OCB 283

Presentation by Paritosh Malick Electronics n Comm. Engg. 06ESKEC0531

MTNL A Brief Introductiony On 28th February Mahanagar Telephone Nigam Ltd.

was incorporated as a Public Limited Company under the Companies Act, 1956. y The company has been set up to take over the management, control and operation of Delhi Telephone District and Mumbai Telephone District of the Department of Telecommunications and to plan, establish, develop, provide, operate and maintain all types of telecommunication.

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Objectives of MTNLTo upgrade the quality of telecom services To expand telecom To raise necessary financial resources To provide new telecommunication services, particularly needed by the business community and public administration such as Cellular Mobile Radio Telephone, Radio Paging, Facsimile Videotex, Teletex, Electronic Mail etc. y To invest in Human Resource Development y To organize and dovetail the training programmes.y y y y3

OCB 283y OCB 283 is digital switching system y It supports a variety of communication needs like basic

telephony, ISDN, interface to mobile communication, data communication etc. y This system has been developed by CIT ALKATEL of France. y The first OCB-283 exchange came to India in1993. y The exchange, which are being supplied to India, belong to R21 version.4

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Silent Features of OCB 283y digital switching system with single T stage Switch , maximum of 2^12 (=2048) y supports both analog and digital subscribers y provides telephony, ISDN, Data communication, cellular radio and other value added services y automatic recovery feature y charge accounts of subscribers are automatically saved in the disc. This avoids loss of revenue in case of total power supply/battery failure.

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y double remoting facility y fast exchange of information and avoids complicated

links and wiring between various units y huge handling capacity

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SUBSCRIBER ACCESS UNITS (CSN)y equipped with either analog or digital subscriber or

both y either placed in the exchange switch room or at a remote location y depending on the location, CSN is known as CSNL or CSND and the subscriber shelf is known as local or remote concentrator i.e CNL or CNE.8

Architecture of CSNCSN

Digital control unit (UCN)

Concentrators (CNL or CNE)

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Digital Control Unity interface between concentrators and the exchangeControl and connection units(UCX) # two such units # operate in the pilot standby mode # In case of any fault in the active UCX, the switch over takes place without interruption to existing traffic Auxiliary Equipment Processing Group (GTA) # Generates tones and recorded announcements for communication # Decodes DTMF dialing

UCN

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Concentratorsy accommodates subscriber line cards y subscribers thatcan be connected to a concentrator areDiscriminated Analog subscriber (TABAE card)

2B+D digital subscriber (TABN 3G card)

30B+D digital access (TADP card)

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Architecture of OCB283y Subscriber Access Units (CSNL, CSND, CSED) y Trunks and Junction connection Units (SMT) y Switching Matrix (SMX) y Auxiliary Equipments (SMA) y Control Units (SMC) y Communication multiplexes (MIS & MAS Token rings) y Time base generator (STS) y Operation and Maintenance Unit (SMM)

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LR Remote Concentrator CSNL SWITCHING MATRIX (SINGLE T )

LR CSNL

LR CSND SMT SMA

PCM Junctions

MASSMCCONTROL UNITS (SMC)

SMC

MISOPERATION AND MAINTENANCE UNIT (SMM A & B ) NMC

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SAB FUNCTIONy Stands for Selection & Amplification of Branches y role - to generate two sets of LRs in Trans direction

with calculation of parity etc. y In case of errors the samples from only the good branches are taken. After automatic testing of the quality of transmission of both the branches by the common control & the faulty bran is withdrawn from the service.

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AUXILIARY EQUIPMENTS CONTROL STATION (SMA)

Has two function unit.. Namelyy y

ETA PUPE

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Connection unit X

SMX ASAB A MLCOM

SAB B

Connection Unit Y

SMX BMLCOM SAB A

SAB B

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ETAy Consists of three components, namelyFrequency receiver/generators Conference call circuits Tone generators

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CONTROL UNITS

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Architecture of Station (SMC)y all control units like MR, MQ, TR, TX etc and SMA are

implemented on the common type of hardware architecture, known as station. y station is built around a multiprocessor station bus BSM y processors are Motorola 68020 processors and operate at 15.6 MHz clock y There can be one principal processor (PUP) and 4 secondary processors (PUS) in a station19

Main Processor Unit (PUP)

Common Memory

Secondary Processor Unit 1 (PUS)

Secondary Processor Unit 4 (PUS)

Main Coupler (CMP)

Secondary Coupler 1 (CMS)

Secondary Coupler 4 (CMS)

Specific Coupler

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CONTROL STATION OF OCB 283GLR (A & B) GLR (A & B)

CSNL

SMXSMA 1 SMA 2 SMA 3

SMTPCM

MAS 2

A&B

MAS1 A & BSmc1 Smc2 Smc3 Smc4 Smc5

MIS A & BSMMA SMMB21

COMMUNICATION MULTIPLEXES (MIS, MAL, MAS)y OCB 283 exchange the communication multiplex

highways are utilized for interchange of messages between various equipments of exchange y communication multiplexes work on the principle of computer s circular LANs using TOKEN RING protocols22

There are three types of communication multiplex highway according to their useMIS -- INTER STATION MULTIPLEXprovided for interchange of messages between two SMCs and between an SMC and SMM

MAS STATION ACCESS MULTIPLEX provided for interchange of messages between CSNL, SMT, SMA and SMX on one- hand and control units on the other hand MAL ALARM MUTIPLEXprovided to handle exchange alarms from all the hardware stations of exchange except CSNL

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OPERATION & MAINTENANCE STATION (SMM)y SMM station has full duplicated hardware SMM A & SMM B. y One of the two SMM is pilot & other works as hot standby y SMM dialogues with all SMCs over MIS token ring y up to 4 alarm reception rings for handling exchange alarms. y SMM receives all alarms from whole exchange on alarm rings MAL y has DIGITAL VOICE ANNOUNCEMENT SYSTEM MPNA24

FUNCTIONS OF MAINTENANCE STATION (SMM)SMM is provided to supervise the functioning of various exchange equipments and to take suitable action in case of malfunctioning of any equipment. It does the defence of control units in case of fault. All the files and data are stored in SMM hard discs, which can be loaded in any time. SMM also carries out the re-initialization of the exchange, when required.25

Time base generator (STS)y synchronize PCM links connected to connection units y has three oscillations, all generating S MHz and SBT

time base. The switching network selects the time base as per majority logic. y switching network selects the time base as per majority logic

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Majority Logic MCX RCHOR 0

SMARCHOR 1 Majority Logic MCX RCHOR 2

CSNL SMA

S MHz & Frame Synch (SBT)

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Architecture of SMMy SMM stands for Maintenance Multi processor Station y It is built around two identical 68030 microprocessors y This multi processor station works in pilot and hot

standby mode

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DIMENSIONS FOR OCB -283 EXCHANGEy y y y y y y y y y

Rack size in (mm) 2200 Hx 950 Wx 690 D No. Of rows (suits) in a Switch Room Not Fixed No. Of racks per suite Not Fixed But for practical convenience May be limited unto 16 Inter Suite Gap Min 800 to 1000 mm Max is variable Clearance from Sidewalls 1500 mm Height of Ceiling Minimum 3000 mm Approximate floor area for 6k 44 sq Exchange Sequence of layout of racks in No special sequence or suites29

FACILITIES PROVIDED BY OCB 283y y y y y y y y y y y y y

A line can be made out going or incoming. Immediate hot line Delayed hot line facility Abbreviated dialing Call forwarding Conference between 4 subscribers Call waiting indication Automatic call back on busy Priority line Malicious call identification Battery reversal Detailed billing Absent subscriber service30

LOCAL CALL PROCESSING IN OCB 283y y y y y y y y y y y

Detection of off hook condition and sending new call message Continuity check between UCN and CN Reception of new call message by PUPE and MR MR processing and connection of dial tone to calling subscriber Reception of digits Pre analysis of digits to determine type of call Analysis to determine called party s physical Address and Charging Test of called subscriber s line & ringing current to called subscriber. Connection of Ring Back Tone to the calling subscriber. Connection of calling subscriber and called subscriber and charging Supervision of subscriber s status by CSN

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Calling Subscriber Line cards LR1 TS1 FF LR CSN

Called Subscriber

SMX COM

UCN

CN

ETA

PUPE

MAS

TX

TR

MR

MQ

GX

PC

MIS

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THANK YOU

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Welcome to any sort of Question / Queries

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