuleV Module

FilteringFiltering

+5+5V/60AV/60A

GNDGND

SlowSlowStartStart

Switch Switch LogicLogic

Comm

onCom

mon

ModeMode

RejectionRejection

Over/underOver/underVoltageVoltage

OverOver//underunderVoltageVoltage

Over/underOver/underVoltageVoltage

I/OI/OMonitorMonitor CircuitCircuit

I/OI/O Vcc Vcc I/OI/O

AlarmingAlarming

485 485 BusBus

PrimaryPrimaryPower Power --48V48V

Fig. 3-42 Block diagram of POWB

The +5V output of the power board is directly supplied to the monitor circuit so as to ensure the priority of the monitor circuit in power supply.

The over/under voltage detection circuits are also found in the power board. Depending on these circuits, principally speaking, if the tested


PAGE: 63/162

voltage exceeds the nominal value by 10%, it is regarded as over-voltage; if the tested voltage is below the nominal value by 10%, it is regarded as under-voltage. Moreover, in case of serious short circuits, the circuit is so overloaded as to exceed the rated value of the power module, and the output will be in the under-voltage state. However, the over/under voltage test circuits are not too sensitive, so as to guarantee the power stability.

The overvoltage/undervoltage detection circuit generates overvoltage/undervoltage logic by means of sampling and comparison. Then the logic is identified and processed by the monitoring circuit, and the processed result is reported to the alarm circuit. In the alarming state, the cut-off action of the power supply is implemented manually.

2. POWB performance index

The performance indexes of POWB are shown in Table 3-3.

Table 3-3 Performance indexes of power B

Name Specifications Maximum surge current of input <14A(the power board can be plugged with power on) DC output ripple <60mv HF noise <500mv System conversion efficiency ≥75% Device temperature <50°C Over-voltage protection Allowable current of fuse<5A When the output voltage range exceeds the rated value by ±10%, an alarm signal will be generated.

3.8 Synchronization system

3.8.1 Overview of synchronization system

ZXG10-BSC is synchronized via the clock interface board (CKI) and the synchronous clock board (SYCK). Generally, if there is no remote module, each BSC is configured with one CKI and two SYCKs (for active/standby multiplexing) to realize the clock extraction functions, so as to recover the external clock, which is used to calibrate the local clock frequency in BSC, with the purpose of keeping BSC clock synchronous with MSC.

This synchronous system, designed strictly in accordance with the related


PAGE: 64/162

international standards, efficiently reduces the code slip loss of data in the process of transmission and switching. Characteristics are as follows:

1. Synchronization follows the active/standby synchronization mode;

2. A variety of synchronization references are available, such as the BITS synchronization, the cesium clock frequency standard synchronization and the digital trunk timed extraction synchronization, etc. In addition, each clock reference is set with four clock input interfaces, which enhances their multi-backup ability as a result;

3. To ensure the reliability of the synchronization system, two sets of SYCK boards are employed to operate in hot standby mode for changeover whenever necessary.

4. The synchronization clock board, employing the “loose couple mode” phase-locked circuit, can work in the following four modes:

(1) Fast capture mode;

(2) Tracing mode;

(3) Holding mode;

(4) Free running mode.

5. The clock can be maintained with the frequency fine adjustment knob calibrating the frequency deviation accurately.

6. Clock references can be selected manually, and shielded by software;

The system has the functions to give alarms at the critical point for regulating the frequency of phase-locked loop. If the aging of clock crystal causes the inherent clock frequency to deviate from the control scope of the phase locked loop (namely, the control signal exceeds 3/4 of the clock regulation scope), an alarm will be given, and the alarming message is


PAGE: 65/162

sent to MP via RS485;

By controlling with high resolution 16bit D/A converters, both the accuracy and the stability of the crystal oscillator frequency are ensured;

The performance indexes in the synchronization system are as Table3-4 shows.

Table 3-4 Performance indexes of clock synchronization system Clock accuracy Clock level Minimum accuracy Maximum initial frequency deviation Level 3 ±4.6≤10-6 ≤1×10-8 Phase stability: ① At any time within 211UI, the variation of phase does not exceed 1/8UI. (1UI=488ns); ② For time periods greater than or equal to 211UI, the variation of phase in each 211UI interval does not exceed 1/8UI, and the total drift will not exceed 1µs; Operating voltage: -57V~5.25V

3.8.2 Synchronizing circuit

The clock interface board CKI mainly performs the monitoring of external clock quality and selection external clock references; and the SYCK board is responsible for communication with the control unit, implements clock synchronization and outputs clock signals. The basic principles of ZXG10-BSC clock circuit are shown in Fig. 3-43.

Its basic working process is like this: CKI board has four clock extraction circuits to respectively shape their external clocks into standard TTL output and send them to their respective frequency dividers so as to generate the 8kHz clock. Then, the CKI output control circuit, under the control of SYCK board, selects a high-quality clock reference from the sixteen 8kHz clock references and send it to the SYCK board to be used as the reference for locking phase.

SYCK selects a clock reference from the reference selection circuit and send it to the comparator. Then 8031 (CPU of SYCK) controls the output of OCXO via a 16-bit D/A converter according to the phase data generated by the phase comparator. After completing the phase lock function, SYCK processes and distributes the clock to output 30 pairs of


PAGE: 66/162

differential clock signals.

In the course of clock extraction and synchronization, CKI is not in direct communication with MP. The message is transmitted by SYCK used as the intermediary. The clock monitor circuit on the CKI board cyclically supervises each clock input reference in order to check whether the reference exists and whether its quality is degraded (the criteria for decision is ∆ f

f> × −2 1 0 8 ), and sends this information through the FIFO to

the SYCK board, which, in turn, reports this information as well as the information of its own status to the MON board over the 485 interface. As a result, after the MON board sends back the corresponding MP command, the SYCK board can control the clock reference selection or carry out other processing work such as fault alarming, and the active/standby changeover in case of alarm, etc..


PAGE: 67/162

CECE

AA

CECE

DD

CECE

CC

CECE

BB

4 4 ChannelsChannelsof 2of 2M bitM bit/s/s

4 4 ChannelsChannelsof 2M Hzof 2MHz

Code FlowCode Flow

Clock SignalsClock Signals

FDFD

FDFD

FDFD

Output

Output C

ontrolC

ontrol Circuit

Circuit

8031 8031 SystemSystem

FIFOFIFO

4 4 channelschannelsof 8Kof 8K

88M HzM HzClockClockSignalS ignal

PCMPCM

DTIDTI

Clock M onitorClock M onitorCircuitCircuit

88K Clock S ignalK Clock S ignal

44

44

44

44

Reference Reference selection circuitselection circuit

Clock Clock receive circuitreceive circuit 8031 8031 SystemSystem

PhasePhaseCom paratorCom parator D/A ConverterD/A Converter

OCXOOCXO

Clock Processing Clock Processing CircuitCircuit

Frequency Frequency Division CircuitDivision Circuit

DifferentialDifferentialline driveline drive

44DTIDTI

88KHZKHZ

1616MM

2020 1010

1616MM，， 8K8K88MM，， 8K8K

485485M onitor BoardM onitor Board

CKICKI

SYCKSYCK

BITSBITS

4 4 ChannelsChannelsof 5M Hzof 5M Hz

Cock S ignalsCock S ignals


4 4 ChannelsChannelsof 8Kof 8K


CE: Clock Extraction, FD: Frequency DivisionCE: Clock Extraction, FD: Frequency Division

Fig. 3-43 Basic principles of ZXG10-BSC clock circuit

SYCK comes with the clock receiving circuit of its own, capable of receiving four channels of 8kHz clock reference signals sent over by the digital trunk board DTI in the balanced transmission mode. In this case, the employment of the CKI clock interface board will be correspondingly unnecessary if there is no clock reference such as BITS etc.

3.8.3 Clock output

The SYCK board outputs twenty channels of 8MHzs plus its frame head clock signals and ten channels of 16MHzs plus its frame head clock signal,


PAGE: 68/162

and sends them to each subsystem in the whole system so as to be used as the synchronization clock reference and the clock source in the global system.

Prior to the clock output, the SYCK board shapes the clock signal into the time sequence shown in Fig. 3-44:

Fig. 3-44 Time sequence of SYCK board

3.8.4 Clock synchronization

In accordance with the GSM900/GSM1800 related specifications, the clock of BSC ought to be synchronized with that of MSC.The clock synchronization mode of this system is basically as shown in Fig. 3-45 and Fig. 3-46.

When the system is configured without remote module, the SYCK board of the control layer is responsible for the clock synchronization of BSC, as shown in Fig. 3-45.


PAGE: 69/162

SSYYCCKK

Central BSC RackCentral BSC Rack

BCTLBCTL（（ SCUSCU））

General BSC RackGeneral BSC RackGeneral BSC RackGeneral BSC Rack

Clock FlowClock FlowAbis Abis InterfaceInterface

Clock Signal of A InterfaceClock Signal of A Interface

Fig. 3-45 Clock synchronization without submultiplexing unit

When the system is configured with remote modules, sub-multiplexing units (SMU) are added , and the SYCK boards in the remote sub-multiplexing units provide the synchronization clock for the corresponding remote module. The SYCK board of the central rack provides clock synchronization for all local modules, as shown in Fig. 3-46.

SSYYCCKK

A Interface A Interface Clock SignalClock Signal

Central BSC RackCentral BSC Rack

BCTL(SCU)BCTL(SCU)

Remote TC RackRemote TC RackRemote RMM RackRemote RMM Rack

Clock FlowClock Flow

SSYYCCKK

SSYYCCKKAbisAbis

InterfaceInterface

Fig. 3-46 Clock synchronization with SMU


PAGE: 70/162

4. Software Functional Structure

According to the realization of BSC’s different functions, 5 kinds of subsystems are classified, i.e., PHS (PHysical Subsystem), OSS (Operating & Support Subsystem), SPS (Service Processing Subsystem), OMS (Operation & Maintenance Subsystem) and DBS (DataBase Subsystem), and the latter four subsystems realize BSC’s software functions.

The general structure is as shown in the following figure:

SPSSPS

DBSDBS OMSOMS

OSSOSS

PHSPHS

Figure 4-1 System hierarchy of BSC system

Inside BSC, the entire software is made up of the programs both on the multiple hardware boards and on the background processor, namely, it employs a hierarchy control mode. To further illustrate, the entire SPS, the entire DBS, the core of OSS and a part of OMS reside in the BSC module processor (MP), while the OSS board control software resides in the corresponding peripheral processor (PP) to serve as the front interface drive in the host processor, and the core of OMS resides in the background processor (the server and various client terminals). These


PAGE: 71/162

four subsystems will be described respectively on their functions in the following.

4.1 Operating & Support Subsystem (OSS)

In terms of hardware, the OSS software resides on the BSC module processor (MP) and each peripheral processor (PP) separately.

OSS OSS

RUNSPTRUNSPT

Process DispatchingProcess Process

DispatchingDispatching Process Communication

Process Process CommunicationCommunication

Time limitManagementTime limitTime limit

ManagementManagement

System Control

System System ControlControl

Environment Monitor

Environment Environment MonitorMonitor

Memory Management

Memory Memory ManagementManagement

File Management

File File ManagementManagement

AlarmManagement

AlarmAlarmManagementManagement

Diagnosis & Test

Diagnosis Diagnosis & Test& Test

LNKCTLLNKCTL INFDRVINFDRV

LAPDLAPDLAPD

HDLCHDLCHDLC

TCP/IPTCP/IPTCP/IP

GPPGPPGPP

BOSNBOSNBOSN

TICTICTIC

(E)DRT((E)DRTE)DRT

COMICOMICOMI

OthersOthersOthersMonitor Control

Monitor Monitor ControlControl

MTP2MTP2MTP2

X.25X.25X.25

Fig. 4-2 OSS block diagram

However, in terms of software, OSS resides between other subsystems and the hardware so as to supervise the hardware resources of the whole system jointly and effectively. In other words, OSS isolates other subsystems from the actual complicated hardware environment, as a result of which, a relatively easily manipulated virtual equipment environment is offered to support the operation of other subsystems. Therefore, the OSS working range should include not only the management of each hardware resource but also the carrier layer for each subsystem.

To be more exact, OSS mainly supports the system running environment,


PAGE: 72/162

takes charge of resource management, aids the execution of the application programs in the upper layer, isolates the application programs from the processor and provides the execution environment for the application programs irrelevant to the processor hardware. OSS actually consists of three major modules: the running support module, the data link control module and the interface equipment drive module. OSS is as Fig. 4-2 shows.

The three modules mainly perform the following functions:

1) RUNSPT-the running support module mainly supports scheduling, handover and communication of the process, as well as the basic operating system required by the system running such as memory management, timing management, system control alarm, system diagnosis & test and system file management, etc.

2) LNKCTL-the data link control module mainly supports the second-layer protocol (namely the link layer protocol, e.g., HDLC, LAPD, TCP/IP etc.) of various communication links inside the system.

3) INFDRV-the interface equipment drive module mainly supports the operation on physical entities such as various hardware units (e.g., transcoding and rate adapting unit, switching network unit and so on).

4.1.1 unning support module

The whole running support module shields the entire operating system in the bottom layer to disable the application programs to interact with the bottom operating system, but through the interface function (the system invokes) offered by the running support module. In this case, the operating system is invisible to other application programs. Neither can the application programs directly employ the system invoke of the operation system as shown in Fig. 4-3. The intention is to ensure programs’ ideal hierarchy, as well as the high maintainability and transplantability.

The handling process of the running support module involves the following


PAGE: 73/162

aspects: controlling the process generation and running; Correspondingly controlling the process scheduling, handover, application and release of the memory, the mutual communication between processes as well as the setting and resetting of timing during the process; controlling the restarting and the restructuring process of the whole system.

The running support module can be further divided into 10 functional sub-modules: process scheduling, process communication, time limit management, memory management, file management, system control, system diagnosis & test, system running supervision, system environment monitor, monitor unit control and alarming control management.

RUNSPTRUNSPT

BBOTTOM OTTOM LAYERLAYER

OSOS

AAPPLICATION PPLICATION PROCESSPROCESS

Fig. 4-3 Program hierarchy

4.1.1.1 Process scheduling

In the BSC software, with the exception of the running support module, all other application programs work in the process mode.

Each process consists of a process code (namely a function), a stack area, a data area and a message queue. Both the stack area and the data area of the process are allocated by the running support module when the system is initialized, when the process is running, the stack area is used


PAGE: 74/162

to store the temporary variables of the process while the data area is used to store the important data of the process. Conveniently, each process has the unique process identifier (PID) of its own.

RUNSPT retains a corresponding PCB (Process Control Block) for each process, such attributes as the message queue, the stack area and the data area, etc. are pointed out in the PCB, and RUNSPT mainly monitors the behavior of the process via the PCB.

ReadyReady BlockedBlocked

Scheduling/message Scheduling/message Processing FinishedProcessing Finished

Dispatch Dispatch

Message Message ReceivedReceived

Message Processing Message Processing Finished/awaiting ResponseFinished/awaiting Response

Message Message ReceivedReceived CreatingCreating

RunningRunning

Fig. 4-4 Process scheduling flow

The running of each process is triggered by a message, which can be either a message transmitted by another process, an external event or an event produced by the hardware.

Each process is only found in one of the following three queues: the ready queue, the running queue, and the blocked queue, and only one process is found in the running queue.

Once a process receives a message, RUNSPT arranges this process into the ready queue.

Once a process runs over, RUNSPT arranges it into the blocked queue (no message needs handling) or into the ready queue (messages still remain unprocessed) in light of specific conditions, then selects a process from the ready queue to run it (into the running queue) as shown in Fig. 4-4.


PAGE: 75/162

The relationships between the task and the process of the operating system are as follows:

10 tasks are defined for the OSS altogether. Task numbers range from 0 to 9, and the priorities descend in order, task 0 with the highest priority, while task 9 with the lowest one. The tasks are arranged respectively as follows:

Task 1Task 1

Task 2Task 2

Task 3Task 3

Process 1Process 1

Process 2Process 2

Process NProcess N

Process 1Process 1

Process 2Process 2

Process NProcess N

Task NTask N

Fig. 4-5 Task scheduling of the operating system

1) Task 0 is used for the system running monitor, it is dedicated to the operating system;

2) Task 1 is used for the control of version upgrading;

3) Task 2 is used for the service processing subsystem and the database subsystem;

4) Task 3 is used for the man-machine interface;

5) Task 4 is used for the man-machine interface;

6) Task 5 is used for file operation;


PAGE: 76/162

7) Tasks 6, 7 and 8 are reserved;

8) Task 9 is used for the computation of CPU seizure rate.

All the application processes in the system are connected under their corresponding tasks. Though the processes themselves have no precedence of priority, the process priority level matching its corresponding task is established when the process is connected with each task. In terms of application in the upper level, if the process is arranged into tasks of different priority levels, the execution will have the coherent different priority levels. As for each process, the task it belongs to is clearly indicated in the process control block (PCB).

As for various processes inside the same task, RUNSPT manages to perform a secondary scheduling for it. In spite of this, the handover and the scheduling of different tasks is controlled by the core of the operating system. In other words, the operating system first activates a certain task and puts it into running, then RUNSPT circulates its dispatch of each process belonging to this task in turn.

Afterwards, when the running of all the processes inside this task terminates or when the running time segment of this task expires, another task will be switched over to another one by the bottom operating system. Similarly, RUNSPT in the new task will be responsible for the circulatory scheduling of each process inside this task. Generally speaking, the message drives the scheduling inside or between the tasks in most cases. Only after receiving the message can the process enter the ready queue, after the message is handled, the process quits running and returns to the blocked queue (no message processing) or to the ready queue (messages still remain unprocessed).

When RUNSPT is running a process, it should create the running environment for this process. When one process runs over, RUNSPT takes charge of returning the dynamic resources occupied during the running and then finds out a ready process from the ready queue to run. If all the processes running inside the task terminate, RUNSPT will invoke


PAGE: 77/162

the mailbox of this task in order to fetch the message via the system. This case repeats itself in endless circles. The specific process scheduling flow is shown in Fig. 4-6.

P roc e ss E n ters R u n n in g P roc e ss E n ters R u n n in g Q u eu e to F etc h its P C BQ u eu e to F etc h its P C B

A d d A d ju s tm en t C ou n tin gA d d A d ju s tm en t C ou n tin g

C on fig u re E n try P aram eters & C on fig u re E n try P aram eters & S tac ks o f P roc es s D ata A re asS tac ks o f P roc es s D at a A re as

R u n n in g p roc e ssR u n n in g p roc e ss

R etu rn to O SR etu rn to O S

P roc e ss E n ters R e ad y Q u eu eP roc e ss E n ters R e ad y Q u eu e

NN

F etc h M es s ag esF etc h M es s ag esF rom M ailb o x o f T as ksF rom M ailb o x o f T as ks

NN

YY

YY

YY

If M e ss ag es in M ailb o xI f M e ss ag es in M ailb o x

P roc e ss E n tersP roc e ss E n tersR e ad y Q u eu eR e ad y Q u eu e

P roc e ss E n ters B loc k ed Q u eu eP roc e ss E n ters B loc k ed Q u eu e

P roc e ss M e ss ag e Q u eu e E m ptyP roc e ss M e ss ag e Q u eu e E m pty

T as k R e ad y Q u eu e E m ptyT as k R e ad y Q u eu e E m pty

Fig. 4-6 Process scheduling flow

4.1.1.2 Time limit management

Time limit management constitutes an important part of the operating system, which performs unified management of the “time” resource and handles all the functions related to time, with major functions as follows:

1) Providing a series of system invoke for application programs, in such aspects as setting/deleting timing requirement, obtaining the current time, time delay, and time format conversion, etc.;

2) Completing such corresponding system control functions as calendar management, periodical dispatch management, relative time limit management, absolute time limit management and time setting management, etc.;

3) Providing time required by man-machine commands to perform such


PAGE: 78/162

functions as follows: acquire the current time, acquire/revise the time length required in time limit timing, revise time, synchronize time of each processor and correct the clock accuracy, etc..

4.1.1.3 Memory management

Memory management is also an important part of the operating system. In OSS of BSC, this part mainly provides dynamic application/release of the system invoke of memory for the application programs.

In most processes, usually at the process creation (at the initialization of the system), sufficient memory space has, in advance, been allocated for the convenience of their free use. Consequently, the application process does not have to apply to OSS for the memory in the course of the operation. The run-out of the memory brought about by the design personnel who improperly use the application process in the dynamic application/release of the memory, which may lead to the breakdown of the whole system, is avoided.

Therefore, the system invoking provided by the memory management is mainly used in the processes at lower layers.

4.1.1.4 Process communication

In the BSC system, the activation and running of all the processes are driven by messages, while the message intercourse between various processes is executed via the inter-process communication.

Process communication falls into two types, i.e., the inter-process communication inside the local computer and the inter-process communication between the computers. The inter-process communication between computers can be further divided into MP_PP communication, MP_MP communication, MP_LMT communication, MP_OMCR communication, the Abis interface communication, MP active/standby communication, and the monitor board communication.

The inter-process message is transmitted in two modes: synchronous


PAGE: 79/162

message transmission and asynchronous message transmission.

4.1.1.5 Environment test

Environment test mainly performs the following functions:

1) Real-time collecting and corresponding processing of the data reported by the MON board, the PEPD board and the SMT board, and subsequent report of these data to the system control module of MP.

2) Receiving man-machine commands sent from the background and transmitting the commands to the corresponding monitor units via MON or SMT for the purpose of implementing the data interchanging between MP and each board.

The environment test approach is as Fig. 4-7 displays:

E nv iron me ntE nv iron me nt T e stT e st

M P P P B oar dM P P P B oar d M O NM O N B oardB oard

A SBA SB

S yste m C o ntro l o f M on it o r U n it S yste m C o ntro l o f M on it o r U n it

T ICT IC B oardB oard

P O WBP O WB B o ardB o ard

P E P DP E P D B oardB oard

P O WB B oar dP O WB B oar d

Temperature

Temperature

Hum

idityH

umidity

Smoke

Smoke

InfraredInfrared

Voltage

Voltage

S Y C KS Y C K

D S N ID S N I B oardB oard

Note: ASB (Asynchronous Serial Bus)

Fig. 4-7 Environment test

4.1.1.6 System control

1. MP system control

MP system control completes the following functions:


PAGE: 80/162

1) MP active/standby competition;

2) Active/standby state monitor;

3) Executing man-machine commands of related MP system control (such as MP active/standby changeover)

BSC actually contains two host processors of equal footing. However, it usually works in active/standby state during running. The state management of the host processor is completed via the BUSI board of the two host processors. The state of each host processor (such as active, standby, fault, request for changeover, etc.) can be set on the BUSI board and it simultaneously monitors the state of the other processor via the BUSI board. The WDOG overflow from either processor will produce an interruption for the opposite side via the BUSI board. Either processor can reset the other one via the BUSI board of the other processor.

There are various reasons for active/standby changeover, for example, background man-machine command changeover, periodic changeover (changeover at daily specific time set by man-machine commands), pressing the switchover button of the active processor, active processor power off or WDOG overflow, etc. All in all, changeover can be divided into two kinds, one is that the active processor requires changeover actively; the other is that the active processor fails. Yet, both of them share almost the same changeover mechanism.

2. PP system control

PP system control mainly monitors and maintains each single board of PP and the state of each related circuit, executes the relevant PP man-machine command by blocking/unblocking the corresponding single board or the circuit in light of PP state.

4.1.1.7 Monitor unit control

All the boards (such as SYCK, DSNI, POWB, etc.) controlled by MON board in the system are called control units. Each board is connected to


PAGE: 81/162

the 485 bus of the MON board to directly communicate with MP via the MON board.

The monitor unit control performs the following functions:

1) Processing the state data transmitted from the peripheral environment & power monitor sub-module. These state data are reported by the MON controlled boards and the PEPD board via the MON board. The control of the monitor unit can be achieved by generating or recovering the alarm in analyzing the reported state data in accordance with each controlled board type.

2) Executing man-machine commands sent by the background operation and maintenance system and transmitting relevant control messages to each control unit via the PEPD sub-module.

4.1.1.8 Alarm control management

The functions completed by alarm control management: collection, classification, transfer and elimination of various levels of alarm, synchronized foreground and background alarms, execution of man-machine commands sent by the background.

The alarm sources in the system include five types: SPS alarm, rack alarm, communication alarm, disk alarm and BTS alarm.

Once detecting a fault, the alarm source will send an alarm message to the alarm control management process. The alarm code, alarm cause, rack position and further description of this alarm are all included in this message. Once receiving an alarm message, the alarm control management stores it in the memory and at the same time sends it to the background for display.

In broad sense, the alarm consists of two types: general notification and severe warning. Since the former only indicates that unrepeatable or instantaneous fault occurs in the running of the system, the processing is easily achieved by making the corresponding display and record in the


PAGE: 82/162

background. However, the severe alarm type is different in that it usually lasts for some time until the fault disappears, besides, the processing of this type is relatively complicated. The severe warning can be further divided into four levels.

At the same time the alarm is under elimination, the alarm source also sends the elimination message to the alarm control management process. The alarm code and other alarm-code-related contents indicating the fault location are all included in the elimination message. After processing, the alarm control management process relays these messages to the background and eliminates the alarm sign at the same time.

4.1.1.9 System file management

The system file management completes management on the files of the foreground and the background, including copy, deletion, rename and query of files, creation and deletion of directories. This is also a basic composition of an operating system.

At the time the file system is started at foreground/background, four default directories are established:

\DATA: To store users’ data

\CONFIG: To save the configuration information.

\TRACE: To save the tracing information.

\VERSION: To save the version information.

Specifically speaking, the system file management performs the following functions:

1) File display: including file displays of local operating terminals, of foreground MPs (active/standby), and of servers;

2) File copy: including file copy between the operating terminal and the


PAGE: 83/162

MP (active or standby), file copy between the operating terminal and the NT server, file copy between the NT server and the MP (active or standby), file copy between the active/standby MPs, file copy inside the active or the standby MP and file copy inside the same module in the background;

3) File renaming: including file rename of local operating terminals, of foreground MPs (active/standby), and of servers;

4) File deletion: including file deletion of local operating terminals, of foreground MPs (active/standby), and of servers;

4.1.1.10 System diagnosis & test

Functions of system diagnosis & test include: providing test and fault location capability for various interface devices, communication and voice channel systems, and external line test on Abis interface, (the fault is located to the board and the interboard connection).

The diagnosis & test system is mainly provided for commissioning and daily maintenance personnel. In designing the system, the single boards will be taken as emphases for test whether they can work normally. If a single board cannot work normally, the related links will be tested step by step, until the reason why the board cannot work normally is found out. Finally, the diagnosis and test result will be presented to the operators in the clear and understanding form, which will enable the operators to easily remove the faults according to the diagnosis and test result.

Specifically speaking, system diagnosis & test has the functions as follows:

1) Test on the 32K switching network unit;

2) Test on communication links (modification) and voice channels of the switching network;

3) Test on the time slot occupied/released by the traffic channel between the unit and the switching network;


PAGE: 84/162

4) Test on TC unit;

5) Test on sub-multiplexing unit;

6) Test on Abis interface functional unit, etc.

4.1.2 Data link control module

The data link control module mainly supports the second-layer (namely the link layer) protocol of various communication links in the system, and it consists of three parts: LAPD communication protocol, MP-PP link communication protocol and TCP/IP communication protocol.

4.1.2.1 D channel link access protocol (LAPD)

The D channel link access protocol (LAPD) belongs to the data link layer of No.1 digital subscriber signaling (DSS1) with the purpose of transmitting messages between each entity in the third layer via the subscriber network interface. LAPD takes the open system interconnection (OSI) as its model for reference, and takes the layer service regulations into consideration. In OSI reference model, the layer technology is a basis for structuring. Details on LAPD, which is based on the above-mentioned design, are described in ITU-T’s Q920-Q921 recommendations.

LAPD contains the following functions:

1) Offering one or more data connections on D channel. Data link connection is identified by the data link connection identifier (DLCI) contained in each frame but performed automatically by the hardware;

2) The demarcation, location and transparency of the frame allow the identification of a string of bits transmitted on the D channel in frame mode, which is automatically performed by the hardware;

3) Sequence control: to keep in order each frame connected by data link;


PAGE: 85/162

4) Error test is performed by the hardware automatically;

5) Error recovery;

6) Notify the unrecoverable errors to the management entity;

7) Flow control.

4.1.2.2 MP-PP link protocol

To ensure the reliability and efficiency of message transmission, a set of perfect HDLC link protocols is established for intra-module communication (MP-PP). The main functions include the following four aspects:

1) Link establishment: The link establishment employs three-channel handshake mode to confirm that the link can be built up only when both directions of the line are in normal state. The “three-channel handshake” mechanism can be either that one party initiates the synchronous handshake process while the other party responds this synchronous process or that both communication parties simultaneously start the synchronous handshake.

2) Link selection: Normally, depending on a pair of mutually aided communication boards, any PP or T-net can exchange data with MP. The communication link on which COMM board to be selected is decided by MP in light of its principles in link selection. Link selection is performed in the communication control process inside the module. This process monitors the link state and selects the link for PP with newly established link timely.

3) Link maintenance: As for the link in which no message is transmitted for a long time, in order to find the fault of the link in time, the COMM board will send its message to PP periodically. Once the message fails to reach the PP end, the service identifier of the link will be removed immediately and the link will be rebuilt.

4) Data transmission: Data transmission is the fundamental


PAGE: 86/162

communication purpose inside the module. Whether the data come from MP and go to PP, are sent to MP by PP or not, reliable transmission is expected.

4.1.2.3 TCP/IP protocol

TCP/IP is mainly employed for communication between the foreground and the background, and TCP/IP-related functions are completed on MP, including IP, DRTP and ICMP protocols. Depending on the protocols realized on MP, three standard functions in the following can be performed:

1) Link establishment: A certain DRTP communication connection is established through “3-channel handshake” mechanism. The “3-channel handshake” mechanism can be either that one party DRTP initiates the synchronous handshake process while the other party DRTP responds this synchronous process or that both parties in communication simultaneously start the synchronous handshake;

2) Data transmission: Data transmission is the fundamental purpose of TCP/IP communication;

3) Cut off connection: In MP there exists no saying of normal exit, so it will not cut off the connection actively. However, if something abnormal is found in the message received on the connection, only by cutting off the connection can MP make its counterpart recover to its normality.

4.1.3 Interface equipment drive module

Interface equipment drive module mainly supports the operation on various peripheral hardware units, i.e. the front interface drive of the programs residing in each PP. It can be divided into the following types according to the hardware units they reside in:

BIE driver;

BOSN driver;


PAGE: 87/162

TC driver;

PECM driver.

The drivers mainly consist of such codes as start code, 10ms clock interrupt service program, main program, interface program, etc. They fulfil the following functions on various PPs:

Manage a number of complicated hardware, mask hardware interfaces for application programs, and simplify the design of application programs;

Process scheduling: the processes are connected via messages, which make it possible to modularize the application programs;

Data management for process;

Timer management;

Memory management;

Provide start codes.

4.2 Database subsystem (DBS)

In BSC, a series of interaction relationships between various resources (such as circuits, channels, frequencies and hardware, etc) are involved. Because each kind of resource has a large capacity, a special management means must be employed to perform easy and reasonable realization of BSC functions, and that is the necessity for the existence of DBS. Most of DBS software reside in MP, while small parts reside in PP.

The overall architecture of DBS is as Fig. 4-8 displays:


PAGE: 88/162

OSS InterfaceOSS Interface

SPS InterfaceSPS Interface

OMS InterfaceOMS Interface

DB

DB

Access Interface M

oduleA

ccess Interface Module

Core Module of Core Module of DB ManagementDB Management

Relationship Table meansRelationship Table means

LoadLoad PlugPlug--inin ModifyModify DeleteDelete

Queue

Queue

Prim

itiveP

rimitive

Relationship

Relationship

Diagram

Prim

itiveD

iagram P

rimitive

IndexIndex

Prim

itiveP

rimitive

Working

Working

Area P

rimitive

Area P

rimitive

DB maintenance moduleDB maintenance module

Receive

Receive

Background

Background

Transmitted D

ataTransm

itted Data

Active/S

tandbyA

ctive/Standby

MP

Data

MP

Data

Synchronization

Synchronization

Real

Real -- tim

etim

eD

ata Storage

Data S

torage

Auxiliary function moduleAuxiliary function module

PP

P

P

Sem

iS

emi -- perm

anentperm

anentD

ata Dow

nloadD

ata Dow

nload

Real

Real -- tim

etim

eD

ata TracingD

ata Tracing

Data

Data

Updating A

larmU

pdating Alarm

System Data Land Resources Data Wireless System Data Land Resources Data Wireless Resource DataResource Data

Fig. 4-8 Overall architecture of DBS

DBS organizes and manages various data inside BSS and offers interfaces of various data operations for outward applications. Therefore, DBS mainly consists of various data and relevant interface functions managing these data. Additionally, if activated by special data conditions, DBS has to send the notification to other subsystems such as the notification of resource availability. Generally speaking, DBS is relatively pure with relatively simple functions. So it passively aids other subsystems to complete their corresponding functions in most cases . Nevertheless, the core of database subsystem in design focuses on how to assort and manage the data reasonably since the types of data it manages are numerous, namely focuses on the design of relation table.

Generally speaking, the data that DBS manages can be further divided into the following three parts:

1) System data: consisting of some data in the system. The data contain BSC hardware device configuration, BSC signaling node configuration, MSC signaling node configuration, etc.


PAGE: 89/162

2) Land resources data: consisting of some data related to land circuit resources. These data contain BSC hardware device configuration, COMM board configuration, ground circuit device configuration of the system, the communication system configuration inside MPPP module, SS7 configuration, LAPD signaling system configuration and so on;

3) Wireless resource data: consisting of some data related to wireless resources. These data contain cell configuration, BSC system configuration, the base station system configuration, the transceiver system configuration, the frequency hopping (FH) system configuration, the wireless channel configuration and the channel status, etc.

The operating interface of the database subsystem provides function or message interfaces for the external applications, realizing the data operation that users need, including the conversion of the interface data message and the realization of various special interfaces. Generally speaking, the database subsystem manages data but it actually operates and manages the data in memory. The loading and the operation of the data in memory is performed by the database core module. Additionally, in order to provide various services for other processes, data access interface module, data maintenance module and database management module are also designed in the database subsystem.

4.3 Service processing subsystem (SPS)

In terms of hardware, all SPS software resides on the BSC module processor (MP).

The service processing subsystem (SPS) mainly realizes the functions of such protocols as BSSAP, RR, RSM, SCCP and MTP in the protocol stack. As for the LAPD protocol of the Abis interface, it is realized by the operating & support subsystem (OSS). The service processing subsystem (SPS) mainly employs the LAPD connection-oriented service. MTP and SCCP of A interface, by and large, retain the signaling boards, codes and data of ZXJ10, which will no longer be discussed here.


PAGE: 90/162

The following SPS mainly refers to the part realizing protocols BSSAP, PR and RSM. BSSAP protocol can be further divided into BSSMAP and DTAP. To be more specific, BSSMAP refers to BSS maintenance application, while DTAP refers to direct data transmission. These messages are transparent on A interface.

The service processing subsystem (SPS) consists of the following four modules:

1) Message assignment module: to handle the maintenance commands of OMS and OSS, and the global process except for circuit maintenance and flow control;

2) Traffic process handling module;

3) Flow control module;

4) Circuit maintenance module.

4.3.1 Message assignment module

The message assignment module assigns the messages and maintains the SPS.

The message assignment module in the system symbolizes the whole service subsystem, receiving all the L3 messages related to A interface, Abis interface related messages, notification sent from the database subsystem, and commands transmitted from the operation and maintenance subsystem. To assign these messages to the corresponding module is one of the main functions found in this module. However, some simple messages such as the management message in the operating system are processed in the message assignment module.

The other main function of the message assignment module is to process the signaling (mainly about some global processing procedures) involved in the following:


PAGE: 91/162

1) Decoding: The information from A interface or Abis interface demands at least one layer decoding to form an easily processed information structure, which can be processed by the message assignment module either on its own or by relaying it to the corresponding module according to specific message types;

2) Relaying the DTAP message: The MM and CM messages sent from MSC or MS are transparent in terms of BSC. BSC simply does its duty of transmitting them transparently to MS or to MSC. However, this case involves not only the DTAP part of BSSAP protocol at the side of A interface but also the data request/designating message of RSM at the side of Abis interface. To be specific, at first, from the data designating messages in the RSM protocol, the message assignment module gets these transparent messages transmitted from MS and then sends them to MSC in the format of DTAP in the BSSAP protocol; or at first it gets the MSC transmitted messages from the DTAP part of the BSSAP protocol and then requests the message center to transmit data to MS in the format of RSM protocol;

3) Relaying Page message: The message assignment module converts the paging message from MSC (in the BSSMAP format) to RSM message format and sends it to BTS. Then BTS transmits this paging message to MS in the cell;

4) Relaying the broadcasting short message: As for the cell broadcasting short message transferred from the operation and maintenance subsystem in the background, the message assignment module relays it to the cell broadcasting short message module. This module processes the cell broadcasting short message;

5) Cell congestion message processing: As for the cell congestion reported by BTS, according to the specific reasons of congestion, BSC can either employ the message assignment module to control the congestion or notify this message to MSC, which will complete the corresponding congestion control;


PAGE: 92/162

6) Corresponding processing for the resource indication: The message assignment module receives/processes the resource indication message from MSC, coordinating with the database subsystem to make the corresponding processing of the resource indication so as to enable MSC aware of the current resource using state in each cell;

7) Processing the operation and maintenance subsystem commands: In the course of the system operation, the operation & maintenance subsystem has to send some commands to the service processing subsystem. These commands include resetting BSC, sending cell system message, etc. These commands are directly processed by the message assignment module;

8) Processing the operating & support subsystem message: After receiving the operating & support subsystem messages such as power-on, communication state modification, active/standby changeover and the timeout message of various timers, etc., the message assignment module can either transfer these messages to its corresponding module to be processed or processes them on its own in accordance with specific situations;

9) Load indication process: in order to have the adjacent BSC aware of the load state on the edge of the cell controlled by this BSC, the message assignment module coordinates with the database subsystem, on the one hand, to transmit the cell load indication message (relayed by MSC) to the adjacent BSC and, to receive the load indication message transmitted from the adjacent BSC (relayed by MSC) on the other hand;

10) The changeover candidate inquiry process: The message assignment module is in charge of the MSC changeover candidate inquiry process. That is, if MSC decides to assign some of the traffic in a busy cell to its adjacent cell, the message assignment module will force part of MS to be changed over to its adjacent cell;

11) Global reset: when receiving the reset command or message from either the operating system, or the operation & maintenance subsystem or


PAGE: 93/162

MSC, the message assignment module will be in charge of all service reset processes, and simultaneously notify /respond to MSC;

12) In receiving the link establishment request of MSC, this module establishes not only the SCCP connection but also responds to the request.

4.3.2 Traffic process handling module

The traffic process handling module performs all processes (including establishment, conversion and release of connection) of all MS connections (including wireless connection, SCCP connection and the ground circuit of A interface)

Exactly speaking, the traffic process handling module mainly realizes and implements the following functions:

1) Initial access process: MS obtains an SDCCH channel or an FACCH channel by establishing connection with the network via the RACH channel and the connection of BSC with SCCP of MSC, as a result, MS, BSC and MSC can transmit signaling;

2) Encryption/decryption process: in order to enhance the privacy of wireless transmission, the traffic process handling module, under the control of MSC, completes the encryption/decryption process of wireless connection. After encryption, what is transmitted over the wireless between MS and BTS is encrypted information;

3) Assignment process: the traffic process handling module, under the control of MSC, orders MS to change a wireless physical channel in the cell such as changing from an SDCCH channel to a TCH channel. After obtaining a TCH channel, MS can perform transmission of the user voice and data. The assignment of the ground circuit may be necessary during the transmission;

4) Model modification process: under the control of MSC, the traffic process handling module orders the wireless channel used by MS to be


PAGE: 94/162

changed for another purpose, for example, the FACCH channel for the signaling can be changed into the TCH channel for the voice and data of subscribers. In this case may involve in the ground circuit change;

5) Switchover process: because of the MS mobility and complexity of wireless transmission, the traffic process handling module can check and detect the deterioration of such conditions as signal quality or intensity (call drop probably will occur soon) to determine if the handover process is performed, so as to ensure the normal interaction between MS and the network. In other words, the traffic process handling module at this time has to perform the switchover, namely to employ a new channel to replace the one that MS is using. This new channel can be either the one in another cell or the one in the local cell. This course may involve the modification of the ground circuit and SCCP connection;

6) Power control process: To ensure the premise of normal communication between MS and the network, to reduce both the battery consumption and the interference as greatly as possible, the traffic process handling module has to control the power, by ordering MS (upward) or TRX (downward) to reduce/enhance the transmission power, according to such conditions as signal quality or intensity;

7) Release process: In a variety of cases such as normal conclusion of a call, handover, assignment, and call drop etc, if MS has left the channel or has the necessity of leaving the channel, the traffic process handling module has to perform the release process of the channel so as to change the channel resources into idle state to be used by other MSs. The whole process possibly involves the release of both the SCCP connection and the ground circuit;

8) MS class mark processing: different MSs are distinguished by their class marks, for example, whether support dual-frequency, the maximum transmitting power and the encryption algorithms supported, etc. The traffic process handling module is responsible for transmitting the messages containing the above-mentioned information to MSC, and transmitting the messages requesting MS class marks sent from MSC to


PAGE: 95/162

MS. During the course, the traffic process handling module will also retain the class mark information, for that will also influence service processing;

9) The link establishment of point to point short message: to transmit the point to point short message between MS and the network, the traffic process handling module will probably establish a dedicated link on either the SACCH channel or on the SDCCH channel.

4.3.3 Flow control module

The flow control module primarily implements temporary control over the flow so as to put the whole system into normal operation. However, this is at the cost of some MS subscribers‘ temporary incapability of access to the system

On the one hand, if MSC overloads, MSC will periodically sends this overload message to BSC. The flow control module, therefore, controls the entire BSC flow process, i.e., to restrict the access of partial subscribers (by the MS access type) in some cells or all the cells.

On the other hand, if BSC overloads, e.g. CPU overloads, CCCH channel overloads, etc., BSC sends the overload message to MSC. Meanwhile, the flow control module performs the corresponding flow control according to the specific cases leading to the overload.

4.3.4 Ground circuit maintenance module

The major functions of the ground circuit maintenance module is as follows:

One is to establish an agreement that some A interface ground circuits between BSC and MSC through the UNBLOCK process and the BLOCK process can be usable or unusable. The other is to establish the agreement of “usable and idle” state to which some A interface circuits can return from any state via the RESET process and between MSC-BSC.

The A interface ground circuit is shared by both BSC and MSC. If one MS


PAGE: 96/162

connection really intends to transmit the subscriber voice or data, it demands a ground circuit, however, it does not need the ground circuit if signaling goes through alone. In light of the features of TC it is connected with, the ground circuit can be further divided into many circuit groups. To list a few here, the circuit linked by the TC only supporting the full rate constitutes the full rate circuit group; the circuit linked by the TC only supporting the half rate constitutes the half rate circuit group; the circuit linked by TC only supporting the enhanced full rate constitutes the enhanced full rate circuit group, etc.

Each ground circuit is in three modes: idle, busy and blocked, the former two states are easy to understand, while the third blocked state mainly means that the ground circuit fails, and has been marked as unusable. MSC performs the assignment of the ground circuit by selecting a suitable circuit in accordance with the MS capability and the service demands. It can be concluded that BSC and MSC must reach the agreement since they share the same ground circuit so as to avoid the case where MSC is marked as idle but BSC is marked as blocked over the same ground circuit.

The message of blocking or unblocking of the ground circuit is notified to MSC by BSC, which is possibly attributed to the interference of the operation and maintenance subsystem or the breakdown of some related devices. In this case, this information should be notified to MSC in no time so as to prevent MSC from allocating invalid ground circuits.

4.4 Operation & Maintenance Sub-system (OMS)

In terms of hardware, the OMS software is dispersed on MP of a BSC module processor and the background Operation and Maintenance Center (OMC) system.

OMS plays the part of the operation and maintenance center of BSS with the base station controller (BSC) and the base station transceiver (BTS) as its maintenance objects. This system fully satisfies the networking demands of the standard network function, additionally, completing the


PAGE: 97/162

standard management function modules the telecommunication network management needs.

These involves the network security management, the processing and analyzing of the network performance, the global net centralized alarm management and the network configuration management, etc. Moreover, this system also supplies the standard interfaces leading to the upper network management center. The operation and maintenance functions of each BSS network element are centralized on the fully graphical operation and maintenance center (OMC).

To provide various management functions that the telecommunication management network (TMN) needs in the running and maintenance, OMS is developed and designed on the standard management object (MO) defined in the ETSIGSM12.20 specifications. In addition to providing the local maintenance, OMS also supplies the remote maintenance as well as the standard Q3 interfaces to the upper level network management center with the major maintenance functions as follows: security management, configuration management, fault management and performance management.

OMS provides the standard Q3 interface access to the upper level network management center (NMC), and manages the multi–sets of base station systems via the Qx interface inside. This plan reduces the effects and the investment on the current system. Still further, OMS can offer both the internal Q3 interface and the external Q3 interface. Via a Q3 interface,the local Manager (OSF) can manage each BSS; Via a Q3 interface,each BSS access to TMN can be realized.

OMS provides several Q3 interfaces to network management based on TMNQ3 protocol, which provides much flexibility for operators to realize TMN:

► The X. 25 private line mode: Transmission rate is 64kbit/s


PAGE: 98/162

► The A interface mode: Transmission rate is N¡Á64kbit/s.

► The DDN private line mode: Transmission rate is 64kbit/s.

In addition to the above-mentioned functions, OMS and the cell broadcasting center can be either integrated into one or set up separately. On the premise of accomplishing the basic cell broadcasting short message service regulated in GSM03.41, ZXG10-BSC can easily add the value-added services conveniently according to the actual requirements of operators and users. ZXG10-BSC has following characteristics and functions:

► Queuing, reinserting, dispatching of short message broadcasting;

► Saving and query of short message broadcasting;

► Management of broadcasting log;

► Supporting English/Chinese short message broadcasting;

► Supporting DRX/none-DRX mode;

► Supplying interfaces to various cell broadcasting entities (CBE);

► Sharing information by accessing to Internet via an Internet gateway.

4.4.1 Fault management

► Timely and detailedly collecting and receiving all alarms, notifications

and status reports generated in the running of network element in base station system;


PAGE: 99/162

► Displaying, supervising and accurately locating the centralized

alarms in the overall network;

► Confirming, investigating, timely diagnosing and correcting faults;

► Routinely maintaining the switching and wireless devices;

► Routinely testing the mobile network and the interconnecting

functions;

► All the alarming information is saved into the database in class,

providing powerful alarming statistics, analysis and query functions.

OMC timely and detailedly collects and receives all alarms, notifications and status reports generated in the running of network element of base station system, and real-timely receives the environment parameters output by the base station equipment. The alarm message contains the equipment room environment alarm (such as temperature, humidity etc), the common signaling channel (CCS7) alarm, the power alarm, the antenna alarm, the alarm of major hardware units (such as switching network board, SMB, BIE, OMU, etc.) of BSC and BTS, and the software restarting alarm.

Afterwards, the OMS server gathers the various alarm messages received from the BSS network elements and keep them in the alarm database of the server according to their dates, types and sources so that each alarm terminal of OMS can query and analyze them. Simultaneously, the local alarm can be reported to the upper network management center through the standard Q3 interface to realize the global network monitor and analysis.

The centralized alarm monitor of the local network is one of the major functions in the fault management system. With a directly perceived graphic display mode (electronic map), this system not only monitors the


PAGE: 100/162

current alarm status in each network element, but also makes statistics of the currently arising important alarms in such aspects of as the longest alarms and the most frequent alarms.

To give an example, if an alarm is arising in a certain network element, the alarm light of this network element in the network graph will change its color correspondingly and produce sound prompting. If the locating of the alarm is necessary, either use the mouse button to click the icon of this network element in the map directly or click the network alarm monitor item on the menu so as to monitor the alarm of this network element.

The NE alarm monitor can perform the current alarm monitoring of the NE that alarm occurs and query location. The location query graph is displayed in a layered mode. Layer 1 is the rack arrangement graph of the whole equipment room in a certain mobile office. Layer 2 is the rack graph of a certain rack to locate the fault to a specific circuit board (If possible, the detailed location can be found in a certain DSP).

However, in query about fault location, first display the rack arrangement graph in Layer1. If the block diagram representing a rack changes its color, it shows that this rack is alarming. Then you click this shelf with the mouse button to enter Layer 2, which displays the shelf arrangement of this rack and also its specific circuit in light of its actual size proportion. In this way, on the one hand, the alarm location can be specialized on a specific circuit board, and on the other hand, the statistical data of current alarms of each level as well as the detailed information about the specific alarms can be displayed.

In addition to real-timely driving the display as well as the sound which produces devices according to the requests set by users, all alarm messages have to be classified and stored in database for statistics, analysis and query. The fields included in the table of the database consist of the alarm office name, the alarm time (year, month, date, hour, minute, second), the alarm restoring time, the alarm flow number, the alarm status, the alarm type, the alarm level, the alarm location and the alarm contents.


PAGE: 101/162

The alarm history data can be inquired about according to designated conditions or combinations of conditions as follows:

► Network unit number(e.g, how many alarms arise in a certain

element unit)

► Alarm type(all alarms of a certain type)

► Alarm time(All alarms arising within a time section)

► Alarm level(All alarms in a certain level)

► Alarm number(All alarms of the alarm flow number within a certain

range)

► Alarm frequency(All network elements or a certain type of alarms

whose alarm times in a certain time unit are larger than a certain value)

Combined conditions (the combination of the above-mentioned conditions).

The query results can be compiled and printed out in report forms according to regulated formats.

4.4.2 Security management

► Security management of the user access and the service usage;

► Security management of the man-machine command and the remote

access;

► Security management of the network management data and the


PAGE: 102/162

PLMN data;

► Detailed definition of various maintenance function levels and the

operation personnel authority in the access system;

► Detailed operation log of users for the convenience of classification

and query.

The security management module mainly provides management functions for both user accounts and system resources, realizing access and authorizing management and protecting the security of the overall network. In addition, this function real-timely monitors the dangerous cases of the network by isolation the dangers and controlling them to the minimal extent.

The security management involves the management of the operation personnel authority, the threshold, the operation log and so on. To be specific, the security management embodies in the security of man-machine command in the network element, the system access, the remote access and the data.

However, by establishing some threshold values for the resource occupation, the threshold manager monitors the use of some system resources or some service resources. Once the occupation rate exceeds the set threshold, on the one hand, the system takes the self protection measures by restricting the use of this resource or restricting the use of other resources so as to ensure the use of this resource, which are automatically realized by the programs. The maintenance personnel manually takes some measures to process the faults.

The thresholds are generally set for the occupation of some important resources such as the processing device of the module processor, the memory resources, the service channel resources and the control channel resources. Some of the important resources are even set with three levels of threshold so as to provide different levels of processing modes and


PAGE: 103/162

different levels of alarming for different levels of resources.

The operation log can not only detailedly record the maintenance behavior of the operation personnel but it can also conveniently locate the faults resulting from the operation error of the operation and maintenance personnel. Consequently, the maintenance responsibility is demarcated, which provides necessary bases to facilitate the check of the maintenance personnel.

4.4.3 Performance management

► In the generation, collection and classification of the performance

data, more than 200 original counters are collected;

► The statistic and management of traffic and traffic event;

► The performance statistics form, both convenient and flexible, can be

defined by subscribers.

► Analysis of various traffic performance indexes and the detailed

analysis of call drop;

► The observation of traffic grade, traffic quality and traffic event;

► The trace record of operator actions and related call route

information;

The performance management includes the monitoring of traffic load and network running, and recording the measurement to long-term and short-term services, operation and traffic quality. The operator can set a series of performance measurement tasks, which, once assigned to their corresponding network elements, will produce corresponding results in the network elements. The measurement results will be saved in the OMS


PAGE: 104/162

server at a certain time interval so that they can be processed, analyzed, displayed and printed out.In terms of network elements, the operator can create/modify/delete/pause/recover the following measurement tasks:

► Traffic measurement;

► Measurement of available radio resources;

► Resource access measurement;

► Handover measurement;

► Power measurement

► Load measurement;

► Availability measurement;

► The A interface signaling measurement;

► The Abis interface signaling measurement;

► Wireless equipment measurement.

About two hundred original counters collected are stored in the OMS server, which record the real running situation and the running parameters of the network in detail. At the same time when the original counters are observed, the original data is also being analyzed, conversed, given pre-statistics and statistically collected in order to be compared according to the different network element objects measured.

Then the compared results are output in directly perceived table or graph


PAGE: 105/162

form, offering flexible performance statistical report. The users can set their statistical reports for their convenience according to the requirements of their own and the higher authorities. Besides, the analysis of as many as 14 call drop causes can particularly be found in these results too, from which the constructive suggestion on the network optimization and the cell planning can be obtained.

In addition, the observation and monitoring of such important traffic events as handover, the occupation/ releasing of channels is an important part of performance management. The observation of these events can help, on the one hand, display the detailed traffic flow clearly, and reveal the problems arising during the service process on the other hand, which facilitates the solution to the problems.

Both the mobile users and the mobile devices are traced and reported. The tracing records, including the trace type and the trace contents (Detailed contents are referred to GSM12.08) are activated by TRACE_INVOKE of MSC or BSS, and should be sent to OMS for analysis if necessary. The records can involve the trace of IMSI and IME by recording the device behavior and the occupied resources. In terms of BSC, the record refers to tracing a service process. The trace records generally focus on the process, with the data as an auxiliary analysis in the network management.

4.4.4 Configuration management

► The management of configuration instruction;

► The management of operation and recording in configuration;

► The radio resource configuration: the parameter setting of the cell, of

the handover, the power control and the frequency point;

► Physical equipment configuration: the management on equipment


PAGE: 106/162

objects, such as the addition and deletion of hardware facilities;

► Signaling link configuration: the configuration and modification of the

No.7 link data;

► Load management: the modification and the management of the

software version;

► Communication configuration: the configuration and management of

the message transmission protocol between the network element equipment and OMS.

The configuration management (namely the upgrading management )wholly dynamically manage the data configuration of the network element equipment in the whole network, the version upgrading of the software module, the state checking an installation, collecting and controlling data from each network element, mainly focusing on the correctness and reasonability checking of soft/hardware data configuration in the whole system, realizing the office data management, the router management, the equipment management, and the management of the cell and frequency, etc..

With the electric map as its background, the configuration manager displays centrally the layout of the switches, the base station controller (BSC), the base station and the cells in the whole network. In addition, it not only directly and graphically displays a variety of configuration information about the network elements by processing them dynamically, but it also has the functions in such aspects as of classified query, statistics, modification and printing of various configuration data, ensuring the correctness and rationality of the configuration data of the whole network.

The major functions of the configuration manager run through the overall process, namely from the initial installation to the serving state. Furthermore, the setting of the state and parameters for each device and


PAGE: 107/162

each unit object makes up another important function in the configuration manager.

4.4.5 System management functions

► The timely and accurate signaling tracing can facilitate the trace of

the A interface and the Abis interface signaling;

► A tool of fast and convenient file management as well as the clock

management;

► Various other convenient debugging tools as accessories.

In addition to providing the standard network maintenance management functions, OMS supplies dozens of auxiliary operation and debugging tools as accessories. Quite many a practical debugging instruments can achieve outstanding results, if they are under the use of the experienced maintenance personnel. In this way, the maintenance work can be reduced considerably.

5. OMC-R Networking Solutions

OMC(Operation and Maintenance Center)is a local network management center to control and manage each equipment entity in a GSM communications system. A GSM system also involves both the radio network and the switching network. Therefore, in the GSM specifications, OMC falls into two parts, namely OMC-S and OMC-R, of which OMC-R refers to the Operation and Maintenance Center in the base station subsystem (BSS), while OMC-S refers to the Operation and Maintenance Center in the switching subsystem (NSS). Usually, the base station subsystem and the switching subsystem are independently controlled and maintained.


PAGE: 108/162

5.1 Design of ZXG10-OMC system

OMCOMC

Upper NM CenterUpper NM Center

BSCBSC

PSPDN/DDN/PSTNPSPDN/DDN/PSTN

PSPDN/DDN/PSTNPSPDN/DDN/PSTN

MTMT

MSC/VLRMSC/VLRHLR/AUCHLR/AUC BSCBSC......

BTSBTS BTSBTS......

SC/VMSC/VM LTLT

LTLT

Q3Q3

LTLT LTLT LTLT

Figure 5-1 Location and function diagram of OMC in PLMN system

The object that OMC-S controls is the network switching subsystem (NSS), including MSC, VLR, HLR, AUC, SC, VM, etc.. The main functions of OMC- are as follows: perform the effective data configuration and equipment management of NSS equipment, alarm on various troubles NSS encounters in its running, regulate the system performance etc.. and provide a visit interface for the upper network management center.

The object that OMC-R controls is a base station subsystem (BSS), which includes a base station controller (BSC), several base station transceivers (BTSs) and TC units. The main functions of OMC-R are as follows: perform the effective data configuration and equipment management for BSS, alarm on various troubles that BSS encounters in its running, monitor both the performance and running state of BSS, regulate the system performance and provide a visit interface for the upper network management center. The location of OMC in the whole system is as Figure 5-1 shows:

The design of OMC diagram considers not only the complying with the 12 series specifications in the GSM recommendation stipulated by ETSI, but


PAGE: 109/162

also the concepts and demands of the telecommunications management network. Its connection with the NM center can be performed via the current X.25 or DDN. The connection of OMC with the upper NM center is uniformly completed via a Q3 interface, so as to facilitate its access to the upper NM center. However, OMC-S and OMC-R can be either merged into one or independently stand alone according to actual situations.

5.2 Structure features and configuration of OMC-R

5.2.1 Architecture features of OMC system

OSFOSF

BSSBSSNEFNEF

BSC NEFBSC NEFBSCBSCMFMF

GSM 12.20GSM 12.20

Q3 GSM12.20Q3 GSM12.20Q3 GSM12.20Q3 GSM12.20

BTSBTSNEFNEF

QxGSM12.21/QxGSM12.21/AbisAbis InterfaceInterface

Figure 5-2 The Q3 interface between BSC and OMC-R

In GSM specifications, different functional modules to realize TMN are defined only in principle, additionally, it is also regulated that the Q3 interface be provided in the network element level so that OMC can manage each network element through the Q3 interface.

As far as a base station system is concerned, as individual manufactures are different from each other in realizing BTS, a Qx interface is used between BSC and BTS. But there are no standardized demands for this part in GSM specifications, except that the NM processes and messages are defined in GSM12.21 as Figure 5-2 shows:

Abbreviated words:


PAGE: 110/162

OSF Operation System Function NEF Network Element Function MF Mediation Function

To realize the basic demands in specifications, ZTE adds a MD-Mediation Device (which is actually a software module to realize MD-Mediation functions) between BSS and OMC under the current conditions according to TMN principles so that OMC can manage NSS/BSS via a Q3 interface. The general principles in designing an OMC system agree with both the TMN specifications and the user demands so as to provide the standard Q3 interface access for the upper NMC.

The final purpose in using an OMC system is to serve the local centralized O&M and also enables the NSS/BSS under its management to access to upper mobile NMC via a Q3 interface. ZXG10-OMC has features as follows:

► The system supports the Q3 interface access of the upper NMC

► Providing management in man-machine interface (MMI) mode;

► The system architecture is more reasonable in such aspects as of

the separation of function realization from the application interface, more flexibility in system and easier upgrading;

► The system supports more application functions, including the

support of multi-module system structures.

► The employment of servers with high performance and high reliability

confirms to the stability and the powerful processing capability of the system.

5.2.2 OMC-R configurations

To ensure the system CPR, the system is demanded to have excellent


PAGE: 111/162

retractility. To reach this aim, the system application software is demanded to run in modularized mode.

The server configuration mentioned above is basically as follows:

CPU a 300MHz Spare II CPU module

Memory: 512Mbyte

Hard disk: 9.1G(The disk space needed by the installation operation system and the application process as well as the disk for saving data has to be provided )

The system provides several integrated policies as follows:

1. Minimum Configurations:

In the case of minimum configuration, the system consists of only one server which not only runs the LMF, LAF modules but also realize the database server functions. Both the loading capacity and the security reliability are relatively lower in the case of the minimum configuration, which is suitable in cases where the system loading is not large(1or 2 BSSs)and the reliability is relatively not high(users don’t mean to invest too much); the disk for additionally storing data is about 40G in size.

2. General cases:

Generally, the system consists of two servers. The function modules running on each server can be combined according to actual situations. Combination solutions are as follows:

1) (LAF+LMF)+DBMS

2) LAF+(LMF+DBMS)

The general configuration suits the average scale network, (2 or 4 BSSs). In this case, the first combination method is recommended, because quite a part loaded in the system belongs to such operations of as data storing


PAGE: 112/162

and inquiring, which are performed via database (DBMS). One server might be dedicated to database;the other part belongs to the distribution, processing and communication of data. This part is completed via the other server.

The second case is aimed at this consideration, namely, when the system bottleneck is in the case of communication instead of in the course of processing information. LAF can run on one server to serve as the communication server of the system so as to ensure the speediness of communication from the system to the BSS network.

In this case, the hard disk for additionally storing data is about 80G in size, and the employment of disk display is recommended to improve the data security.

3. Large configurations:

The system with a maximum configuration consists of three servers,on which respectively run LMF,LAF and DBMS serving as the application server,the communication server and the database server.

In this case, the hard disk for additionally storing data is about 80G in size, and the employment of disk display is recommended to improve the data security .

4. Larger configurations:

If the configuration is extremely large, its processing capability can be strengthened via adding CPU modules (multi-modules) of servers and memory. The necessary disk space is decided on the TRX amount.

5.3 ZXG10-OMC concentrated maintenance networking solutions

The integration of OMC-R with BSS is decided on the networking modes provided by the subscribers, with the purpose of improving the transmission CPR and reducing the transmission cost of the subscribers. The current networking solutions include X.25, PCM and LAN.


PAGE: 113/162

5.3.1 X.25

Since ZXG10BSC currently communicates with OMC via TCP/IP, the IP over X.25 solution is employed so as to ensure the stability of the old system. by installing a board on the BSC shelf, then on which the X.25 protocol is converted to IP . The line interfaces may be one or several types in V.35, V.24, X.21, and X21bis. Since the rate provided by V.24 is 9600bit/s, it is outside the consideration temporarily. The router performs the protocol conversion between LAN and X.25 network, which enables the OMC-R host computer to establish connection with each BSS.

OOMMCC--RR SSeerrvveerr

BBSSCC 11 BBSSCC 22

LAN

CClliieenntt TTeerrmmiinnaall

RRoouutteerr//FFEE PPSSPPDDNN//DDDDNN

LLAANN XX..2255

Figure 5-3 X.25 Mode

5.3.2 PCM-A interface

This mode transmits the IP packet via the timeslots in PCM. The timeslots can take up those in PCM transmission from MSC to BSC via MSC. The maximum transmission rate of each time slot is 64kbps. Or passage technology is employed to simultaneously take up N timeslots to reach a rate of *64kbps.

OMC-R can realize the connection from OMC to MSC via a router or a front PC as shown in the following figure.


PAGE: 114/162


BBSSCC 11 BBSSCC 22

LAN


RRoouutteerr//FFEE

LLAANN PPCCMM

MMSSCC

Figure 5-4 PCM-A Interface Mode

5.3.3 LAN

In this mode, the OMC server is directly connected with the BSS under its management via a LAN. It demands that this BSS be physically located at the same place as the following figure shows:


BBSSCC 11 BBSSCC 22 MMSSCC

LLAANN CClliieenntt AApppplliiccaattiioonnTTeerrmmiinnaall

Figure 5-5 LAN

5.3.4 Special modes

Here an introduction is given to the local terminal BSC-LMT.

5.3.4.1 LMT category

LMT includes two types, which are divided according to their relationship with the OMC server. Physically speaking, they are together with a remote


PAGE: 115/162

BSC. What differs is that the management of MP is via an OMC server, which is equal to a remote terminal of OMC, while the other type manages MP directly, without via the OMC server. To the former type, it is called a type I LMT. To the latter, it is called a type II LMT as the following figure shows:


BBSSCC 11


RRoouutteerr //FFEE

LLAANN PPCCMM

LLMMTT ((II))

LLMMTT ((IIII))

MMSSCC

Figure 5-6 Two types of LMT

LMT can be connected with BSC via a LAN or a RS-232 port. If the connection is carried via a LAN mode,BSC is equal to a type I terminal router. The LAN lower layer driving process of BSC needs no modifications. However, messages from terminals in two types have to be demarcated on the application layer. The type I terminal messages are directly transferred to the passage connected with the OMC server via MP. If it is via an A interface, the messages are switched to the timeslot where OMC is connected with BSC; MP directly processes the type II terminal message.

If the remote BSC is connected with an OMC server via a router, the type I terminal can be in the same sub-network as BSC via a LAN and its connection to the OMC server is directly completed via a router.

5.3.4.2 Usage of LMT

The applications provided by the above two types of terminals are not necessarily exactly the same. The type I application agrees with the client end applications provided in OMC, but its operation range is limited as it


PAGE: 116/162

can only manage the BSC it depends on. The type II terminal is a mobile one. The functions it provide is directly completed by MP but it merely runs when the system is commissioned or encounters troubles, providing favorable testing tools for maintenance personnel and enabling them to troubleshoot rapidly.

5.3.4.3 Maintenance for unusual cases

When the equipment is unmanned, if the normal O&M passage is faulty, then a standby passage is needed to serve processing.

In an OMC central equipment room, the type II terminal can be configured and connected with the MP of the remote BSC via MODEM. As the normal maintenance passage breaks down, this passage can be employed to manage and maintain BSC. The terminal communicates with MP via a RS232 serial port.


BBSSCC 11

LLMMTT((IIII))

RRoouutteerr//FFEE

LLAANNPPCCMM

LLMMTT ((II))

LLMMTT ((IIII)) MMSSCC

PPCCMM

LLAANN//RRSS--2233MMooddeemm PPSSTTNN CClliieenntt TTeerrmmiinnaall

Figure 5-7 Maintenance Passages in Unusual Cases

Details about O&M can refer to ZXG10-BSC O&M Manual.

6. Function Description

6.1 Basic flow

6.1.1 Allocation flow of access and initialization

MS is in two statuses, that is, the “idle” mode and the “dedicated” mode.


PAGE: 117/162

Under the “idle” mode, the MS does not allow any transmission to network infrastructure. Under the “dedicated” mode, the MS performs valid transmission over the channels assigned to it.

The MS gives access reasons and their analysis via an 8-bit information bit in access application, and obtains the channels that satisfy the access requirement via channel allocation. If the type of channels can not be decided by analyzing limited reasons, distribute one SDCCH as the default. If there are no usable channels during channel allocation, instantly assign a deny command to notify the MS to try access later.

After the channel activates the process over the Abis interface, an instant assignment command is sent to the MS. After the MS receives the instant assignment command, a dedicated channel is established with the network infrastructure via an establishment instruction message, and the MS enters the “dedicated” mode.

After BSC receives the establishment instruction message reported by the MS, necessary analysis is conducted for the contents of the establishment instruction message, including the MS class mark processing, the related power control recording and encrypting information, etc., then, send the establishment instruction reported by the MS to MSC.

6.1.2 Paging flow

When a call reaches an MSC that is considered the subscriber can be found out, the MSC determines the location area that the MS registered, and sends paging messages to all BSCs in the location area. The paging message contains the information that can identify the subscriber ID. When the flow volume control is allowed, BSCs can automatically adjust PAGCH configuration.

At present, the M900/M1800BSC system supports all three paging modes, that is: “normal” paging mode, “full” paging mode and “alternate” paging mode. Therefore, the subscribers in the service cell will not lose paging texts when the PAGCH channel is adjusted due to flow volume. After


PAGE: 118/162

receiving the paging text, the MS enters the access and initialization allocation flow via the access application.

6.1.3 Management flow of transmitting mode and encrypting mode

There are 12 transmitting modes defined in the GSMPhasse2+ protocol. In addition, the contents related with the transmitting mode also include encrypting mode and DTX mode. After completing the access and initialization allocation flow, the MS will enter the management flow of the transmitting mode and encrypting mode. Selection of the transmitting mode will depend on the communication requirements and is completed by the MSC.

The MSC will notify BSCs the transmitting mode required by the communication via the assignment message, and request BSCs to complete the related circuit exchange. After receiving the assignment text, BSCs will compare the current transmitting mode with the transmitting mode required by the MSC, and make the corresponding action. If the modes are the same, BSCs will send a message to the MSC indicating that the assignment is completed. If the modes over the wireless links are the same, but the sent information types are different, modify the modes.

After modification of the modes, the BSC will send a message to the MSC indicating that the assignment is completed. If the mode required by the MSC is different from the one being used over the wireless links, the BSC will complete an initial assignment flow, then, it is able to send a message to the MSC indicating that the assignment is completed. If it fails during the assignment process, the BSC will send a message to the MSC indicating that the assignment has failed.

6.1.4 Executing flow of handover

What differences between the executing flow of the handover and the previously described access and initialization allocation flow, as well as the management flow of the transmitting mode and encrypting mode are as follows: Management of time advanced is added. Whether the time


PAGE: 119/162

advanced amount is proper will determine the continuity of the MS conversation during the executing flow of the handover.

For the BSC internal handover, since there is no difficulty in estimation of the time advanced amount, the executing flow of the BSC internal handover is basically the same as the initial allocation flow. For the inter-BSC handover, the source BSC must notify the MSC, then, the MSC establishes a land link with the target BSC, and notifies the source BSC of the new wireless channel. The source BSC will provide such information as follows to the target BSC via the MSC: transmitting mode, encrypting mode, synchronous mode, and the MS class mark, etc.

The target BSC will allocate a new channel according to the information, and generate the handover command message required by the source BSC, and then, send it to the source BSC via the MSC. The source BSC will notify the MS of the received handover command message, and the MS will be handed over to the target BSC. After detecting that the MS has been handed over, the target BSC will notify the source BSC to enter the channel release flow via the MSC.

6.1.5 Call reestablishment flow

Under the wireless mobile environment, one connection might be suddenly cut off. It might be caused by severe transmission loss because of some obstacles or buildings. The call reestablishment is divided into two parts: the first part is that the MS uses the access and initialization allocation flow. The second part is that the context environment for the network infrastructure to recover the call. The speed in the call reestablishment flow is very critical. When the timer in the MSC is timeout, any information related with the call shall be cleared.

The MS reports the subscriber ID and the class mark to the BSC via the access and initialization flow. Then the BSC sends the information to the MSC, and the MSC will perform the call reestablishment process according to the information.


PAGE: 120/162

6.1.6 Channel release flow

Upon completion of the call, normally, the channel release flow is originated by the MSC. The MSC sends a clear command to the BSC. After the BSC receives the command, it will send back a clear completion message while sending a channel release command to the MS, and the BTS will await the MS to complete the release.

To guarantee the MS has released the wireless channel before the network infrastructure releasing the channel, the BSC notifies the BTS to stop sending the SACCH message to the MS. After the BTS detects that the MS completes the release, the BSC will disconnect the link with the BTS.

6.1.7 Load management flow

The overall load management flow is jointly accomplished by BTS, BSC and MSC. The BTS is responsible for monitoring load status over RACH, PCH and PAGCH, and notifies the BSC via the load instruction message. The BSC is responsible for monitoring load status over the dedicated channels, and notifies the MSC via the resource instruction. In addition, the overload instruction message can be used to notify the service load status between the BSC and the MSC.

6.1.8 BCCH broadcasting message processing flow

Under the idle mode, the MS needs to know some technical information of the network infrastructure. The BSC will send universal broadcasting information to the BTS, and the BTS will broadcast it over the BCCH channel. The BCCH channel is a low capacity channel, which can send a message 23-byte long in 0.235 second. The broadcasting information includes: cell selection information, adjacent cell information, access control information, dedicated channel control information, cell identification code, location area, etc.


PAGE: 121/162

6.1.9 SACCH message processing flow

When the MS is in the dedicated application mode, besides one allocated service channel, another limited capacity SACCH channel is also allocated to it. The SACCH channel is used to monitor links, control transmission power, control time advanced amount, and report measurement in the mobile environment. Furthermore, the SACCH sends system messages to the MS. If possible, it can send short messages.

6.2 Handover

6.2.1 Overview

In the cellular system like GSM, the multiplexing of the radio frequency resources is fully employed, which enables one area is jointly covered by multiple cells. In this case, the concept of automatic trans-cell handover is brought about. For instance, when a mobile subscriber is in the process of conversation that is moved from the coverage range of a cell to the coverage range of another cell, automatic channel handover should be conducted, so as not to interrupt the conversation.

This process should be done under the condition without being sensed or involved by the subscriber. Therefore, how to realize the trans-cell handover successfully and rapidly constitutes one of the critical aspects in designing the cellular system.

Handover is one of important functions of the cellular mobile communication system. As a wireless link control measure, handover enables subscribers to keep continuous conversation during trans-cell movement. Besides, handover can also adjust the traffic of certain cells.

6.2.1.1 Classification of handover

According to the home locations of the two cells the handover involves (before handover and after handover), the handover can be classified into:

► Intra-cell handover: Such handover can be controlled independently


PAGE: 122/162

by the BSC in the cell;

► Inter-cell handover within BSC: the cells before and after the

handover are two different ones but within one identical BSC. Such handover can be performed by BSC independently without the involvement of MSC;

► Inter-BSC handover within MSC: the two cells before and after the

handover are respectively controlled by two BSCs, which, however, are controlled by one MSC. Such handover requires the involvement and control of the MSC and two BSCs.

► Inter-MSC handover: the two cells before and after the handover id

respectively controlled by two MSCs. Such handover requires the joint control of multiple MSCs and the BSCs the two cells belong to.

As for how MS establishes the connection with the target cell during the handover, the handover can fall into:

► Synchronous handover: MS adopts the same TA in both the target

cell and the source cell. Such handover mode is featured by rapidness and usually takes place within cells as well as between two sectors in the same site;

► Asynchronous handover: MS is not aware of the time advanced the

target cell should adopt. Such handover mode is characterized by slowness and used on condition that either of the two cells is in synchronization with BSC;

► Pseudo-synchronous handover: MS can figure out the time

advanced the target cell should adopt. Such handover mode is featured by rapidness and can be used when both cells are synchronized with BSC;


PAGE: 123/162

► Pre-synchronous handover: the source cell knows the time

advanced that MS should adopt in the target cell, and notifies it to MS. Such handover mode is featured by rapidness.

6.2.1.2 Handover conditions

Conditions leading to handover are listed as follows:

► Signal intensity too weak;

► Signal quality too poor;

► Serious signal interference: Handover in this case is mainly

attributed to the interference. To illustrate, suppose the channel that a mobile subscriber occupies is under sudden interference, then the subscriber is handed over to another channel in the same cell so as to escape the interference;

► Mobile users are too far from the base stations;

► The upper stream level is suddenly attenuated.

► The macro-micro cellular handover:

► The micro-micro cellular handover:

► A more appropriate cell exists: from the angle of the whole system, if

the mobile subscriber can be handed over to a more appropriate cell, the interference of the whole system can be decreased.

The conditions mentioned above are only what the most basic handover algorithm needs processing, however, more and more factors have to be


PAGE: 124/162

taken into account in handover algorithm as various new technologies are put forward in the following.

► Concentric Circle Technology

The concentric circle technology refers to dividing ordinary cells into two areas: the overlay and the underlay, namely, the coverage range of the overlay refers to the traditional cell, and the frequency point of the overlay usually employs the 4X3 multiplexing mode.

However, the coverage range of the underlay is mainly centered near the base station and the frequency point of the underlay usually employs the more condensed multiplexing mode, e.g. 2X3 or 1X3. Both the overlay and the underlay share not only the site, one set of antenna system but also the same BCCH channel. Yet, the common control channel must belong to the overlay.

The concentric circle technology has multiple types, but the relatively common ones are ordinary concentric circle and the intelligent underlay overlay. They are different from each other in the transmission power of the underlay as well as the handover algorithm between the underlay and the overlay.

Generally speaking, the transmission power of the underlay of the general concentric cell is lower than that of its overlay with the handover between the underlay and the overlay based on both power and distance. The maximum transmission power of the underlay of the intelligent underlay overlay is equal to that of its overlay with the handover algorithm based on the ratio of C/I.

► Micro-cellular

The antenna of the micro-cellular is generally installed under the housetop, therefore, the radio propagation is in the line-of-sight propagation mode and greatly affected by the buildings around, moreover, its coverage


PAGE: 125/162

scope is limited with low transmission power. Yet, it is small in size and convenient in installation, mainly applied in the subway and the basement where the macro cellular can hardly cover, and areas with high traffic such as downtown, the shopping centers, etc.

The micro-cellular and the macro-cellular constitute a multi-layered network. To illustrate, as the top layer of the multi-layered network, the macro-cellular performs continuous large-area coverage, by contrast, the micro-cellular performs continuous small-area coverage lapping over the macro-cellular, forming the bottom layer of the multi-layered network. The micro-cellular mainly serves the low speed mobile users.

As for the high speed mobile users, the macro-cellular should be their options so as to avoid the call drop caused by the excessively frequent handover or the too late handover. To realize this, the system must have the handover algorithm based on the mobile speed, for this handover algorithm has a direct influence on the capacity of the micro-cellular to offer the capacity and the network service quality.

► Dual frequency network

In recent years, the 1800MHz frequency range GSM has gradually been put into use domestically as the solution to the serious 900M resource shortage in peak traffic areas. In this case, two coverage lays of 900M and 1800M may simultaneously exist in one area.

The two coverage lays may be either two mutually irrelevant networks or a dual frequency network of the two coverage lays. However, in the dual frequency network, the handover between 900M and 1800M has to be taken into account. Particularly at the current stage, since the traffic that the 900M lay covers is comparatively large, the dual frequency mobile phone subscribers should be led to the 1800M lay as much as possible so as to balance the service of the two lays. In terms of handover, priority should be given in handing the subscribers over to the cell of the1800M lay. In fact, another still more complex case-dual frequency cell exists.


PAGE: 126/162

In other words, both 900M and 1800M frequency points exist in one cell. However, the frequency points of two kinds of frequency ranges in one dual frequency cell are different from each other in radio performance, consequently, in handover algorithm special attention has to be paid to the handover between channels of different frequency ranges in the dual-frequency cell.

6.2.2 Handover types and flow of ZXG10-BSC

Due to the advanced design of ZXG10-BSC software, a variety of efficient hangovers can be achieved, not only raising the handover speed to decrease the handover failure rate, but also enlarging the network capacity and improving the service quality in cooperation with other various new technologies.

6.2.2.1 Handover classification of ZXG10-BSC

In light of the home location of two cells (before and after the handover) involved in handover, ZXG10-BSC supports all handover types:

► Intra-cell handover: ZXG10-BSC can independently control and

perform it;

► Inter-cell handover within BSC: ZXG10-BSC can independently

control and perform it;

► Inter-BSC handover within MSC: ZXG10-BSC cooperates with MSC

to perform it.

► Inter-MSC handover: ZXG10-BSC cooperates with MSC to perform

it.

In terms of how MS establishes relationship with the target cell during the handover, ZXG10-BSC supports three handover types:


PAGE: 127/162

► Synchronous handover:

► Asynchronous handover:

► Pseudo-synchronization handover:

As for pre-synchronous handover, due to the shortage of appropriate cases corresponding with it, ZXG10-BSC does not support it for the time being.

6.2.2.2 Handover flow of ZXG10-BSC

During the handover process, many factors have to be taken into account. The ZXG10-BSC handover control possesses the following features:

► The queuing process during the handover: During the handover

processing, the applicants can be temporarily queued to await the release of a certain source to increase the handover success rate in the case of temporary lack of radio resources;

► Forced disconnection process during the handover: During the

handover, if the case is urgent, furthermore, if the target cell is lacking of radio resources, forced disconnection or forced handover can be performed on some subscribers of lower priority so as to release corresponding radio resources to guarantee the continuous conversation of the subscribers of higher priority;

► MSC traffic handover: ZXG10-BSC can join MSC to complete the

traffic handover by transferring the traffic of a busy cell to an adjacent cell of relatively lower traffic;

► BSC traffic handover: To further lighten the burden of MSC,

ZXG10-BSC can perform the traffic handover independently, which


PAGE: 128/162

balances traffic on the premise of guaranteeing the network service quality.

6.2.2.3 Special handover functions of ZXG10-BSC

The emergence of new technologies adds corresponding functions to the ZXG10-BSC handover:

► Concentric circle handover: One way to increase the network

capacity is to employ special network planning method. The concentric circle technology is the most commonly used one with various types, aimed at enlarging the network capacity. ZXG10-BSC employs the concentric circle technology based on carrier interference ratio with comparatively high efficiency. Based on this technology, the special handover strategy has been designed to enlarge the network capacity by 30% or more.

► The micro-cellular handover: Another way to enlarge the network

capacity is to employ micro-cellular technology, which is also an efficient solution to the network coverage. To consider the handover means to test MS speed. The service had better not be given to the MS micro-cellular with high speed. ZXG10-BSC can currently test the MS relative moving speed to the base station through software, which can be depended on performing the micro-cellular handover based on the speed;

► Dual frequency handover: The third way to enlarge network capacity

is to enlarge the 1800M lay so as to constitute the dual frequency network, which can completely change the situation of the 900M frequency points insufficiency. However, at the present time, the 1800M lay capacity can not be fully made use of, consequently, how to make the 1800M cell absorb traffic to the utmost should be taken into main account in terms of handover. ZXG10-BSC can manage the 900M cell and the 1800M cell simultaneously. In addition to enhancing the 1800M cell absorbing capability through the common cell parameter configuration, special


PAGE: 129/162

priority level can be set to the handover from 900M to 1800M. For a dual frequency cell, ZXG10-BSC temporarily does not support it since its possibility is too low for the time being.

6.2.3 Handover flow

The implementing of handover depends on two aspects: one refers to the measurement report of MS and BTS; the other refers to various handover control parameters. The following description mainly centers about the basic handover control flow, excluding the concentric circle, the micro-cellular and dual frequency handover.

6.2.3.1 Handover control flow

The whole handover control flow is divided into:

► The saving of measurement report;

► The computing of mean value;

► The comparison of threshold values;

► The selection of candidate cells.

► The saving of measurement report

► This part mainly fulfils the following tasks:

► Save the upstream measurement data;

► Save the downstream measurement data;

► Save the time advanced;


PAGE: 130/162

► Save the measurement data of adjacent cells;

► Save the measurement data of interference cells.

Computing of mean value

This part mainly fulfils the following tasks:

► Compute the mean value of upstream measurement data;

► Compute the mean value of downstream measurement data;

► Compute the mean value of time advanced;

► Compute the mean value of measurement data in adjacent cells;

► Compute the PBGT value of adjacent cells.

Note: The PBGT value of the adjacent area symbolizes the superiority degree that the signal in the adjacent cells is stronger than that in local cells.

The mean value computation employs some parameters in the handover control such as the sample numbers (the window size) in mean calculation, different weight values that DRX and non-DTX modes use in measuring data, the numbers of negligible zeros in the measurement report, etc.

Comparison of threshold

The parameters involving the mean value comparison of handover control are:

► (UpLevTh, N, P): the intensity threshold in the upstream direction;


PAGE: 131/162

► (UpQualTh, N, P): the quality threshold in the upstream direction;

► (DwLevTh, N, P): the intensity threshold in the downstream direction;

► (DwQualTh, N, P): the quality threshold in the downstream direction;

► (UpIntfTh, N, P): the interference (intensity) threshold in the

upstream direction;

► (DwIntfTh, N, P): the interference (intensity) threshold in the

downstream direction;

► (MsDistTh, N, P): distance threshold (the unit is the same as that of

time advanced);

► HoMargin (n): HoMargin value of adjacent cells.

There can be many handover thresholds according to different handover conditions, but most handover thresholds include three parameters: the threshold itself, N value and P value. To illustrate simply, if P of the most recent N average values exceeds thresholds, the corresponding handover has to be performed.

The threshold comparison process can be simply described as follows:

► In the most recent N upstream intensity mean values, at least P of

them are lower than the threshold UpLevTh, handover happens;

► In the most recent N downstream intensity mean values, at least P of

them are lower than the threshold DwLevTh, handover happens;

► In the most recent N upstream quality mean values, at least P of


PAGE: 132/162

them are higher than the threshold UpQualTh, handover happens;

► In the most recent N downstream quality mean values, at least P of

them are higher than the threshold UpQualTh, handover happens;

► At the same time when condition 3 is satisfied, in the most recent N

upstream intensity mean values, at least P of them are higher than the threshold UpIntfTh, handover happens;

► At the same time when condition 4 is satisfied, in the most recent N

downstream intensity mean values, P of them are higher than the threshold DwIntfTh, handover happens;

► In the most recent N time advanced mean values, at least P of them

are larger than the threshold MsDistTh, handover happens;

► If the latest PBGT value of a certain adjacent cell is greater than that

of its counterpart HoMargin, handover happens. The target cell list includes this adjacent cell.

The selection of candidate cells

In performing each handover between cells, the target adjacent cell table has to be computed, that is, to select the adjacent cell satisfying the following conditions. These cells are arranged in order according to the computing value of formula (2). The bigger the value is, the more forward it is ordered:

► RXLEV_NUNIT(n)>RXLEV_MIN(n)+MAX(0,Pa)

Where, Pa=MS_TXPWR_MAX(n)-P

► Priority =PBGT(n)-HO_MARGIN(n)>0


PAGE: 133/162

Where, Formula (1) illustrates whether the intensity of signal n of the adjacent cells MS receives is powerful enough. Formula (2) shows whether the intensity of signal n of the adjacent cells MS receives is powerful enough when compared with the local cell signal.

6.2.3.2 Handover signaling flow

When we discuss a comparatively complicated handover signaling flow, we are actually referring to the trans-MSC handover. In order to simplify the explanation, we mainly discuss the routine flow. The processing of abnormal cases will not be discussed. Neither will the signaling between MSCs be explained in detail. Handover signaling flow is as shown in Fig. 6-1:

MSMS OLD BSCOLD BSC OLD MSCOLD MSC NEW MSCNEW MSC NEW BSCNEW BSC NEW BTSNEW BTS MSMS

HANDO REFHANDO REFRR HANDORR HANDO

CMDCMD

TIMEOUT RESENDING TIMEOUT RESENDING

HANDO RQDHANDO RQD

RSM DR(RR RSM DR(RR HANDO CMD)HANDO CMD)

KEEP OLD CHANNEL (HANDOVER KEEP OLD CHANNEL (HANDOVER

INSIDE THE BSC CELL )INSIDE THE BSC CELL )

RR HANDORR HANDOFAILFAIL RSM DR(RRRSM DR(RR

HANDO FAIL)HANDO FAIL)

BSSMAP HANDOBSSMAP HANDORQDRQD

HAND REFHAND REFBSSMAP HANDOBSSMAP HANDO

CMDCMD

T8T8

CAUSE: SUCCESSFUL HANDOVER CAUSE: SUCCESSFUL HANDOVER

BSSMAP CLEAR CMDBSSMAP CLEAR CMD

BSSMAP HANDOBSSMAP HANDOREQREQ

BSSMAP HANDOBSSMAP HANDOREQ ACKREQ ACK

T9113T9113

BSSMAP HANDO COMBSSMAP HANDO COM

T9103T9103

BSSMAP HANDOBSSMAP HANDO

DETDET

BSSMAP HANDOBSSMAP HANDO

DETDET

BSSMAP HANDO BSSMAP HANDO PER FOR MEDPER FOR MEDBSC INTERNAL BSC INTERNAL

HANDOVERHANDOVER

RSM CHANRSM CHANACTIVACTIV

RSM CHAN ACTIVRSM CHAN ACTIVACKACK

RSM HANDORSM HANDODETDET

T3105T3105

RSM EST RSM EST INDIND

RSM DI(RR RSM DI(RR HANDO COM)HANDO COM)

RELEASE HANDO REFRELEASE HANDO REF

SYNCHRONOUS CONDITIONSSYNCHRONOUS CONDITIONS

RSM HANDORSM HANDODETDET

HANDO REFHANDO REFRRHANDO ACCESSRRHANDO ACCESS

RR PHY INFORR PHY INFO

HANDO REFHANDO REFRR HANDO ACCESSRR HANDO ACCESS

SABMSABMUAUA

RR HANDO RR HANDO COMCOM

MAP/EMAP/EASSIGNMENT ASSIGNMENT HANDO REFHANDO REF

MAP/EMAP/E

MAP/EMAP/E

FAILED FAILED CONDITIONSCONDITIONS

T3124T3124

OLD BSCOLD BSC

ASYNCHRONOUS ASYNCHRONOUS CONDITIONSCONDITIONS

T3103T3103

T7T7

Fig. 6-1 Handover signaling

Note: In the following, the source cell will be called old cell while the target cell will be called new cell. Similarly, there are old BSC, BTS and MSC as well as new BSC, BTS and MSC.

► If the old BSC, according to the above-mentioned handover control


PAGE: 134/162

flow, considers it necessary to perform the inter-cell handover, and if the first cell in the candidate cell list is not controlled by the old BSC, BSC transmits a requirement for handover to the old MSC that BSC belongs to. In the message, the candidate cell list and the call-involved attributes will be notified to the old MSC;

► The old MSC finds the first cell in the candidate cell list not under its

control but under another MSC control, then, the old MSC will notify the handover requirement to the new MSC via a MAP/E message. However, the message will continue to transmit the candidate cell list and the call-involved attributes;

► After the new MSC receives the message, it will transmit a handover

requirement message to the new BSC that the new cell belongs to. However, the message will continue to transmit the candidate cell list and the call-involved attributes;

► The new BSC generates a handover reference number, then

employs the known call-involved attributes to activate a wireless channel in the new cell (BTS), simultaneously, notifying the handover reference number to the new BTS and transmitting a handover request reply to the new MSC. A handover command message (containing handover reference number and the descriptions of the new channel) is included in the reply;

► The new MSC transmits the handover command to the old MSC

through a MAP/E message;

► The old MSC transmits the handover command to the old BSC;

► The old BSC transmits a similar handover command to MS through

the old BTS;


PAGE: 135/162

► MS employs the descriptions of the new channel it receives to

attempt its access to the new BTS. The handover reference number is included in the access attempt, which prevents the new BTS from mistaking MS.;

► After establishing contact with the new BTS, MS will transmit a

handover completion message to the new BSC via the new BTS;

► After receiving the handover completion message, the new BSC will

notify this case (similar to the handover completion message) to the new MSC;

► The new MSC notifies this case to the old MSC via a MAP/E

message;

► After receiving this notification, the old MSC knows that MS has

successfully handed over to the new cell, at this time, the new MSC can release the old channel.

6.2.4 Handover control parameters

From the above-mentioned handover control flow, we can find many control parameters related to the handover. However, they are only the most basic part and just given a brief account here. As for the control parameters of the concentric circle, the micro-cellular and the dual frequency handover, they will not be discussed here in detail.

6.2.4.1 Mean window

In GSM system, BSC has to make handover decisions according to the measurement data. In order to avoid the disadvantageous effects brought about by the suddenly changed measurement value the complicated radio transmission causes, what BSC uses in making handover decision is no longer the original measurement data, but a series of mean values of


PAGE: 136/162

measurement data instead. In this way the effects caused by the suddenly changed measurement values are reduced. According to different handover conditions, different mean window values can be designated to different measurement data.

► Handover of the upstream intensity mean window: Computing the

window size employed by the mean values of the upstream signal intensity, namely giving an average computation of the sample numbers used;

► Handover of the upstream quality mean window: Computing the

window size employed by the mean values of the upstream signal quality, namely giving an average computation of the sample numbers used;

► Handover of the downstream intensity mean window: Computing the

window size employed by the mean values of the downstream signal intensity, namely giving an average computation of the sample numbers used;

► Handover of the downstream quality mean window: Computing the

window size employed by the mean values of the downstream signal quality, namely giving an average computation of the sample numbers used;

► Distancing mean window: Computing the window size employed by

the mean values of the distance from MS to BTS (actually the time advanced TA), namely giving an average computation of the sample numbers used;

► Adjacent cell mean window: Computing the window size employed

by the mean values of the adjacent cell signal intensity, namely giving an average computation of the sample numbers used.


PAGE: 137/162

6.2.4.2 Discontinuous transfer (DTX) weighted value

According to the GSM specifications, the discontinuous transfer (DTX) mode refers to the process in which the system transmits no signals during the speech intermission in the course of the subscribers’ conversation. After applying the DTX mode, the measured data reported to the BSC are divided into two categories: one refers to non-DTX mode, that is, an average value of the tested results of all the slots during the testing cycle.

The other one refers to DTX mode, that is, an average value of the tested results of some specified slots during the testing cycle. The BSC will select one type of the tested data for the average value computation in accordance with the actual conditions However, the first type is of better correctness than the second type because the measurement data of the first type is the mean value of the whole slots measurement results while the measurement data of the second type is the mean value of partial slots measurement results.

As a result, when BSC is performing the average computing of the measurement value, it has to use different weighted values to cohere with the two types of measurement data. According to different handover conditions, different weighted values can be designated to different measurement data:

► Upstream intensity weighted value: it is decided that the weighted

value is used in the non-DTX (all slots) measurement data in the handover purposed average computing of the upstream signal intensity, the default weighted value employed by DTX (partial slots) measurement data is 1;

► QualU Weight: it is decided that the weighted value is used in the

non-DTX (all slots) measurement data in the handover purposed average computing of the upstream signal quality, the default weighted value employed by DTX (partial slots) measurement data is 1;


PAGE: 138/162

► Downstream intensity weighted value: it is decided that the weighted

value is used in the non-DTX (all slots) measurement data in the handover purposed average computing of the downstream signal intensity, the default weighted value employed by DTX (partial slots) measurement data is 1;

► Downstream quality weighted value: it is decided that the weighted

value is used in the non-DTX (all slots) measurement data in the handover purposed average computing of the downstream signal quality, the default weighted value employed by DTX (partial slots) measurement data is 1..

6.2.4.3 Zero allowed

According to the GSM specifications, MS can only report the measurement data of six most powerful adjacent cells each time. Therefore, the measurement results that BSC records about the adjacent cells are most probably discontinuous. As for the missing measurement data, we shall record the measurement data of this adjacent cell as zero (0) (namely smaller than -110dBm).

In order to escape the disadvantageous effects brought about by 0, the occasional hypothesis of 0 is permissive, however, too frequent emergence of 0 reveals that the signal of this adjacent cell is really not so good. The zeros parameter allowed (Zero Allowed) used in the primary mean value computation are just used to decide on how many zeroes can be regarded as normal, or say, can be neglected by the mean process.

In detail, supposing to calculate a mean value, there are more 0s exceeding the ZeroAllowed in the sample numbers, indicating that these sample numbers are less reliable. The measured average value = the reported sum / NcellWindow; If 0s do not exceed the ZeroAllowed in the reported values, indicating that these sample numbers are reliable.

The measured average value = the reported sum / (NcellWindow – number of 0s).There can be many handover thresholds according to


PAGE: 139/162

different handover conditions, but most handover thresholds include three parameters: the threshold itself, N value and P value. To illustrate simply, if P of the most recent N average values exceeds thresholds, the corresponding handover has to be performed.

► The handover threshold of the upstream receiving intensity: The

upstream receiving intensity is one of the reasons causing handover with its judging process like this: if there are P mean values lower than the related threshold in the most recent N upstream signal intensity mean values, handover happens, which attributes to upstream signal intensity too weak.

► The handover threshold of the downstream receiving quality: The

upstream receiving quality is one of the reasons causing handover with its judging process like this: if there are P mean values higher than the related threshold in the most recent N upstream signal quality mean values, handover happens, which attributes to the upstream signal quality too poor;

► Downstream intensity handover threshold: The downstream

receiving intensity is one of the reasons causing handover with its judging process like this: if there are P mean values lower than the related threshold in the most recent N down signal strength mean values, handover happens, which attributes to the upstream signal intensity too weak;

► The handover threshold of the downstream receiving quality: The

downstream receiving quality is one of the reasons causing handover with its judging process like this: if there are P mean values higher than the related threshold in the most adjacent N downstream signal quality mean values, handover happens, which attributes to the downstream signal quality too poor;


PAGE: 140/162

► The handover threshold of the upstream interference: the upstream

interference is one of the reasons causing the handover with the judging process like this: at the same time the handover condition of the up quality is satisfied, if there are P of the most recent N upstream signal intensity mean values higher than the related threshold, handover happens, which attributes to the upstream (same frequency) interference too intense;

► The handover threshold of the downstream interference: the

downstream interference is one of the reasons causing the handover with the judging process like this: at the same time the handover condition of the downstream quality is satisfied, if there are P of the most recent N downstream signal intensity mean values higher than the related threshold, handover happens, which attributes to the downstream (same frequency) interference too intense;

► Distance handover threshold: the distance from MS to BTS is also

one of the reasons causing the handover with the judging process like this: In the most recent N time advanced (distance) values, if there are P higher than the related threshold, handover happens, which attributes to MS exceeding the cell service range;

► PGBT handover threshold: the PBGT value of a certain adjacent

area is also one of the reasons causing the handover with the judging process like this: if the PBGT value of a certain adjacent area is higher than the related threshold, handover happens, which attributes to finding a more appropriate cell.

6.2.4.4 Minimum interval of handover

In order to prevent MS that has newly handed over into the cell from being instantly handed over into other cells (this usually takes place on the boundary of two cells), the system can depend on the parameter, the handover minimum interval, to restrict the frequent handover between cells. Otherwise, the communication quality of the subscribers and the


PAGE: 141/162

performance of the system will be affected. This parameter defines a time length.

Only if the interval at which the last inter-cell handover of MS is greater than this value can the next inter-cell handover be permitted. What should be noted is that this parameter only affects the inter-cell handover process without the lightest impact on the common intra-cell handover as well as the concentric circle handover within cells.

6.2.4.5 True time base difference

This parameter stands for the true time base difference of various adjacent cells used as the handover target cell and the local cell. In light of the GSM specifications, when the pseudo-synchronous handover takes place, BSC has to provide MS with the true time base difference of both cells before and after the handover. In spite of this, how much this parameter is equal to at the beginning is not known.

Only after a successful handover (asynchronous handover) can BSC calculate the true time base difference of a certain adjacent area and the local cell from the MS feedback information. Note: if at least one SITE that the cell either before or after the handover belongs to does not use the 8K clock on the 2M line from BSC to SITE as the synchronous clock resource, no true time base difference exists in this area.

6.3 ZXG10-BSC power control

6.3.1 Overview

The power control refers to correspondingly controlling the actual transmission power of the mobile phones or the base stations over the wireless propagation, in other words, maximally decreasing the transmission power of the base station or the mobile phones.

This kills two birds with one stone by decreasing not only the power consumption of mobile phones and base stations but also the interference of the whole GSM network. Of course, the precondition of the power


PAGE: 142/162

control is to guarantee the call in process with better communication quality. To simply explain the power control process, Fig. 6-2 can illustrate it.

A B

Fig. 6-2 Power control

The Fig. shows that the mobile phone at Point A has to rely on relatively higher transmission power in communication in order to guarantee the communication quality because it is comparatively farther from the transmission antenna of the base station.

The electric wave consumption in space transmission is in reverse proportion to the N power of distance. Comparatively speaking, the mobile phone at Point B can use comparatively lower transmission power to guarantee the similar communication quality because it is comparatively nearer to the transmission antenna and consumes relatively less propagation power.

However, if a mobile phone in conversation is roaming from A to B, the power control can make its transmission power gradually decrease. On the contrary, if a mobile phone in conversation is shifting from B to A, the power control can make its transmission power gradually increase.

Power control can be divided into upstream power control and downstream power control, which are performed independently. The upstream power control is to control the transmission power of the mobile phone, while the downstream power control is to control the transmission power of the base station.

Whether it is upstream power control or downstream power control, both


PAGE: 143/162

of them can, on the one hand, reduce the interference in the upstream or downstream direction, and simultaneously decrease the power consumption of mobile phones or base stations by decreasing the transmission power on the other hand. The most obvious advantages shown by them are: the considerable improvement of the average conversation quality in the whole GSM network and the prolonged usage of the mobile phone batteries.

6.3.2 Power control process

The raw information offered to help the power control make decisions comes from the measurement data of mobile phones and base stations, which is similar to the handover control process. After these raw data are processed and analyzed, corresponding control decisions are made. Generally speaking, the whole power control process is as shown in Fig. 6-3:

S a v in g M e a s u re m e n t D a ta S a v in g M e a s u re m e n t D a ta

A v e r a g e P ro c e s s in g A v e r a g e P ro c e s s in g o f M e a s u re m e n t D a tao f M e a s u re m e n t D a ta

D e c is io n M a k in g D e c is io n M a k in g fo r P o w e r C o n tro l fo r P o w e r C o n tro l

S e n d in g P o w e r S e n d in g P o w e r C o n tro l C o m m a n d sC o n tro l C o m m a n d s

M o d ify in g M o d ify in g M e a s u re m e n t D a taM e a s u re m e n t D a ta

Fig. 6-3 Power control process

1. Saving measurement data

Similar to the handover process, in order to eliminate the accidental factors in power control judgement, the forward average mode is employed to give smoothing handling to the measurement data involved.


PAGE: 144/162

Consequently, the received raw measurement data have to be stored for some time.

2. Average processing of measurement data

Similar to the handover process, in order to eliminate the accidental factors in power control judgement, the forward average mode is employed to give smoothing treatment to the measurement data involved. During the following power control decision process, the mean value after the average handling rather than the raw measurement data is used. The types of the actual measurement data related to the power control include: upstream signal level, upstream signal quality, downstream signal level and downstream signal quality. Different measurement data may have different average process parameters, to be more exact, the numbers of measurement data to be used will be different.

3. Power control decision

The corresponding control decision is made of the comparison between a series of average values already obtained and the various control thresholds preset, shown in the following aspects:

► If the upstream signal level is too low or the upstream signal quality

is too poor, the upstream transmission power (mobile phone) can be increased;

► If the upstream signal level is too high or the upstream signal quality

is too good, the upstream transmission power (the mobile phone) can be decreased;

► If the downstream signal level is too low or the downstream signal

quality is too poor, the downstream transmission power (the base station) can be increased;

► If the downstream signal level is too high or the downstream signal


PAGE: 145/162

quality is too good, the downstream transmission power (the base station) can be decreased.

Generally speaking, the amplitude of increase or decrease depends on the preset value.

4. Transferring power control commands

In accordance with the conclusion of the power control decision, the corresponding control command is notified to the base station in message mode, in turn, to be executed or relayed to the mobile phone by the base station.

5. Modifying measurement data

After the power is controlled, the initial measurement data and the average value are of no longer significance. However, if they are maintained intact, they can lead to the consequently wrong power control decision. As a result, these raw data should be either deleted completely or modified correspondingly so as to be capable of continuing its usage.

The maximum speed of the power control is 480ms per time, or to say exactly, this is the fastest velocity in reporting the measurement data. In other words, a complete power control process is executed at the maximum speed of every 480ms one time.

What has been discussed above is about the power control process recommended in ETSI specifications, based on which, ZXG10-BSC has also introduced its unique rapid power control. The following will be a brief account of it.

6.3.3 Rapid power control

The previous introduction reveals that the control amplitude of the power control process recommended by FTSI is fixed and valued with 2dB or 4dB. But in most actual cases, the fixed power control amplitude can not achieve optimal results, as is illustrated in the following example:


PAGE: 146/162

If a mobile phone starts a call in a place very close to the base station antenna, its transmission power will reach its maximum (namely MS_TXPWR_MAX_CCH) of the broadcasting system message in the BCCH channel of the cell where the mobile phone is located. This value can be considered as the maximum transmission power that a mobile phone can be used to the best in the cell.

Obviously, the power control process ought to lower the transmission power as quickly as possible since the mobile phone is so close to the base station antenna. However, the power control process recommended in the specifications can not perform it, for it can only order the mobile phone to decrease 2dB or 4dB each time. Still further, since there will be an interval (due to the necessary collection of sufficient new measurement data) between every two power controls, as a result, it has to take a relatively longer time to cut down the mobile phone transmission power into a reasonable value.

The case is the same of the downstream direction. It can be concluded that this does not facilitate the decreasing of the interference in the whole GSM network. In this case, we have to extend the amplitude of each power control in order to improve this situation and this is just the core of the rapid power control.

In light of actual signal intensity and signal quality, the rapid power control process can flexibly decide on the power control amplitude it should use. In other words, it is no longer limited to the fixed amplitude. As a result, the power control problem of mobile phones arising in the initial access can be easily solved. Of course, the rapid power control process is not only limited to these applications, but it is also used in other cases in such aspects as of the rapid mobile phones, the sudden occurrence of interference or obstacle, etc. To conclude, once there comes the urgency of necessary large-scale power control, there comes the rapid power control process as its solution.


PAGE: 147/162

7. System Mechanical Structure and Its Configuration

Instructions

Details of ZXG10-BSC hardware structure are generally as Figure 7-1 shows ( Both redundancy and compatibility are taken into consideration in the figure):

A A InterfaceInterface

Abis Abis Interface

Interface

TICTIC

BIPPBIPP

TICTIC

#1#1

#6#6

COMICOMI

LAPDLAPDMPMPMPMP MPMPMPMP

MP(RMM)MP(RMM) MP(RMM)MP(RMM)

BIPPBIPP

COMICOMI

FSPPFSPP

FSPPFSPP

TICTIC

TICTIC

#1#1

##m1m1

TICTIC

TICTIC

#1#1

##n1n1

SYCKSYCKSYCKSYCK

NSPPNSPP

NSPPNSPP

DSNIDSNI

DSNIDSNI

BOSNBOSN

BOSNBOSN

DSNIDSNI

DSNIDSNI

SYCKSYCKSYCKSYCK

NSPPNSPP

NSPPNSPP

TICTIC

TICTIC##n2n2

TICTIC

TICTIC##n2n2

FSPPFSPP

FSPPFSPP

DSNIDSNI DSNIDSNI

SYCKSYCKSYCKSYCK

MPPPMPPPMPMPMPMP MPPPMPPPMPMPMPMP LAPDLAPDMTPMTP PEPDPEPD MONMON

MP(SCM)MP(SCM) MP(SCM)MP(SCM)

CKICKI

((E)DRTE)DRT

((E)DRTE)DRT#8#8

TCPPTCPP

TCPPTCPP

TICTIC

TICTIC

AIPPAIPP

AIPPAIPP

#1#1

#8#8

#1#1

#1#1

#1#1

RelayRelay

Transmission

Transmission

RelayRelay

Transmission

Transmission


HoldingHoldingSystemSystem




HoldingHoldingSystemSystemHoldingHolding

System System




PCUPCUGbGbInterfaceInterface

LEGEND:LEGEND:

Optional PartsOptional Parts

Frame content Frame content

HoldingHoldingsystemsystem BackboardBackboard＋＋

m1, n1, n2 m1, n1, n2 ≤≤ 8 ; m18 ; m1≤≤ n1n1

PEPDPEPD

BBIUBBIU

BCTLBCTL

BCTLBCTL

BSMUBSMU

BSMUBSMU

BSMUBSMU

BSMUBSMU

BNETBNET

BATCBATC

SMBSMBDTIDTIDRTDRT

Abis Abis InterfaceInterface

POWBPOWB

POWBPOWB

Figure 7-1 A Demonstration of ZXG10-BSC hardware connection

Details of ZXG10-BSC mechanical structure are in Chapter 2. No further illustrations will be given here. Subscribers will only be provided with the introduction on the rack configuration.


PAGE: 148/162

7.1 Shelf configuration

ZXG10-BSC includes five types of shelves, constituting a BSC shelf in a certain combination mode.

► BBIU:

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

PPOOWWBB

PPOOWWBB

TTIICC

BBIIPPPP

BBIIPPPP

CCOOMMII

BBIIPPPP

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

CCOOMMII

BBIIPPPP

The BBIU shelf provides the Abis interface function, two BIU units, with each unit consisting of two BIPPs and one TIC. If a BBIU shelf is provided, there must be two COMIs; if two POWBs must be provided, there might be one or two BIUs. In one BIU, there must be two BIPPs. The TIC block number can be sampled as 1, 2, 3, 4, 5 and 6. Each TIC can carry 4 E1 relay circuits.

► BCTL

PPOOWWBB

MMPP

MMPP

SSMMEEMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

PPOOWWBB

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

RMURMU

PPOOWWBB

MMPP

MMPP

SSMMEEMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

CCOOMMMM

PPEEPPDD

MMOONN

PPOOWWBB

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

SCUSCU


PAGE: 149/162

The BCTL shelf is where the system core software is placed. It contains one SMEM, which must be provided; two MPs, which must be provided;two POWBs, which must be provided; maximally 12 COMMs to be provided according to configuration; one PEPD, which is optional; one MON, which is compulsory to SCU but unnecessary to RMU. When RMU and SCU are locally placed, the POWB board of RMU is monitored by the MON board of SCU but by ESPP when RMU is remotely placed

If COMM is not powerful enough ( larger than the 960 carrier), in SCU, ECOM is used to replace the location of COMM.

► BNET:

PPOOWWBB

CCKKII

BBOOSSNN

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

DDSSNNII

PPOOWWBB

SSYYCCKK

SSYYCCKK

BBOOSSNN

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

The BNET shelf provides the switching functions of ZXG10-BSC, where there are two POWBs , which must be provided;one CKI, which is optional;two SYCKs, which must be provided two BOSNs , which must be provided;and there are maximally 10 DSNIs to be sampled as 6, 8 and 10.

► BATC:

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

PPOOWWBB

PPOOWWBB

TTCCPPPP

AAIIPPPP

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

EE/D/DRRTT

EE/D/DRRTT

EE/D/DRRTT

AAIIPPPP

TTCCPPPP

EE/D/DRRTT

EE/D/DRRTT

EE/D/DRRTT

EE/D/DRRTT

EE/D/DRRTT

The BATC shelf provides functions of both transcoding and rate adaptation. It consists of two POWBs, which must be provided;two TCPPs , which must be provided, If a BIU shelf is provided, there must be two COMIs;two POWBs, which must be provided;the BIU unit can be one


PAGE: 150/162

or two. In one BIU unit, there are two BIPPs which must be provided, The TIC number can be sampled as 1, 2, 3, 4, 5 and 6. If the BBIU shelf is provided, there must be two COMIs;two POWBs which must be provided; the BIU unit can be one or two.

In one BIU unit, there are two BIPPs which must be provided, the TIC number can be sampled as 1, 2, 3, 4, 5 and 6;there are two AIPPs which must be provided;the DRT number can be maximally 8, and can be sampled as 1, 2, 3, 4, 5 a6, 7 and 8, each DRT can process 124 lines of EFRs, the 32 lines of EFRs can be changed to EDRT, each block can process 124 lines of EFR;the TIC number can be maximally 8 and can be sampled as 1, 2, 3, 4, 5, 6, 7 and 8, each TIC can carry 4 E1 relay circuits.

► BSMU:

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

PPOOWWBB

PPOOWWBB

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

NNSSPPPP

TTIICC

NNSSPPPP

Local SubLocal Sub--multiplexing multiplexing

The BSMU shelf can provide near-end submultiplexing functions, called NSMU. It consists of two POWBs, which must be provided;two NSPPs, which must be provided;the TIC number can be maximally 8, and can be sampled as 1, 2, 3, 4, 5, 6, 7 and 8.

The BSMU shelf can provide near end submultiplexing functions, called FSMU, with the rack structured as follows:


PAGE: 151/162

11 33 5544 66 8877 99 11111010 1212 14141313 1515 17171616 1818 20201919 2121 23232222 2424 2626252522 2727

PPOOWWBB

CCKKII

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

TTIICC

PPOOWWBB

SSYYCCKK

SSYYCCKK

FFSSPPPP

FFSSPPPP

Remote SubRemote Sub--multiplexingmultiplexing

Where, there are two POWBs which must be provided;one CKI which is optional;two SYCKs which must be provided and two FSPPs which must be provided;the TIC number can be maximally 8 and can be sampled as 1, 2, 3, 4, 5, 6, 7 and 8.

7.2 Rack configuration

The equipment we offer to the subscribers is generally not completed via one rack. The amount of racks is related to the carrier total. We set the carrier total of BSC as N_trx.

Several basic parameters need to be stressed here:

The module implication corresponds with one BCTL layer (namely the layer where MP processor is located ) on the physical rack .

One BBIU layer has two BIU units, one BIU unit is connected with the BNET layer via one cable (two 8M lines), the other BBIU layer corresponds with one RMU unit. The total capacity is as 128Ts×4Tch×4HW ＝ 2048TCH=240 TRXs;the capacity of one BATC layer is of approximately 124 TRXs.

7.2.1 Units excluding sub-multiplexing functions

7.2.1.1 N_trx smaller than 240

When the capacity is relatively small, if there are 240 TRXs, only one rack


PAGE: 152/162

#1#1

BBIUBBIU--11

BCTL(RMUBCTL(RMU--1)1)

BCTL(SCU)BCTL(SCU)

BNETBNET

BATCBATC--11

BATCBATC--22

needs to be configured, called a double module BSC--SCM and a RMM respectively:

If the carrier is relatively small, only one BATC layer can be needed according to factual situations

7.2.1.2 240<N_trx<480

In this case, two racks can be configured to meet the capacity at this time, called a three-module BSC:

#1#1 #2#2

BBIUBBIU--22


BATCBATC--33

BATCBATC--44

BBIUBBIU--11


BCTL(SCU)BCTL(SCU)

BNETBNET

BATCBATC--11

BATCBATC--22


PAGE: 153/162

7.2.1.3 480<N_trx<720

In this case, three modules need to be configured so as to meet the capacity, called a four-module BSC:

#1#1 #2#2 #3#3

BBIUBBIU--33


BBIUBBIU--22


BATCBATC--33

BATCBATC--44

BATCBATC--55

BATCBATC--66

BBIUBBIU--11


BCTL(SCU)BCTL(SCU)

BNETBNET

BATCBATC--11

BATCBATC--22

7.2.1.4 720<N_trx<960

In this case, three racks need to be configured so as to meet the capacity, called a five-module BSC:

#1#1 #2#2 #3#3

BBIUBBIU--33


BBIUBBIU--44


BATCBATC--77

BATCBATC--88

BBIUBBIU--22


BATCBATC--33

BATCBATC--44

BATCBATC--55

BATCBATC--66

BBIUBBIU--11


BCTL(SCU)BCTL(SCU)

BNETBNET

BATCBATC--11

BATCBATC--22


PAGE: 154/162

7.2.1.5 960<N_trx<1200

In this case, four modules need be configured so as to meet the capacity, called a six-module BSC:

#1#1 #2#2 #3#3 #4#4

BBIUBBIU--55


BATCBATC--99

BATCBATC--1010

BBIUBBIU--33


BBIUBBIU--44


BATCBATC--77

BATCBATC--88

BBIUBBIU--22


BATCBATC--33

BATCBATC--44

BATCBATC--55

BATCBATC--66

BBIUBBIU--11


BCTL(SCU)BCTL(SCU)

BNETBNET

BATCBATC--11

BATCBATC--22

7.2.1.6 1200<N_trx<1440

In this case, five racks need be configured to meet the capacity, called a seven-module BSC:

#1#1 #2#2 #3#3 #4#4 #5#5

BBIUBBIU--11


BCTL(SCU)BCTL(SCU)

BNETBNET

BATCBATC--11

BATCBATC--22

BBIUBBIU--22


BATCBATC--33

BATCBATC--44

BATCBATC--55

BATCBATC--66

BBIUBBIU--33


BBIUBBIU--44


BATCBATC--77

BATCBATC--88

BBIUBBIU--55


BATCBATC--99

BATCBATC--1010

BATCBATC--1111

BATCBATC--1212

BBIUBBIU--66



PAGE: 155/162

7.2.1.7 1440<N_trx<1680

In this case, five modules need be configured to meet the capacity, called an eight-module BSC:

#1#1 #2#2 #3#3 #4#4 #5#5

BBIUBBIU--11


BCTL(SCU)BCTL(SCU)

BNETBNET

BATCBATC--11

BATCBATC--22

BBIUBBIU--22


BATCBATC--33

BATCBATC--44

BATCBATC--55

BATCBATC--66

BBIUBBIU--33


BBIUBBIU--44


BATCBATC--77

BATCBATC--88

BBIUBBIU--55


BATCBATC--99

BATCBATC--1010

BATCBATC--1111

BATCBATC--1212

BBIUBBIU--66


BBIUBBIU--77


BATCBATC--1313

BATCBATC--1414

7.2.1.8 1680<N_trx<1800

In this case, six racks need be configured to meet the capacity, called a nine-module BSC:

#1#1 #2#2 #3#3 #4#4 #5#5 #6#6

BBIUBBIU--11


BCTL(SCU)BCTL(SCU)

BNETBNET

BATCBATC--11

BATCBATC--22

BBIUBBIU--22


BATCBATC--33

BATCBATC--44

BATCBATC--55

BATCBATC--66

BBIUBBIU--33


BBIUBBIU--44


BATCBATC--77

BATCBATC--88

BBIUBBIU--55


BATCBATC--99

BATCBATC--1010

BATCBATC--1111

BATCBATC--1212

BBIUBBIU--66


BBIUBBIU--77


BATCBATC--1313

BATCBATC--1414

BBIUBBIU--88



PAGE: 156/162

7.2.2 Units including submultiplexing functions

In this BSC, there are two submultiplexing access points to be selected by subscribers. Both the Acon and the Ater interfaces are respectively the submultiplexing interfaces of RMM and the side of TC.

The amount of sub-multiplexing units is counted according to the module numbers placed in the far-end. When the Ater interface is sub-multiplexed, all TC units are placed in the far end. At this time, every four TC shelves need a pair of sub-multiplexing units(one near-end sub-multiplexing unit and one far-end sub-multiplexing unit)and one far-end TC shelf; when the Acon interface is sub-multiplexed, every two far-end RMM modules need one near-end sub-multiplexing unit, while the amount of far-end sub-multiplexing units is equal to that of the far-end RMM shelves.

However, the counting depends on the actual cases in commissioning, which can be obtained according to the following principles: in one RMM equipment room, every two far-end RMM modules may share a far-end RMM shelf, but far-end RMM modules in different RMM equipment rooms can’t share a far-end RMM shelf or a far-end sub-multiplexing unit(though they may share a near-end sub-multiplexing unit.

7.2.2.1 Far-end shelves in sub-multiplexing cases

1) Far-end RMM shelf

One far-end RMM shelf consists of one far-end sub-multiplexing shelf and one or two groups of RMMs. Its shelf diagram is as follows:


PAGE: 157/162

Layer 6Layer 6

Layer 5Layer 5

Layer 4Layer 4

Layer 3Layer 3

Layer 2Layer 2

Layer 1Layer 1

#1#1

BBIUBBIU--11


BBIUBBIU--22


FSMUFSMU

According to configuration demands, select one or two RMM modules on one’s own.

2) Far-end RMM shelf

One far-end RMM shelf consists of one far-end sub-multiplexing shelf and one or two groups of RMMs. Its shelf diagram is as follows:

Layer 6Layer 6

Layer 5Layer 5

Layer 4Layer 4

Layer 3Layer 3

Layer 2Layer 2

Layer 1Layer 1

#1#1

FSMUFSMU

BATCBATC--11

BATCBATC--22

BATCBATC--33

BATCBATC--44

According to configuration demands, add BATC-1, BATC2... in sequence.


PAGE: 158/162

7.2.2.2 Far-end shelves in sub-multiplexing cases

Examples will be listed in the following diagram of the central shelf (i, e, BSC shelf) in the case of sub-multiplexing. Conventionally established abbreviations will be employed in illustrating these examples:

N13-- indicates the case where TC is placed at the near-end , one RMM module at the near-end and three RMM modules at the far-end;

F52-- indicates the case where TC is placed at the near-end , 5 RMM modules at the near-end and two RMM modules at the far-end;

Furthermore, in BSMU( ), the contents in the bracket indicate that what they are connected with are far-end units.

The general principle of placing the near-end shelves is to put the sub-multiplexed ones in the shelves No.1 and No. 2. The rest ones are in seriation.

1) The configuration of near-end BSC shelf in the case of N51

This time, the BSC near-end has all TCs, 5 RMM modules, while the BSC far-end has 1 RMM module. The near-end BSC shelf is configured as follows:

#1#1 #2#2 #3#3 #4#4 #5#5

BSMU(BBIUBSMU(BBIU--1)1)

BCTL(SCU)BCTL(SCU)

BNETBNET

BATCBATC--11

BATCBATC--22

BBIUBBIU--22

BCTK(RMUBCTK(RMU--2)2)

BATCBATC--33

BATCBATC--44

BATCBATC--55

BATCBATC--66

BBIUBBIU--33


BBIUBBIU--44


BATCBATC--77

BATCBATC--88

BBIUBBIU--55


BATCBATC--99

BATCBATC--1010

BATCBATC--1111

BATCBATC--1212

BBIUBBIU--66



PAGE: 159/162

2) The configuration of near-end BSC shelf in the case of N32

This time, the BSC near-end has all TCs, 3 RMM modules, while the BSC far-end has 2 RMM modules. The near-end BSC shelf is configured as follows:

BSMU(BBIUBSMU(BBIU--1~2)1~2)

BCTL(SCU)BCTL(SCU)

BNETBNET

BATCBATC--11

BATCBATC--22

#1#1

BBIUBBIU--33


BATCBATC--33

BATCBATC--44

BATCBATC--55

BATCBATC--66

#2#2

BBIUBBIU--44


BATCBATC--77

BATCBATC--88

BATCBATC--99

BATCBATC--1010

#3#3

BBIUBBIU--55


#4#4

3) The configuration of near-end BSC shelf in the case of F51.

This time, the BSC near-end has all TCs, 5 RMM modules, while the BSC far-end has 1 RMM module. The near-end BSC shelf is configured as follows:

Layer 6Layer 6

BSMU (BBIUBSMU (BBIU--1)1)Layer 5Layer 5

BCTL (SCU)BCTL (SCU)Layer 4Layer 4

BNETBNETLayer 3Layer 3

BSMU (BATCBSMU (BATC--1~4)1~4)Layer 2Layer 2


#1#1

BBIUBBIU--22

BCTL (RMUBCTL (RMU--2)2)

BBIUBBIU--33


#2#2

BBIUBBIU--44


#3#3

BSMU (BATCBSMU (BATC--9~12)9~12)

BBIUBBIU--55


BBIUBBIU--66



PAGE: 160/162

4) The configuration of near-end BSC shelf in the case of F52.

This time, the BSC near-end has all TCs, 5 RMM modules, while the BSC far-end has 2 RMM modules. The near-end BSC shelf is configured as follows:

Layer 6Layer 6

BSMU (BBIUBSMU (BBIU--1~2)1~2)Layer 5Layer 5

BCTL (SCU)BCTL (SCU)Layer 4Layer 4

BNETBNETLayer 3Layer 3



#1#1

BBIUBBIU--33


BBIUBBIU--44


#2#2

BBIUBBIU--55


#3#3

BSMU(BATCBSMU(BATC--9~12)9~12)

BBIUBBIU--66


BBIUBBIU--77

BCTL (RMUBCTL (RMU--7)7)BSMU (BATCBSMU (BATC--13~14)13~14)


PAGE: 161/162

Appendix List of BSC Abbreviations

AIPP A Interface Peripheral Processor AIU A Interface Unit BATC Backplane of A interface and TransCoder BBIU Backplane of aBis Interface Unit BCTL Backplane of ConTroL BIE Base station Interface Equipment COMI COMmunication Interface board DBS Data Base Subsystem DRT Dual-Rate Transcoder EDRT Enhanced DRT BIU aBis Interface Unit BNET Backplane of NET BOSN Bit_Oriented Switching Network BIPP aBis Interface Peripheral Processor BSC Base Station Controller BSMU Backplane of SubMultiplexing Unit FSMU Far SubMultiplexing Unit GPP General Peripheral Processor GPRS General Packet Radio Service HDLC High-level Data Link Control protocol NSU Net Switching Unit OMS Operating Maintenance Subsystem BSS Base Station System BTS Base Transceiver Station FSPP Far Submultiplexing Peripheral Processor HSCSD High Speed Circuit Switched Data LAPD Link Access Procedure on the D channel NSMU Near SubMultiplexing Unit OSS Operating & Support Subsystem PHS PHysical Subsystem NSPP Near Submultiplexing Peripheral Processor PCU Packet Control Unit SMPP Subchannel Multiplexing Peripheral Processor SMU Subchannel Multiplexing Unit SPS Service Processing Subsystem TC TransCoder MTP Message Transfer Protocol MS Mobile Station MSC Mobile Switch Center MSS Mobile Switch System RMM Radio Management Module TCPP TransCoder unit Peripheral Processor


PAGE: 162/162

TCU TransCoder Unit TIC Trunk Interface Circuit RMU Radio Manage Unit SCM System Control Module SCU System Control Unit

ZXG10-BSC(V2) Technical Manual

Documents

physical structure

module structure

hardware structure

rack structure

bss system

s y s t e

system interface protocols

system networking mode