02 Hardware Description

Technical Manual M900/M1800 MSC/SSP/IP

Hardware DescriptionTable of Contents

Huawei Technologies Proprietary

i

Table of Contents

Chapter 1 Overall Hardware Structure ........................................................................................ 1-1

Chapter 2 Rack .............................................................................................................................. 2-1 2.1 Physical Features .............................................................................................................. 2-1

2.1.1 Design Features...................................................................................................... 2-1 2.1.2 Material and Color................................................................................................... 2-1 2.1.3 Dimensions and Weight .......................................................................................... 2-1 2.1.4 Other Features ........................................................................................................ 2-2 2.1.5 Rack Installation...................................................................................................... 2-2

2.2 Functional Configurations .................................................................................................. 2-2 2.2.1 AM/CM Rack ........................................................................................................... 2-2 2.2.2 SM Rack.................................................................................................................. 2-4 2.2.3 BAU Rack................................................................................................................ 2-5

Chapter 3 Frames .......................................................................................................................... 3-1

Chapter 4 Boards........................................................................................................................... 4-1 4.1 Functions and Features ..................................................................................................... 4-1 4.2 Board Structure.................................................................................................................. 4-1

Chapter 5 Functional Units........................................................................................................... 5-1 5.1 Control System .................................................................................................................. 5-3 5.2 Switching Network ............................................................................................................. 5-6 5.3 Digital Trunk System.......................................................................................................... 5-7

5.3.1 GDTM...................................................................................................................... 5-8 5.3.2 GECR ...................................................................................................................... 5-9

5.4 Signalling System ............................................................................................................ 5-10 5.5 Clock Synchronization System ........................................................................................ 5-11 5.6 Alarm System................................................................................................................... 5-13 5.7 Back Administration Module (BAM)................................................................................. 5-14 5.8 Bill Administration Unit (BAU) .......................................................................................... 5-16 5.9 Visitor Location Register (VLR) ....................................................................................... 5-19 5.10 Shared Resources ......................................................................................................... 5-21

5.10.1 IWF...................................................................................................................... 5-21 5.10.2 SRF ..................................................................................................................... 5-22 5.10.3 Signal Tone Generation Circuit ........................................................................... 5-24


Hardware DescriptionChapter 1 Overall Hardware Structure


1-1

Chapter 1 Overall Hardware Structure

The hardware system of the M900/M1800 MSC/SSP/IP has a 4-level hierarchical structure, as shown in Figure 1-1. The lowest level comprises several circuit boards. Various circuit boards are combined together to form frame units. Each frame unit accomplishes specific functions. Frame units with various functions are combined together to form a module and respective modules can implement specific functions independently. Different modules are combined together to form the MSC.

Modules

Functional frames

Circuit boards

MSC

Figure 1-1 Hierarchical structure of M900/M1800 MSC/SSP/IP

The modular design makes the installation and expansion of MSC convenient & flexible i.e., new functions and technologies can be introduced by just adding/removing respective functional frames.

Application of Very Large Scale Integrated (VLSI) circuit gives a compact and highly reliable system with low power consumption. Hardware design is simplified due to the application of microprocessors and programmable logic chips. The addition of corresponding hardware and software can enhance functions.

According to hardware entities, M900/M1800 MSC/SSP/IP can be subdivided into the Administration Module/Communication module (AM/CM), Switching Module (SM), Visitor Location Register (VLR) and Bill Administration Unit (BAU).

M900/M1800 MSC/SSP/IP adopts the distributed modular structure based on AM/CM as shown in Figure 1-2.


Hardware DescriptionChapter 1 Overall Hardware Structure


1-2

AM/CM

SM

SM

VLR BAU

BAM

LAN/WAN

Billing center

OMC

LAN HDLC

Optical fiberE1E1

E1

MSC/SSP/IP

BSCHLRTMSCGMSC

PSTN

LAN/WAN

SCP

Optical fiber

Optical fiber

SM

Figure 1-2 Modular structure of the M900/M1800 MSC/SSP/IP

AM/CM is the switching center for speech and signalling in MSC. It provides interconnection between SMs.

SM performs most of the call handling, signalling processing and circuit maintenance functions.

BAU handles bill saving, interconnects with the billing center and supports bill browsing.

VLR is a real-time database. It is in charge of storing and managing the corresponding data of MS (Mobile Station) currently registered in the MSC/VLR. The VLR also provides security management to related subscribers.


Hardware DescriptionChapter 2 Rack


2-1

Chapter 2

2.1

2.1.1

2.1.2

2.1.3

I.

Rack

M900/M1800 MSC/SSP/IP racks include AM/CM rack, SM rack, BAU rack and PDF (Power Distribution Frame) rack. BAU rack adopts the B-type server rack structure, while the other three racks adopt the assembled rack structure.

Physical Features

Design Features

Side panels of assembled racks and B-type server racks adopt the suspended quick-assembly structure. Front and back doors are provided with the latch installation locking structure that enables easy assembling and disassembling. The rack is designed with upper and lower outlet holes to enable upper or lower access according to practical scenarios.

Material and Color

The rack material is the cold steel board. The fireproof performance of internal materials is in compliance with the UL standard 94.V0.

The rack surface color is Huawei white. The rack part is plated with colored zinc.

Dimensions and Weight

Assembled rack

Rack dimensions: Width: 800mm (without side panel)

Depth: 550mm

Height: 2100mm (with top cover), 1946.5mm (without top cover)

Side panel dimensions: Height: 2100mm

Width: 550mm

Depth: 40mm

Weight: 224kg (empty rack), 310kg (fully configured)




2-2

II.

2.1.4

2.1.5

2.2

2.2.1

B-type server rack

Rack dimensions: Width: 600mm (without side panel)

Depth: 800mm

Height: 2100mm (with top cover), 1946.5mm (without top cover)

Side panel dimensions: Height: 2100mm

Width: 800mm

Depth: 40mm

Weight: 193kg (empty rack), 440kg (fully configured)

Other Features

Special care is taken for the design of rack aspects, such as shielding, wiring, dust prevention and radiation. An assembled rack has three fans at the top and three fans at the bottom to form a closed single air duct for forced draught. B-type server rack adopts the natural radiating mode, i.e. wind enters from the front door & the rack bottom and exits from the back door & the rack top.

Rack Installation

The assembled rack and the B-type server rack can be installed on cement floor or on the anti-static floor. Complete accessory code and operation guide are available for the rack support during installation. Special mounting holes for earthquake-proof reinforcements and supports are provided in each assembled rack and B-type server rack.

Each assembled rack has mounting holes for fastening bolts to provide simple and easy combination of racks.

Functional Configurations

AM/CM Rack

The standard configuration of AM/CM rack is shown in Figure 2-1.




2-3

(1)

(2)

(3)

(4)

(5)

(1) Clock frame (2) Main control frame (3) Interface frame (4) VLR frame (5) BAM frame

Figure 2-1

AM/CM rack configuration

From top to bottom, the frames are:

Clock frame: Its standard configuration is GCKS×2 boards. It provides 32MHz, 2MHz and 8kHz clocks. Main control frame: Its standard configuration includes GSNT×2+GMCC×12+GALM boards. This frame manages the module communication and signalling switching. It also performs the alarm and maintenance functions.




2-4

2.2.2

Interface frame (DT frame): Its standard configuration includes GCTN×2+GFBI×32. It performs the inter-module speech channel switching and provides clock for the switching module. VLR frame: Two VLRs work in the active/standby mode. BAM frame: It contains an industrial PC, loaded with special software.

SM Rack

The standard SM rack configuration is shown in Figure 2-2.

(1)

(2)

(3)

(4)

(5)

(1) Trunk frame (2) Trunk frame (3) Number receiving frame (4) Main control frame (5) Empty frame

Figure 2-2 SM rack configuration




2-5

2.2.3

From top to bottom, the frames are:

Trunk frame: Its standard configuration includes GDTM (or GECR) ×16 boards. The digital trunk equipment provides standard E1 interfaces used in connecting with other MSCs, HLRs and STPs. Number receiving frame: Its standard configuration includes GSPT×2+GDRV×16 boards. It broadcasts the prompt tone and receives numbers in the subscriber-network interaction process of IN service. Main control frame: Its standard configuration includes GMPU×2+GNET×2+GMEM×2+GNOD×11+GSIG×2+GEMA+GLAP (or MFC) ×8+GMC2×2+GOPT×2+GALM+TCI boards. It manages the module communication and traffic switching. It also performs the alarm and maintenance functions.

In addition, the IWF (Interworking Function) frame can be configured as required. When fully configured, the IWF frame can hold 16 IWF boards, each of which provides 4 channels of data.

BAU Rack

The physical configuration of the standard BAU rack is shown in Figure 2-3.




2-6

POWERSYNON

BATL/HFAULT

ONALARM

FAULTINVERTER

BATL/HOFF

OFF

POWERSYNONINVERTERFAULTBATL/H

OFF

⑸

⑹

⑻

⑼

⑴

⑵

⑶

⑷

⑺

(1) Power distribution box (2) Monitor (3) LAN switch (4) Shifter (5) Keyboard (6) Server 1 (7) Server 2 (8) Controller (9) Converter

Figure 2-3 BAU rack configuration


Hardware DescriptionChapter 3 Frames


3-1

Chapter 3 Frames

As discussed earlier, various circuit boards are combined to form a frame, which is relatively an independent unit, e.g. Main Control frame, Trunk frame, Clock frame, VLR frame, IWF frame, DTMF receiver frame, EC frame, TC frame and BAM frame.

All frames have the same dimensions except the Control frame whose height is twice as the rest. Each frame has 26 slots.

The physical/mechanical structure of the frame includes circuit boards, backplane, front & back beams, sideboards and slides. Physical structure of clock frame is shown as an example in Figure 3-1.

⑴

⑵

⑶

⑷

⑸

⑽

⑼

⑻

⑺

⑹

(1) Left side plate (2) Upper front beam (3) Board name strip (4) Lower front beam (5) Plug-in board (6) Dummy panel (7) Guide rail (8) Right side plate (9) Upper back beam (10) Guide rail

Figure 3-1 Frame illustration


Hardware DescriptionChapter 4 Boards


4-1

Chapter 4

4.1

4.2

Boards

Functions and Features

Boards in the M900/M1800 MSC/SSP/IP system have the following general features:

Each board consists of advanced integrated circuits, such as ASIC, EPLD and FPGA. It features high integrity, fine technique and high reliability. Boards are designed by strictly following unified hardware design regulations, which inherit the existing circuit design. Supports the ‘hot plug/unplug’ function. Boards have built-in Watchdog that can automatically reset boards in case of severe problems. Supports the online software loading of board. Provides the serial port printing function and the resetting switch.

Board Structure

Dimensions of boards in the M900/M1800 MSC/SSP/IP system are unified. Except the switching network board (GCTN and GNET), all boards have the same dimensions of 280mm(L) × 233.35mm(W) ×2.0mm (PCB thickness).

The board structure is shown in Figure 4-1.




4-2

(1) Indicator (2) Pull-down panel (3) Elastic locking hook (4) Handle bar (5) Board name (6) Plug

Figure 4-1 Board structure

Most functional boards consist of PCB boards, each of which occupies only one/two slots of a shelf.

In some boards, the pull-down panel can be opened to display the parts on the PCB board, such as the reset button, DIP switches and serial port. The maintenance staff can implement operations on the board without pulling out the board.

The board panel is shown in Figure 4-2.




4-3

RUN

FAIL

ON

1 2 3 4

(1)

(2)

(3)

(1) Serial port (2) DIP switches (3) Reset button

Figure 4-2 Pull-down panel of the board


Hardware DescriptionChapter 5 Functional Units


5-1

Chapter 5 Functional Units

According to the functional structure, M900/M1800 MSC/SSP/IP mainly comprises Control System, Switching Network, Digital Trunk System, Clock Synchronization System, Alarm System, Back Administration Module (BAM), Bill Administration Unit (BAU), shared resources, Monitoring System and VLR.

The functional structure of the M900/M1800 MSC/SSP/IP is shown in Figure 5-1.

GNET

VLRBAU

GMEM GNOD

GMPUGMPU

GDTM

AIE

ECR

Digital trunk system

BillingCenter

BSC

HLRMSCSTP

PSTN

PRAISDN

MFC

LPN7

LPRA

SRF

IWF

GMPUGMCC

Alarm sys.

Clock sys.

BAM

Monitoring

Switc

hing

net

wor

k

Shared resourcesGSIG

Signalling system

Control system

Figure 5-1

Functional structure of the MSC/SSP/IP

The Control System works on the principle of distributed processing and centralized control. It comprises the processor, intra-module communication, inter-module communication, signalling switching and signalling processing circuitry.

The central switching network board (GCTN) and the intra-module switching network board (GNET) form a large capacity T-T-T switching network to complete the speech information switching function. GCTN is a 16k×16k T-network. 4k×4k single-T switching board (GSNT) accomplishes the intra module communication.

M900/M1800 MSC/SSP/IP’s Digital Trunk System offers:

Standard open A-interface to BSS equipment of other vendors. Standard E1 interface to other MSCs. Standard signalling link to HLR.




5-2

Standard signalling link to STP equipment. Standard signalling link to gsmSCF (GSM Service Control Function). Standard E1 interface to SGSN MSC/SSP/IP provides standard E1 interface to connect with PSTN through the built-in echo canceller.

The signalling system handles the access and processing of SS7, R2 & DSS1 signalling.

The Clock Synchronization System mainly comprises the clock frame and is used to provide stable clock source to the system.

The Alarm System of the MSC/SSP/IP adopts the distributed collection and centralized processing technique. Various types of alarm information are sent to the alarm box, alarm indicators & OMC alarm console accordingly and corresponding audio & visual alarms are generated.

BAM is a communication bridge between MSC and OMC. It enables operations and maintenance on MSC via OMC. BAM communicates with the Control System via HDLC links and also communicates with OMC directly or indirectly via the Network Adapter.

BAU receives bills sent from the GMPU and saves them as files under the directory open to the Billing Center. The collector of the Billing Center collects the data from this directory and then deletes the files. The Client can view or query the charging files via the BAU. BAU is connected with the collector of the Billing Center via LAN or WAN.

VLR is a real-time database. It is in charge of storing and managing the corresponding data of mobile subscribers currently registered in the MSC/SSP/IP. VLR also provides security management to related subscribers.

The shared resources mainly include the Interworking Function (IWF) unit, Special Resources Function (SRF) unit and GSIG. These are invoked by GMPU as the resource modules to perform some special functions.

The monitoring system provides two monitoring schemes, i.e. SOSM and SPBX to implement call monitoring.




5-3

5.1 Control System

The M900/M1800 MSC/SSP/IP adopts distributed processing and centralized control system. The internal control structure of multi-SM configuration is shown in Figure 5-2.

GMCCM

GMCCS GMCCS GMCCS GMCCS GMCCS

GMCCM

GMCCS GMCCS GMCCS GMCCS GMCCS

16 digit parallel bus

SNT

GSNT

GMPU

GMC2

GOPT

GFBI

LAPD

GFBI

GNET

GNOD

SNT

GSNT

GMPU

GMC2

GOPT

GFBI

LAPN7/GLAP

GFBI

AM/CM

GNET

GNOD

Optical fiber

SM

GMPU

GMC2

GOPT

GNET

GNOD

GMPU

GMC2

GOPT

GNET

GNOD

SM

LAPDLAPN7/GLAP

Figure 5-2

I.

M900/M1800 MSC/SSP/IP control system

System structure

The Control System comprises the processor, inter-module communication, intra-module communication, signalling switching and signalling processing circuitry.




5-4

II.

GMCCM is the main processing board of AM/CM and GMPU is the main processing board of SM.

The inter-module communication circuit comprises mainly GMCCS in AM/CM and GMC2 in SM.

The intra-module communication function of AM/CM is implemented by GMCCS. Mainly, GNOD board implements the intra-module communication function of SM. GNOD board contains four independent main nodes. Each main node communicates with the GMPU board and the slave node under the control of CPU. The GMPU board and GNOD communicate through mailbox. At the same time, the main node communicates with the slave node via serial port. It transparently transfers the high-level commands of the GMPU board and accepts the response of the slave node. It also queries and collects the status of slave nodes.

The signalling switching circuit is mainly used to control the switching of signalling, which refers to various control and status information. In AM/CM, the GSNT board implements the function of signalling switching between different boards. GNET board is responsible for signalling switching in SM.

The signal processing circuit mainly refers to the processing board of SS7 signalling and GLAP performs this function in SM.

Inter-module communication

GMCCM is the main controlling board of AM/CM and GMPU is of SM. These boards communicate through data channels, which are established by GMCCS (AM/CM) and GMC2 (SM), as shown in Figure 5-3.

The information communicated between these modules includes data management, call handling information, maintenance test information and traffic statistics information.




5-5

GMCCS

AM/CM

GMC2

SM

Data bus

GMCCS GMCCS GMCCS

GMC2 GMC2 GMC2 GMC2

SM SM

GMC2

GMPUGMPU GMPU

GMCCM

Figure 5-3 Principle of inter-module communication

The above figure shows that GMC2 is the single-channel HDLC communication board and is in charge of inter-module communication in SM. GMCCS is the multi-channel HDLC communication board for the inter-module communication in AM/CM.

Both GMCCS and GMC2 work in load-sharing mode. Each SM contains two GMC2 boards that communicate with two GMCCS boards respectively. The two GMCCS boards work in the load-sharing mode, that is, if the two GMC2 links in SM are normal, each link carries half of the system load. In case of any failure or abnormality in one link, the other will take over the full load, as shown in Figure 5-4.




5-6

GMCCS GMCCS GMCCS

GMC2

GMPU

GMC2

GMPU

GMC2

GMPU

GMC2

GMPU

GMPU

SM

GMCCM

AM/CM

AM/CM

SM SM SM SM

GMCCM

HDLCHDLC HDLC HDLC

Dual port

AM/CM

Bus

GFBIOptical fiber

(a) Communication between two SMs that areconnected to one MCCS board (b)

(c) Communication between SM and AM/CM

Communication between twoSMs that areconnected to different MCCS boards

GOPTGMC2 GMCCS

Dual port Dual port Dual port

Figure 5-4

5.2

Inter-module communication

The communications between GMPU & GMC2 in SM, between GMCCM & GMCCS in AM/CM and between GMCCSs are all implemented through mailbox. The communication between GMC2 and GMCCS is implemented through HDLC links. AM/CM & SM are interconnected through optical fibers, which also provide the communication path for GMC2 and GMCCS boards via optical interface (GFBI and GOPT), as shown in Figure 5-4 (c).

The physical layer of the inter-module communication is mainly implemented via optical fibers and HSCX (High-level Serial Communication Controller with extended feature and functionality). The link layer is in conformity with X.25 LAPB. The transfer layer is implemented by GMCCS. The transmission and application layers are implemented via the GMCCM board and software.

Switching Network

The central T network board (GCTN) and the intra-module switching network board (GNET) form a large capacity T-T-T switching network. GCTN is a 16k×16k T




5-7

switching network. The intra-module switching network is a 4k×4k single T switching network. The structure of the switching network is shown in Figure 5-5.

GCTN

GFBI GFBI

AM/CM

GOPT

SMGOPT

GNET

SM

GNET

GDTM GECR

BSC PSTN

GDTM GECR

BSC PSTN

Figure 5-5

5.3

Structure of the switching network

GCTN board is the central switching network board of the MSC/SSP/IP. It implements the middle “T” function of the “T-T-T” switching. GCTN board adopts the cross timeslot division of streamline working mode to enable the non-blocking switching of the 16k×16k time slots. It drives the 32 MHz, the frame synchronization 8kHz & the code element synchronization 4MHz signals from the clock frame and sends them to the GFBI board. It also adjusts the time delay of HW, 32MHz and 4MHz signals sent from the GFBI board. It can exchange O&M information between GMCCM & GMCCS via HDLC channel and at the same time, handles calls.

Digital Trunk System

Digital trunk equipment is the interface equipment between MSC/SSP/IP & other external systems, such as MSC, HLR, STP, BSC, SCP, PSTN and SMC. It provides standard E1 interface and is mainly used to perform code translation.




5-8

The position of the digital trunk equipment in the system is shown in Figure 5-6.

GNET

GNOD

GMPUGMPU

GDTM

AIE

GECR


BSC

HLRMSCSTPSCP

PSTN

PRAISDN

Control system

GMPUGMCC

MSC/SSP/IP

Switc

hing n

etwor

k

Figure 5-6

5.3.1

I.

Position of the digital trunk equipment in MSC/SSP/IP

In M900/M1800 MSC/SSP/IP, the digital trunk equipment adopts the PCM30/32 CEPT mode to receive & transmit the primary digital signals between MSC/SSP/IP and other external equipment. The digital trunk board (such as GDTM, GECR or PRA boards) implements the functions of digital trunk equipment.

GDTM

A GDTM (Digital Trunk Module) is used when MSC/SSP/IP connects with other GSM network equipment including BSC, HLR, EIR, STP, SCP, GGSN, SGSN, SMC and another MSC.

Basic functions

The digital trunk equipment has the following basic functions, such as code translation, re-timing and control function.




5-9

II.

5.3.2

Digital Trunk Module accomplishes the code conversion between High Density Bipolar of order 3 (HDB3) coding used in external trunks and Non Return to Zero (NRZ) coding used internally.

The digital trunk equipment can generate a clock signal internally to be synchronous with the signal frequency on the trunk. This signal is used to extract information from the trunk channel. The digital trunk equipment can co-ordinate different external and internal clock signals to eliminate the frequency difference of the internal and external clocks.

It also enables frame synchronization monitoring and self-loop test.

Digital trunk configuration

According to the equipment connected, digital trunk equipment shall be configured as different types. While configuring digital trunk equipment, same hardware is used but different software is loaded in order to provide different interface functions.

When MSC/SSP/IP is connected with network entities, such as HLR, EIR, STP, SCP, GGSN, SGSN, SMC and another MSC, the digital trunk equipment should be configured as “TUP”.

When MSC/SSP/IP is connected with BSC, the digital trunk equipment should be configured as “AIE”.

Through the PRA board, MSC/SSP/IP can connect with ISDN PBX. It provides 30B+D channels and fulfills telephony, MODEM transmission & facsimile services. In this case, the digital trunk equipment should be configured as “PRA”.

GECR

A GECR (Echo Canceller for R2 signalling) board is used when MSC/SSP/IP connects with PLMN network entities using R2 signalling. It has echo cancellation function.

The EC is required at the MSC-PSTN interface to reduce the effect of GSM delay when the mobile is connected to the PSTN circuit. Echoes can be generated due to the impedance mismatch in two-wire to four-wire hybrid transformer, or the poor separation of transmission and reception of the telephone set as shown in Figure 5-7.

When the path time delay of the echo is more than 30ms, the speaker will hear the echoing voice, which influences the communication quality or even interrupts the normal communications. For GSM system, due to the following reasons, echoes with 64ms time delay will be generated when the MS (Mobile Station) is connected with the PSTN subscribers.

Time delay in information transmission over radio links.




5-10

Time delay caused by the equalization against multi-path delay by the BSS or MS. Time delay due to code translation by TRAU (Transcoder & Rate Adapter Unit)

Therefore, GSM system must be equipped with EC.

H

Receive

4 wire 2 wire

Transmit

Far end

Near end

TelephoneElectric echo

Acoustic echo

Figure 5-7 Generation of echoes

The M900/M1800 MSC/SSP/IP adopts embedded EC and provides standard E1 interface to PSTN. The position of EC in the system is shown in Figure 5-8.

BSS

MS

MSC/SSP/IP

GECRE1

PSTN

Telephone

2-wire

Figure 5-8

5.4

Position of EC in the system

Signalling System

M900/M1800 MSC/SSP/IP supports three signalling systems: SS7, R2 and DSS1.

A signalling system can be divided into two parts according to hardware functions: signalling access part and signalling processing part. The signalling access part mainly comprises the digital trunk system (AIE, GDTM, GECR and PRA boards) and the switching network (GNET and GSNT boards), while the signalling processing part mainly includes the signalling processing units (LPN7, MFC and LPRA boards) and the control system (GMPU and GMCC boards), as shown in Figure 5-9. For details, refer to Signalling System of this manual.




5-11

GNET

GNOD

GMPUGMPU

GDTM

AIE

GECR

BSC

HLRMSCSTP

PSTN

PRAISDN

Control system

MFC

LPN7

LPRA

Signalling system

GMPUGMCC


Sw

itch i

n g n

etw

o rk

Figure 5-9

5.5

I.

Structure of the signalling system

Clock Synchronization System

The clock synchronization system of MSC/SSP/IP phase-locks the clock reference sources of the upper-level PSTN, BITS or GPS to provide AM/CM and SM modules with stable clock sources. Functions of the clock synchronization system are implemented mainly by GCKS in the clock frame of AM/CM.

System features

The clock synchronization system of the M900/M1800 MSC/SSP/IP has the following features:

The MSC/SSP/IP clock synchronization system adopts digital phase-locked loop and reliable software phase lock mode, which enables the clock of the whole system to follow reliably, the clock of PSTN, BITS or GPS. MSC/SSP/IP adopts the Stratum 2 Class-A clock, and the indices of the clock are fully compliant with the specifications. The clock system provides a complete display, alarm, maintenance and operation system. The operator, directly via the OMC, may set internal parameters of the clock.




5-12

II. System structure

The structure of the MSC/SSP/IP clock synchronization system is shown in Figure 5-10.

SM1

AM/CM

GCKS

GCKS

GSNT

GMCC GALM

GCTNGFBI

GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

SM2 GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

SM2 GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

Ref erence source

……

SM1

AM/CM

GCKS

GCKS

GSNT

GMCCGMCC GALM

GCTNGFBI

GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

SM2 GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

SM2 GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

PSTNPSTNBITSBITSGPSGPS

……

GECRUp lev el GMSC

SM1

AM/CM

GCKS

GCKS

GSNT

GMCC GALM

GCTNGFBI

GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

SM2 GOPTSM1

AM/CM

GCKS

GCKS

GSNT

GMCC GALM

GCTNGFBI

GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

SM2 GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

SM2 GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

Ref erence source

……

SM1

AM/CM

GCKS

GCKS

GSNT

GMCCGMCC GALM

GCTNGFBI

GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

SM2 GOPT

GNET

GMPU

GMC2

G

GCKS

GCKS

GSNT

GMCCGMCC GALM

GCTNGFBI

GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

SM2 GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

SM2 GOPT

GNET

GMPU

GMC2

GDTM

GECR

PRA

PSTNPSTNPSTNPSTNBITSBITSBITSBITSGPSGPSGPSGPS

……

GECRGECRUp lev el GMSC

Figure 5-10

III.

Structure of the clock synchronization system

The MSC/SSP/IP clock synchronization system receives the phase-locked clock provided by GECR, BITS or GPS. It extracts the clock and synthesizes it into the needed clock synchronization signals and sends these signals to GCTN & GSNT switching networks. GCTN and GSNT in turn, send the clock to other parts of the AM/CM. The GOPT board of SM extracts the clock from the optical signals, generates the required clock synchronization signals and sends them to the GNET board. The GNET board in turn, sends the clock synchronization signals to other parts of SM.

Control mode

The main hardware of the clock synchronization system is the clock frame, which contains two GCKS in hot backup mode. GMCCM performs operation and maintenance over GCKS boards via serial ports.




5-13

5.6

In case of remote operations (e.g. operation & maintenance) through OMC, OMC communicates with the MSC via BAM and the GMCCM communicates with the GCKS board via the RS422 serial port.

Alarm System

The alarm system of M900/M1800 MSC/SSP/IP works on the principle of distributed collection and centralized processing. The alarm information is collected on the alarm communication board and is processed according to the alarm types. This information is then sent to the alarm box and the OMC alarm console.

The whole alarm system is composed of the alarm box, OMC alarm console and alarm communication board. The structure of the alarm system is shown in Figure 5-11.

GMPU

GALM

Room environment alarm collection

Secondary power alarm collector

Secondary power alarm collector

GMC2

GMCCSGMCCM

BAM OMC alarm subsystem

GALM

AM/CM

SM

Alarm box

Figure 5-11 M900/M1800 MSC/SSP/IP alarm system

GMPU of SM & the GMCCM of AM/CM handle the software & hardware faults on boards and classify these alarms into different levels. The alarms are accordingly sent to the OMC alarm console & alarm box and corresponding audio & visual alarms are generated.




5-14

5.7

The alarm communication board (GALM) provides hardware interfaces for equipment room environment alarms, which enable the collection of alarms of temperature, humidity, fire, etc., as well as the collection of secondary power alarms from the racks.

Back Administration Module (BAM)

BAM is the bridge for communications between the MSC/SSP/IP and the OMC system. The user can conveniently and flexibly implement maintenance & operations on the switch via BAM.

BAM transfers the maintenance & operation commands from terminals to the foreground and directs the MSC responses to the corresponding terminals. Meanwhile, it enables the storage and transfer of charging information, alarm information and traffic measurement data. It stores important data on the hard disk, MO disk, magnetic tape or network server according to the requirements.

In normal cases, when the communication between BAM and MSC are not interrupted, all the functions of the terminal software can be fulfilled. In case the software is working abnormally or the system is down, BAM can automatically reset and restart within the set time. Through the network adapter, BAM can be connected with multiple WSs, and the same operations can be executed on the WS, to enable multi-point remote maintenance.

BAM is connected with the Front Administration Module (FAM) via a 2Mb/s HDLC link. The terminal system is connected with BAM via the network as shown in Figure 5-12.

PI NI

MCP

FAM

CM

Terminal network systemPeripheral

SM SM

HDLC

BAM

Figure 5-12 Principle of BAM




5-15

I.

II.

III.

BAM is an industrial computer running on the Windows operating system. It is placed in the AM/CM cabinet and occupies a standard frame. BAM comprises three major parts:

PI (Peripheral Interface)

PI can be connected with various external devices, including two MO disk drives, hard disk array, printer and tape drives, for the purpose of storage, transfer and hard copy of data.

NI (Terminal Network Interface)

NI is adopted to form the terminal systems (maintenance, testing, traffic statistics, special service and data setting) into a LAN, which can be connected with network servers and provide 10M~100M transmission channels, to enable data sharing in a larger range by extending the network via network bridge/routers.

MCP (Module Communication PC card)

Each MCP card provides two 2Mb/s HDLC channels to FAM to serve as the information channel between FAM and BAM. The logic of the BAM system is shown in Figure 5-13.

ISA/PCI BUS

PI

CD-ROM Hard disk Flop. disk COM

Video blaster

Video

SCSI card

MO

WDT

NI MCP card MODEM

OMC Server WS AMC PSTN

CPUMEM

Main board

BAM display

Figure 5-13 BAM logic map

BAM communicates with the control system through HDLC link and connects to OMC via LAN or WAN as per the network requirements.

When the MSC/SSP/IP and the OMC are co-located, BAM and OMC can be connected through LAN. When MSC/SSP/IP and OMC are far apart, they are connected via WAN. The position of BAM in the system is shown in Figure 5-14.




5-16

WS WSOMC server

WS

E1 X.25…...

PSTN

RAS router

Router

Router

LAN

LAN

Dial-up network

DDN

BAM BAM

BAM

TS multplexer/demultiplexer

TS multplexer/demultiplexer

Figure 5-14

5.8

Position of BAM in the system

Bill Administration Unit (BAU)

The BAU (Bill Administration Unit) receives the bills from the MSC, converts them into a special file format and saves them in a special directory from which the bill collector in the billing center can get the bills. Besides, it sends the charging files to the OMC SERVER, for the client to browse and query.

The SM sends the bills to the BAU for processing. BAU verifies the individual bill serial numbers from different modules, to ensure no bill loss or repetition and saves these verified bills. It then converts their format and stores them in a designated directory, for the reference of the billing center. The bill collector obtains these bills through the FTP or FTAM. After the bills in the BAU are taken away and the bill collector confirms the same, they are deleted. However, the BAU still keeps a backup directory of them and communicates with the OMC bill server through the TCP/IP protocol, to facilitate future browsing of these bills.

The position of BAU in the system and its connections are shown in Figure 5-15.




5-17

BAU0 BAU1

HUB

IP Router

HUB

BAU0 BAU1

MSC

HUB

DDN / E1 / X.25

LAN

MSC

IP Router

Figure 5-15

I.

Position of BAU in the system and its connections

System hardware

BAUs ensure the reliability of the system with the active/standby structure.

Each BAU is equipped with multiple, large-capacity pluggable hard disks in hot backup mode. It supports the hard disk with the redundancy technology and any failed hard disk can be recovered without interrupting the system running. To guarantee the security of the operation and the file system, a hard disk is divided into two logical arrays and the charging data is saved on both these logical hard disks to prevent any deletion by mistake. The bill collector can use the FTP or FTAM protocol to access the active/standby BAUs.

The BAU is connected to the billing center through Ethernet. Multiple remote MSCs can be connected to the bill server through WAN.

The charging system comprises the bill server and maintenance terminals. The bill server runs on Windows NT and the maintenance terminals can run on any platform supporting Java. Maintenance function can also be executed on server. The system structure is shown in Figure 5-16.




5-18

GMEM(Active)

GMEM(Standby)

GMPU(Standby)GMPU

(Active)

BUS

SM1

BAU (active)

GMEM(Active)

GMEM(Standby)

GMPU(Standby)GMPU

(Active)

BUS

SM2

GMEM(Active)

GMEM(Standby)

GMPU(Standby)GMPU

(Active)

BUS

SM16

BAU (standby)

LAN (Active)

LAN (Standby)

Private LAN heartbeat path

AM/CM

Serial port heartbeat path

Billing center

HUB

Figure 5-16

II.

BAU system structure

The two servers are connected through different network ports with the MSC and the billing center. In Figure 5-16, all the ports are 10M/100M Ethernet interfaces with no X.25 interface and they can be connected to the WAN via router or E1 multiplexer.

There are two heartbeat paths: one is connected through the serial ports and the other through a private network. They are used to transmit the timed handshaking information between the active server & the standby server and to monitor the running of these two servers so that a stable system running is ensured.

System performance and features

The performance and features of the BAU are listed below:

The MSC provides the interfaces to the billing center through BAU. The two BAUs are working in active/standby mode. Each BAU has its own interface with the billing center and the billing center collects the charging files from the two BAUs




5-19

5.9

simultaneously. The MSC ensures the availability of at least one BAU always. BAU can support the FTP and FTAM protocols.

BAU is equipped with arrays of disks and a CD-R drive, for the backup and storage of a large volume of bills.

The generation of MSC charging files is subject to the parameters, generation time and file size. A new charging file is generated either after a certain time, or when the file size reaches a preset value and both these parameters can be set/adjusted.

Two types of charging files can be generated, hot billing files and ordinary bill files.

Visitor Location Register (VLR)

In M900/M1800 digital cellular mobile switching system, VLR and MSC are merged into an entity named MSC/VLR.

The VLR database is located in AM/CM and its signalling processing is implemented by GMPU of MSC. MSC adopts the fully distributed modular design and VLR database adopts a centralized scheme.

To ensure good system reliability, hot backup is supported for all the VLR database parts. The SMs communicate with the VLR database server via Ethernet interfaces provided by the active/standby database interface boards (GMEM). Meanwhile, the handshaking message protocol between the active and standby VLRs is done through the private network.

The position of VLR in M900/M1800 MSC/SSP/IP is shown in Figure 5-17.




5-20

AM/CM

GMEM(Active)

GMEM(Standby)

GMPUStandby)GMPU

(Active)

BUS

SM1

VLR(Active)

GMEM(Active)

GMEM(Standby)

GMPU(Standby)GMPU

(Active)

BUS

SM2

GMEM(Active)

GMEM(Standby)

GMPU(Standby)GMPU

(Active)

BUS

SM16

VLR(Standby)

LAN(Active)

LAN(Standby)

Private LAN

........

AM/CM

GMEM(Active)

GMEM(Standby)

GMPUStandby)GMPU

(Active)

BUS

SM1

VLR(Active)

GMEM(Active)

GMEM(Standby)

GMPU(Standby)GMPU

(Active)

BUS

SM2

GMEM(Active)

GMEM(Standby)

GMPU(Standby)GMPU

(Active)

BUS

SM16

VLR(Standby)

LAN(Active)

LAN(Standby)

Private LAN

........

Figure 5-17

VLR position

The VLR provides the following basic functions:

Subscriber data storage: The subscriber data refers to the IMSI number, MSISDN number, location area, HLR address, user type and user state. Besides, the authentication and encryption data are also stored. Subscriber data retrieval: When a call is being set up, according to the MSC requests, the VLR provides the subscriber information for the MSC, including IMSI, TMSI and MSRN. IMSI attach/detach: It supports the IMSI attach/detach function. Location registration: When a mobile subscriber appears in a new location, or a location update message is received from the MS, VLR will initiate the location update to the HLR and retrieve the relevant subscriber information from the HLR or the previous VLR. Authentication: VLR supports HLR to retrieve the authentication triplet (RAND/SRES/Kc) from the AUC and stores them, or requests the authentication parameters from the previous VLR during location registration. In addition, the VLR supports the MS authentication at the request of the MSC.




5-21

5.10

5.10.1

MSRN allocation: It supports the MSRN allocation on a per call basis. While allocating the MSRN, it starts the 90s release timer to ensure the timely release of MSRN in case of failure. Handover number (HON) allocation: When handover is performed between two MSCs, the VLR provides the HON for the MSC and releases the HON after the call is set up. TMSI allocation: It keeps the identity of mobile subscribers confidential. Whenever the location is updated, it may reallocate the TMSI number. Regional subscription restriction: When the user location is to be updated, it decides if the location update is allowed in the area according to the zone code list of the user. Purge MS: When the MS does not connect or respond to the network within a specified time, VLR will delete the relevant subscriber data and notify the HLR about this. VLR data restoration: Upon restarting, VLR deletes all the IMSI record and TMSI number of the affected users. When the VLR receives the MSRN allocation and location update requests, it starts the data restoration process. The M900/M1800 VLR has the following features: It can store and manage 300,000 mobile subscribers. The reference load is: call handling 1.5 times/per user/per hour, mobility management 8.5 times/per user/per hour. Information retrieval delay≤1000 ms, Information registration delay≤2000 ms. The system parameters can be flexibly configured, e.g. number of subscribers in the system, through the OMC according to the user requirements. All the parts, such as GMEM board, network concentrator and database server, are configured in the hot standby mode to ensure the high reliability of the system.

Shared Resources

IWF

The IWF (Interworking Function) unit is necessary for interconnections between GSM network and other networks, such as PSTN, ISDN and PSPDN. It supports data services and fax service in the GSM system. It implements the functions of rate adaptation, radio link protocols (RLP/L2R), fax adaptation etc., provides 3.1kHz interface availability and supports transparent & non-transparent services. Figure 5-18 shows its position in the MSC/SSP/IP system.




5-22

PSTN

Internet

ISDN

计算机

传真机

ISDN话机

BSS

便携机

手机

MSC/VLR

IWF

MSC/SSP/IP

IWF

ISDN

PSTN

Internet

Fax

Computer

ISDN telephone

BSSMS

Portable computer

Figure 5-18

5.10.2

Position of IWF in the MSC/SSP/IP system

SRF

The SRF (Special Resource Function) equipment is used in the Mobile Intelligent Network and its functions include generation of signal tones, sending of the pre-recorded announcement (fixed or variable), collection of digits and synthesis of voices. These functions are implemented by the dual-tone number transceiver frame. SRF is generally configured in an SM to act on this SM, or it acts on other SMs containing no SRF, through data configuration.

There are two boards in the dual-tone number transceiver frame: GSPT and GDRV. The structure of SRF is shown in Figure 5-19.




5-23

GNET

GNOD

GMPUGMPU

AIE

GECR


BSC

PSTN

Control system

GSPT

GSPT

GMPUGMCC

GNOD

GDRV

GDRV

SRFSwitc

hing n

etwor

k

Figure 5-19

I.

II.

Structure of SRF

Intelligent speech board GSPT

A GSPT board is used to broadcast different prompt tones and waiting tones. The EPROM on the board can store 2.2-hour (62Mb) prompt/waiting tones. There is no limit to the prompt tone length and through the T-net switching on the board, GSPT can simultaneously provide 128 tone-broadcasting channels. In addition, it provides HW drive for GDRV board in the frame.

The memory unit EPROM is used to store various prompt tones. When a prompt tone is required, the GMPU issues commands through the serial port to GSPT board. GSPT board controls the T-net to switch the prompt tone to the designated time slot and sends it to other boards within the same frame. The HW signals from other boards in the same frame are also driven by GSPT board and changed into different signals before being sent to the main control frame.

DTMF number receiver and drive board GDRV

The GDRV and the GSPT boards are configured in the same frame to jointly broadcast the prompt tone and receive numbers in the user-network interaction process of IN service. Their main functions are:

NOD and HW signal level conversion.




5-24

5.10.3

Provides 16 DTMF number receivers.

The GDRV board uses the Digital Signal Processor (DSP) to provide the DTMF transceiving function. When the DTMF number receiving is necessary, the GMPU issues commands through the main node to the single chip processor on the GDRV. The GMPU controls the switching network to switch the relevant time slot to the serial port of the DSP. When the DSP detects the number, it reports the number to the single chip processor, which reports the number through the serial port to the GMPU. If DTMF signals are to be sent, the single chip processor instructs the DSP through the control logic to dial the number, which is then switched to the HW.

Signal Tone Generation Circuit

In the connection process, MSC/SSP/IP should provide signal tones to subscribers, including new service prompt, time report and weather broadcast. Digital tone signal generation circuits generate the digital signals needed for the above-described tones.

The digital tone signal generation circuit function is implemented by the GSIG board. Its position in the system is shown in Figure 5-20.

GNET

GNOD

GMPUGMPU

AIE

GECR


BSC

PSTN

Control system

GSIG

Switc

hi ng n

etwo r

k

GMPUGMCC

GSIG

HWHW

Figure 5-20 Position of GSIG

The GSIG circuit is controlled by the GMPU board. Its working status and playback contents are issued via commands or tables. Incoming and outgoing speech signals go through the GNET board via 2.048Mbit/s HW.




5-25

GSIG can be connected with two PCM HW to provide at any time 64 announcements which have been saved in the memory. Any HW channel can be used to record in any TS (Time Slot).

Signal tone generation circuits are of two sets in each module, A and B, which work as mutual backups. The circuits are the same in their hardware structure and can be interchanged with each other.

02 Hardware Description

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