bts

outliney Overview

y y y y

BTS Structure BTS hardware description Baseband Digital Subsystem (BDS) Channel Processing Module (CHM)y

Basic Structure and Functions of CHM

y Communication Control Module (CCM) y CCM Structure Diagram y Basic Composition and Functions of CCM y Description of Panel Indicators and Buttons y RF Interface Module (RFIM) y Diagram of RFIM Structure y Functions of the RFIM

y E10B switching system(Term paper) y Block diagram of E-10-B system y CSE(Electronic subscriber connection)y

CSE functions

y URM (Multiplex connection unit) y Functions of URM y ETA (Frequency sender and receiving unit) y Frequency receiver (RF) y Tone generator (GT) y CX (Switching Network) y MR (Multi register) y TR (Translator) y TX (Charging Unit) y MQ (Markers) y OC ( Monitoring Unit)

overviewy BTS contain base band system and transceiver system y The base band system includes: y CHM, CCM, RFIM, CDSU, SAM and power supply module. y The transceiver system includes: y RF front end (RFE), transceiver (TRX), high power amplifier (HPA) and power supply module.

y According to the structure, the system includes the

following components from the top to the bottom:y FE plug-in frame y HPA plug-in frame y Power distribution & module (PSMD/PPM/PSMC)

plug-in frames y TRX plug-in frame y BDS (baseband digital subsystem) plug-in frame

BTS Structure

BTS HARDWARE DESCRIPTIONy Base Station Transceiver(BTS), including the following

components:(1) BDS: Baseband Digital Subsystemy CHM: Channel Processing Module y CCM: Communication Control Module y RFIM: RF Interface Module y SAM: Site alarm module y BTS_CDSU: BTS-side CDSU module

(2) TFS: Timing Frequency Subsystemy GPSTM:

GPS Timing Module (optional, customized) y FDM: Frequency Distribution Module y TCM: Timing Control Module

to

be

(3) RFS: RF Subsystemy TRX: RF Transceiver y HPA: High Power Amplifier y RFE: RF Front End y RFCM: RF Control Module y BTM: Base station Management subsystem

Baseband Digital Subsystem (BDS)y The main functions of the BDS are y To implement the modulation and demodulation of baseband signals y To interface with the RF part and the Abis interfacing with the BSC. y BDS is composed of up to 12 channel processing

modules (CHMs), 2 communication control modules (CCM), 2 RF interface modules (RFIMs) and 1 BTS_CDSU module.

y The BDS system can provide the modulation and

demodulation of up to 192 wireless channels (including overhead channels, soft handoff service channels and subscriber service channels).y The BDS system can provide one non-channelized E1

interface (Abis interface) with the data rate of 2Mb/s or two non-channelized E1 interfaces of the same data rate working in load sharing mode.

Channel Processing Module (CHM)y The

channelSignal processor unit Bus interface To CCM To CCM

processing module (CHM) is the basic part of CDMA channels, mainly implementing the modulation and demodulation of various CDMA channels.

CMDU

To RFIM

MAIU

Basic Structure and Functions of CHMy Channel processing unit: y The kernel control part of a CHM, implementing the board internal management and maintenance. y Bus interface unit: y Implementing the communication connection between the CHM and other boards in the BSS. y Channel modulating/demodulating unit: y Implementing the modulation and demodulation of the CDMA channels. y Maintenance/alarm interface unit: y Sending the maintenance/alarm information in the CHM to the upper-level board.

Communication Control Module (CCM)y the major function of the CCM is to implement

centralized control over the whole BDS subsystem s data signaling routing, signaling processing, resource management and maintenance operations.y The various factors such as thermal design and

electromagnetic compatibility design have been taken into consideration from the selection of components to PCB arrangement, so as to ensure board reliability.

CCM Structure Diagram

Basic Composition and Functions of CCMy CPU system: y The kernel of the CCM, responsible for the processing of related protocols (such as Abis interface protocol) and BDS external communication, maintenance, management etc. y MTSI: y Master-to-slave interface y U-gateway: y Implements BDS internal communication control and the connection with other subsystems;

y Dual-bus logic interface: y Implementing the communication between the CCM and other boards in the BDS and the communication between the CCM and other boards in the BSS system; y 5MHz clock generation and duplication: y Generating the working clock for the gateway and dual buses.

Description of Panel Indicators and Buttonsindicator Blinking when the board is working normally when board error occursACT(green)Active ALM(red):-Alarm indicator Lighting up RUN(green):-Running

state indicator Lighting up when board is in active stateM/S button:-Master/slave switchover RST :-Button Manual reset TEST:-Socket Debugging port

RF Interface Module (RFIM)y RFIM is the short form of Radio Frequency Interface Module. y This module belongs to the digital subsystem in the BTS system, Controlled by the communication control module (CCM), is the connection point between the digital subsystem and the RF subsystem. y The major functions of this module are as follows: y transmission and processing of transmission and reception baseband data. y transmission and processing of non-emitted and nonreceived basebands data (such as configuration control, status alarm etc.) y distribution and driving of clock signals.

Diagram of RFIM Structure

Functions of the RFIMy MCU system: y Implementing board startup, self-test, status error reporting etc. y DISCO logic: y It receives the signaling from the CCM and then distributes it to the RFCM of three sectors and the board s own MCU, and receives the signaling from the RFCM of three sectors and reports the CCM after the interrupt polling processing. y Forward link processing: y Mainly implementing the summing processing and filtration processing on the baseband data from the channel board as per the sectors.

y Backward link processing: y Mainly implementing synchronization check on the data from the RFCM (RF control module). y Data multiplexing/demultiplexing unit: y It mainly implements multiplexing processing on the forward data and signaling, transmits them to the FRCM through LVDS y performs demultiplexing processing on the backward data and signaling from the RFCM and then sends them to the board s FPGA for corresponding processing.

Term paper

Block diagram of E-10-B system

CSE(Electronic subscriber connection)y Its primary role is to connect subscriber line to

different exchange units.

y The electronic subscriber unit contains 8 racks with 16

PCB cards in each rack and each PCB card contains 16 connections. Hence, total of 1024 connections.

y NE= Equipment no is given from CSE. From

equipment no or no given to subscriber all the details about subscriber line can be known

y The CSE performs the following functions:y The management of subscribers. y interface between subscribers and the E 10 B units. y fault handling and identification of faulty units.

y The

functions related to subscribers are as follows:y feeding of subscriber lines. y detections of loop status.

the

management

of

y processing of remote control signals. y connection or disconnection of a subscriber's equipment

on an TS. y search for a free time slot (TS).

y The functions related to interface between subscribers and the E 10 B units: y Analogue/digital conversion of speech paths y processing of new call, on-hook functions y test of a called subscriber y monitoring of subscribers during the communication phase y subscriber lines and equipment test y management of traffic counters y sending of alarms and error messages y The functions related to security and recovery y detection of international faults y tracing these faults

y The CSE is divided into four functional areas: y Subscriber connection unit y concentration network y transmission unit y control logic y The subscriber lines are connected to the connection

units whose purpose are:y power to telephone sets. y detection of line loops. y sending of bell currents. y transfer to tests

y The concentration network concentrates 1024 incoming lines onto 120 outgoing ones. y The transmission unit performs analog/digital and digital/analog conversion, transmission and reception of speech samples on the LRs (CSEL) or the PCMs (CSED). y The control logic manages the speech path system comprising the three units defined above and ensures interchanges with the units of the exchange.

URM (Multiplex connection unit)y The

multiplex connection unit provides the connection interface between the E 10 B exchange and:y remote subscriber connection units (URAD) y trunk circuits from remote exchanges (E 10 B or other).

y Within the URM is found PCM resynchronization,

speech-path mixing, signal injection and extraction, as well as fault -handling and location functions.

Functions of URMy transmission of speech channels between PCM links

and network lines or multiplexes (transcoding, incoming speech channel resynchronization with local clock)

y Interchange with remote URA and other exchanges y URM also controls and supervises speech channel

status, and switches incoming PCM links so that in the event of a switching network failure, traffic from an MRM module is not entirely blocked.

ETA (Frequency sender and receiving unit)y It performs the following functions: y Reception of frequencies sent by pushbutton telephones, exchanges using multi frequency signaling and circuit testing frequencies (LRS links). After decoding, these frequencies are sent to the MR (LTRF). y Generation of tones, multi frequency signaling and circuit testing frequencies (GVS). y Simultaneous connection of subscribers: conference circuits (links LRE-LRS). y Connection with central units (LU/LC).

y Frequency receiver (RF): A minimum of 2 frequency

receivers for each ETA: RF1, RF2.These process the frequencies or frequency combinations form 31 time division channels

y Tone generator (GT):A maximum of 3 tone generators

for each ETA: GT1, GT2, GT3.These continuously send the various tones and frequencies over the GVS links and convey the following signals:y usual tones, interrupted or continuous, IT, routing etc., y Multi frequency signaling ensuring interchanges with

the remote exchanges y pure frequencies at preset levels intended for circuit testing

CX (Switching Network)y The switching network CX receives commands from control units for switching digital signals from one time slot(TS) on an incoming network line (LRE) to a TS on an outgoing network line (LRS). y The CX is connected to: y To the connection unitsy y

for speech paths for signaling

y to the control units y to UGCX for command or control y to OC for positioning

y Each module can switch any TS from any LRE line to

any TS on any LRS line. y In other words, all incoming TS are accessible on all outgoing TS. This concept is referred to as full accessibility . y The total switching network capacity is 384 LR lines(LRS/LRE pairs). Since each module handles 16 lines, the maximum configuration is 24 switch modules. y Each switch module is subdivided into three sections:y input time switch CTE y space switch CS y output time switch CTS

MR (Multi register)y Multi registers MR are control units. y They are the main decision making units during call set up and release. y The 256 registers in each multi registers can supervise simultaneously the setting up and clearing down of 254 calls, registers 0 and 255 being assigned to routine tasks. y There are 2 to 6 multi registers in exchange.

y Each multi register can: y exchange messages with all central units, y send commands to the switching network, y receive subscriber or circuit signals from connection units UR. y Functions of multi registers:y call processing functions y operation and maintenance function y environmental and links functions y Hardware of MR:y The multi register has two sections:y y

the interchange unit the register unit

TR (Translator)y The translator is a control unit. y It is duplicated for reasons of security, Two translators

operate in load sharing mode.

y The translator provides the multi registers with all

data needed to set up and clear down calls, including that relating to additional services.

y On request from multi registers, the translator

supplies the characteristics of subscriber lines and trunk circuits.

y The translator executes the following operations: y seeking subscriber line or circuit class of service data when a new call ( calling subscriber off hook) condition is detected. y translating prefixes or the first digits dialed by the calling party. y translating called party directory numbers into equipment or circuit numbers. y handling translation operations for chaining and overflow routing functions. y managing additional services.

TX (Charging Unit):y The charging unit handles subscriber line accounts,

computes the number of basic metered units chargeable for a given telephone call and outputs detailed billing data for some subscribers.

y Charging unit operations are initiated by multi

registers. At the start of each telephone call, on receiving a command from a multi registers, the charging unit seeks and assigns a charging register.

y It receives charge metering pulses from trunk circuits.

y It commands signal transmission where required. y It sends detailed billing messages and observation

messages to standby charge recording unit DSF where the OMC is down or unavailable.

y It sends subscriber meter readings detailed billing

messages ad traffic observation messages to OMC.

y It stores traffic observation data. y Each exchange has two charging units operating on a

load sharing basis.

MQ (Markers)y The marker routes the main switching messages

between the different units in an exchange

y This involves: y receiving new call and subscriber line or circuit on good conditions from connection units y sending requests to connection units:y

y

signaling sender/receiver, trunk circuit or subscriber line test message subscriber line or circuit supervision start or end message.

y sending and receiving messages from the OMC.

OC ( Monitoring Unit)y The monitoring unit, one of the exchange central

units, provides the interface between the operation and maintenance centre (OMC) and E 10 B exchange units connected to the OMC.

y It is connected to message transmission equipment

ETM at the OMC end.

y The monitoring unit receives and processes messages

from the OMC addressed to exchange units, and forwards messages from these units to the OMC.