B-Tech Switching.doc MTNL

8/22/2019 B-Tech Switching.doc MTNL

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DEPARTMENT OF

ELECTRONICS AND COMMUNICATIONS

SWITCHING SYSTEMS

Report of Practical Training undergone atthe end of VI Semester by


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CERTIFICATE

This Practical Training Report entitled SWITCHING SYSTEMS is

being submitted by Bright Student of2005-2009 batch as

a report of the work undertaken by them at MTNL company. This work is

the result of the students own effort, and was undertaken by them at the end

of the VI semester.

( Director, ASE)

(H.O.D, ECE deptt.)


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ACKNOWLEDGEMENT

I would like to thank the various SDEs (Senior Divisional Engineers) in MTNL (NP)

who taught and guided me throughout the six week training period. I would also like to

thank my Parents(especially my mother) and without whom this training

report would not have been possible. Finally, I thankGod for sending all the above

people in my life.


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ABSTRACT

During the six weeks of training at MTNL, I was assigned to various switching rooms for

some time.I studied the manuals first and got familiarized with the basics of the particular

switching system.I also learned general information about the system.This was followedby a tour of the actual hardware units installed in the MTNL switching rooms with the

SDEs(Senior Divisional Engineers) who explained their general working and

functions.I, then, learned how the switching system was controlled through software andhow subscriber management took place through commands.I also did some of the trivial

work like making lists,cross-checking data,etc.

Also, I took a tour of the Power Room and the MDF Room and learned their working.ThePower Room is responsible for the entire plants Power Supply. The MDF Room housed

the Main Distribution Frame and the PCM systems which are connectors between the

switching rooms and the outside world.


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INDEX

Chapter 1(a) Company Profile

Chapter 1(b) History

Chapter 2 EWSD Switch

Introduction

System Features

System Architecture

Digital Line Unit

Line/Trunk Groups

Switching Network

Coordination Processor

Common Channel Signalling Network Control

Data Maintained In Exchange

Chapter 3 AXE-10 Switch

Introduction

Design Features

Functional Hierarchy

APT Subsystem Functions

APZ Subsystem Functions

Organization Of APT Subsystem

Equipment Location

Subscriber Switching Subsystem(SSS) Subscriber Management Command

Mechanical Features

Summary Of Principle Features Of AXE-10

General Features Of Interest

AXE-10!

Hardware Of AXE-10

Exchange Capacity

Chapter 4(a) Power Plant

MaintenanceChapter 4(b) MDF(Main Distribution Frame)

PCM(Pulse Code Modulation) System

Chapter 5 OCB-283 Switch

Introduction

Alcatel Global Network


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Architecture

- Host Switching Matrix

- PCM Controller- Auxillary Equipment Manager- CCS7 Protocol Handler & CCS7 Controller

- Call Handler(MR)- Subscriber & Analysis Database Manager(TR)- Call Charging & Traffic Measuremebt(TX)- Matrix System Handler(GX)- Message Distributer(MQ)- Communication Multiplexing- Operation & Maintenance Function(OM)

Chapter 6 5ESS Switch

Introduction

Switching Module

Communication Module Administrative Module

Exchange Biodata

Chapter 7 Conclusion


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CHAPTER 1(a)

COMPANY PROFILE

MTNL was set up on 1st April, 1986 by the Government of India to upgrade the qualityof telecom services, expand the telecom network, introduce new services and to raise

revenue for telecom development needs of India.s key metros . Delhi, the political capital

and Mumbai, the business capital of India. In the past 20 years, the company has taken

rapid strides to emerge as India.s leading and one of Asia.s largest telecom operatingcompanies. Besides having a strong financial base, MTNL has achieved a customer base

of5.92 million as on 31st March 2006.

The company has also been in the forefront of technology induction by converting 100%

of its telephone exchange network into the state-of-the-art digital mode.

The Govt. of India currently holds 56.25% stake in the company.


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CHAPTER1(b)

HISTORY

Historical Development

1911 Establishment of Delhi telephones system with manual exchange

1926 Opening if 1st automatic exchange (Lothian exchange)

1937 Opening of Connaught Place exchange.

1945 First Manual Trunk exchange opened.

1950 Opening of Cantt exchange

1953 Tiz Hazari Exchange (Lothian exchange ceased working) commissioned.

1955 Secretariat exchange commissioned

1958 Karol Bagh exchange (SXS) commissioned.

1961 Jor Bagh exchange (SXS) commissioned.

1961 Shahadara exchange (SXS) commissioned.

1962 Opening of First STC service to Agra.

1963 Delhi Gate (27) exchange commissioned.

1964 Delhi telephone crosses 50,000 lines.

1966Opening of exchanges at Nangloi, Narela, Najafgarh, Bahadurgarh andBallabgarh.

1967 Rajpath (38) exchange commissioned

19681st X-Bar exchange (KB58) commissioned. X-Bar exchange (JB62)

commissioned

1969 Trunk automatic exchange (TAX) commissioned

1970 Okhla X-Bar exchange commissioned.

1972 Opening of Idgah-I (51) Strowger exchange.

1972X-Bar (31) Janpath-I exchange commissioned. Delhi telephones crosses 1

lac lines.


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1973 Opening of X-Bar (67) Chanakya Puri exchange.

1975X-Bar Janpath-IV (34) exchange commissioned. X-Bar Shahdara East (20)

exchange commissioned.

1976 Shakti Nagar (74) exchange commissioned. Idgah-II (52) X-Bar exchange

inaugurated by Mr. Fakhuriddin Ali Ahmed, President of India, on 28.8.76and presided over by Mr S.D. Sharma (Minister of Communications).

Opening of Shahdara East (20) Extension-I, X-Bar exchange on 31.8.76. It

was inaugurated by Mr H.K.L Bhagat (Minister of State for Works &

Housing) and Mr S.D. Sharma (Minister of Communications).Opening of Hauz Khas (65) X-Bar exchange on 18.10.76. It was

inaugurated by Mr S.D. Sharma (Minister of Communications) and presided

over by Mr Radha Raman (Chief Executive Councillor, Delhi).

1977 Opening of STD Service to Indore and Ambala on 5.10.77 by Mr Brij Lal

Verma (Minister of Communications).

1978 Opening of Rajouri Garden-I (59) X-Bar exchange in Feb 78

Opening of Hauz Khas -II (66) X-Bar exchange on 15.2.78, by Mr Brij LalVerma (Minister of Communications).

Opening of Janpath-V (35) X-Bar exchange.

Opening of Nehru Place (68) Strowger exchange on 4.11.78 by Mr Brij LalVerma (Minister of Communications) and presided over by Mr R.K. Gupta

(Mayor of Delhi).

1986 Creation of Mahanagar Telephones Nigam Limited

1986 First digital exchange world technology brought to India

1987 Largle Scale introduction of push button telephone made dialling easier.

1988 Phone Plus services multiplied benefits to telephone users.

1992 Voice Mail Service Introduced

1996 ISDN services introduced

1997 Wireless in Local loop introduced

1999 Internet services introduced.

2000 Millennium Telecom Limited, a wholly owned subsidary of MTNL is born2001 Launched GSM Cellular Mobile service under the brand name Dolphin

Launched WLL Mobile services under the brand name Garuda.The company listed at New York stock exchange(NYSE)

United telecom ltd.,MTNL Joint venture in Nepal,for providing WLL based

services in Nepal became operational.CLI based Internet express services introduced.


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2002 Launched pre-paid GSM Mobile services under the brand nameTrump.Email on PSTN lines introduced under the brand name mtnlmail.

2003 Introduced CDMA 1x 2000 Technology under the brand name Garuda 1-x.Introduced pilot project of ADSL based Broadband services.Introduced

Virtual Phone services.Mahanagar Telephone Mauritius Ltd. bagged secondoperator license in Mauritius.

2004 Expanded GSM & CDMA capacity by 800,000 lines each (total 1.6 million

lines expanded) STD/ISD rates slashed by almost 60%. MTNL subsidiary

MTML obtained license to provide fixed, mobile & ILD services inMauritius. Launched Wi-Fi & digital certification services. State of the art

training centre CETTM commissioned.

2005 Leading market in GSM customer additions. Launched broadband services

under the brand name TRI BAND. Floated tender for 1 million 3G GSM

lines.

CHAPTER 2

EWSD SWITCH

Introduction

Six new technologies were validated by the Department of Telecommunication. These

foreign suppliers set up the exchanges, each of 10,000 lines capacity (including twoRSUs of 2K each), at different places. One of these technologies is EWSD.

EWSD stands for Electronische Wheler Systeme Digitale, in German and means

Electronic Switching System Digital.It is one of the technologies selected for TAX and also for Intelligent Network and

Mobile Communications.

System Features

EWSD Digital Switching System is designed and manufactured by M/s

Siemens,Germany.

It can support maximum 2,50,000 subscribers or 60,000 incoming, outgoing or

both way trunks, when working as a pure tandem exchange.

It can carry 25,200 Erlang traffic and withstand 1.4 million BHCA. It can work as local cum transit exchange and supports CCS No.7, ISDN and IN

and V5.X features.

System Architecture

The main hardware units of an EWSD switch are: -


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1. Digital Line Unit (DLU): It is the functional unit on which subscriber lines are

terminated.

2. Line/Trunk Group (LTG): Digital Trunks and DLUs are connected to LTGs. Theaccess functions determined by the network environment are handled by DLUs

and LTGs.

3. Switching Network (SN): All the LTGs are connected to the SN whichinterconnects the line and trunks connected to the exchange in accordance with

the call requirement of the subscribers. CCNC and CP are also connected to the

SN.4. Coordination Processor (CP): It is used for system-wide coordination functions

such as routing, zoning, etc. However, each subsystem in EWSD carryout

practically all the tasks arising in their area independently.

5. Common Channel Signaling Network Control (CCNC) Unit: It functions as theMessage Transfer Part of CCS#7.UP(User Part) is incorporated in the respective

LTGs.

Below, the Block Diagram of EWSD shows that the most important controls in EWSDare distributed throughout the system. This distributed control:-

- reduces the coordination overheads and necessity of communication between theprocessors,

- and results in high dynamic performance standard.

In EWSD, for inter-processor communications, 64 kbps semi permanent connections are

set through SN. This avoids the necessity for a separate interprocessor network.


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Digital Line Unit (DLU)

Analog or Digital (ISDN) subscribers, PBX lines or V5.1 interface are terminated on

DLU. DLUs can be used locally within the exchange or remotely as remote switch

unit, in the vicinity of the group of subscribers.

DLUs are connected to EWSD sub-systems via a uniform interface standardized by

CCITT, i.e., Primary Digital Carrier (PDC) to facilitate Local or Remote installation.A subset of CCS#7 is used for CCS on the PDCs.

One DLU is connected to two different LTGs for the reasons of security.

Within the DLU, the analog subscribers are terminated on SLMA (Subscriber Line

Module Analog) cards (module). Similarly, Digital (ISDN) subscribers are terminatedon the SLMD (Subscriber Line Module Digital) modules.

Each module can support 16 subscribers, hence has 16 SLCA/SLCDs (Subscribers

Line Circuit Analog/Digital) and one processor SLMCP/SAP.

One DLU can carry traffic of 100 erlangs.

A standard rack of DLU (local) can accommodate two DLUs of 952 subscribers each.

In case the link between a remote DLU and the main exchange is broken, thesubscribers connected to the remote DLU can still dial each other but metering will

not be possible in this case.

For emergency service, DLU controller (DLUC) always contains up-to-date

subscribers data. Stand Alone Service Controller Card (SASCE) is provided in each

R-DLU for switching calls in such cases (call setup and release for analog and ISDN

subscribers and enables DTMF dialing for push-button subscribers).

This card is also used for interconnecting a number of remotely situated DLUs

(maximum 6), in a cluster, called a Remote Control Unit (RCU), so that subscribers

connected to these remote DLUs can also talk to each other in case the link of more

than one DLU to the main exchange is broken.

All DLUs are provided with a Test Unit (TU) for performing tests and measurementson SLCAs, subscriber line sand telephones.

An ALEX (Alarm Externals) module is used for forwarding external alarms, i.e., fire,

temperature, etc. to System Control Panel (SYP).Numbers of SLMAs are accordinglyreduced to accommodate these modules.

The main components of a DLU are:

- SLMAs and/or SLMDs

- Two Digital Interface Units for DLU(DIUD)for connections of the PDCs.


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- Two DLU Controls (DLUC).

- Two 4 Mbps networks for the transmission of user information between SLMs

and the DIUDs.

- Two control network for the transmission of control information between SLMs

and DLUCs.

- TU, ALEX modules.

Line/Trunk Groups

The line/trunk groups (LTG) forms the interface between the digitalenvironment of an EWSD exchange and the switching network (SN). The primary

functions of the LTGs are as follows: -

(i) Call processing functions, i.e., receiving and analyzing line and register signals,injecting audible tones, switching user channels from and o the switching

network, etc.

(ii) Safeguarding functions, i.e., detecting errors in the LTG and on transmission

paths within the LTG, analyzing the extent of errors and initiating counter

measures such as disabling channels or lines, etc.(iii) Operation and maintenance functions, i.e., acquiring traffic data, carrying out

quality-of-service measurements, etc.

The LTGs can work with all standard signaling systems (e.g. CCITT No. 5,R2,

No.7).Echo suppressers can be incorporated in the LTGs for the connection of long-haul circuits(e.g., via satellite).

Although the subscriber lines and trunks employ different signaling systems, the LTGs

present signaling-independent interface to the switching network. This facilitates thefollowing :-

- Flexible introduction of additional or modified signaling procedures,

- A signaling-independent software system in the CP for all applications.

Switching Network

Different peripheral units of EWSD, i.e., LTGs, CCNC,MB are connected to the

Switching Network (SN) via 8192 kbps highways called SDECs (Secondary

Digital Carriers), which have 128 channels each.

The SN consists of several duplicated Time Stage Groups (TSG) and Space Stage

Groups (SSG) housed in separate racks.

Connection paths through the TSGs and SSGs are switched by the Switch Group

Controls (SCGs) provided in each TSG and SSG, in accordance with the

switching information from the coordination processor (CP).

The SGCs also independently generate the settling data and set the message

channels for exchange of data between the distributed controls.

The switching network is always duplicated (planes 0 and 1). Each connection is

switched simultaneously through both planes, so that a standby connection isalways immediately available in the event of a failure.

Main functions: -


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* Speech Path Switching

* Message Path Switching

* CCS#7 Signaling Channels Connection (NUC)

Coordination Processor

The Coordination Processor (CP) handles the data base as well as

the configuration and coordination functions, e.g., storage and administration of allprograms, exchange and subscriber data.

Other units assigned to CP are: -

Message Buffer (MB) for coordinating internal message traffic between the CP,

the SN, the LTGs and the CCNC in an exchange.

Central Clock Generator (CCG) for the synchronization of the exchange and

where necessary, the network.

MBs and CCG are equipped in two racks in maximum configuration.

System Panel Display (SYPD) to display system internal alarms and the CP load. Operation and Maintenance Terminals / Basic Craft terminal for input/output.

Two OMPs / BCTs are provided for O&M functions.

External Memory (EM), for

- Programs and data that do not always have to be resident in the CP,- An image of all resident programs and data for automatic recovery,

- Call charge and traffic measurement data.

To ensure that these programs and data are safeguarded under all circumstances,the EM is duplicated. It consists of two magnetic disk devices (MDD). The EM also has a

magneto optical disk (MOD) and/or magnetic tape device(MTD), for input and output.

MTD is mounted in a separate device rack (DEVD).

Common Channel Signaling Network Control

The CCITT standardized signaling system No. 7 (CCS#7) is one of the systems

that is used for interexchange signaling in EWSD.

To promote flexibility in the use of this system a distinction is made between a

message transfer part (MTP) and the user parts (UP). The user parts varyaccording to the specific application.

The common MTP functions in an EWSD exchange are handled by the common

channel signaling network control (CCNC).The UP is incorporated in the

software of the relevant LTG.

For reasons of reliability, the CCNC has a duplicated processor (CCNP), which is

connected to the CP by means similarly duplicated bus system.

The functions of the CCNC depend on its position in a signaling link. In the

originating or destination exchange in associated signaling, it operates assignaling point (SP) and in transit exchange in quasi-associated signaling, it

operates as a signaling transfer point (STP).


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Data Maintained In EWSD Exchange

(1) CCR (Call Completion Rate) Report on Exchange Performance

- There are various routes under the exchange .B in the report denotes Both way androutes like Lodi Road are denoted by LDR.

- The number of calls processed and answered is recorded.

- The busy hour taken for record is 11-12.- It is a daily process where the 1-hour traffic is divided into 15-minute slots and

processed. All big stations are made tandem and local connections are accessed through

them. All routes data is there, but important routes are processed.

(2) Exchange BIODATA: -

1. Date Of Commissioning: 31-01-2003

2. Signaling Points: 1076

3. Equipment Capacity: 21KGK II RSU: 13K

OKH Ph-II RSU: 8K4. Average Erlang Traffic = 1000 Erl.

Average BHCA = 45,000

5. Main ISDN = 99ISDN PBXLN = 77

6. Working Levels of the exchange are: 2921, 2922, 2638 (3000-9999, i.e. 7000

nos).

7. Environmental Conditions: -- Ambient Temperature: 5C to 40C

- Relative Humidity: 10% to 80%

(3) System Status Display (SYSD)

The SYSD is maintained on a PC screen at all times. It

contains alarms for any power failure or equipment failure. It is also used to display thestatus of equipment-blocked or working. It, thus, provides a continuous overview of the

state of the system. The SYP also displays external alarms such as fire and air

conditioning system failure for example. It is installed in the Equipment Room or in the

Exploitation Room.

(4) Metering

- The process of metering is done every fortnight on the 15 th and 30th of the month.- All billing information is stored on MOD (Magneto Optical Drive).

- Golden Generation: is the backup maintained by the exchange.

o Insert MOD in the CP (Coordination Processor) drive.

o At the maintenance terminal: SAVEMET (Username Id and Password asked)

o EDITMET: TYPE=METSUB, FILE=CA.SU.CHA.300608,

FUNC=ACCOUNT;

-File is created and tells how many records are created (in hard disk)


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-There are 5 counters for metering: CNTR2 + CNTR4 gives the bill. The

accounts office carries this out.

-If you want to see meter of any number: DISPMET: DN=29222511,TYPE=METSUB;

o (To see files in hard disk) DISPFILE: VSN=SUBMET;

o (Saving file VSN in MOD) TRANSFILE: FILE=CA.SU.CHA.300606,VSNR=SUBMET, COPMOD=POST;

o DISPFILE: VSN=SUBMET;

o RSETMO: MOD=1;

o (Now, detail bills of STD are also to be saved.) RELCYCFILE:

FILE=1A.ICAMA;

o DISPFILE: FILE=1A.ICAMA.ALL=Y;

o TRANSBUFFER: TYPE=AMA;

o TRANSFILE: FILE=NPD7.300608/1A.ICAMA,VSNR=SUBMET,

COPMOD=POST;

o DISPFILE: VSN=SUBMET;

o (Now, well check whether the metering has been done properly or not by

checking one or twonumbers.)DISPCHAREC:OWNERDN=1129222511,VSN=SUBMET,

FILE=NPD7.300608, TYPE=AMA;

o (Sending to two hard disks in CP.) TRANSFILE: FILE=NPD7.300608,

VSNS=SUBMET, MODE=CRD;

o Then, transfer to official PC using FTP (File Transfer Processes). Hence, one

copy is at PC, one at hard disk and one to the metering department.


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CHAPTER 3

AXE-10 SWITCH

Introduction

E-10B Digital Switching System in our DOT/MTNL network gave tremendous boost to

our up gradation and modernization plans. It has offered an excellent grade of service yet

it is found to have failed in metro and major districts under traffic spurts resulting intochaotic conditions. Main reason being: -

i) Lower BHCA Handling Capacity =1,90,000

ii) CCS-7 signaling (CCITT No.7) and ISDN not supportediii) Maximum size of TAX is


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SPC

PCM Principles

Time Division Switching (Digital Switching)

Duplicated Central Processor (CP), working synchronously(hot standby mode)

Regional Processors (RPs)

Offload CP; perform tasks of simple but repetitive nature

Highest degree of Backward Compatibility

One system for all applications

(Local, Transit, CTMX, Mobile Switching Center, Hybrid and any combination of

above)

Functional Modularity: Advantages: -

i) Smoother, Quicker Hardware Extensionsii) System Upgradation is easier

iii) Few functions easily incorporated


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Functional Hierarchy

SWITCHING

EQUIPMENT

COMPUTER

APT - Telephony Part Of AXE

APZ - Control Part Of AXE

THE TWO PARTS OF AN AXE EXCHANGE

CP Central Processor

RP Regional Processor

THE ARCHITECTURE OF THE CONTROL SYSTEM


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BT - Bothway TrunkBTR - Regional Software Of Block BT

BTU - Control Software Of Block BT

INTERWORKING OFFUNCTION BLOCK


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APT Subsystem Functions

(a) Subsystems realized in hardware and software

SSS Subscriber Switching Subsystem

-Handles traffic from and to subscribers.

TSS Trunk and Signaling Subsystem-Handles signaling on trunks.

-Supervises connections over trunks.

GSS Group Switching Subsystem-Sets up, supervises and clears connections in digital group switch.

CCS Common Channel Signaling Subsystem

-Handles CCS-7 functions.OMS Operation and Maintenance Subsystem

-Performs supervision functions on hardware.

-Traffic and Service Measurements

(b) Subsystems realized in software onlyTCS Traffic Control Subsystem

-Controls Call setup, Supervision and Release.-Stores Subscriber Data, Circuit Data and other Office Data.

CHS Charging Subsystem

-Call Charging FunctionsSUS Subscriber Services Subsystem

-Provides subscriber services like Call Transfer, Call Waiting, Dynamic STD

Barring, etc. (Other than basic facilities like push button dialing, detailed billingetc.)

APZ Subsystem Functions

CPS Central Processor Subsystem

Program Administration

Data storage and handling

Changing of programs

RPS Regional Processor Subsystem

Offloads Central ProcessorsMAS Maintenance Subsystem

Locates hardware and software faults in Central Processor

IOS Input Output SystemConsists of following subsystems

SPS - Support Processor Subsystem

FMS - File Management Subsystem

MCS - Man-machine Communication Subsystem

DCS - Data Communication Subsystem

CCS Common Channel Signalling SubsystemCHS Charging Subsystem

GSS Group Switching Subsystem

OMS Operation and Maintenance SubsystemSSS Subscriber Switching Subsystem

SUS Subscriber Services Subsystem

TCS Traffic Control SubsystemTSS Trunk and Signalling Subsystem

SUBSYSTEMS IN A LOCAL EXCHANGE


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Organization Of APT Subsystem

(SSS, GSS, TSS, CCS)

Subsystem (Hardware)

Extension Modules (EMs)

Equipment Location

Cabinets

Shelves (6 per cabinet except CP cabinets)

Magazines (Assemblies of PCBs;1 to 4magazines per shelf)

PCBs


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CP - Central ProcessorEMRP - Entersion Module Regional Processor

EMRPB-A EMRP SUS, A-sideEMRPB-B EMRP SUS, B-sideETB - Exchange Terminal Board

ETC - Exchange Terminal Circuit

GSS - Group Switching SubsystemSTR - Signalling Terminal Regional

CO - Channel On the PCM line

THE CONTROL PART

OF SSS


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Subscriber Switching Subsystem (SSS)

Consists of two types of switches:

(i) Local Subscriber Switches (also commonly known as local EMG; Extension Module

Group): LSS(ii)Remote Subscriber Switches (Remote EMG): RSS

All the Remote Subscriber Switches at a location are together called RSU, RemoteSwitching Unit.

An LSS or RSS will consist of the following magazines:

LSM-A: Line Switch Module Analogue

CP- Central Processor

EMRP- Extension Module Regional Processor

GSS- Group Switching SubsystemJTC Junction Terminal Circuit

RPBC- Regional Processor Bus Convertor

SSS IN PARENT EXCHANGE

(TSB NOT INCLUDED)


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LSM-BA: LSM ISDN, Basic Access (2B+D)

LSM-PRA: LSM ISDN, Primary Rate Access (30B+D)

SEPRM: Special equipment for private meters (optional)

Each fully equipped SEPRM magazine has eight private meter cards, each catering toeight meters.

In addition there will be(i) a SULTACCS magazine for every 4 LSSs. SULTACCS is used for subscriber

line testing and feeding howler tone.

(ii) A pair of RPBC magazines in every LSS for interfacing with LSS hardware

and CPs.(iii) IOSULT magazine, one per RSS. This equipment performs three functions:

Testing of subscriber lines in the RSS

Generation of howler tone

V24 I/O Interface for connection of an alphanumeric terminal to be used at

RSS for Man-Machine CommunicationEach LSS or RSS consists of upto 16 LSMs.

Subscriber connection capacity of an LSM:

LSM-A - 128 Analog Subs.(16 LI PCBs x 8 Subs. per LI)

LSM-BA - 64 x (2B+D)Subs.

(8 LIBA PCBs x 8 (2B+D) subs. per LIBA)LSM-PRA- 4 x (30B+D) Subs.

(4 LIPA PCBs x 1(30B+D) Subs.)

Each LSM is contained in one full shelf size magazine.One fully equipped EMG occupies 3 cabinet space.

One fully equipped EMG can accommodate upto 2048 analogue subs.

Each EMG can have minimum 2 PCM lines and maximum 32 PCM lines towards theswitching network called Group Switch.

We can provide the required no. of PCM lines depending upon the traffic requirements so

as to fully utilize 2048 PCM equipment, if provided.

Concentration ratio achieved:With 8 PCMs: 2048:240 i.e. 8:1

16 PCMs: 2048:480 i.e. 4:1

32 PCMs: 2048:960 i.e. 2:1

Basic Functions of Subscriber Switching Stage

Battery feed to subs. Lines (-48V)

Over voltage protection

Scanning (Supervision) of subs. lines

A/D and D/A Conversion(Coding)

Concentration of Traffic to Group Switch

Reception of Digits from Subs.( Decadic as well as DTMF)

Ringing current to subs. telephone sets.

Sending tones to subs./circuits.


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Testing of subs. lines(BORSHCT functions)

Other functions:

Polarity reversal to CCB PCOs. Every LI device can provide battery reversal.

16 kHz Home-metering pulses (only if SEPRM magazines are equipped in the

EMG.)

Traffic Handling Capacity of RSS

16 PCMs: 494 Channels; 30 x 2 + 31 x 14

32 PCMs: 990 Channels; 30 x 2 + 31 x 30

Time slot No.16 on the first two PCM of every RSS is used for building up C-7 signaling

channels between RSS and the MSU.Time slot 0 on every PCM line is used for alarm and other functions.

In case of LSS all 32 channels on every PCM line can be used for traffic handling.

Hence, for an LSS with 32 PCMs, 1024 channels can be used for handling the traffic.

No traffic balancing is required while loading subscribers, i.e. any subscriber can be

connected to any LI PCB in any LSM.Call meter is associated with subscribers telephone number and not equipment number.

Each LSM need not have a dedicated PCM link with the group switch.

Each LSM need not have a KRC Board.Time Switch Bus among all LSMs of an EMG is used to time slots on PCMs, and KRC

devices. That means channels on PCMs and the KRC devices are available in a common

pool and as such any channel/KRC device can be used for any call in the EMG.

Subscriber Management Command

Today is the age of ICE i.e. Information, Communication and Entertainment.

Telecommunication is not limited to simply communication between two people but it

has also grown to include various Value Added Services(VAS) for the subscribers. VASare hotline, Internet, call transfer etc.

1. To check status of telephone

suscp: SNB=2xxxxxxx;

if suscp: SNB=2xxxxxxx;& if NC comes => no. is closed

2. To open a numbersulii: SNB=2xxxxxxx,dev=Li3-xxxxx;

CMU-meter reading

3. To provide facilities on a no.

suscc: SNB=2xxxxxxx,SCL=IPT-3 & APT-1 & ANT-1 & CAW-1 & FLA-2 &

CCB-2 & KWC-1 & CBA-4


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Description

(a) IPT-3 & APT-1 & ANT-1 Clip facility/Caller ID

(b) CAW-1 & FLA-2 Call Waiting(c) CCB-2 & KWC-1 Dynamic Lock

(d) CBA-4 Local

CBA-1 STDCBA-0 ISD

CBA-2 PCO (local)

TCS-11TLT-2

OCG-61

CBA-0 STD/ISD PCO

TCS-11TLI-2

OBA-65

sucbc: SNB=2xxxxxxx,BP=1&2&4; - Local

BP=1&&4; - STDBP=1&&6; - ISD

sucbi: SNB=2xxxxxxx,BP=1;

4. To put accessories

(a) Unconditional Call Transfer

suscc: SNB=2xxxxxxx,SCL=CFUV-1;(b) Voice mail

suscc: SNB=2xxxxxxx,SCL=CFNRV-1 & CFBV-1;

(c) Call Conference

suscc: SNB=2xxxxxxx,SCL=ENQ-4;

(d) Abbreviated Dialingsuscc: SNB=2xxxxxxx,SCL=ADI-1;

(e) Hotlinesuscc: SNB=2xxxxxxx,SCL=FDC-2 & OBA-80;

suscc: SNB=2xxxxxxx,SCL=FDC-1; Direct Hotline

suhli: SNB=2xxxxxxx,DIN=2xxxxxxx(other telephone no.);

5. To put a no. on DNP-1(outgoing bar)

suscc: SNB=2xxxxxxx,SCL=TBO-2;

6. To put a no. on DNP-2(incoming bar)

suscc: SNB=2xxxxxxx,SCL=TBO-2;suscc: SNB=2xxxxxxx,SCL=TBI-1;

7. To put a no. on RNP(normal working)

suscc: SNB=2xxxxxxx,SCL=TBO-0;suscc: SNB=2xxxxxxx,SCL=TBI-0;

8. To close a no.


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sulie: SNB=2xxxxxxx;

There are several Barring Programs available to the subscriber which they canactivate/deactivate at their telephone sets.

To enter code: 123ABCDABCD,where ABCD is the desired code

To open STD: 124ABCD3 To open ISD: 124ABCD0

To close STD & ISD/To open Local: 124ABCD1

To close Local: 124ABCD4(No outgoing)

To bar special services: 124ABCD2

Mechanical Features

Equipment is housed in cabinets.

Each cabinet has 6 shelves. Each Shelf: 1.2 m (W) x 0.4 m(D) x 2.135 m(H)

Magazines are fitted in the cabinets.

Each magazine has

-Its own back panel (mother board)-Power supplies (DC-DC)

-Front-end connectorised cabling to and from magazines, cabinets.

Magazines

-Are of variable width-Can be slid into or out of shelves

-There can be 1, 2, 3 or 4magazines in one shelf depending on the size of

magazine. Magazines with their own PCBs inside are received from the factory.

All magazines except CP cabinets are of the same height.

Magazines need not be rigidly associated with a particular cabinet or shelf.

Cabinets are independent, supported by the base and coupled with adjacent as

well as hind cabinet (when placed back to back).

The exterior of cabinet body acts as electromagnetic screen.

Rear of cabinet has exhaust vent for heat dissipation.

Cabinets can be placed

-Back-to-back

-Back-to-wall Cabinets require natural cooling, except central processor cabinets and IOG-11B

cabinets.

(Fans are mounted on top of these cabinets to suck hot air; thus providing forced

air-cooling.)

Summary Of Principle Features Of AXE-10


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Capacity Aspects

-64k subscribers (65536 subs.)-2048 PCMs terminated on GS>=64k ports (time slots)

-26,000 Erl. Traffic with a blocking factor of 10 -6 at 0.8 Erl. per port

-8,00,000 BHCA(40% CCS-7, 40% R@ MF, 10% Decadic, 10% Intra-office traffic.)

A number length = 16 digits

B number length = 28 digits

Area codes in own exchange upto 200(12 in E-10B)

No. of LSS/RSS per host upto 256 .

APZ 212 20

-Size of PS (Program Store) = 64 MW-Size of DS (Data Store) = 380MW

-Size of RS (Reference Store) = 2MW

-No. of RP buses = 32, duplicated(32 RPB A from CP-A)(32 RPB B from CP-B)

-Maximum no. of RPs = 1024

-Forced cooling-MTBSF>1000 YEARS

-Fully equipped APZ consumes 1750 watts.

Environmental Conditions

-Floor Space for 10k AXE 10(Main) = 35 sq. meter approx.-Floor Space for 40k (Main) = 120 sq. meter approx.

-Temperature: + 5 to 40C

-R.H. : 15 80%Temperature Gradient: 10C/hour

Power Consumption

- for 10K Main = 300A ( 1 to 1.4 Watt per line )

- for 2K RSU = 35A

General Features Of Interest

1. More than 5000 commands (E-10B has 380 commands)

2. Acronyms are derived from English words (unlike E-10B)3. Documentation is comprehensive and self-explanatory.

4. It is possible to open Hundred Groups as against Thousand Groups in E-10B.e.g.

4400, 4401, 4402.

5. It is possible to have A-Party, B-Party, and NO-Party charging.6. Call Meter is associated with directory no.s (unlike E-10B, =>equipment-related)

7. 200 alternative routing are possible.

8. Switching of Transit calls/O/G calls onto different routes on %age basis ispossible; for example 40% on route A, 40% on route B, 20% on route C.


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9. Rerouting of calls under different conditions like route congestion is operator

controlled and not macro-program controlled as in E-10B.

10. Second stage remoting is not possible as in case of OCB-283.11. Detailed billing data stored in Data Store is copied on the hard disk periodically

and not on magtape. =>Minimum loss probability

12. Too much cabling on the front; this offers flexibility but leads to complexity infront-end cabling.

13. No reply cases are tested automatically and if found faulty are fault-marked. Such

lines are routinely tested. Alarm is given threshold value is crossed.14. All automatically blocked devices are routinely tested by the system.

15. Maintenance action is based on alarm reports mostly, unlike E-10B where the

corrective action is based on the analysis of Alarms, Fault messages, and

Diagnostic messages, Repots etc.16. All Operation and Maintenance documents are available on CD-ROM for easy

access.

17. Additional facilities (abbreviated dialing, dynamic STD, Call Transfer, call

waiting, morning alarm) can be given to 100% subs.18. Call Meters can be saved on hard disks automatically in every 15, 30,60, 120

minutes as programmed.19. Changes in Routing, Analysis, and charging data is first done on the Non-

operating area in the Data store of CP, tested and then copied onto operating area.

Old data protected in the Non-operating area for the following 24 hours.

AXE-10!

Practically maintenance-free(as claimed by M/s Ericsson)

Functional Modularity upto block level. Hardware modularity offers

-Smooth, Easy Extension-Easy Up gradation

Backward Compatibility

Cabinets can be placed

-Back-to-back-Back-to-wall

=>Saving of Space.

Environmental Conditions are not very stringent.

(26C recommended.)

False Floor and False Ceiling are Not obligatory.=>Saving on Infrastructure.

Hardware Of AXE-10

EMGs (Extension Module Groups) contain subscriber numbers.


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One EMG has 16 EMs (Extension Modules) numbered from 0 to15.

One EM can support maximum 42(cards) x4=168 subscribers.

It also has a power card.

Junction lines connect various exchange and Tandem to each other.

The junction cable has 31 channels supporting both way communications

i.e. at a time 30 people can talk to each other.

The exchange is directly connected to Optical fiber cable, which is

connected to other exchange.

All EMs have power cards and RPs (Regional Processors) without which

work is not possible in exchange.

Power from the Power Room comes to local Power Distribution Frame

and then supplied to the exchange.

It also contains alarms for fault finding.

The optimum temperature maintained is 19C.

IOG (Input Output Group) of Man-Machine Communication has hard

disk, which contains all log information of exchange. The hard disk of CP (Central Processor) contains all programs, software

and application running in the exchange.

Inverter of 1kVA is used to supply power to PCs and computers used in

exchange office.

There are four main terminals in the exchange office:-

1. Alarm Terminal: Contains log of all alarms generated in the exchange.2. Traffic Terminal: Used to maintain log of the complete traffic flow in

the exchange.

3. Subscriber Management Terminal: Used to process commands whichcater to subscriber needs and

4. Maintenance Terminal: Used to carry out metering, etc.

Exchange Capacity

22K: RSU (Tughlakabadh)40K: Main (NP)

62K: Total

3.5K in RSU and 17K in Main is in use. The RSU will be recommissioned in 3-4 monthsand the capacity will then be 40K.

3,20,000 pulses are generated every day and the Busy Hour Traffic is 900-1000 Erlang.

Outgoing calls are more (about 12,000) and incoming calls are less (about 9,000).The exchange basically caters to commercial area in Nehru Place .The Sunday metering

is 1,40,000 only which indicates that it works for commercial area as it is a holiday.


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CHAPTER 4(a)

POWER PLANT

The Power Plant, which supplies power to exchanges, is external andcommon for all exchanges present in NP building.

The Power Plant obtains AC current from outside. It is converted to 53.5-54V DC usingmodules, which transform according to switch room requirement.

Even though, the supply starts at around 54V, all exchange equipment receive the

required 48V only (thus, some losses take place in transmission).

Before going to the switch rooms, supply comes to the DCDB: DC Distribution Frame,

which is a cabinet. It has three sections, which are used to distribute the supply among the

various exchanges.

In case of Electricity Failure, secondary source: Battery automatically takes the load.(Primary source being rectifiers: electric current supply)Therefore, AC Volt and AC Ampare down and DC Volt and DC Amp take all the load.

A third source is Generator: the battery ensures that the exchanges do not suffer any loss.

The generators are also used to produce ac current supply for the plants.

The conventional modules (racks) have single rectifier of 600 A capacity whereas the

modern have two rectifiers of 100A to 200A.

There is also a Float Rectifier cum Battery Charger Switching Cubicle, which can beused as charger, as well as rectifier.

There are various battery sets and each set contains 24 cells connected in series with2.22V between two cells.

Maintenance: -

DEEP DISCHARGE TEST is conducted every year in which the sets are discharged

using artificial load to 1.75V.It is discharged at 10% load, e.g. for a battery of capacity


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5000AH,the discharge load will be 500A.After every one hour reading is taken across the

shunt in artificial load to test its value. Every year the battery value depreciates and this

factor must be considered to determine the load value to be used for the test. This testrefines and renews the batteries.

Weekly reading of the batteries is taken to find any weak cell among the battery sets.

The manufacturers take any weak cell for Reconditioning, where the cell contents arechanged. It improves the life of the battery.

Details Of Power Plant Details Of Battery

D 3 Type - SMPS VRLA

AXE-10 Make - ITI Ltd. HBL

T.capacity -22x100A 03x4000AH

Dt.of install - 15-11-03 5-03 and 8-04

DC Load - 800A

D 4 Type - Conventional VRLA

5 ESS Make - ELCOT EXIDET.capacity - 03x600A 03x5000AH

Dt.of install - 09-95 9-04

DC Load - 1000A


OCB Make - ITI Ltd. EXIDE

TANDEM T.capacity -18x100A 02x5000AH

Dt.of install - 03-99 18-10-06

DC Load - 750A

D 6 Type - SMPS VRLAOCB Make - Tata Lucent Amara Raja,HBL,Exide


Dt.of install - 04-00,01 4-00and01

DC Load - 600A


EWSD Make - Amara Raja HBL


Dt.of install - 10-02 10-02

DC Load - 350A

The exchange DC Load means the working load and indicates how many calls areoperational in that exchange.


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CHAPTER 4(b)

MDF (Main Distribution Frame)

How hardware is connecting the switch room with the outside world.

The various switch rooms have cables labeled LI and NE, which are joined to the MDFusing jumper. MDF has main pairs from 1 to 100, which are joined to outside cable.

Main pair has 2 contacts:-

-Lower: connected to jumper

-Upper: connected to the outside cable.

The outside connection is as follows: -

To protect the switching room equipment from getting burned in the event of excess

current or voltage from the outside cable, GD TUBE is provided which acts as a fuse.Earlier, heat coil and carbon arrester were used for excess V and I respectively.

Testing of Main Pairs is done through Testing Board in MDF to check the condition of

line:-

A Testing clip is connected to a pair, which consists of two wires.-If ROT is green: line is OK

-If ROT is red: line is faulty or there is earthing.

PCM (Pulse Code Modulation) System

e.g. if a call is to made from Mumbai to a subs. in Delhi ,the communication path

established will be as follows :Mumbai to the main centre in Kedvai Bhavan at Janpath to

PCM in MDF at MTNL(NP) to cabinets ,then to DP(Distribution Points) and finallyterminating at windows(subscriber end)

PCM CABLE: Used for transferring less than or equal to 2MB data.

In Primary MUX used in PCM, there are two parts divided by a Central Card: -

The left part-Used for speech signaling

-Have 10 slots

-Supported by voice card-Each voice card has 3 channels

The right part

-Used for data transmission

-Have 5 slots


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-Supported by data card

-Each data card has 6 channels

Speed of transmission is 64kbps.

MODEM is used along with Primary MUX as well as at the subscriber end.

Modified version of above combination is MLLN (Manage Lease Line Network)previously known as MLDN(Manage Lease Digital Network).It has several economical

benefits:-

1. It is faster because MODEM is in-built and monitoring can be done at same place.2. It uses one pair of wires for transmission and reception of data as against two

pairs used by the earlier combination.

3. Flexible Speed of Operation i.e. 64,128,256,512,1024 kbps. 9.6kbps can also be

used for traveling etc. which is a cheap way of transmission.

OFC(Optical Fiber Cable) is superior to above cable as it supports high operational

speeds, i.e. greater than 2 MB till 140 MB.


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CHAPTER 5

OCB-283 SWITCH

Introduction

One of the first switches of Alcatel is theE10B, also called the OCB-181. The E10B isone of the earliest SPC digital exchanges in the world. They were commissioned first in

France sometime in the mid-eighties. One of the best moves the Indian Telephone

Industries ( a Government-owned company ) did was to enter into an agreement wherebythe E10B was manufactured under license by the ITI in India. E10Bs started entering

service all over India by 1989-1990. The E10Bs were deployed in huge numbers all over

India to such an extent that a separate wing of the Department of Telecommunicationswas created to provide service and maintenance for the E10B installations. This wing is

called the National Center for Electronic Switching.

The second switch made by Alcatel is the OCB-283, also called just the OCB. The OCB-

283 is the successor to the E10B, and is called the 1000 E10, or justE10. The OCB isalso manufactured by ITI under license, just like the E10B. All installations of the E10B

are being replaced by the OCB. The OCBs account for a major portion of the landline

network of the Government-owned Department of Telecommunications (DOT) in India

today, at least the end-offices (exchanges directly serving customers ).

The OCB is better than the E10B in that it simply packs more punch for today's advancedservices, and for tomorrow's too. It supports SS7 and therefore is ISDN-ready. It has a

fast signaling processor, which makes call setup time much lesser. The OCB is thepreferred choice in the DOT for ISDN installations. On a minor note, the ITU refers to

the OCB283 as the E10.

Alcatel Global Network

The development of Alcatel 1000 E10 is a key element in Alcatels concept of a Global

Network. The Alcatel Global Network offers a complete service for all current and future

needs of our customers.

The Alcatel Global Network encompasses the telephone network and its evolution

towards ISDN, data and value-added networks (particularly message handling systems

and video text), intelligent networks, cellular radio systems, operation and maintenancenetworks and finally, the evolution towards broadband ISDN using Asynchronous

Transfer Mode (ATM) techniques.


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These developments are common to the entire Alcatel group. Modern, proven

technology, the multi-application telecommunication processor ALCATEL8300, field-

proven experience, versatile software, and open architecture support them.

Services Provided: -

- Calls Handled

The Alcatel 1000 E10 handles telephone calls from and to the national and internationalpublic switched telephone network. It also transfers data between its ISDN subscribers as

well as to and from the packet switched network.

These calls include:- Local calls (private, public),

- Regional calls: outgoing, incoming, transit,

- National calls: outgoing, incoming, transit,

- International calls: automatic or semi-automatic, outgoing or incoming,- Manual calls (operator assisted): outgoing, incoming,

- Outgoing calls to special services,- Test calls.

- Services Access Switching Function

In case of call between and processed by the

. The SSP (Service Switching Point) application of the Alcatel

1000 E10 allow to access to the specific component (SCP) of the intelligent network.

By a prefix allocated to the service, the ssp (Service Switching Point) call the SCP(Stored

Control Point) to set up a dialogue between the and the (using CCITT No. 7 channel). The interface used is called INAP (Intelligent

Network Access Protocol).

The call processing is managed by SCP.

During the call processing , the SSP is managed by the SCP.

- Operator Connection

Where intervention of an operator is necessary, Alcatel E10 with OCB283 uses the

SYSOPE operator system.

This system is:

- modular and flexible: it can be used to handle just a few to several hundred localor remote operator positions, on one or more sites,

- high-performance: its software permits hierarchical organization ( operator,

supervisor, chief supervisor) which can be changed at any time and offers a wide


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range of functions: traffic groups, queues, computerized tickets, load and traffic

measurements, etc.


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Host switching matrix (SMX)

The SMX is a square connection matrix with a single time stage, T , duplicated in full ,

which enables up to 2048 matrix links (LR) to be connected.

A matrix link is an internal PCM, with 16 bits per channel (32 channels) .The MCX can execute the following:

1. An unidirectional connection between any incoming channel and any outgoing

channel. There can be as many simultaneous connections as there are outgoingchannels. It should be remembered that a connection consist of allocating the

information contained within an incoming channel to an outgoing channel,

2. Connection between any incoming channel and any M outgoing channel,

3. Connection of N incoming channels belonging to one frame structure of anymultiplex onto N outgoing channels, which belong to the same frame structure,

abiding to the integrity and sequencing of the same frame, received. This functionis referred to as connection with N * 64 kbits/s.

The MCX is controlled by the COM function (matrix switch controller) to ensure the:

Set up and breakdown of the connections by access to the matrix

command memory. This access is used to write at the output T.S. address

the incoming T.S. address

Defense of the connections. Security of the connections in order to assure

a good data switching.

PCM controller (URM)

These PCM come from either:

A remote subscriber digital access unit (CSN) or from a remote electronic satellite

concentrator CSE,

Another switching center, on channel-associated signaling or CCITT No. 7,

The digital recorded announcement equipment.

In particular, the URM carries out the following functions:

HDB3 conversion to binary (PCM matrix link),

Binary conversion to HDB3 (matrix link PCM),

Extraction and pre-processing of the channel-associated signaling of T.S16

(PCM command),

Transmission of channel-associated signaling in T.S6 (commend-PCM).


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Auxiliary Equipment Manager (ETA)

The ETA supports:

The tone generator (GT),

The frequency receiving and generation (RGF) devices,

Conference circuits (CCF),

The exchange clock.

CCS7 protocol handler (PUPE) and CCS7 controller (PC):

CCITT No.7 protocol processing:-

For connection of 64 kbits/s signaling channels, semi-permanent connections areestablished via the connection matrix, to the PUPE which process the CCITT No. 7

protocol.

More precisely, the PUPE function carries out the following:

Signaling channel level 2 processing,

The message routing function (part of level 3),

The PC carries out:

The network management function (part if level 3),

PUPE defense,

Various observation tasks which are not directly linked to CCITT No. 7.

Call Handler (MR)

The MR is responsible for the establishment and breaking of the communication.

The call handler takes the decision necessary for processing of communications in

terms of the signaling received, after consultation of the subscriber and analysis

database manager(TR) if necessary. The call handler processes new calls and


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hanging-up operations, releases equipment, commands switching on and

switching off etc.

In addition, the call handler is responsible for different management tasks

( control of tests of circuits , sundry observations).

Subscriber and Analysis Database Manager (TR) (TRANSLATOR)

The TR function carries out management of the analysis, subscriber and the circuitgroups database.

The TR supplies the call handler, on request from it, with subscribers and circuits

characteristics necessary for establishing and breaking off communications. The TR also

ensures match between the dialing received and the address of the circuit groups orsubscribers (pre-analysis, analysis, translation functions).

Call charging and Traffic measurement (TX)

The TX function carries out charging for communications.

TX is responsible for:

Calculating the amount to be charged for each communication,

Keeping the charge account of each subscriber served by the switching

center,

Supplying the necessary information for drawing up detailed billing,

on line to the OM. In addition, TX carries out tasks of observation of

(circuits and subscriber observation).

Matrix system handler (GX)

The GX function is responsible for processing and for defense of connections

on receipt of:

Request for connection or disconnection coming from call handler (MR) or

message distributor functions (MQ),

Connection faults signaling by the matrix switch controller function (COM).

In addition, the GX carries out monitoring of certain links of the connection central

subsystem (access links LA and links internal to the host switching matrix LCXE),periodically or on request from certain links.

Message distributor (MQ)

The MQ functions is responsible for distribution and formatting of internal message,

but, above all it carries out:-


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Supervision of semi-permanent connections (data links),

Transmission of messages between the communication multiplexes

(gateway function).

Communication multiplexing

One to five communication multiplexing are used to transmit messages from one station

to another. This transfer of messages is carried out by only one type of medium, the

TOKEN RING, with a unique protocol, which is processed in accordance with IEEE802.5 Standard.

Single multiplex (COMPACT configuration):

It is then referred to as the intersection multiplexing (MIS).

More than one specialist multiplex:

1 interstation multiplex (MIS) for interchanges between the command

functions or between the command functions and operation andmaintenance software,

From 1& 4 station access multiplexes (MASs) for interchanges

between the connection functions (URM, COM, ETA, PUPE) and thecommand functions.

Operation and maintenance function (OM)

The functions of the operation and maintenance subsystem are carried out by theoperation and maintenance software (OM).

The operating authority accesses all the hardware and software equipment of the Alcatel1000 E10 system via computer terminals belonging to the operation and maintenance

subsystem: consoles, magnetic media, intelligent terminal. These functions can be

grouped into categories:

Operation of the telephone application,

Operation and maintenance of the system.

In addition, the operation and maintenance subsystem carries out:

Loading of softwares and of data for connection and command and for thesubscriber digital access units,

Temporary backup of detailed billing information,

Centralization of alarm data coming from connection and control stations

via alarm rings,

Central defense of the system.

Finally the operation and maintenance subsystem permits two-way communication with

operation and maintenance network, at regional or national level (TMN).


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SMC: Main Control Station

SMA: Auxiliary Equipment Control Station

SMT: Trunk Control StationSMX: Matrix Control Station

SMM: Maintenance Station

STS: Synchronization and Time Base Station


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CHAPTER 6

5ESS SWITCH

Introduction

The hardware in the switch is designed in a modular fashion. At the lowest level, thereare individual circuit packs. Next, there are units which are several circuit packs grouped

together to perform specific functions. The hardware units are grouped together to form

modules. The units within a module work together to perform specific functions. Finally,all of the different modules grouped together form the exchange.

With this modular design, the switch can be tailored to various applications or have itscapabilities enhanced in the future by adding or deleting different units. Many of the units

currently used in the switch are designed to be able to function with ISDN (integratedservices digital network) capabilities.

The circuits within the switch are designed using very large-scale integrated circuits. The

use of large-scale integrated circuits allows the switch hardware to be more compact,

consume less power, and operate more reliably than systems that rely on smaller scaleintegration. Also, many of the units are designed with microprocessors for control.

The switch is divided into three functional parts or modules. These are the

SWITCHING MODULE

COMMUNICATION MODULE

ADMINISTRATIVE MODULE

The following description includes the design and working of the hardware.


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Switching Module

The SMs (switching modules) within a switch perform 90% of the call processing

functions, as well as the circuit maintenance functions. Among the functions provided for

call processing are:-

Line scanning for originations

Dial tone generation


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Digital collection and analysis

Call supervision

An SM terminates along lines, analog trunks, and digital trunks and lines. Within theswitch architecture, SMs performs the time division switching functions.

There are three basic types of SMs according to function and location of SM:

Local

Host

Remote

RSMs are located at sites up to 175 kilometers from the remainder of the switch. An

RSM is an economical way of providing digital services to communities that wouldnormally be too small to justify the cost of an entire switch. The difference between a

local SM and a host SM is that a host SM serves as the interface between the remainder

of the switch and one or more RSMs.

The SM performs the main telephone functions within the system. An SM needs

communication with the AM for maintenance purposes or for obtaining routing

information.

The three main functional areas that exist in a SM are: -

Control Units: The control unit controls the operation of the SM and performs the

time switching of a speech sample. A speech sample can be switched either

between two subscribers connected to the same switching module, or between two

subscribers on two different SM2000s via the CM. The control units are fullyduplicated in an active/standby configuration.

Interface Units: The interface units interface the telephone lines with the system.

There are various types of interface units need to convert the telephone signalingsystem into the format of the internal digital format used by the exchange. The

interface units send their output to both the active and the standby control.

Interface units exist for all types of analog and digital lines and trunks, as well asfor transmission systems between the central offices.

Service Units: Service units perform all tone detection and generation functions.

They also provide certain test functions and special call processing functions suchas three party or six party services.

The SMs connect to the duplicated CM via NCT (Network Control and Timing) links.Two NCT links connect an SM to the active side of the CM and two links connect an SM

to the standby side of the CM. In a standard configuration, the total switching capacity of


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the SM control is 512 time slots, which is also the transmission capacity of each of the

two NCT link pairs.

Control messages needed for communication between an SM and the AM or between two

SMs are also transmitted over the NCT links.

The SM has two versions depending upon the subscriber and control cards: -

SM Classic: - ISLU (Integrated Services Line Unit) ranging from 0-3: provides the capability to

interface with analog or digital subscriber lines.

-Each subscriber card has 0-15 subscribers. There are three types of subscriber cards:

1. MPA 8-B: for STD, ISD and PCO2. MPA 23: for Local and PCO

3. MPA 27: for normal Local

SM 2000: -.

AIU: It has a single control card at the beginning. One subscriber card connects 0-31 subscribers. Hence, it is more compact. It has two types of subscriber cards:

1. LPU: for ISDN subscribers2. LPP: for PCO

3. LPZ: for normal subscribers.

Communication Module

The CM performs the space switching functions within the system. The CM is also usedfor distribution and reception of control messages transmitted between the following:

- The Am and individual SMs

- Two SMs.The CM can be divided into two units:

- Message Switch, which handles the distribution and collection of control

messages from AM and the SMs. It is also used for timing synchronization.- Time Multiplexed Switch, which handles the set up of paths between the SMs and

between the message switch and the SMs. It switches speech samples and control

messages between the inputs and the outputs. This switching function is executed

under control of the AM.

CM Hardware: - The basic work of CM is to coordinate between the SM and AM and individual

SMs.

Its hardware takes space of one rack with two sides-SIDE0 and SIDE1 with

orange cables connected to all SMs and AM.

Administration Module


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The AM is a processor in the 5ESS switch that provides the general control over the

switch, monitoring the SMs through the CM. The AM uses the UNIX-RTR (Real Time

Reliable) operating system as its memory manager, for input/output, and for executingprograms. It is the unit within the system, which has overall control of all operations.

This control mainly concerns routing, resource allocation, data storage, backup,

input/output functions, system maintenance in addition to the execution of the systemsoftware. The AM is duplexed 32-bit mini-computer to which a wide range of utility

equipment can be connected.

AM Hardware: -

The basic function of AM is to store and maintain billing data. The storage device

used is Data Cartridge of size 4GB. There is only one rack for this module in the total exchange hardware. Cables from this rack are connected to the exchange PCs. AM can also be

connected to distant LAN PCs through modem.

EXCHANGE BIODATA

Total Capacity: 84K; In Use: 39KMetering is done every fortnight. Detailed billing is also carried out, if required.

The working levels are: 2601, 2602, 2603, 2623, 2624, 2625, 2626, 2628, 2629, 2641,

2642, 2645, 2646, and 2649.There are five RSUs located at Asiad Village, Sadiq Nagar, Savitri Nagar, GK-1,

Rampuri.

The exchange maintains a one-month backup of the SM ODD (Office Dependent Data

like metering, subscriber status, etc.).


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CHAPTER 7

CONCLUSION

I learned about the four electronic switching systems being used in the MTNL Nehru

Place office- EWSD, AXE-10, OCB-283, 5ESS.They are four of the most popularelectronic switching systems being used in landline telephoning systems.

However, the subscribership has been decreasing over the past few years due to the

following reasons:-- Rising popularity of mobiles,

- New service providers like BSNL, etc.

But, the number of subscribers opting for the various Value Added Services(VAS) hasincreased tremendously.MTNL is also keeping in pace with the times with launch of

Garuda (its mobile service) and also MTNL internet facilities.

Date post:	08-Aug-2018
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