GSM BSNL Training Part1

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Reading Material

Handout No-ALTMCUP106 02 Ver 3 28.02.2008

Technical Module


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i

About this Handout

This handout provides reading material on the technical topics included in theSyllabus of E2 to E3 Time scale promotion linked training of Officers belonging toTelecom wing of BSNL. The examination at the end of this one-week module will

include discussions that take place in the class and general understanding ofBSNL executives about the companys telecom infrastructure.

Mode of Examination

The examinations will be conducted with break-up of 30% subjective & 70%objective pattern questions in each of the modules.

Duration of Examination

Examination duration will be 90 minutes

Qualifying marks

For the successful completion of the training, the executive undergoing thetraining ought to score a minimum of 50% of the total marks in each of themodules.

Failure & Re-appearance

The Executives who dont qualify the examination would be given anotherchance to undertake/clear the examination in continuation of their training. Thissupplementary examination would be arranged within 3 days of the declaration ofthe results at the same venue.

For still failing executives, a second / subsequent supplementary examinationwould be held on the date & place as finalized by ALTTC. However no TA/DAwould be admissible to the executives appearing for the same. No repeat oftraining would be provided for the unsuccessful executives, unless specificallyagreed by the CGM ALTTC in consultation with corresponding circle CGM.

Reference:

1. Order No. 32-27/04/Trg dated 19th July 2007 of BSNL Corporate office

2. Order No. 32-27/04/Trg dated 12th April 2007 of BSNL Corporate office


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CONTENTS

TOPIC Chapter Page

SECTION-I Switching

Digital Switching systems: Concepts 1 1-4Signaling in Telecom Networks: CAS & CCS7 2 1-10

Switching systems in BSNL & introduction to NGN 3 1-15

Intelligent Network 4 1-9

Maintenance issues of battery and power plant 5 1-5

Air conditioning & Engine Alternator 6 1-10

Section-II Transmission

OFC characteristics & laying 7 1-9

Testing & Measuring instruments 8 1-4

SDH Overview 9 1-9Protection schemes in SDH 10 1-9

Synchronization 11 1-13

SECTION-III Mobile

Overview of Mobile Communication & cellular concepts 12 1-6

GSM Architecture 13 1-5

GPRS/EDGE 14 1-6

GSM Services 15 1-9

Overview of CDMA Technology 16 1-14

SECTION-IV Data CommunicationsBroadband Wire line Access Technologies 17 1-7

Broadband Wireless Technologies 18 1-5

Broadband Core Network 19 1-3

TCP/IP/Ethernet, IP Addressing 20 1-10

IP Routing, RIP, OSPF 21 1-3

MPLS-VPN 22 1-7

Multiplay 23 1-4

SECTION-V Information Technology

BSNL Application Packages 24 1-12Overview of NOS & RDMS Package 25 1-4

IT Security Policy 26 1-3

SECTION-VI Sample Questions 27 1-3


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iii

Amendment Record

TOPIC Version Date

SECTION-I Switching

Digital Switching systems: Concepts 2 28.02.2008

Signaling in Telecom Networks: CAS & CCS7 2 17.11.2007

Switching systems in BSNL & introduction to NGN 2 17.11.2007

Intelligent Network 2 17.11.2007

Maintenance issues of battery and power plant 1 24.08.2007

Air conditioning & Engine Alternator 1 24.08.2007

Section-II Transmission

OFC characteristics & laying 2 17.11.2007

Testing & Measuring instruments 1 24.08.2007

SDH Overview 1 24.08.2007

Protection schemes in SDH 1 24.08.2007

Synchronization 1 24.08.2007

SECTION-III Mobile

Overview of Mobile Communication & cellular concepts 2 28.02.2008

GSM Architecture 2 28.02.2008

GPRS/EDGE 2 28.02.2008

GSM Services 2 28.02.2008

Overview of CDMA Technology 1 24.08.2007

SECTION-IV Data CommunicationsBroadband Wire line Access Technologies 2 28.02.2008

Broadband Wireless Technologies 2 28.02.2008

Broadband Core Network 3 28.02.2008

TCP/IP/Ethernet, IP Addressing 3 28.02.2008

IP Routing, RIP, OSPF 3 28.02.2008

MPLS-VPN 3 28.02.2008

Multiplay 2 28.02.2008

SECTION-V Information Technology

BSNL Application Packages 1 24.08.2007Overview of NOS & RDMS Package 1 24.08.2007

IT Security Policy 2 28.02.2008

SECTION-VI Sample Questions 1 28.02.2008


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Section-I

Chapter-1

Digital Switching Systems


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E2E3 Switching Concepts, Ver2 28.02.2008 1 of 4

1.0 DIGITAL SWITCHING CONCEPTS

Telephony was invented in 1876 and automatic telephone exchangeswere developed in 1895. All these exchanges were analog. Now we have onlydigital exchanges in the network, which work on time switching or time and space

switching. The digital exchanges are compatible to provide value added servicesand Intelligent servicesCommunication can be defined as the transfer of information from one point

to another point as per desire of the user under the control of some system.

The key aspects of a communication network are :

1) Switching2) Transmission3) Call control or signaling4) End terminals or network elements

2.0 SWITCHING

Switching is basically establishing a temporary path or connectionbetween two points or it can also be defined as writing at one point of timeand reading at another point of time.

There are two modes of switching employed in our network.

2.1 CIRCUIT SWITCHING

In normal telephone service , basically, a circuit between the calling partyand called party is set up and this circuit is kept reserved till the call iscompleted. Here two speech time sots are involved one of callingsubscriber other of called subscriber. It is called circuit switchingCircuit switching is based on the principle of sampling theorem.

2.1.1 SAMPLING THEOREM

Sampling Theorem StatesIf a band limited signal is sampled at regular intervals of time and at a

rate equal to or more than twice the highest signal frequency in the band, thenthe sample contains all the information of the original signal. Mathematically , if fhis the highest frequency then sampling frequency Fs needs to be greater than orequal to 2 fh

i .e. Fs >=2 fhLet us say our voice signals are band limited to 4 KHZ and let samplingfrequency be 8KHZ.

.


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. . Time period of sampling Ts = 1 secs.8000

. or Ts = 125 micro second

If we have just one channel then this can be sampled every 125

microseconds and the resultant samples will represent the original signal. But ifwe are to sample N channels one by one at the rate specified by the samplingtheorem, then the time available for sampling each channels would be equal toTs/N microseconds The time available per channel would be

Ts=125sN=32 for 32 chl PCM

125/32=3.9 microseconds per chlThus in a 30 channel PCM system, time slot is 3.9 microsecond

and time period of sampling i.e. interval between 2 consecutive samples of achannels is 125 microsecond. This duration i.e. 125 microsecond is called timeFrame. A signal band is limited to max freq of say fm if sampled at the rate of

2fm then this signal can be reconstructed at the receiving end. This theorem wasgiven by Nyquist.

2.2 PACKET SWITCHING

The information (speech, data etc) is divided into packets each packetcontaining piece of information also bears source and destination address.These packets are sent independently through the network with thedestination address embedded in them. Each packet may follow differentpath depending upon the network.

3.0 SWITCHING CONCEPT

To connect any two subscribers, it is necessary to interconnect the time-slots of

the two speech samples which may be on same or different PCM hightways. The

digitalised speech samples are switched in two modes. Viz. Time Switching and

space Switching . This time Division Multiplex Digital Switching System is

popularly known as Digital Switching System

3.1 Digital Time Switch

Principle

A Digital Time Switch consists of two memories, viz., a speech or buffer

memory to store the samples till destination time-slots arrive, and a control

or connection or adddress memory to control the writing and reading of

the samples in the buffer memory and directing them on to the appropriate

time-slots.


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Speech memory has as many storage locations as the number of time-slots

in input PCM,e.g.,32 location for 32 channel PCM system.

The writing / reading operations in the speech memory are controlled by

the control Memory It has same number of memory locations as for

speech memory, i.e.,32 locations for 32 channel PCM system. Eachlocation contains the address of one of the speech memory locations where

the channel sample is either written or read during a time-slot. These

address are written in the control memory of the CC of the exchange

depending upon the connection objective.

A Time Slot Counter which usually is a synchronous binary counter. is

used to count the time slots from 0 to 31 as they occur. At the end of

each frame, it gets reset and the counting starts again. It is used to control

the timing for writing/reading of the samples in the speech memory.

Buffer/speech memory

Incoming PCM 01 Outgoing PCM02

04

TS4 TS6

31

Read address

00

01

06

31

Control

/Connection/Address

Memory

Fig. output Associated Control Switch

3.2 SPACE SWITCH:

A space switch is used to simple change the PCM of a incoming time slotkeeping the time slot number same in the outgoing PCM.

The memory location requirement rapidly go up as a Time Switch is expanded

making it uneconomical. Hence, it becomes necessary to employs both types of

switches, viz.., space switch and time switch, and therefore is known as two

dimensional network. These network can have various combinations of the two

types of switches and are denoted as TS, STS TSST, etc.

4 ( four)

Time slot

counter


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4.0 Telecom network structure

The telecom network consists of Local exchanges (LE) Which has only subscribers connected to it.TAX Exchanges (TAX) Trunk automatic exchanges contains only outgoing

and incoming circuits and no subscriber is connected to it. It is used only forrouting calls.Tandem exchanges Out going and incoming tandem exchanges arebasically exchanges between TAX and local exchanges for bettermanagement of traffic. These exchanges do not connect subscribers.Network elements (like telephone, fax, modem etc.)

The telephone network is also referred as PUBLIC SWITCHED TELEPHONENETWORK (PSTN) .The offered voice service is referred as PLAIN OLDTELEPHONE SERVICE (POTS)The PSTN network is organized in a hierarchical manner with Lev-1/Lev-2 TAX

exchanges and then tandem and Local exchanges.Trunk Automatic Exchange

Lev-I TAX -------In 21 places

Lev-II TAX-------In 301 Places

Types of call

Local call: Call originated and terminated in the same exchange is called local

call

Outgoing call: Call originated from local exchange and terminated in other

exchange after picking up outgoing circuit.

Incoming call: Call received from other exchange and terminated in local

exchange.

Transit call: Call received from other exchange and terminated in other exchange.

When a new call is set up, it needs to be routed from calling party to the called party

through the switch network. The routing is based on the called party number. Normally in

PSTN the switching is static type. In case of link failure alternate paths are available

and routing is done through the alternate paths.


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Section-I

Chapter-2

Signaling: CAS & CCS7


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E2E3 Signaling: CAS & CCS7, Ver2 17.11.2007 1 of 10

Signaling in Telecom Networks

Channel Associated Signaling

1.0: IntroductionThe exchange communicates with other equipment in the telephone networkaccording to the committed signaling system(s). A signaling system defines themeaning and physical characteristics of the signals or messages and the applicablesignaling procedures.

A signaling system is called a channel associated signaling system when thelocation of the signaling information is related directly to the user voice/data. The

location of the signaling information always identifies the related user voice/data.

Fig.1 Channel Associated Signalling

Examples are signaling systems which use the same circuit for signaling anduser voice/data, and signaling systems which transport the signaling information in

timeslot 16 of a PCM link.

The 30 channel PCM link (also called 2Mb link) consists of 32 timeslots. Of the 32

timeslots, 30 channels are used to transport user voice/data, one channel (timeslot 0) is used

for timing, status and synchronization. One channel (timeslot 16) is used to transport

signaling information related to the 30 voice/data channels. Figure 2 shows the structure of a

PCM link. The traffic on the PCM link consists of consecutive multiframes, which are

transmitted at 8000 Hz. These multiframes consist of 16 frames. Every frame consists of 32

timeslots onto which the 30 channels are mapped. Every timeslot consists of 8 bits. In

timeslot 16, frame 1, signaling information related to the user voice/data in timeslots 1 and 17

is located. In timeslot 16, frame 2, signaling information related to the user voice/data in

timeslots 2 and 18 is located, etc. Timeslot 1 to 15 and 17 to 31 are used for user voice/data

(channels). After one multiframe has been sent, signaling information related to all 30channels in a PCM link has been sent.


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Fig.2 30 chl PCM Link

Subscriber Signaling Signaling systems used between the exchange andsubscriber equipment, such as terminals and PBX (Private Branch eXchanges), arecalled subscriber signaling systems. Subscriber signaling must not be confused withline signaling. Subscriber signaling can be transported over lines and subscribertrunks.

Trunk SignalingTrunk signaling are signals used between public exchanges. Theyare used to connect exchanges in order to build up a circuit. The signals can bedivided in supervision and address signaling.

Supervision SignalingSupervision signaling (also called line signaling) is used tocontrol and monitor the status of the transmission circuits. Examples of supervisionsignals are the seizure signal and idle state signal. Supervision signals do notcontain any specific subscriber information such as the directory number.

Address SignalingAddress signaling (also called build-up or register signaling) is aprotocol which is used to transfer the specific subscriber information necessary toconnect the calling party to the called party. Address signaling is related to a certaincall. Examples of address signaling information are the called party's directorynumber and the calling party's category.

Compelled SignalingA signaling protocol is called compelled if a forward signal is

transmitted until it is acknowledged with a backward signal. The backward signal istransmitted until a forward signal is received.Non-Compelled Signaling In a non-compelled signaling protocol, the signals arepulsed out for a specified duration. All signals are sent as a block, without anyacknowledgement from receiving side.

Inband SignalingA signaling system is called inband when the frequencies of thesignals are inside the band of frequencies used for voice transmission(300-3400Hz ).


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Out-of-band Signaling A signaling system is called out-of-band when thefrequencies of the signals are outside the band of frequencies used for voicetransmission.Link-by-Link Signaling A signaling system is called link-by-link when the totalsignaling information is sent from one exchange to the other. The receivingexchange uses a part of the information for routing. When all digits are received, the

exchange takes over control of the originating exchange and sends the totalsignaling information to the next exchange.End-to-End Signaling A signaling system is called end-to-end if the originatingexchange remains the originating exchange for the entire signaling procedure. Theoriginating exchange sends the specific signaling information needed by thesubsequent exchange to establish the signaling path. As soon as the next exchangehas received enough digits to determine the routing, the exchange switches throughhis voice path and becomes transparent for the originating exchange.

2.0 Supervision Signaling Systems

Supervision systems are used to control and monitor the status of lines and trunks.These signaling systems are link-by-link.

2.1: Signal Definitions

Answer SignalSignal sent to the outgoing exchange to indicate that the called party has

answered the call. On metering trunks the first metering pulse is considered as theanswer signal.

Blocking SignalA signal sent for maintenance purposes to the exchange at the other end of a

circuit. It causes engaged conditions on that circuit for subsequent calls outgoingfrom that exchange.

Clear-Back SignalSignal sent in the backward direction to indicate that the called party has cleared.

Clear-Forward SignalA signal sent in the forward direction to terminate the call or call attempt and to

release all switching units held on the call in the incoming exchange and beyond it.

Metering SignalA signal sent in the backward direction to charge the call to the A-party. The

metering signal consist of metering pulses, which are sent periodically. One meteringpulse normally corresponds with a certain monetary value.

Reanswer SignalA signal sent in the backward direction indicating that the called party, after

having cleared, again lifts his receiver or in some way reproduces the answercondition.


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Release-Guard SignalA signal sent in the backward direction in response to a clear-forward signal to

indicate that the circuit concerned has been brought into the idle condition. The"Release-Guard" signal is also called "Return to Idle" signal.

Seizure-Acknowledgement Signal

A signal sent in backward direction to indicate the transition of the equipment atthe incoming end from the idle state to seized state. The "SeizureAcknowledgement" signal is also called "Seizure Control" signal.

Seizure SignalA signal sent in the forward direction at the beginning of the call to initiate

transition of the circuit at the incoming end from the idle state to seized state.

Unblocking-Acknowledgement SignalA signal sent in response to an unblocking signal indicating that the speech circuit

has been unblocked.

Some of the supervision signals for operator functions are as follows:

Force Release SignalA forward operator-originated line signal that requests a terminating exchange to

connect a busy terminating subscriber line to the incoming toll operator, anddisconnect the third subscriber who is in conversation with the operator-calledsubscriber.

Forward-Transfer SignalA signal sent in the forward direction on semi-automatic calls when the outgoing

international exchange operator wants the help of an operator at the incominginternational exchange.

Intrusion SignalA forward operator-originated line signal used for requesting that the terminating

exchange connect the incoming toll operator with an established speech path.

Operator Ring-Back SignalA backward line signal initiated by an operator terminating subscriber to request

that an originating toll operator be re-connected into the conversation.

Re-ring SignalA forward operator-originated line signal sent to the terminating exchange (after

answer and clear back) to request re-ringing of a now on-hook terminatingsubscriber line.


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2.1: MFC Address Signaling

Signaling ProcedureThere are 6 forward frequency combinations i.e. 1380,1500,1620,1740,1860

and 1980 Hz each having spacing of 129 Hz. In backward direction MFC freq are1140,1020,900,780,660 and 540 Hz. For a particular signal we need combination oftwo frequencies.

MFC (Multi Frequency Code) signaling is an in-band address signaling system. Thesignals consist of a combination of two of a set of six frequencies between 300 and3400 Hz. This implies that fifteen different combinations can be made. Since morethan fifteen signals are needed, signal groups are implemented. There are twoforward groups, I and II, and three backward groups called A, B and C.

Common Channel Signaling System No. 7

A signaling system is called a common channel signaling system when thesignaling information related to a group of circuits is transported over a separatecommon signaling link.

3.0 Basic Concepts

CCS No. 7 is a CCS (Common Channel Signaling) system which may be used in anassociated and non-associated mode of operation.

CCS7 being a common channel signaling system, has following features

Based on separation of speech circuit from the signaling link. Speech ckt has no signaling function except when a continuity check is done. Results in faster call setup

Efficient utilisation of speech ckts.

The overall objective of CCS No. 7 is to provide an internationally standardizedgeneral purpose CCS system:

optimized for operation in digital telecommunications networks in conjunctionwith stored program controlled exchanges.

that can meet present and future requirements of information transfer for inter-processor transactions within telecommunications networks for call control,

remote control and management and maintenance signaling that provides a reliable means of transfer of information in correct sequence

and without loss or duplication.

The signaling system is optimized for operation over 64-Kbit/s digital channels. It isalso suitable for operation over analog channels and at lower speeds. The system issuitable for use on point-to-point terrestrial and satellite links.


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3.1: Functional Blocks in CCS No. 7The CCS No. 7 consists of the following functional blocks:

MTP (Message Transfer Part) TUP (Telephone User Part)

ISUP (ISDN User Part) SCCP (Signaling Connection Control Part) TC (Transaction Capabilities)

Fig.3 Architecture of CCS no7

Level Structure of CCS No. 7

The CCS No. 7 protocol has a layered structure consisting of four levels (fig 4):

Level 1 defines the physical, electrical and functional characteristics of thesignal link.

Level 2 defines functions relevant to individual signaling links, including errorcontrol and link monitoring. This level is responsible for reliable transfer ofsignaling information between two directly connected signaling points.

Level 3 defines network functions such as message routing and networkmanagement.

Level 4 defines application and user functions. User parts are defined tocontrol the establishment and release of traffic circuits.

The first three levels together form the Message Transfer Part (MTP). The functionsof each of the CCS No. 7 layers are transparent to one another because of well-defined interfaces between them. A mechanism has been provided to deliver CCSmessages of up to 272 octets between the MTP and the user part, and within theuser part.


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Fig .4

Signalling Associations

A CCS7 network can have following types of associations between speech andsignaling path

Associated -Signaling path same as speech path Non-associated - Signaling path different from speech path and the signaling

path to be used not specifically determined. Quasi-associated - Non-associated with a predetermined signaling path.

Fig. 5 Associated and Quasi-associated mode of signalling

3.3: CCS No. 7 Network ElementsThe signaling network consists of several network elements:

SEP (Signaling End Point) STP (Signaling Transfer Point) STEP (Signaling Transfer and End Point)

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

CCS link

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

SWITCHING

SIGNALING

CCS link


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- - - - - Voice cktSignalling link

Fig.6 Network Elements

An SEP provides high speed, Common Channel Signaling connections for thespeech circuits which terminate at its exchange. Signaling messages arriving at anSEP are used to set up the necessary speech circuits to complete a telephone call tothe end user.The STP transfers signaling messages that arrive on one signaling link to a secondsignaling link where the message will then be routed toward the destination. An STPdoes not contain voice circuits, but it does provide the important function oftransferring messages (either to another STP or to an SEP) towards their ultimatedestination.The STEP performs both the SEP and STP functions. The STEP can transfer

signaling messages that are destined for another exchange, and it can analyzesignaling messages used to set up speech circuits in its exchange.

3.2 Signal Unit CompositionITU-T Signaling System No. 7 signals are sent in packets known as signal units.

The signal units vary in length according to the type of information transferred. Thereare three types of signal units:

MSU(Message Signal Unit): This is used for transferring signaling informationsupplied by the MTP itself or by the user part or SCCP.

LSSU (Link Status Signal Unit: This is used for transferring signalinginformation used to indicate and monitor the status of the signaling link.

FISU (Fill-In Signal Unit): This is used when there is no signaling traffic tomaintain link alignment.


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Point Codes

Every SP (Signaling Point) and STP (Signaling Transfer Point) when integrated in anetwork will be allocated its own unique point code. This is used by the MTP routingfunction to direct outgoing messages towards their destination in the network asindicated by the inclusion of the appropriate point code in the routing label. This pointcode is known as the DPC (Destination Point Code). The routing label also containsthe point code of the SP originating the message known as the OPC (OriginatingPoint Code). The combination of the OPC and the DPC will determine the signalingrelation. If two or more signaling links are required then the message handlingfunction performs load sharing over the links. In this case the SLS (Signaling LinkSelection) field is used to identify the chosen link.

3.3 User Part

The CCS No. 7 functional Level 4, known as the MTP User functions, defines thefunctions of the signaling system that are particular to users. The ITU-T has defined

several user functions of CCS No. 7, important are:TUP - Telephone User PartISUP - ISDN User PartSCCP - Signaling Connection Control PartTCAP - Transaction Capabilities Application Part

Telephone User PartThe TUP defines the telephone signaling functions necessary for CCS No. 7 tocontrol national and international telephone calls.

ISDN User Part

The ISUP defines the signaling functions needed for basic and supplementaryservices for ISDN voice and non voice applications.

Signaling Connection Control PartThe SCCP is used by call control for non-circuit related message transfer. Intelligentnetwork features requiring database access, such as credit card verification, virtualprivate network services, and 800 services use connectionless SCCP in conjunctionwith TCAP to query these databases. ISDN supplementary services use TCAP andconnectionless SCCP for sending information end-to-end. OMAP (Operations,Maintenance, and Administration Part) uses TCAP and the SCCP connectionlessservice in MTP and SCCP routing verification tests, and in circuit validation tests.Connection-oriented SCCP can be used for the ISUP user-to-user service 3 for data

transfer, and is used for reliable data transfer on the interface between a basestation and MSC (Message Switch Controller) in the GSM network.


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Transaction Capabilities Application Part (TCAP)

The TCAP provides services for interactive applications distributed over exchangesand specialized centers in an CCS No. 7 telecommunication network. The TCAPprovides the means to establish non-circuit related communication between twonodes in the signaling network. Some examples of interactive applications that use

the services of TCAP are as follows:

MAP (Mobile Application Part) used by GSM (Global Systems of Mobilecommunications)

INAP (Intelligent Network Application Part) OMAP (Operations and Maintenance Application Part)

5.0 CCS7 Normal Call Processing Messages

IAM (Initial Address Message): The IAM contains the dialed digits,voice/data trunk identity, and other related info. IAM/SAM contains all

necessary information to set the path from one switch to the other. Check tone (optional): For speech path continuity check After completion the

COT (Continuity Signal) message is sent. If the check tone fails, theCCF(Continuity Check Failure) message is sent .

ACM (Address Complete Message) Audible ringing tone ANC (Answer, Charge): On receipt of the answer signal, charging is started.

CLF (Clear Forward): If called subscriber hangs up first, the CLB (Clear-back) signal is sent in the other direction, followed by the CLF.

RLG (Release Guard): When the incoming equipment is released, a release-guard signal is sent back.

Advantages of CCS7 signaling:

1. Faster call setup.2. No interference between signalling tones by network and frequency of human

speech pattern.3. Greater trunking efficiency due to thequicker set up andclear down, thereby

reducing traffic on the network.4. No security issues related to the use of in-band signalling with CAS.5. CCS allows the transfer of additional information along with the signalling

traffic providing features such as caller ID.6. New services like IN services are possible because of CCS7 signaling.7. Efficient utilisation of speech ckts.
http://en.wikipedia.org/wiki/In-band_signallinghttp://en.wikipedia.org/wiki/Caller_IDhttp://en.wikipedia.org/wiki/Caller_IDhttp://en.wikipedia.org/wiki/In-band_signallinghttp://en.wikipedia.org/wiki/Caller_ID


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E2E3 Switching systems & NGN, Ver2 17.11.2007 1 of 15

EWSD - System Overview

1.0 System Features :

EWSD Digital switching system has been designed and manufacturedby M/s Siemens, Germany. The name is the abbreviated form of Germanequivalent of Electronic Switching System Digital (Electronische WhelerSysteme Digitale). EWSD switch can support maximum 2,50,000 subscribers

or 60,000 incoming, outgoing or both way trunks, when working as a puretandem exchange. It can carry 25,200 Erlang traffic and can withstand 1.4million BHCA. It is claimed that with the latest hardware and software version(Ver. 16), the system can withstand a BHCA of 16 million , can connect6,50,000 subscribers or 2,40,000 trunks and handle 1,00,800 Erlang traffic. Itcan work as local cum transit exchange and supports CCS No.7, ISDN and INand V5.X features.

3.0 System Architecture :

The main hardware units of an EWSD switch are as under:-

(1) Digital line unit (DLU) - functional unit on which subscriber lines areterminated.

(2) Line/Trunk Group (LTG) - Digital Trunks and DLUs are connected to

LTGs.

The access function determined by the network environment are handled

by DLUs and LTGs .

CCNC

MDDMTD

MB

CCGSYP CP

LTG(B)

LTG(C)

SN

TTRRUUNNKKSS

OMT PRINTER

DLUSSUUBBSS


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(3) Switching Network (SN) - All the LTGs are connected to the SN which

inter connects the line and trunks connected to the exchange in

accordance with the call requirement of the subscribers. CCNC and CP

are also connected to SN.

(4) Coordination Processor (CP) - It is used for system-wide coordination

functions, such as, routing, zoning, etc. However each subsystem inEWSD carryout practically all the tasks arising in their area

independently.

(5) Common Channel Signaling Network Control (CCNC) Unit or Signaling

System Network Control (SSNC)- This unit functions as the Message

Transfer Part (MTP) of CCS#7. The User Part (UP) is incorporated in the

respective LTGs.

2.1 Digital Line Unit (DLU)

Analog or Digital (ISDN-BA) subscribers, PBX lines are terminated on

DLU . DLUA, DLUB, DLUD & DLUG are the existing types in hardwareconfiguration of the DLU. DLUs can be used locally within the exchange or

remotely as remote

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. A local

DLU is connected to two LTGs via two 4 Mbps (64 TSs) links, each towards a

different LTG. In case of remote DLUs, maximum 4 PDCs of 2 Mbps (32

TSs) are used per DLU, two towards each LTG. Signaling information is

carried in TS16 of PDC0 and PDC2. In case of a local DLU interface, TS32

carries the signaling information.

Within the DLU, the analog subscribers are terminated on SLMA

(Subscriber Line Module Analog) cards (module). Similarly Digital (ISDN)

subscribers are terminated on the SLMD modules. Each module can support

16 subscribers (in case of DLUB or DLUD), and one processor SLMCP. One

DLU can carry traffic of 100 Erlangs. A standard rack of local DLU (in case

of DLUD) can accommodate two DLUs of 992 subscribers each.

In case the link between a remote DLU and the main exchange is

broken,

the subscribers connected to the remote DLU can still dial each other butmetering will not be possible in this case. For emergency service DLU-

controller (DLUC) always contain up-to-date subscribers data. Stand Alone

Service Controller card (SASCE) is provided in each R-DLU for switching

calls in such cases 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


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DLUs can also talk to each other in case the link of more than one DLU to the

main exchange is broken.

DLUG:

The latest type of DLU is DLUG which can accommodates upto 1984

analogue subscribers with 32 ports per SLMA but the SLMD stillaccommodates 16 subscribers. A standard rack of DLU can accommodate two

such DLUGs . The DLUG can be connected to four LTGs with 16 PDCs with

a provision of one signalling channel (CCS) per LTG. It can handle up to 390

Erlangs of traffic.

2.2 Line/Trunk Groups

The line/trunk groups (LTG) forms the interface between the digital

environment of an EWSD exchange & SN. MMaaxxiimmuumm ttrraaffffiicc hhaannddlliinnggccaappaacciittyyppeerrLLTTGGiiss110000EErrllang as it is able to connect four PDCs either from

lines or trunks. Hardware-wise LTGG, LTGM, LTGN and LTGP are existing

in our country.The LTGs are connected in any of the following ways :

(i) Via 2/4 Mb/s PDCs with remote/local DLUs to which subscribers areconnected

(ii) Via 2 Mbps digital access lines to other digital exchanges in the network((MMFFRR22TTrruunnkkss,, CCCCSS##77TTrruunnkkss))

(iii) Via Primary rate Access lines to ISDN PBXs (ISDN subscribers withPA)

((iivv)) VV55..22IIFF,, AAnnnnoouunncceemmeennttssTTrruunnkkss,,OOCCAANNEEQQ,, IIPP((IInntteelllliiggeennttPPeerriipphhrraall))((SSSSPP))

Functionwise LTGs are of two types:

(i) B Function LTG is used to connect lines e.g. DLU, PA, V5.2 IF etc.

(ii) C Function LTG is used to connect trunks on CAS and CCS#7

The bit rate on all highways linking the LTGs and the switchingnetwork is 8192 kbps ( 8 Mbps ). Each 8 Mbps highway contains 128 channelsat 64kbps each ,

2.3 Switching Network

Different peripheral units of EWSD, i.e., LTGs, CCNC, MB areconnected to the Switching Network (SN) via 8192 kbps highways calledSDCs (Secondary Digital Carriers), which have 128 channels each. The SNconsists of several duplicated Time Stage Groups (TSG) and Space StageGroups (SSG) housed in separate racks. Connection paths through the TSGsand SSGs are switched by the Switch Group Controls (SGC) provided in eachTSG and SSG, in accordance with the switching information from the


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coordination processor (CP). The SGCs also independently generate thesetting data and set the message channels for exchange of data between thedistributed controls.

The switching network is always duplicated (planes 0 and 1). Eachconnection is switched simultaneously through both planes, so that a standbyconnection is always immediately available in the event of a failure.

SN(B) has only 5 types of modules and each TSG and SSG isaccommodated in only two shelves of the respective racks. Here one shelf caneither accommodate one TSG or two SSGs thus requiring maximum 10 racksfor 504 LTGs. Remaining four shelves normally accommodate LTGs. Thelatest, SN (D) can connect 2016 LTGs and thus handle traffic of 1,00,800erlangs

Main Functions:*Speech Path Switching

*Message Path Switching

*CCS#7 signaling channels connection (NUC)

2.4 Coordination Area

2.4.1 Coordination Processor

The coordination processor (CP) handles the data base as well asconfiguration and coordination functions, e.g.:

- Storage and administration of all programs, exchange and subscriberdata,

- Processing of received information for routing, path selection,

zoning, charges,

- Supervision of all subsystems, receipt of error messages, analysis of

supervisory result messages, alarm treatment, error detection, error

location and error neutralization and configuration functions.

- Handling of the man-machine interface.

The Basic functional units of CP 113C are as follows:

- Base Processor (BAP) for operation & maintenance and call processing,

- Call Processors (CAP) for sharing call processing load if the exchange

BHCA cannot be handled by BAPs. Maximum 10 CAPs can be provided.- Common Memory (CMY)- 64 to 1024 MB mainly for resident programs

& database.

- Bus to Common Memory (BCMY)- For giving a time shared access to

processors to read CMY whenever a number of processors give such a

request.


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- Input / Output Controller (IOC)- 2 to 4 IOCs coordinate and supervise

accessing of CMY by IOPs.

- ATM Bridge Processor (AMP) If a SSNC (EWSD powernode) is

connected, the AMP is used (usually instead of the second IOC pair). It

represents the interface between the ATM equipment in the SSNC and the

CP. Its task is to convert theATM

oriented data streams from SSNC to theinternal EWSD format.

- Input/output processors (IOP) - Various types of IOPs are used to

connect the CP113C to the other subsystems and functional units of the

exchange as well as to the external mass storage devices (EM i.e.,

MDD, MTD, MOD), the two O&M terminals (OMT/ BCT), to OMC via

data lines etc. Maximum 12 IOPs can be connected to one IOC. The figure

is shown on next page.

2.4.2 Other units assigned to CP are:

Message Buffer (MB) for coordinating internal message traffic between

the CP- SN, CP-LTG, LTG-LTG, LTG- CCNC/SSNC in the exchange.

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

and, where necessary, the network. The CCG is extremely accurate with

error rate (10-9). It can, however, be synchronized even more accurately

by an external master clock (10-11).

System Panel Display (SYPD) to display system internal alarms & the CP

loadIt thus provides a continuous overview of the state of the system. The SYPcan also displays external alarms such as fire & air-conditioning system

failure .

Operation and Maintenance Terminals/ Basic Craft Terminal forInput/output. Two OMTs/ BCTs are provided for O&M functions.

2.5 Units for Message transfer part (MTP) of CCS#7 e.g. CCNC/SSNC

The common MTP functions in an EWSD exchange are handled by thecommon channel signaling network control (CCNC) or Signaling SystemNetwork Control (SSNC). The UP is incorporated in the software of therelevant LTG.


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2. Brief description of the functional components:-

2.1STS ( BT Time base): Time pulses are generated in triplicate anddistributed to LRs at Switching unit. The time base is usuallysynchronised with the network by a synch. interface. Synchronisationinterface gets the clock from PCMs which carry traffic also andsynchronises the local clock with the PCM clock and thus networksynchronisation is achieved.

2.2 SMX Host switching Matrix (MCX)/Switch Control FunctionCOM

This is a pure time switch of maximum 2048 LRs connectivitycapability. The switching of LR time shots are controlled by thefunction COM which in turn obtains the connection particulars from callhandler known as Multiregister.

LRs are 2 Mbps binary coded PCM links with 32 time slots.

2.3 SMA Auxiliaries : Following auxiliary functions areavailable

- Auxiliary Equipment Manager (ETA) :

The ETA supports the following function:- Tone generation (GT) e.g. dial tone, busy tone etc.- Frequency generation & reception (RGF) for R2 MF signal, tone

dial reception etc.- Conference call facility (CCF).- Exchange clock.

2.3.2 CCS # 7 Protocol Manager (PU/PE)

64 kbps signalling channels are connected to this by semipermanentlink and carries out level 2 and level 3 of the signalling messagetransfer.

The defence and signalling link resource allocation is done by a controlfunction PC.

2.3.3 V 5.2 Protocol Handler : The signalling protocol between anaccess network an d local exchange is processed and managed by thisfunction.

2.4 SMC Call Handler MRThis obtains necessary data from subs and circuits and process forconnection and disconnection of call with the help of a databasemanager TR. In addition this helps in carrying out circuit tests andsome observations. Besides MR function there is one CC (Call Contorl)function which again contains register to handle CCS # 7 calls inconjunction with MR registers.


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2.4.2 Data Manager TR:This function is responsible for managing and storing various

subscriber and trunks related data base. The data is returned bythe call handler MR as and when required during call processing.

2.4.3 Charging function (TX):This function is responsible for charge computation on the basis of

certain charging parameters supplied by the translator duringanalysis of digits received from a source (Subs or Circuit). Thisalso prepares detailed billing messages and forwarding the sameto the operation & maintenance function for further processing.Besides the charge related function the TX also is responsible forcarrying out some traffic observation on subscriber and trunks.

2.4.4 Matrix handler (GX)This function is responsible for processing and for defence of

connections on receipt of :-

(a) request for connection and disconnection from MR or MQ(marker).

(b) fault in connection signalled by the switching controller function(COM).

GX also carrier out monitoring of connections and checks data linksperiodically..

2.4.5 Message Distribution function (MQ) marker:Its function is to format if required and distribute messages- It also supervises semi permanent links .

- Interchange of messages between different communicationmultiplexes.

2.5 SMT PCM controller (URM) :PCM interface receives PCM from other exchanges remote subsaccess units, access networks and digital recorded announcementsystems and the URM function carrier out the following:

HDB3/Binary code conversion Injection / extraction of TS 16 for CAS.

2.6 SMM OM Function:This function enables to create all data required for subs/circuits and theirtesting. This also enables spontaneously issuing fault and alarmmessages in case of indications coming from OCB units. OM functionfurther provides features for saving detail billing/ bulk billing messages onmag tape (cartridge) . The OM function possess a two way communicationpath with the exchange system.


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INTRODUCTION TO THE 5ESS SWITCH

The 5ESS switching system has been designed M/s AT & T and supplied by

M/s Lucent Technologies Ltd.The 5ESS-2000 Switch has 3 major types ofequipment modules:

1. SM/SM-2000 (Switching Module),

2. CM (Communication Module)

3. AM (Administrative Module).

1.0 BASIC CHARACTERISTICS OF THE 5ESS SWITCH

The 5ESS-2000 Switch is a digital exchange that can serve as a local (lines),toll (trunks), tandem (lines and trunks), OSPS (Operator Service PositionSystem) or international gateway exchange, depending on the type of switch.It can serve a small community with fewer than 100 subscribers or a largemetropolitan area serving more than 200,000 subscribers.

Modular Distributed Design

AM

CMSM SM

DSCH

NCT Links

NCT

Link

SM

Fig. 1 Different Modules of 5-ESS Switch

The SM connects all lines and trunks . It performs most of the call processingfunctions. There can be many SMs per 5ESS-2000 Switch.

The CM provides communication between the SMs and the AM. There is oneCM per 5ESS-2000 Switch.

AM provides O& M functions for the switch.

2.0 SWITCHING MODULE

All external lines, trunks, and special services circuits like tones,announcements , testing and conferencing circuits are terminated at theswitching module. The analog and digital signals are converted to the digitalformat used inside the 5ESS-2000 Switch. The SM performs almost 95% ofthe call processing and maintenance functions including:


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MSGS

- MSCU (Message Switch Control Unit): It controls MSPU unit

- MSPU (Message Switch Peripheral Unit):It stores control informationof different SMs

ONTC

- CMCU (Communications Module Control Unit):It controls TMSU andclock generator is available.

- TMSU (Time Multiplexed Switch Unit) Where NCT links areterminated

CM3: is the latest hardware version of CM. In this type of CM there is asingle rack/shelf.

4.0 ADMINISTRATIVE MODULE

In the 5ESS-2000 Switch, the AM (Administrative Module) is a switch

equipment module which has the overall control of the entire 5ESS-2000Switch. The AM controls the CM and communicates with all the SMs (throughthe CM).

Administrative Module Functions

The AM has a minimum of one cabinet and can have a maximum of threecabinets. The AM performs resource allocation and processing functions thatare done more efficiently on a centralized basis such as:

Call routing for inter module and intra module calls

Administrative data processing/billing data

Traffic measurement reports/system performance reports

Memory management

System maintenance

Maintaining file records of changes to the system SoftwareRelease.

Personnel interface/system monitoring

Allocating trunks for call processing.

4.1 Administrative Module Components

There are three main units located within the AM :

CU (Control Unit)

IOP (Input/ Output Processor)

DFC (Disk File Controller)

The CU monitors overall system operation. The IOP interfaces with the MCC (Master

Control Center), ROP (Receive Only Printer) and other peripheral devices. The DFC

controls the TD (Tape Drive) and (DD) Disk Drive.


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- Manages data transfer - controls memory transfer between its ownmemory, its hard disk, and the microprocessors that serve theperipheral units in the IOP.

- The MM stores program instructions and data. The MM storesthe instructions and other data needed by the processor to processcalls, collect administrative information, and perform systemmaintenance.

CU

CC

MM

DFC

IOP

TD

DD

MCC

ROP

Fig. 2 Administrative Module Components

4.3 AM Peripheral Component Functions

Disk File Controller

The DFC is responsible for interfacing with the SCSI (Small Computer SystemInterface) Peripheral Devices, such as the disk and tape drives.

Tape DriveThe tape drive is a backup for information stored on disk.

Input/ Output Processor

The IOP is the interface for other peripheral devices used by the switch, suchas maintenance interfaces (MCC and ROP), datalinks and alarm signaling.

Master Control Center

The primary functions of the MCC are to provide the following

- Visual displays of system status and alarm information

- The means to control, test and reconfigure the system

- The means to manually recover the system

- Access to exchange data

The ROP (Receive-Only Printer) provides a printed copy of reports fromthe MCC.


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NGN: CONCEPT AND ARCHITECTURE

The current generation network of BSNL, popularly known as PSTN is mainly circuit

switching based network and it is organized into an hierarchical architecture viz.

Level I TAX exchanges, then Level-II exchanges and then tandem/local exchanges.

The PSTN network is mainly optimized for voice calls and not much suited for data

services. We have a separate network for data services. Today the world over trend isfor a single converged network used for all type of services viz. voice, data, video

which is called Next Generation Network and is a packet switching based network. To

change over from current generation network to next generation network we have to

move in a step-by-step manner to safeguard our existing network infrastructure and

investment and therefore we have to follow an evolutionary path.

2.0 Why NGN?The NGN concept takes into consideration new realities in the telecommunication

industry characterised by factors such as: the need to converge and optimise the

operating networks and the extraordinary expansion of digital traffic (i.e., increasing

demand for new multimedia services, increasing demand for mobility, etc.). The other

reasons why we should evolve our existing network to NGN are that the existing

circuit switched networks have following problems:

Slow to develop new features and capabilities. Expensive upgrades and operating expenses. Proprietary vendor troubles Large power and cooling requirements. Limited migration strategy to New tech. Model obsolescence.

3.0 What is NGN?

3.1 ITU-Ts Definition of NGN

A Next Generation Network (NGN) is a packet-based network able to provide

Telecommunication Services to users and able to make use of multiple broadband,

QoS-enabled transport technologies and in which service-related functions are

independent of the underlying transport-related technologies. It enables unfettered

access for users to networks and to competing service providers and services of their

choice. It supports generalised mobility which will allow consistent and ubiquitous

provision of services to users.

3.2 ETSIs Definition of NGN

As per ETSI NGN is a concept for defining and deploying networks, whichdue to their formal separation into different layers and planes and use of openinterfaces, offers service providers and operators a platform, which can evolvein a step-by-step manner to create, deploy and manage innovative services.

The following diagram depicts the concept of NGN.


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Current Gen networks NGN

In NGN basically the call control (i.e. signaling) and the switching is separatedout in different layers and between these layers open interfaces are used. Thecall control functionality is realized by the component which is called callserver or softswitchor media gateway controllerand the interfaces to theexisting PSTN switches is done with the help of media gateways for voicetransport and by signaling gateways for signaling transport. For switching andtransport of the packets existing IP/MPLS backbone is used. With NGNarchitecture the new and innovative services can be given very fast and cost

effectively. Also the capital expenditure and operational expenditure comedown drastically.

The NGN is characterized by the following fundamental aspects:

Packet-based transfer Separation of control functions among bearer capabilities,

call/session, and application/service

Decoupling of service provision from transport, and provision ofopen interfaces

Support for a wide range of services, applications and mechanismsbased on service building blocks (including real time/streaming/non-

real time services and multi-media) Broadband capabilities with end-to-end QoS and transparency Interworking with legacy networks via open interfaces Generalised mobility Unfettered access by users to different service providers

Interfaces

Switching

Call

ControlCall

Server

IP/MPLS

SDH Transport

with Overlaypackets for data

Common

IP MPLS


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E2E3 IN Ver2 17.11.2007 1 of 9

INTELLIGENT NETWORK

Over the last thirty years one of the major changes in the implementation of Public

Switched Telephone Networks (PSTN) has been the migration from analogue to digitalswitches. Coupled with this change has been the growth of intelligence in the switching

nodes. From a customers and network providers point of view this has meant that newfeatures could be offered and used. Since the feature handling functionality was residentin the switches, the way in which new features were introduced into the network was by

introducing changes in all the switches. This was time consuming and fraught with risk of

malfunction because of proprietary feature handling in the individual switches. Toovercome these constraints the Intelligent Network architecture was evolved both as a

network and service architecture.

In the IN architecture, the service logic and service control functions are taken out of the

individual switches and centralized in a special purpose computer. The interface between

the switches and the central computer is standardised. The switches utilize the services of

the specialized computer whenever a call involving a service feature is to be handled. Thecall is switched according to the advice received by the requesting switch from the

computer. For normal call handling, the switches do not have to communicate with the

central computer.

1.1. Objectives of the Intelligent Network

The main objectives of the IN are the introduction and modification of new services in a

manner which leads to substantial reduction in lead times and hence development costs,and to introduce more complex network functions. An objective of IN is also to allow the

inclusion of the additional capabilities and flexibility to facilitate the provisioning of

services independent of the underlying network's details. Service independence allowsthe service providers to define their own services independent of the basic call handlingimplementation of the network owner. The key needs that are driving the implementation

of IN are:

Rapid Service DeploymentMost businesses today require faster response from their suppliers, including

telecommunication operators. By separating the service logic from the underlying switchcall processing software, IN enables operator to provide new services much more rapidly.

Reduced Deployment Risk

Prior to IN, the risk associated with the deployment of new services was substantial.Major investments had to be made in developing the software for the services and then

deploying them in all of the switches. With the service creation environment available,

the IN services can be prototyped, tested and accessed by multiple switchessimultaneously. The validated services can then be rolled out to other networks as well.


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E2E3 IN Ver2 17.11.2007 2 of 9

Cost Reduction

Because the IN services were designed from the beginning to be reusable, many newservices can be implemented by building on or modifying an existing service. Reusability

reduces the overall cost of developing services. Also, IN is an architecture independent

concept, i.e. it allows a network operator to choose suitable development hardware

without having to redevelop a service in the event that the network configurationchanges.

CustomizationPrior to IN, due to complexity of switch based feature handling software, the

considerable time frame required for service development prevented the provider fromeasily going back to refine the service after the customer started to use it. With IN, the

process of modifying the service or customization of service for a specific customer is

much less expensive and time consuming. The customization of services is further

facilitated by the integration of advanced peripherals in the IN through standardinterfaces. Facilities such as voice response system, customized announcements and text

to speech converters lead to better call completion rate and user friendlinessof the services.

1.2. IN Architecture

Building upon the discussion in the previous section, one can envisage that an IN would

consist of the following nodes:

Specialized computer system for - holding services logic, feature control, servicecreation, customer data, and service management.

Switching nodes for basic call handling

Specialized resources node

The service logic is concentrated in a central node called the Service Control Point

(SCP).

The switch with basic call handling capability and modified call processing model for

querying the SCP is referred to as the Service Switching Point(SSP).

Intelligent Peripheral (IP) is also a central node and contains specialized resources

required for IN service call handling. It connects the requested resource towards a SSP

upon the advice of the SCP.

Service Management Point (SMP) is the management node, which manages services

logic, customers data and traffic and billing data. The concept of SMP was introduced in

order to prevent possible SCP malfunction due to on-the-fly service logic or customerdata modification. These are first validated at the SMP and then updated at the SCP

during lean traffic hours. The user interface to the SCP is thus via the SMP.


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E2E3 IN Ver2 17.11.2007 3 of 9

Physical Plane

Service Switching Point (SSP)

The SSP serves as an access point for IN services. All IN service calls must first

be routed through the PSTN to the "nearest" SSP. The SSP identifies the incoming call asan IN service call by analysing the initial digits (comprising the "Service Key") dialled by

the calling subscriber and launches a Transaction Capabilities Application Part (TCAP)query to the SCP after suspending further call processing. When a TCAP response is

obtained from the SCP containing advice for further call processing, SSP resumes call

processing. The interface between the SCP and the SSP is G.703 digital trunk. The MTP,SCCP, TCAP and INAP protocols of the CCS7 protocol stack are defined at this interface

Service Control Point (SCP)

The SCP is a fault-tolerant online computer system. It communicates with the

SSP's and the IP for providing guidelines on handling IN service calls. The physicalinterface to the SSP's is G.703 digital trunk. It communicates with the IP via therequesting SSP for connecting specialized resources. SCP stores large amounts of data

concerning the network, service logic, and the IN customers. For this, secondary storage

and I/O devices are supported. As has been commented before, the service programs andthe data at the SCP are updated from the SMP.

Service Management Point (SMP)

The SMP, which is a computer system, is the front-end to the SCP and provides

the user interface. It is sometimes referred to as the Service Management System (SMS).

It updates the SCP with new data and programs(service logic) and collects statistics fromit. The SMP also enables the service subscriber to control his own service parameters via

a remote terminal connected through dial-up connection or X.25 PSPDN. This

modification is filtered or validated by the network operator before replicating it on theSCP. The SMP may contain the service creation environment as well. In that case

the new services are created and validated first on the SMP before downloading to the

SCP. One SMP may be used to manage more than one SCP's.

Intelligent Peripheral (IP)

The IP provides enhanced services to all the SSP's in an IN under the controlof the SCP. It is centralized since it is more economical for several users to share the

specialized resources available in the IP which may be too expensive to replicate in all

the SSPs. The following are examples of resources that may be provided by an IP:

Voice response system

Announcements

Voice mail boxes Speech recognition system

Text-to-speech converters


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E2E3 IN Ver2 17.11.2007 4 of 9

The IN architecture is depicted in below given Figure:

Data

Base

CCS7 Network

IP SSP

USER USER USER USER

Communication Interface

Data

BaseCommunication Interface

Program Interface

Communication Interface

Legend

SMP: Service Management Point

SCP: Service Control Point

Service switching Point

IP: Intelligent peripheral

SMP

SCP


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E2E3 IN Ver2 17.11.2007 5 of 9

1.3. DESCRIPTION OF IN SERVICE FEATURES

An IN service comprises mandatory (providing core functionality) and optional features.

A brief description of the various features that constitute the IN services offered as part of

IN solution is given in the following paragraphs.

Call Forwarding on Busy/No Answer (CFC): This service feature allows the called

user to forward calls if the called user is busy or doesn't answer within a specifiednumber of rings.Customer Profile Management (CPM): This feature allows the user to perform online

modification of the password (authorization Code).

Mass Calling (MAS): This service feature allows processing of large numbers of

incoming calls in a given time span, generated by call-in broadcasts, advertisements or

games, etc.

Origin Dependent Routing (ODR): This service feature allows the subscriber to have

calls routed according to the calling party's area of origination. Based on the area of

origination the subscriber can also accept or reject the call.

Origination Call Screening (OCS): This service feature allows the subscriber to bar thecalls originating from certain areas identified by their area codes.

Off-net Access (OFA): This service feature allows a VPN user to access his or her VPN

from any non-VPN station by using a personal identification number.

Off-net Calling (ONC): This service feature allows the VPN user to call any external

public number from a VPN location. Authorization is required for accessing this feature.

Premium Charging (PRMC): This service feature allows for the pay back of the part ofthe cost of a call to the called party, when he is considered a value added service

provider. The call is charged at a premium over normal call charge.

Private Numbering Plan (PNP): This service feature allows the subscriber to maintain a

numbering plan within his private network, which is separate from the public numberingplan.

Reverse Charging (REVC): This service feature allows the service subscriber to receive

calls at his own expense and be charged for the entire cost of the call.

Time Dependent Routing (TDR): This service feature enables the subscriber to route

calls based on time of day, day of week and day of year. The precedence when more than

one type of parameters are specified for determining routing shall be1. Day of year2. Day of week

3. Time of day

Call Distribution (CD)

This service feature allows the subscriber to have the calls routed to more than onedirectory number. Based on the values defined, only a percentage of calls are routed

to a directory number.


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E2E3 IN Ver2 17.11.2007 6 of 9

IN Services and access codes

Existing New Codes Service Access

1600 1800 Free Phone

1601 1801 VPN

1602 1802 VCC(ITC)1603 1803 Tele voting (no charge)

1604 1804 ACC

1901 1860 UAN(Local)

1902 1861 Tele voting(Charge)

0900 1867 PRM

0901 1860 UAN(LD)

1868 UPN

1907 1807 UAN Mgmt

1808 UPN Mgmt

1809 VPN Mgmt

FLPP

IN platforms in BSNL and its SCP Codes:

Kolkata(East Zone)

345 General purpose(GPIN)

Bihar, Jharkhand, WestBengal,Orissa,Assam, North East-I & II,

CTD and A&N Islands

Bangalore

(South Zone)

425 General purpose

(GPIN)

TamilNadu, Kerala, Karnataka, Chennai T.D.

Lucknow

(North Zone)

180 General purpose

(GPIN)

UP (E), UP (W), Uttaranchal, Punjab,

Haryana, H.P., J&K and RajasthanAhmedabad

(West Zone)

233 General purpose

(GPIN)

Gujarat, Maharashtra, Madhya

Pradesh, Chattisgarh, AP

Hyderabad

(Central)

424 Mass Calling IN

(MCIN)

All India(Mass Calling)

Virtual Card Calling Service (ITC)Also known as Indian Telephone Card. Meant for customers who want to makeSTD/ISD calls from any Bfone (may not be his own) and limit the usage. Nometering will be there on the Calling Telephone Number. Metering will be thereagainst the VCC account.

Access code : 1602-SCP Code- PIN Destination No.(1802 by 30-04-2009)


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E2E3 IN Ver2 17.11.2007 8 of 9

Universal Personal Number ServiceOutgoing facility also available in UPN service. It introduces the concept of

Personal mobility rather than terminal mobility.

A subscriber to this service can receive or make calls using his UniversalPersonal Number from any BSNL phone.

The subscriber will be given some management codes and password.Using that he can convert/reconvert any BSNL phone into his UniversalPersonal Number.

All the calls made by subscriber using his UPN will be billed at his UPN bythe IN platform.

The subscriber will be able to get all his calls incoming on the UPNnumber anywhere in India.

This is a service newly introduced through Alcatel IN Platform.

Virtual Private Network Enables the subscriber to establish a private network using existing public

network resources.

Virtual PABX and it can be nation wide.

Individual members can have privileges-ON net.

Calling possible from outside VPN-Off net

Billing will be against the Group id

VPN Features Multi site Organization

Short Group Numbers

Abbreviated Dialing Date & Time Screening

Exception List

Call Duration Control

Multiple Account Codes

Dual Invoicing

Call Forwarding Hunting List

Substitution

Tele-Voting Service To conduct telephonic public opinion polls and surveys. Thus provides

easiest way to conduct poll/survey.

Opinion by dialing the advertised Tele-voting number. The calling user canbe charged (Unit) or charge free.

The service can be available based on origin or time basis.

Tele Vote Features Validity Period

Counters

Global Vote Counter

Local Tele voting Counter perVOT number

Winner Counter

Black List Origin Dependent Handling

Day Type/Time DependentHandling

Pre Filtering at SSP


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E2E3 IN Ver2 17.11.2007 9 of 9

Fixed Line Pre-paid Service

Types of FLPP Services in BSNL

1. PCO FLPP Account - offering only Prepaid Services (for Local +STD+ISD)2. General FLPP Account - offering both Prepaid & Postpaid services

3. General FLPP Account offering only Prepaid services

FLPP PCO and FLPP General Pure pre paid- can be given to subscribers from AXE-

10, 5ESS, EWSD, E-10B, OCB-283 and not from CDOT.

Dialing Plan: Only Destination Number needs to be dialed.

Internal Routing Plan:

As on date only OCB-283 exchanges can act as SSP and trigger the FLPP Calls to

the SCP. Rest of the new Technology exchange shall only prefix the FLPP Call with 1805-

345/ 233 and then the call shall be routed to nearest OCB 283 exchange whichwill further trigger the FLPP Calls to the SCP.

If the FLPP Call is originated from E-10B Exchange then the exchange shallsimply route to any of the new technology exchange. Further routing shall be as

explained above.

FLPP General Pre paid over post paid- can be given to subscribers from AXE-10,

5ESS, EWSD, OCB-283 and not from E-10B, CDOT.Dialing Plan:

a. Post paid by default : Only Destination Number needs to be dialed(this shall not beFLPP Call).b. To Make prepaid call: 1805 345/233 + destination number

Internal Routing Plan:

As on date only OCB-283 exchanges can act as SSP and trigger the FLPP Calls tothe SCP.

Rest of the new Technology exchange shall simply route the FLPP Calls tonearest OCB -283 exchange which will further trigger the FLPP Calls to the SCP.

(Not available from CCB PCOs)

Note: FLPP Prepaid over Post paid can not be provided from E-10B and C-DoT

exchanges because of its inability to send more than 16 digits on trunks.

FLPP Pure Prepaid can not be provided from C-DoT exchanges because of itroutes the local without treating it as IN Call and ISD calls can also be not made

because of its inability to send more than 16 digits on trunks.


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E2E3 Battery Power plant, Ver1 24.08.2007 2 of 5

water and the positive plates generate oxygen gas and the negative plates generatehydrogen gas.

Under typical charging conditions, oxygen at the positive plate occurs before hydrogenevolution at the negative. This feature is utilized in the design of VRLA batteries. In

flooded cells, the oxygen gas evolved at the positive plate bubbles upwards through theelectrolyte and is released through the vents. In MF-VRLA batteries the oxygen gasevolved, at the positive plate, instead of bubbling upwards in transported in the gasphase through the separator medium to the negative plate. The separator is a highlyabsorbent glass matrix type with very high porosity, designed to have pore volume inexcess of the electrolyte volume (starved electrolyte design), due to which the oxygengas finds an unimpeded path to the negative plate. the oxygen gas gets reduced byreaction with the spongy lead at the negative plate, turning a part of it into a partiallydischarged condition, there by effectively suppressing the hydrogen gas evolution at thenegative plate. This is what is known as the oxygen recombination principle.

The part of negative plate which was partially discharged is then reverted to the originalspongy lead by subsequent charging. Thus a negative plate keeping equilibriumbetween the amount which turns into spongy lead by charging and the amount ofspongy lead which turns into lead sulphated by absorbing the oxygen gas generated atthe positive plate. The oxygen recombination principle can be shown by the followingreaction:1. Reaction at positive plate :

H2O = 1/2 O2 + 2e (1)

2. Reaction at negative plate :

Pb + 1/2 O2 = PbO .(2)

PbO + H2SO4 = PbSO4 + H2O .(3)To reaction (1)

PbSO4 + 2H + 2e = Pb + H2SO4 (4)To reaction (3)

To reaction (2)3. The total reaction at negative plate

1/2 O2 + 2H = H2O

Thus, the recombination technology makes the battery virtually Maintenance Free.


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Battery capacity :The energy that can be taken out of a battery before the cellvoltage collapses is called the battery capacity. It is defined as Discharge current (A) Discharge Duration time (hours).

MONITORING OF VRLA BATTERIES

Following steps are required for monitoring of the VRLA Batteries:(a) Periodic physical inspection of each cell of the battery for cracks and leaking etc.(b) Discharge of battery for a short duration and recording the voltages of each cell

in the string.(c) Measurement of a mark deviation (>30%) in the impedance or conductance of

the cell as compared to the one recorded at the time of commissioning.(d) Measurement & recording of cell temp. periodically.(e) Float Voltage of cells & its comparison with the mid point voltage.(f) Float current in fully charged battery.

Periodic Physical Inspection: Check for any crack or leakage every month. If notevery month, at least once in two months.

Battery Partial Discharge Test: Put battery to a test discharge for 30 minutes byshutting power plant so that 20% of the battery is discharged. This can be decided bythe table supplied by the manufacturer. Record the Voltage of each cell. Any cellshowing more than 5% variation compared to voltage of other cell can be potential weakcell.Impedance Measurement:Take impedance measurement when the charger is on andthe battery is on float. Any change in impedance/conductance of the cell more than 40%shows imminent failure of the battery/cell. A change of


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Effect of Temperature on the battery:With rise in temperature the battery life decreases.For every 10 degree rise in temperature, the capacity of battery becomes half.There is a temperature compensation in SMPS Power Plants and it is 3 milli-volt perdegree rise in temp.

Life of battery:

Batteries upto 200AH: 4 Years

Batteries more than 200 AH: 6 years

SMPS(Switched Mode Power Supply) Power plant:

The salient features of SMPS power plant are:1) The power system is intended primarily to provide uninterrupted DC power to

telecom exchange and current for charging the batteries.2) The system works from commercial AC mains which is rectified and regulated to

-54 V DC and is fed to the equipment (exchange).3) The modules switching frequency for SMPS is 107.5 kHz. Therefore size of the

module is very compact.4) The system has provision to connect three sets of VRLA batteries and facility to

charge them simultaneously to ensure that uninterrupted DC power is alwaysavailable to the exchange.

5) The power systems is suitable for VRLA batteries.

Life of Power Plant:

Static P/P : 15 years SMPS P/P: 15 years


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Earthing

Purposes of Earthing

Apart from protection from hazardous stray currents in electrical equipment inTelecommunication circuits and equipments, earthing is provided for the followingpurposes:

(a) Reduction of Crosstalk and Noise :One pole of the battery (+ve pole) is earthed in the telephone exchange sothat cross talk between the various circuits due to the speech currents ofone circuit finding path through the other via common battery feed points ofthe transmission bridge and poor NSN via earthed terminal of the battery isreduced.

(b) Protection of buildings and equipments from lighting strikes.

(c) Used as return path for the conductors in some telegraph and voice circuits.(d) Protection of costly apparatus and persons against foreign voltages and

leakage currents from power wirings to the metallic frame of the equipment.(e) Earth is used to afford convenience & reliability, in the operate path of the

circuits involved in the switching apparatus of telecom circuits.(f) Earthing power supply systems is used to effect reliability of power as it

helps to provide stability of voltage conditions preventing excess fluctuationsand providing a measure of protection against lighting.

Earth Electrodes :

Three types of earth electrodes are commonly used for earthing systems.

1) Rod electrodes2) Plate electrodes3) Strip electrodes

Instruction for monitoring of Earth resistance were issued from Corporate office. As perthe instruction:

E/R is to be measured every six months.

Earth resistance should be less than 0.5 for electronic

One dry season must be included in these two occasions.

For lightning prone area, it should be measured every month.

Wherever, it is beyond limits, it should be immediately brought within limits.

Procedure for laying earth resistance may be followed as prescribed in the latestissue of EI on Protection Earthing I-001.

Reduction in card failure has been observed by improving the earth resistance.


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E2E3 AC and EA, Ver1 24.08.2007 1 of 10

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E2E3 AC and EA, Ver1 24.08.2007 6 of 10

ENGINE & ALTERNATOR

The standby power supply commonly used in T.E buildings is from DieselEngine Alternator Set .In the Engine Alternator Set, the Diesel engine is

the prime mover which rotates the alternator of the engine Alternator set

and alternator in turn produces Electrical energy. In the first stage of

energy conversion, the chemical energy of fuel is converted in to the

mechanical energy at the common shaft of Engine & Alternator. This

mechanical energy is then converted into electrical energy at alternator in

the second stage of energy conversion.

PRINCIPLE OF OPERATION OF ENGINE

When the fuel ignites in the combustion chamber, energy in the form of

heat and gases is generated. The rapid expansion of hot gases creates

pressure in the combustion chamber which pushes the piston away. The

reciprocating motion of the piston is converted in to the circular motion by

the engine crankshaft, which is connected to the piston by the connecting

rod.

FOUR STROKE PRINCIPLE OF DIESEL ENGINES

The four stroke working principle of Diesel Engine is as under:

(i) ADMISSION STROKE

The piston draws fresh air into the cylinder on its downward travel

through the open admission valve. With turbo charged engines the

air is first compressed by a blower and admitted to the cylinder

under increased pressure.

(ii) COMPRESSION STROKE

On its upward travel the piston compress the fresh air in the cylinder

with the valves closed. The temperature of the fresh air is thus

increased to exceed the ignition temperature of the fuel. Shortly


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E2E3 AC and EA, Ver1 24.08.2007 7 of 10

before the piston reaches the top dead centre, fuel is injected into

the combustion space.

(iii) POWER STROKE

The fuel injected ignites in the hot air and burns. The combustion

causes a high pressure which forces the piston down. Resulting intoreciprocating movement of the shaft.

(iv) EXHAUST STROKE

The piston moving upward forces the exhaust gas through the open

exhaust valve into the exhaust pipe. When the exhaust stroke is

terminated the exhaust valve close and the admission valve opens

for a new operation cycle.

SYSTEMS OF A DIESEL ENGINE

Various systems of diesel engine constituting the working system are as below:


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E2E3 AC and EA, Ver1 24.08.2007 8 of 10

(1) LUBRICATION SYSTEM

The moving parts of the diesel engine are lubricated for their optimum operation

by this lubrication system. A dipstick in the oil sump serves to check the oil level.

The lub oil level and the lubrication oil pressure have to be checked for

satisfactory performance and long life of the engine.

(2) FUEL SYSTEM

Depending on the position of the fuel, the fuel is supplied to the distributing pipe

through fuel filter either by natural head from an elevated tank or by a fuel pump.

Fuel is supplied inside the cylinder by injection nozzles.

(3) AIR EXHAUST SYSTEM

For the combustion of fuel sufficient quantity of the filtered air is taken in the

combustion chamber. After the combustion the exhaust gases are taken away

from the engine through suitable ducting or piping. This is known as air exhaustsystem.

(4) COOLING SYSTEM

Cooling System is essential for cooling the engine body, and to act as a heat

exchanger for lubricating oil. This can be either water-cooled or air cooled.

(5) STARTING SYSTEM

The Diesel Engine can be equipped with the starting system i.e. with

an electric starter with a pinion, which engages with the fly wheel of the engine.

The power to the electric starter is provided by means of a battery which is kept

in charged condition by means of a dynamo or electric rectifier.

ALTERNATOR

Alternator works on Faradays law of Electromagnetic induction. There are two

requirements for the functioning of Alternator (1) Magnetic field & (2) Rotation.

Magnetic field is produced by passing direct current through the field winding ofthe Alternator an

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