E3E4 Telecom Factory CHAPTER-18 FAMILIARIZATION OF...

E3E4 Telecom Factory


CHAPTER-18

FAMILIARIZATION OF TELECOM

TECHNOLOGIES


Consumer Fixed Access Network Overview-I

The telephone network used for fixed line services is also referred as PUBLIC

SWITCHED TELEPHONE NETWORK (PSTN). There are different types of the

telephone exchanges or elements (switching systems) in PSTN which work on circuit

switching principle.

While the data networks, on the other hand use the principle of Packet

Switching. In Packet switching the information (speech, data etc.) is divided into

packets, each packet containing piece of information also bears source and destination

address.

1.0 PSTN Elements

The telephone network is consists of various PSTN elements like local

exchanges, transient exchanges, local cum transient exchanges, NGN /IP TAX and

standalone signaling transfer point (SSTP).

These element, consists of new technology switching systems, were inducted

in our network. Mainly 4 NT switching systems were inducted in BSNL network:

EWSD Supplied by M/s Siemens, Germany

OCB-283 Supplied by M/s Alcatel, France

5ESS Supplied by M/s Lucent, USA

AXE-10 Supplied by M/s Ericson

For rural area in our country where small capacity exchanges were required,

CDOT equipment (CDOT 128P, 256P, SBM, MBM etc) was installed. CDOT

technology is indigenously developed technology in our country. Initially standalone

128P, 256 P CDOT exchanges were installed but now these small independent

exchanges have been converted into AN-RAX (Access Network Rural Automatic

Exchange) and they are parented to nearby CDOT SBM/MBM or NT exchange. With

this development now all remote ANRAXs can be maintained from the SBM/MBM.

It improved O& M functions/issues of small exchanges.

In the BSNL network about 30% of the total switching capacity is on CDOT

technology. The total equipped capacity in BSNL as on Sept 2010 is about 6, 21,

98,000 (including WLL and DLC).

In the BSNL network about 38% of the total working connection is on CDOT

technology. The total working connection in BSNL as on Sept 2010 is about 3, 10,

36,276 (including WLL and DLC).


The WLL FWT (Fixed wireless terminals and the connection given over DLC

are counted in Basic service (Fixed Network).

2.0 Network Organization:

The PSTN network is organized in a hierarchical manner with Lev-1/ Lev-2/

Tandem/ Local Exchanges. The calls from a local exchange are routed to Lev-I TAX

either directly or through Lev-II TAX. From Lev-I TAX it is routed to the destination

exchange either directly or through another Lev-I/Lev-II TAX. For ISD calls ISD

Gateway is used.

Existing network node:-

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

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

International gateways at 6 places (Delhi, Chennai, Mumbai, Kolkata

Jallundhar and Ernakulam ).

Local Exchanges: About 36,000

New network (Upgradation) node:-

NGN/ IPTAX -------2 (Delhi and Chennai) and other are at the sites

of Lev-I TAX .

SSTP ---------24

3.0 Interconnection with the private operator:

Any operator can take license for providing basic telephone service on circle

basis. Licenses are issued by DOT. Once an operator gets a license in a particular

circle, after installing the necessary equipment it is required to be interconnected with

the BSNL network for making the calls into/from BSNL network. For this either the

connectivity is taken at local exchange level for local calls and also at Lev-I/Lev-II

TAX for long distance calls. It is called POI (Point of Interconnection). POI

charges are prescribed by TRAI.

4.0 NGN Architecture & IP TAX

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 is for a single converged network used for all type

of services viz. voice, data, video which is called Next Generation Network and is a

based on packet switching principle. 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.

4. 1. Why NGN?


The NGN concept takes into consideration new realities in the telecom industry

characterized by factors such as the need to converge and optimize 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 costs.

Proprietary vendor troubles

Large power and cooling requirements.

Limited migration strategy to new tech.

Model obsolescence.

4. 2. What is 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 generalized mobility which will allow consistent and ubiquitous

provision of services to users. < ITU-T Recommendation Y.2001 (12/2004) - General

overview of NGN>.

ETSI (European Telecommunication Standardization Institute) defines the

NGN as a concept for defining and deploying networks, which due to their formal

separation into different layers and planes and use of open interfaces, offers service

providers and operators a platform, which can evolve in a step-by-step manner to

create, deploy and manage innovative services.


The following diagram depicts the concept of NGN.

Current Gen networks NGN

Fig. 1

In NGN basically the call control (i.e. signaling) and the switching is separated

out in different layers and between these layers open interfaces are used. The call

control functionality is realized by a component which is called call server or soft

switch or media gateway controller or call agent and the interfaces to the existing

PSTN switches is done with the help of media gateways for voice transport and by

signaling gateways for signaling transport.

For switching and transport of the packets existing IP/MPLS backbone is used.

With NGN architecture the new and innovative services can be given very fast and

cost effectively. Also the capital expenditure and operational expenditure come down

drastically.

4.3 The NGN is characterised 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 of open interfaces

Support for a wide range of services, applications and mechanisms based on

service building blocks (including real time/streaming/non-real time services and

multi-media)

Broadband capabilities with end-to-end QoS and transparency

Interfaces

Switching

Call

Control Call

Server

IP/MPLS

Gateways

SDH Transport with

Overlay packets for

data

Common IP MPLS

Transport over

SDH/ DWDM/Fiber


Interworking with legacy networks via open interfaces

Generalized mobility

Unfettered access by users to different service providers

As the BSNL is having a huge PSTN network consisting of local and TAX

exchanges, therefore we have to gradually migrate towards NGN. Initially BSNL has

planned to implement NGN at the TAX level and subsequently will be implemented

at the local exchange level.

5.0. IP TAX in BSNL

IP TAX is the first step towards the evolution of current generation network to

next generation network in BSNL. In other words IP TAX is the replacement of

existing Level –I/Level-II TAX exchanges to IP based network (Packet Switching

Network) and rest all the network still remaining circuit switched network. Presently

IP TAX will be installed in parallel to the Lev-I TAX and then it will replace circuit

switched TAX completely with IP TAX.

In BSNL 40K IP TAX at New Delhi and 16K IP TAX at Chennai have been

installed. There is a further plan of installing 6476 K IP TAX in all places where

Level –I/Level-II TAX exchanges are existing.

Generic reference diagram for IP TAX is shown in Fig.2 .

Based on the GR the implementation plan is as below:

The IP TAX architecture is planned in the multiple capacities of 200K circuits.

The architecture of one 200KC is as below:

Setting up two Soft Switches

Two or three Signalling Gateways

Providing Trunk Media Gateways (TMGs) at different locations with 200KC

Capacity.

Providing one Announcement Servers in each IP domain i.e. one with each

soft switch

Billing interface to Centralized Billing Server at Chennai.

NMS at Chennai with FCAPS capability. (Fault, Configuration, Accounting,

Performance, Security)

No separate NTP server is being used in IP TAX, the existing NTP server of

our data network will be used for synchronization.


Fig. 2

5.1 Functions of Soft Switch (or Call Agent or Call Server or Media

Gateway Controller)

Based upon open architecture

Provide all existing services available in TDM network

Performs media gateway Control function

Performs call control, signalling and interworking, traffic measurement and

recording functions

Provides addressing, analysis, routing and charging facilities

Interacts with application server to supply services not hosted on soft switch

5.2 Functions of Signalling Gateway (SGW)

Provides interworking function between SS7 network and IP network

This involves providing various types of User Adaptations so that the SS7

signalling can be terminated in SGW and can be translated and messages

transported over IP Network

Performs packetization of signalling and ensures its transport through IP

network

5.3 Functions of trunk media gateway (TMG)

Performs the functions of

Voice encoding & Compression


Packetization of voice channels

CNF (Comfort Noise Generation)

VAD (Voice Activity Detection)

Echo Cancellation

5.4 Advantages of IP TAX deployment:

One backbone for voice and data services instead of two parallel ones.

No maintenance of proprietary switching systems.

Fewer call controlling entities in the network so less capital and operating

cost.

Less space and power requirement.

Easier configuration of equipment.

6.0 SSTP (Standalone Signal Transfer Point)

6.1 Need of SSTPs

The efficiency of SS7 had made a numbers of applications possible e.g. fast

connection setup in PSTN, “short message service” and “location update” messages

in GSM world.

As the size of the network grew, it became more and more difficult to manage

the direct SS7 links between the switches and from switches to other network

elements like HLR, SMSC, SCPs etc. The introduction of Standalone Signal Transfer

Point (SSTP) was a historic step from that perspective. It immediately solved issues

related to the complexity by converting the mesh networks into the star networks. It is

now possible to handle the signalling very efficiently. This capability also offloads

some of the processing power required in the Level-1 TAX and all switches could

breathe easier.

SSTP also handle the non call related messages efficiently. These messages

exist in all the technology and may not be needed to be handled by a switch. Many

times these will actually involve multiple technologies and in absence of the uniform

signalling layer, the complexity increase many fold. For example a simple service like

SMS, a CDMA subscriber may send the message to a GSM subscriber that could go

through the long distance network. This involves three different networks and three

technologies. However one thing is common, which is signalling as the transport to

carry this.

The SSTP suddenly became the vantage point in the network because of the

simple reason that the signalling protocol was common i.e. SS7, independent of the

technology and the access. Be it GSM or CDMA, the connectivity was based on SS7

with different application parts (MAP, INAP etc.). Thus the SSTPs are actually a

centralized routing database and not a transmission system for SS7 packet.

As the number of subscribers is growing, the number of nodes involved in the

routing is also increasing exponentially. If the management of the routing is to be

done on these individual nodes, the complexity increases accordingly, which also

mean the increased chances of error and hence loosing the revenue. The SSTP,


enabling the uniform signalling in SS7 domain, provided a single routing database,

which is managed centrally. This routing database is able to make the routing decision

based on the destination point codes (DPC), global title translation (GTT), routing

keys etc.

When any mobile subscriber of a private operator roams into service area of

other operator (say BSNL), the signaling traffic or SMS are being handled by

signaling channel of BSNL taken by private operator against the POI. BSNL was not

able to measure the traffic and it was also not known about the type of signaling

traffic. To measure and know type of signaling traffic, SSTP was planned and

installed so that billing to private operators can be done accordingly.

Due to reasons explained above, BSNL decided to have a separate signalling

network by installing a number of SSTPs at various locations.

6.2 Objectives of SSTP’s

Following were the main objectives:-

• Regulate, measure, and account for inter-network traffic including SMS

messages from mobile networks including GSM and CDMA

• Achieve a flexibility and transparency in management of signalling for

BSNL‟s wired and wireless networks.

• Optimal expansion of GSM & CDMA network of BSNL

• Introduction of new services.

• Offer CCS#7 & IP Signalling Services to other Wire line & Wireless

Network Operators.

With the above objectives in mind, BSNL awarded a contract to Ms. ITI for the

supply and installation of 10 SSTP nodes in September, 2005. Later on, the scope of

the project was further expanded to provide 24 nodes in total covering all the major

location including all the Level-1 TAX locations. This was a significant step in the

direction of the giving the decades old BSNL network an uplift.

6.3 SSTP’s at BSNL Network

21 TAX Locations with an STP at each location.

Pair of STPs designated as mated pair with identical routing data and

complete failover capability.

• Phase 1 - 10 Locations

• Phase 2 - 11 additional locations: This was later changed to 24

locations to take care of the connectivity issues.

• 4 Additional locations are Jammu, Shimla, Dimapur, Shillong and

dropping Raipur

• Phase 3 Expansion of all 24 nodes to about capacity of 1800 LSL per

node

• Six STPs are designated as ANSI-ITU MTP gateway (ILD

Gateways).

• Connect multiple SS7 nodes (MSC, Level-1 TAX, Level-2 TAX, Local

Exchanges, SMSC, HLR, SCP) to a mated pair using SS7 E1 links.

• SSTPs interconnected using BSNL‟s IP/MPLS network on M2PA


Later on M3UA functionality is also included to connect the access nodes

e.g. Soft switch, GMSC, IN, HLR etc.

• Centralized Network Management with an Active and DR Standby

site

• Central Billing Server for billing inter-carrier SS7 usage

6.4 Planned Applications on SSTP Network

Lawful Intercept of SMS

Mobile Number Portability

Questions For Assessing “Transfer Of Learning

Question 1. Explain PSTN organization within BSNL indicating all main

types of network elements.

Question 2. Limitations of existing circuit switched networks vis-a-vis

advantages of NGN.

Question 3. Diagrammatically depict the concept of current generation

network vis-à-vis next generation network.

Question 4. Briefly describe the functions of soft switch in NGN.

Question 5. Briefly describe the functions of Signalling Gateway (SGW) in

NGN.

Question 6. Briefly describe the functions of Trunk Media Gateway (TMG) in

NGN.

.

Question 7. Briefly describe the objectives of SSTP in BSNL.

Question 8. Briefly describe the Deployment of SSTPs in BSNL network.

Question 9. What are the planned applications of SSTP in BSNL network.


CFA Technology Overview-II (Service)

1.0 Introduction

BSNL had been the largest telecom operator in India and is known to everybody

for Basic Telephony Services for over 100 years. Presently the plain old, countrywide

telephone service is being provided through around 36,000 electronic exchanges, 326

places digital trunk automatic exchanges (TAX), digitalized public switched

telephone network (PSTN) all interlinked by over 2.4 lakh km of optical fiber cable,

with a host of phone plus value additions to our valued customers. BSNL's

telephony network expands throughout the vast expanses of the country (excluding

Mumbai and Delhi) reaching to the remotest part of the country.

Gone are the days when basic telephones were used only to make and receive

calls. With the aid of state-of-the-art digital exchanges, BSNL offers a host of phone

plus services, converting old basic telephones to a sophisticated tool which can be

used for a variety of applications.

Most of the phone plus facilities are available free of cost with effect from

January 22nd

, 2003

1.1 Numbering Scheme in BSNL:

DoT assigns the initial code for all the operators. BSNL having licenses in all

the circle in the whole country except Delhi and Mumbai has been assigned digit „2‟.

The actual number which is dialed by the calling subscriber is prefixed with the

SDCA code. At present the SDCA code+ Local no are of 10 digits e.g in Jaipur

SDCA the local number is identified as 141 (SDCA Code)+2601602(local Number).

Some special services like directory enquiry (197), fault booking (198),

railway enquiry (139) etc are provided by these standard short codes.

1.2 Services offered by BSNL’s Landline:

Main service are related to - speech, data, audio & video

1.21. Supplementary services in PSTN (phone plus services)

a. Abbreviated Dialing

For registration Dial 110 + short code + destination number

For use Dial 111+ short code i.e. 11115

b. Call Waiting

For activation of the service dial: 118 (wait for the acknowledgement

tone/announcement)


For deactivation of the service dial: 119 (wait for the acknowledgement

tone/announcement)

c. Hot Line

A subscriber may want to be connected directly to a pre-determined

number as soon as he/she lift the hand set even without dialling. At the same

time he/she may want to have the flexibility to dial any other number of

his/her choice.

d. Call Transfer (Call Forward)

For activation Dial 114 and DN for which the call is to be

transferred (wait for the acknowledgement tone/announcement).

For deactivation dial 115 and wait for the acknowledgement

tone/announcement.

e. Automatic Wake-Up/Reminder Call Service

For entering : Dial 1160615 (wait for the acknowledgement

tone/announcement).

For cancellation : Dial 117 (wait for the acknowledgement

tone/announcement).

f. Number/Call Hunting Service

If subscriber have more than one telephone line, this facility is very

helpful for caller. If the called line is engaged, caller does not have to

disconnect and dial other line(s). This facility automatically transfers the

incoming call to whichever line is free.

g. Calling Line Identification Presentation (CLIP)

To get the calling identity on subs. Telephone set.

h. Calling Line Identification (CLI) Announcement Service

Dial 164 and listen to the DN of the phone line that you have used to

make the call. Very useful when in doubt about your phone number.(Subject

to technical feasibility)

i. Electronic Locking For STD/ISD ( Dynamic Locking Facility)

For registration of code (one time only): To register secret code

Dial 123 ABCD ABCD then wait for the acceptance tone (ABCD is the

secret code chosen by the subscriber)


For changing secret code: To change already created secret code Dial

123 ABCD PQRS then wait for the acceptance tone (PQRS is the new secret

code chosen by the subscriber)

For locking/unlocking with secret code: A subscriber has to dial

123ABCDX (wait for the acknowledgement

tone/announcement).

Here ABCD is the subscriber‟s current secret code.

X value indicate : 0 STD/ISD open (subject to provisioned by xge.)

1 STD/ISD lock but local call open

2 STD/ISD, Level-9,trunk call booking etc. locked but

local call open

3. STD open (subject to provisioned by Xge.)

4. All O/G calls locked

j. Call Conferencing

With this service telephonic conference can be set up within 3 or more

parties. This service is available subject to technical feasibility.

1.22 Services Offered By ISDN:-

1. Normal Telephone & Fax (G3) and G4 Fax

2. Digital Telephone -with a facility to identify the calling subscriber

number and other facilities.

3. Data Transmission at 64 Kbps with ISDN controller card

4. Video Conferencing

1.221 Supplementary Services supported by ISDN

Calling Line Identification Presentation(CLIP)

Calling Line Identification Restriction(CLIR)

Multiple Subscriber Number(MSN)

Terminal Portability(TP)

Call Hold(CH)

2. Landline VAS

Value-added services (VAS) are those services that offer differentiation or a

value to the bearer service and the ability for telecom operators to charge a premium

price. For a telecom operator‟s perspective VAS is very important as it is a revenue

driver. All the telecom service users want to have many other services over and above

the basic service. VAS plays a very important role when the telecom market moves

towards saturation level.

BSNL as a telecom service provider is providing following value added

services over basic service:


2.1 Internet Facility:

BSNL is providing internet service throughout the entire country (except in

New Delhi and Mumbai) under the brand name of "Sancharnet". Sancharnet provides

free all India roaming and enables it's users to access their accounts, using the same

access code (172233) and user ID from any where in the Country. In order to make

internet available throughout the length and breadth of the Country, Internet Dhabas

have been commissioned at all the Block Head quarters.

BSNL provides the following types of connections to access internet to customer:

2.11 PSTN Dial Up Access

BSNL internet service offers flexible options of access plans for PSTN dial-up

in various slabs of 25,50,100, 200, 500 and 1,000 hours. With “Sancharnet dialup

account” subscriber get all India roaming advantage which is not available with any

other ISP because one can access “Sancharnet internet” by dialling '172233' from any

city in India.

2.12 ISDN Dial Up Access

Subscribers can have blazing fast Internet surfing and download speeds in 64

and 128 Kbps ISDN dial up connections. The uniform all India access no. for ISDN

access is '172225'.

2.13 Account Free Internet Dial Up Access Based On CLI

CLI based internet service is a unique method providing internet service in

which the customer can access the internet service from any telephone through dial

up. The service allows automatic registration on first LOGIN. The authentication will

be based on CLI of the telephone with the password supplied by the caller. The

charging is totally usage based and the service is a post paid service like normal

PSTN. The billing will be separate based on the duration of use and will be charged to

normal telephone bill (CLI based) as internet access charge at the prescribed rate. The

service is available in selected cities. The access no. of this service is '172222' in all

cities.

2.2 Broad Band Connection

Broadband service is based on DSL technology (on the same copper cable that

is used for connecting telephone). This provides high speed internet connectivity upto

8Mbps. This is always - on internet access service with speed ranging from 256Kbps

to 8 Mbps.

2.2 Sancharnet Card

BSNL has also launched "SANCHARNET CARD" recently. The Sancharnet

Card" is a prepaid Internet Access Card with following features for customers:

http://www.sancharnet.in/


Self-register for internet access with your choice of user id

Renew your existing Sancharnet Account

Wide Range of Internet Access Packages

3. Intelligent Network Services:

3.0 Present IN Set Up In BSNL

• These IN platforms have been supplied by M/s Alcatel

• Four general purpose IN (GPIN) platforms are working at Kolkata

(345), Lucknow (180), Bangalore (425) and Ahmedabad (233)

• One mass calling IN (MCIN) platform is working at Hyderabad

(424)

• NT switches are being used as SSP.

• GPINs are being used to provide all IN services except

Tele-voting

• MCIN is being used for Tele-voting and other IN services except ACC

• New platforms have enhanced capacity for all IN services

Following IN Services Are Offered By BSNL:-

3.1 Free-phone Service (FPH) (Access code : 1800)

Or Toll Free Service (TFS)

This service gives service users (calling party) the opportunity of calling the

service subscriber (called party) free-of-charge via the PSTN by dialing a universal

directory number from any part of the country. The call-fee is charged to the service

subscriber.

By subscribing to this service business, commerce industry and trade

organizations can advertise and sell their products and services.

Dialling plan: 1800 + SCP code + XXXXXX

SCP code is a three digit code of the concerned SCP from where free phone

service has been provided to the service subscriber while XXXXXX is five/six digit

free phone number allotted to a service subscriber

3.2 Virtual Card Calling services (VCC) (Access code : 1802)

Or Universal India Telephone Card(UITC)

Virtual Card Calling service allows a customer to make calls without cash.

This service allows users to make calls from any telephone in the network to any

destination. It is a powerful pre-paid card for those who are on the move and who do

not own a telephone.


Virtual card calling service is an access code based service. All virtual card

calls are preceded by the access code 1802 + SCP code. After dialing the access code,

the subscriber is prompted to enter a virtual card number. The validation is done at the

SCP. After this, subscriber is prompted to enter the destination number. This card is

available under the brand name ITC catd.

3.3 Account Card Calling (ACC) (Access Code : 1804)

It is a pre-paid card more powerful than VCC having features of renewability

and dynamic PIN that make it easy to use and more secure.

This service allows customer to make calls from any telephone in the network

to any destination. The call charges will be debited to subscriber account number. The

originating telephone number will not be charged. Registration fee is Rs.5000/- +

Taxes.

Card can be renewed by paying additional installment in multiple of Rs.1000/-

. The account number is eight digits & PIN is four digits.

3.4 Virtual Private Networks (VPN) (Access code: 1801)

The VPN service allows public network operators to provide private network

features, e.g. Private Numbering Plan (PNP) and Screening capabilities, using the

public network infrastructure. The service subscriber can directly manage and

administer his VPN via the Customer Control Feature. VPN is typically used to

interconnect geographically distributed PBXs. This service enables the subscribers to

form an imaginary network within a real network on existing telephone lines.

Corporate and others can subscribe to VPN service i.e. they can have their own VPN

network by utilizing the existing telephone lines. VPN subscribers can have their

own private numbering plan.

The VPN users can make calls inside VPN group, outside VPN group to

external numbers or they can use resources of VPN to make calls inside VPN from

off-net positions or calls can be made from off-net to external numbers while using

VPN resources.

Who can subscribe for Voice Virtual Private Network service?

• Good for institutions, Government departments and businesses.

• All type of companies, distributors, firms, institutions, housing society etc.

e.g. State Bank of India, ONGC, State Police department etc.

3.5 Premium Rate Services (PRM) (Access code: 1867)

The Premium Rate service enables service users to access the information

offered by the service subscriber against payment of a fee. This is accomplished via

the announcement facilities or in direct dialog mode. This way, information can be

“sold” over the telephone. The fee charged to the calling party for using the service is


composed of the connection part of the network operator and a part for the

information of the service subscriber. The network operator collects the total amount

which, based on the call-related data, is split on an agreed-upon key between the

service subscriber and network operator.

The service subscriber is given a 4-digit PRM number which can be accessed

form any where in the network.

3.6 Universal Access Number Services (UAN) (Access Code: 1860)

And

Universal Personal Number Services (UPN) (Access Code: 1868)

This service allows a subscriber to have a universal access number (UAN).

All the incoming calls for this number shall be routed to different destinations

depending upon the geographical location of the caller, the time, the day, or the

date on which the calls are made. Company/ Corporate can assign single access

number to their offices located at different places.

Based on the network involved in routing the call, the UAN service is

divided into two categories:

1) UAN Local: When the calling party and the destination number of UAN are in

same city i.e. they have same STD code, the UAN calls are local calls and calling

person will be charged at normal local call rates. The dialing plan for UAN Local is :

1860 + SCP code + 4 (digit UAN No.)

2) UAN National: When the calling party and the destination number of UAN are in

different cities i.e. they have different STD codes, the UAN calls are long distance

calls and calling person will be charged at normal long distance call rates. The dialing

plan for UAN National remains same as UAN local:

1860 + SCP code + 4 – digit UAN No.

UAN calls can be charged on full charge basis to calling party or on split basis to

calling & called party also.

3.7 Tele-voting Services (VOT) (Access code : 1803, 1861,1862)

This service allows conduct of public polls and surveys through normal

telephones. It is a boon for TV producers, serial makers, manufacturers, service

providers and all others who conduct surveys for their products and services

including public opinion on various issues of common interest etc.

Dialing plan:

There are four options available for tele-voting service:


(i) The tele-voting number is kept as a toll free number and subscriber of tele-voting

service pays the charges for incoming calls.

The numbering/ dialing plan is: 1803 + SCP code + XX YY where XX will be

assigned to subscriber and are fixed while YY are choice digits.

(ii) The subscriber of tele-voting service does not pay for the incoming calls and

calling party pays for the call charges for participating in the tele-voting by one pulse.



(iii) The subscriber of tele-voting service does not pay for the incoming calls and

calling party pays for the call charges for participating in the tele-voting by two

pulses.



(iv) The subscriber of tele-voting service does not pay for the incoming calls and

calling party pays differential for the call charges for participating in the tele-voting.



3.8 FLPP (Fixed Line Pre-Paid Telephone) (Access code: ,1805,1806)

FLPP (Fixed Line Pre-Paid) Service enables a subscriber to make calls from a

prepaid account linked to his telephone number. Unlike the prepaid card 'ITC'

service, where the authentication is done every time through a 16-digit PIN the

authentication of FLPP is linked to his telephone line & the user is not required to dial

the Account number/ PIN for authentication making it simpler to use.

Advantages of Fixed Line prepaid service offers:

Conversion of fixed line to Pre Paid and get rid of telephone bills.

Easy de-linking from telephone line when prepaid is not required

No need to dial Account number/ PIN every time you make a call.

STD/ISD Facility

On Line balance enquiry

Easy recharge and no problem of bills

Free Level 1 service like 100, 101, 102 etc. available.

Free Level 1 IN services which are free to end-customers like Free

Phone etc. are available.

http://www.bsnl.co.in/service/itc.htm


There can be four types of FLPP accounts namely

PCO FLPP Account,

PCO Local FLPP Account,

General FLPP Prepaid Account and

General FLPP Prepaid + Post paid Account.

Presently this service has been started on PCO and on post paid numbers as

General FLPP+ Post paid account.

3.9 Call Now Cards:

It is a normal ITC card but specifically designed tariff to suit the requirement

of users making heavy International/STD calls. Dialling procedure and features are

same as that of ITC but the tariff is different from ITC and also different for different

denomination of Call Now cards.

3.10 Personalised Ring Back Tone Service: This service is just like the caller tune service in mobile phones. The landline

subscribers can also set the ring back tone to be heard by the calling customer as per

his choice.

4. Multi-play

Multi-play service allows the customer to have data, video and voice service

on the same line. The video service can be IPTV (broadcast) and video on demand.

This service was launched in Pune and now available in all main cities.

5. Audio Conferencing

Audio Conferencing service allows multiple participants to converse with each

other regardless of their location through the normal fixed line telephone or cellular

phone. An audio conference subscriber can add two or more participants in a

particular conference. The customers can schedule their audio conferences through

the Web or through IVR. The service is available to existing BSNL subscribers only.

Conference can be scheduled one time or standing. A standing conference is always

on. The authorized participants have just to dial in a particular telephone number

followed by a password to enter into a conference. On demand conference can be

made. The chairperson can invite several users one by one in the conference without

using the web.

6. Video Conferencing

Video Conferencing service allows multiple participants to converse with each

other regardless of their location through the video end-points or personal computers.


It involves video and audio communication. A video conference subscriber can add

two or more video participants in a particular conference. The customers can schedule

their video conferences through the Web. The video conferencing service can be

availed by any user through IP or ISDN interface. The service is available to existing

BSNL subscribers only. Personal computer user can download the software called

"PVX" from BSNL's Video Conferencing Portal to avail the Video Conferencing

facility with their web-cam.

7. Short Message Service:

SMS can be send and received through landline telephones. For this the

subscriber will have to purchase a SMS enabled handset.

8. Online Billing Enquiry and Payment Online billing enquiry and payment service is made available by BSNL for

many cities where one can see the status of telephone bills as well as pay the bills

online.

9. Centrex Service:

Centrex is a communication service which integrates a subscriber‟s all multi

located telephone lines (Existing and New) into a single highly functional

communication group with more distinctive features without any additional

equipment (like EPABX) at the subscriber‟s premises.

A group of subscriber or a subscriber having two or more telephone

connections can avail this service in which a centrex group will be formed. All the

calls made between the members of the group will be free of charge and are made by

using a short code consist of last 2- 5 digits (maxi.) of their number. But all the calls

made outside the group will be charged at the normal applicable tariff.

In a way centrex facility is like having a PBX like facility between the

numbers which are geographically distant away in a city without owning a PBX and

maintaining it.

11. Answering Machine Service:

On the landline numbers answering machine service can be provided by the

centralized equipment installed at the exchange. The subscriber can divert his/her

calls to answering machine in case of no reply or busy to record some messages and

later on he/she can take the messages from the answering machine.

12. 12555 Service:

On landline numbers by dialling 12555 the subscribers can have many types of

services like:


Latest Bollywood songs

Old classic songs

Jokes

Horoscope

International/National news

Cricket news

Different contests

Finance/stocks related news

Travel information etc

Different services can be added /deleted from time to time as per the

agreement with the third party content provider.

Questions For Assessing “Transfer Of Learning

Question 1. Write short note on numbering scheme in BSNL.

Question 2. What are the supplementary services available to a landline

subscriber with and without access codes? Indicate their code for

activation/de-activation etc.?

Question 3. What are the additional supplementary services available to any

ISDN subs? What are the different types of landline VAS

available to any subscriber for using internet?

Question 4. What are the different types of landline VAS available to any

subscriber for using internet?

Question 5. Name the cities where IN plate-form are working in BSNL with

their SCP code. List out the different IN services offered by

BSNL with their access codes and dialing plan.

.

Question 6. What are the different types of FLPP service and their

advantages?

Question 7. Compare the feature of ITC card and Call Now card.

Question 8. Write short note on Centrex Service.

Question 9. What are the different types of FLPP service and their

advantages?

Question 10. Critically examine “12555” service provided by BSNL.


OVERVIEW of CDMA TECHNOLOGY

The CDMA air interface is used in both 2G and 3G networks. 2G CDMA standards

are named as CDMAone includes IS-95A and IS-95B. Systems based on IS-95

standards have lots of the limitations as Spectral efficiency, low data speed, limited

roaming, no multimedia, asymmetric data rate etc. Therefore Qualcomm proposed

another CDMA standard as IS-2000 with different releases and commonly known as

CDMA 2000 1x networks.

IS-95A was the first CDMA system commercially used for cellular networks. The

next evolution was IS-95B which provided higher data rate of 64 Kbps instead of

maximum of 14.4 Kbps in IS-95B.

CDMA 2000 1x systems are a major evolution over IS-95 standards where much

improvement has been done in radio reverse link. In CDMA 2000 1x systems an

attempt has been made to make reverse link more synchronous by adding a pilot in

reverse link to reduce interference. This reduced interference leads to enhanced

system capacity over the same carrier of 1.25 MHz which is approximately 35

channels/sector/FA as compared to 27 channels/sector/FA in IS-95 systems. A

separate Packet Core Network (PS-CN) takes care of data calls. Enhancements of

CDMA 2000 1x over IS-95 are

Enhanced Voice Capacity

Better handling of packet data

CDMA2000 1x Network Architecture:

CDMA 2000 1x Network Architecture is divided in to three parts.

• CS-CN (Circuit Switched Core Network)

• PS-CN (Packet Switched Core Network)

• RAN (Radio Access Network)

E1

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BTS

BTS FWT/HHT

BSC

BSC BTS

BTS MSC

VL

R

PST

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Ex. FWT/HHT

HLR AU

C

PDSN F

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AAA

Server

HA

HA

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World

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E1

Link

Packet

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Network Circuit

Switch Core

Network


Circuit Switched Core Network: This section is dedicated for voice

communication and also for wireless authentication. This section includes four parts

MSC (Mobile Switching Center): It is responsible for setting up, managing and

clearing connections as well as routing the calls to the proper user & provides the

network interfaces, the charging function and the function of processing the

signaling.

HLR (Home Location Register): It is a static database. It has information of a

subscriber like ESN, MDN, IMSI, MIN, service information and valid term. It also

stores the mobile subscriber location (MSC/VLR address), to set up the call.

VLR (Visitor Location Register): VLR is a dynamic database. It stores all related

information of mobile subscribers that enter its coverage area, which enables MSC to

set up incoming and outgoing calls. When the subscriber leaves this area, it should

register in another VLR, and the previous VLR will delete all the data about this

subscriber.

AUC (Authentication Center): It is an entity to prevent illegal subscribers from

accessing CDMA network. It can generate the parameter to confirm the subscriber‟s

identity.

Packet Switched Core Network: To provide better connectivity to the internet a

new core network i.e. PS-CN is introduced to the CDMA 2000 1x network. This

section includes four parts.

PDSN (Packet Data Serving Node): Packet Data Serving Node (PDSN) provides

the function of routing of data between Radio Access Network (RAN) and internet.

It does all the processing related to the data services.

AAA Server: PS-CN also has the responsibility to authenticate, authorise and

account for the CDMA 2000 subscribers wishing to obtain packet data services & to

fulfil these task PDSN requires support of AAA server.

Home Agent/ Foreign Agent Server: HA & FA server is used when mobile IP

services are supported by CDMA 2000 PDSN.

Key Features of CDMA 2000 1x:

CDMA 2000 has fundamental requirement to maintain compatibility with IS-95 air

interface. This means that IS-95 handsets will continue to work in CDMA 2000

network as well as CDMA 2000 mobiles will work in IS-95 network. This is the key

aspect of providing a cost effective solution for 2G operators to gracefully upgrade to

3G networks and completely new network and new mobiles are not required.

Faster Forward Power Control: CDMA 2000 1x standard has a faster power

control compare to IS-95 counterpart. The power control is done every 1.25 ms.


New Radio Configurations (RC): It support Radio configuration RC1 to RC9 in

Forward Link and RC1 to RC6 in Reverse link. Radio configuration defines Rate Set,

Spreading Rate, Channel Coding (Turbo or convolution), channel coding rate for

forward or reverse traffic channel.

Variable length Walsh Codes: CDMA 2000 uses variable length Walsh codes of

length 4 to 128 to support variable data rate. Higher data rate channels uses shorter

length walsh codes and vice versa.

Efficient use of spectrum: CDMA2000 technologies offer the higher voice capacity

and data throughput using the least amount of spectrum, lowering the cost of delivery

for operators and delivering superior customer experience for the end users.

Seamless Evolution Path: CDMA2000 has a solid and long-term evolution path

which is built on the principle of backward and forward compatibility.

Flexibility: CDMA2000 systems have been designed for urban as well as remote

rural areas for fixed wireless, wireless local loop (WLL), limited mobility and full

mobility applications. It also supports R-UIM for open market handsets.

High-Speed Data: Release 0 supports bi-directional peak data rates of up to 153 kbps

and an average of 60-100 kbps in commercial networks in a 1.25 MHz channel.

Release A can deliver peak data rates of up to 307 kbps.

CDMA 2000 1x EV-DO:

Although IS-2000 is already capable of meeting the 3G data rate requirement of 2

Mbps, Qualcomm proposed a new standard 1xEV-DO in March of 2000 as another

option that supports high-rate data services.

1x EVDO (1x Evolution for Data Optimized) is optimized for delivering high speed

IP wireless data to many mobile and stationary terminals running multiple

applications. EVDO is designed for an always on user experience. The standards for

Ix EVDO are defined as IS-856.

Salient features of EV-DO

EV-DO uses both CDMA and TDMA.

Uses its own dedicated 1.25 MHz carrier.

No power control on forward link is required.

EV-Do has two versions as Rel. 0 & Rev. A.

RF system components may be shared with 1xRTT.

EV-DO Reverse Link and Forward Link Data Rates

IS-856 Rel. 0 Forward Link

Variable Data Rates ranges from 38.4 Kbps to 2.4 Mbps

IS-856 Rev-A extends this to 3.1 Mbps

IS-856 Rel. 0 Reverse Link

Data Rates ranges from 9.6 Kbps to 153.6 Kbps


IS-856 Rev-A extends this to 1.8 Mbps.

Services in CDMA:

BSNL is providing the following services using CDMA technology.

Voice

SMS

Packet data (144 Kbps / 2.4 Mbps) – NIC and EV-DO cards: Provided by

P200 PDSS installed at Noida, Vadodara, Bangalore and Kolkatta.

CRBT: Provided by CRBT Platform.

Prepaid: Provided by Wireless Intelligent Network installed on zonal basis at

Vadodara, Bangalore and Kolkatta.

Bank ATM / Branch ATM Connectivity: A very good business opportunity

form bank ATMs and provided by using CDMA network with MPLS

backbone together.

R-UIM (Removable User Interface Module): It is like a SIM card as in GSM

and used for open market handsets. It makes the subscriber independent to the

operator‟s handset. R-UIM is both 1x and EV-DO enabled.

OVERVIEW of WiMAX TECHNOLOGY Introduction

The WiMAX (Worldwide Interoperability for Microwave Access) technology,

based on the IEEE 802.16-2004 Air Interface Standard is rapidly proving itself as a

technology that will play a key role in fixed broadband wireless metropolitan area

networks. In December, 2005 the IEEE introduced the 802.16e which adds the

features and attributes to the standard necessary to support mobility.

Mobile WiMAX is a broadband wireless solution that enables convergence of mobile

and fixed broadband networks through a common wide area broadband radio access

technology and flexible network architecture. The Mobile WiMAX Air Interface

adopts Orthogonal Frequency Division Multiple Access (OFDMA) for improved

multi-path performance in non-line-of-sight environments. Scalable OFDMA

(SOFDMA) is introduced in the IEEE 802.16e to support scalable channel

bandwidths from 1.25 to 20 MHz. Mobile WiMAX will cover 5, 7, 8.75, and 10 MHz

channel bandwidths for licensed worldwide spectrum allocations in the 2.3 GHz, 2.5

GHz, 3.3 GHz and 3.5 GHz frequency bands.

The WiMAX Forum brings together leaders in the communication and computing

industries to drive a common platform for global deployment of IP based wireless

broadband services. The WiMAX forum certifies products for conformance and

interoperability based upon IEEE 802.16 standards. WiMAX forum has various

working groups as follows.


Network Working Group (NWG) is developing the higher-level networking

specifications for Mobile WiMAX systems beyond what is defined in the IEEE

802.16 standard that simply addresses the air interface specifications. Some of the

salient features supported by Mobile WiMAX are

High Data Rates: Mobile WiMAX technology to support peak DL data rates

up to 63 Mbps per sector and peak UL data rates up to 28 Mbps per sector in a

10 MHz channel.

Quality of Service (QoS): WiMAX defines Service Flows which can map to

different service code points that enable end-to-end IP based QoS for different

types of services.

Scalability: Mobile WiMAX technology designed to be able to scale to work

in different channelization from 1.25 to 20 MHz to comply with varied

worldwide requirements.

Security: The features provided for Mobile WiMAX security aspects are EAP

(Extensible Authentication Protocol) based authentication, Support for a

diverse set of user credentials exists including Digital Certificates, and

Username/Password schemes.

Mobility: Mobile WiMAX supports full mobility for all types of CPE.

WiMAX forum Profiles are defined by the following parameters:

Spectrum band

Duplexing-TDD/FDD

Channel bandwidth

End-to-End WiMAX Architecture

The IEEE only defined the Physical (PHY) and Media Access Control (MAC) layers

in 802.16. WiMAX Forum‟s Network Working Group, which is focused on creating

higher-level networking specifications for fixed, nomadic, portable and mobile

WiMAX systems beyond what is defined in the IEEE 802.16 standard.


The Mobile WiMAX End-to-End Network Architecture is based on an All-IP

platform. The use of All-IP means that a common network core can be used. The

architecture is based on a packet-switched core network.

WiMAX Forum has identified a WiMAX Network Reference Model (NRM) that is a

logical representation of the network architecture. The NRM identifies functional

entities and reference points over which interoperability is achieved between

functional entities. Figure illustrates the NRM, consisting of the following logical

entities: MS, Access Service Network (ASN), and Connectivity Service Network

(CSN) and clearly identified reference points for interconnection of the logical

entities.

WiMAX Network Reference Model

The Access Service Network (ASN) It provides the connectivity between CPE (or

MS) and CSN.

The Connectivity Service Network (CSN) is defined as a set of network functions

that provide IP connectivity services to the WiMAX subscriber(s). A CSN may

comprise network elements such as routers, AAA proxy/servers, user databases and

Interworking gateway devices.

Physical Layer Description:

Orthogonal Frequency Division Multiplexing (OFDM) is a multiplexing technique

that subdivides the bandwidth into multiple frequency sub-carriers. In an OFDM

system, the input data stream is divided into several parallel sub-streams of reduced

data rate and each sub-stream is modulated and transmitted on a separate orthogonal

sub-carrier.

In OFDM the time and frequency resources can be organized into sub-channels for

allocation to individual users. Orthogonal Frequency Division Multiple Access

(OFDMA) is a multiple-access/multiplexing scheme that provides multiplexing

operation of data streams from multiple users onto the downlink sub-channels and

uplink multiple accesses by means of uplink sub-channels.


TDD Frame Structure

The 802.16e supports TDD & FDD operation; however the initial release of Mobile

WiMAX certification profiles will only include TDD. With ongoing releases, FDD

profiles will be considered by the WiMAX Forum to address specific market

opportunities where local spectrum regulatory requirements. TDD is the preferred

duplexing mode over FDD.

Advanced Features of Mobile WiMAX:

Smart Antenna Technologies: Mobile WiMAX supports smart antenna technologies

to enhance system performance. The smart antenna technologies supported include:

Beam-forming: With beam-forming, the system uses multiple-antennas to

transmit weighted signals to improve coverage and capacity of the system and

reduce outage probability.

MIMO Spatial Multiplexing (SM): Spatial multiplexing is supported to take

advantage of higher peak rates and increased throughput. With spatial

multiplexing, multiple streams are transmitted over multiple antennas. If the

receiver also has multiple antennas, it can separate the different streams to

achieve higher throughput compared to single antenna systems. 2x2 MIMO

(Multiple Input Multiple Output), increases the peak data rate two-fold by

transmitting two data streams.

BSNL Plans for WiMAX

In line with the government objective of bridging digital devide and with a vision of

inclusive growth, BSNL has been looking forward to extensive WiMax deployment to

provide wireless broadband solution to a larger section of population.

In 2004 itself BSNL deployed 802.16d-2004 standard based WiMAX system at 10

locations- 6 being in urban metros and 4 locations being in rural areas of Haryana on

pilot basis. The equipment deployed was of M/s Aperto Network.

Now BSNL has adopted different models for deployment of WiMAX Services:

In GJ, MH & AP Circle- deployment by M/s Soma Network in revenue

sharing agreement with BSNL.

In PB & KL Circle – Own deployment by BSNL about 1600 WiMAX BTS of

802.16e-2005 standard.

DIT Bharat Nirman Project- About 1000 BTS to cover16000 blocks of rural

areas and provide access to wireless broadband.

In remaining 16 LSA deployments through franchise on revenue sharing

agreement basis.

Spectrum for BSNL 20 MHZ spectrum has been allocated to BSNL in July 2008.

Gujarat, Maharashtra & Andhra Pradesh in FDD Mode 2540 & 2640 MHZ with 10

MHz in each band and Rest of India 20 Mhz with TDD Mode with carrier frequency

of 2645 Mhz.


Status of WiMAX Projects:

WiMAX Rural (Phase-I) Project of 1000 Base Stations

BSNL has been deploying WiMAX Rural (Phase-I) Project of 1000 Base Stations for

covering 11666 Rural Common Service Centers (CSC). These CSCs will be set up by

Dept. of information Technology (DIT) for prestigious e-governance project. M/s

HCL has supplied Core Equipment along with 592 BTS. WiMAX Service for M/s

HCL equipment was launched on 13.12.2009. M/s Gemini has supplied core

equipment and all 408 BTS delivered, 325 installed and 187 integrated.

WiMAX Rural (Phase-II) Project of 6863 Base Stations

Under this project 6863 BTSs are to be deployed in BSNL network to cover 51000

Rural Common Service Centers (CSC). This project is also funded by DIT. The

tender for this project has already been opened and APOs was issued to 3 bidders and

fourth is pending under clearance.

WiMAX Urban Project (For Kerala & Punjab Circle)

The PO for supply of 450 BTS was awarded to M/s ICOMM under WiMAX Urban

Project (Kerala Circle). The PO for supply of 350 BTS was awarded to M/s Huawei

under WiMAX Urban Project (Punjab Circle). WiMAX urban service has been

launched on 31.03.2010 in 22 cities /towns of Punjab Circle.

Status of AP, Gujarat and Maharashtra (Franchisee with SOMA): The services

launched in January 2009 in Gujarat and in April 2009 in Maharashtra and Andhra

Pradesh.

Franchisee rollout in other circles: BSNL has decided to award franchisee on

revenue share basis for 11 circles i.e. Karnataka, Rajasthan, Bihar, Tamil Nadu, UP

(West), Orissa, Kolkata, Madhya Pradesh, Chennai, Haryana & Himachal Pradesh.

Questions for Review

1. What are the different services in CDMA?

2. What is the Data throughput in EV-DO Rev. A?

3. EV-DO stands for …………………………………….

4. What are the five key features of 1x EV-DO?

5. What are the enhancements of CDMA 2000 1x over IS-95?

6. What are the physical layer properties of WiMAX?

7. What are the five key features of Mobile WiMAX?

8. Write down four working group of WiMAX Forum.

9. WiMAX stands for …………………………………….

10. What are down various channel bandwidths and spectrum in WiMAX?


E5-E6 CM TECHNOLOGY OVERVIEW (GSM&3G)

Agenda: Various sub system in GSM Technology.

GPRS and its function

Requirement of 3G

Why WCDMA ?

Function of nodes

GSM Network Architecture- Typical


VARIOUS SUBSYSTEMS 1. MS:-Mobile Station

2. Radio Subsystem includes the equipments and functions related to the management of the connections on the radio path.

3. Network Subsystem (NSS) includes the equipments and functions related to end-to-end call.

4. Operations and Maintenance subsystem (OSS) includes the operation and maintenance of GSM equipment for the radio and network interface.

Mobile Station (MS)

Mobile Station consists of two units :


Mobile Hand Set Subscriber Identity

Module (SIM)

MS SIM

SIM is a removable module goes into the

Mobile Hand set is one of the most mobile handset. Each SIM has unique

number called International Mobile

complicated GSM device. It provides

Subscriber Identity (IMSI). It has built in

user the access to the Network. Each

Micro-computer & memory into it. It

handset has unique identity no. called

contains the ROM of 6 to 16KB,RAM of

IMEI.

128 to 256 bytes and EEPROM of 3 to

8KB.

Mobile Station (MS)

The Mobile Station consists of the Mobile Equipment (ME) and the Subscriber Identity Module (SIM).

Mobile Equipment The Mobile Equipment is the hardware used by the subscriber to access the network.

The mobile equipment can be Vehicle mounted, with the antenna physically mounted on

the outside of the vehicle or portable mobile unit, which can be handheld. Mobiles are classified into five classes according to their power rating.

CLASS

POWER OUTPUT

1 20W 2 8W 3 5W 4 2W 5 0.8W


SIM (Subscriber Identity Module) The SIM is a removable card that plugs into the ME.

It identifies the mobile subscriber and provides information about the service that the subscriber should receive. The SIM contains several pieces of information

International Mobile Subscribers Identity (IMSI) - This

numberidentifies the mobile subscriber. It is only transmitted over

the air during initializing.

Temporary Mobile Subscriber Identity (TMSI) - This number also

identifies the subscriber. It can be alternatively used by the system. It

is periodically changed by the system to protect the subscriber from

being identified by someone attempting to monitor the radio interface.

Location Area Identity ( LAI ) - Identifies the current location of the subscriber.

Subscribers Authentication Key ( Ki ) - This is used to authenticate the SIM card.

Mobile Station International Subscriber Directory Number (MSISDN) - This is the telephone number of the mobile.

Most of data contained within the SIM is protected against reading (e.g Ki) or alterations after the SIM is issued.

Some of the parameters (e.g.. LAI) will be continuously updated to reflect the current location of the subscriber.

The SIM card can be protected by use of Personal Identity Number (PIN) password.

The SIM is capable of storing additional information such as accumulated call charges.

BASE STATION SUB-SYSTEM (BSS)

The BSS is the fixed end of the radio interface that provides control and radio coverage functions for one or more cells and their associated MSs.


It is the interface between the MS and the MSC.

The BSS comprises one or more Base Transceiver Stations (BTSs), each containing

the radio components that communicate with MSs in a given area, and a Base Site

Controller (BSC) which supports call processing functions and the interfaces to the

MSC.

Digital radio techniques are used for the radio communications link, known as the Air Interface, between the BSS and the MS. The BSS consists of three basic Network Elements (NEs).

Transcoder (XCDR) or Remote transcoder (RXCDR) .

Base Station Controller (BSC).

Base Transceiver Stations (BTSs) assigned to the BSC. .

Base Transceiver Station (BTS)

The BTS network element consists of the hardware components, such as radios,

interface modules and antenna systems that provide the Air Interface between the

BSS and the MSs. The BTS provides radio channels (RF carriers) for a specific RF coverage area.

The radio channel is the communication link between the MSs within an RF coverage area and the BSS.

The BTS also has a limited amount of control functionality which reduces the amount of traffic between the BTS and BSC.

Base Station Controller (BSC) The BSC network element provides the control for the BSS.

It controls and manages the associated BTSs, and interfaces with the Operations and Maintenance Centre (OMC).

The purpose of the BSC is to perform a variety of functions. The following comprise the functions provided by the BSC:

Controls the BTS components.-

Performs Call Processing.

Performs Operations and Maintenance (O & M).


Provides the O & M link (OML) between the BSS and the OMC.

Provides the A Interface between the BSS and the MSC.

Manages the radio channels.

Transfers signaling information to and from MSs.

Transcoder( XCDR )

The speech transcoder is the interface between the 64 kb/s PCM channel in the

land network and the 13 kb/s vocoder (actually 22.8 kb/s after channel coding)

channel used on the Air Interface.

This reduces the amount of information carried on the Air Interface and hence, its bandwidth.

If the 64 kb/s PCM is transmitted on the air interface without compression, it

would occupy an excessive amount of radio bandwidth. This would use the

available radio spectrum inefficiently.

The required bandwidth is therefore reduced by processing the 64 kb/s PCM

data so that the amount of information required to transmit digitized voice

falls to 13kb/s.

The XCDR can multiplex 4 traffic channels into a single 64 kb/s timeslot. Thus a E1 serial link can carry 4 times as many channels.

This can reduce the number of E1 leased lines required to connect remotely located equipment.

When the transcoder is located between the MSC and the BSC it is called a remote transcoder (RXCDR).

TRANSCODING: Transcoding is explained from below figure:-


NETWORK SWITCHING SUBSYSTEMS (NSS):

The Network Switching Subsystem includes the main switching functions of

GSM as well as the databases needed for subscriber data and mobility

management. The NSS also manages the communications between the GSM

users and other telecommunication network users.

The basic switching function like setting up calls to and from GSM users is

performed by the MSC. The MSC has interface with the BSS on one side

(through which MSC/ VLR is in contact with GSM users) and the external

networks on the other (ISDN/ PSTN/ PSPDN) & other PLMN or MSCs.

Mobile Switching Centre (MSC): The Mobile services Switching Centre (MSC) co-ordinates the setting up of

calls to and from GSM users.

It is the telephone switching office for MS originated or terminated traffic and

provides the appropriate bearer services, teleservices and supplementary

services.

It controls a number of Base Station Sites (BSSs) within a specified

geographical coverage area and gives the radio subsystem access to the

subscriber and equipment databases.

The MSC carries out several different functions depending on its position in the network.

When the MSC provides the interface between PSTN and the BSS in the GSM network it is called the Gateway MSC.

Some important functions carried out by MSC are Call processing including

control of data/voice call setup, inter BSS & inter MSC handovers, control of

mobility management, Operation & maintenance support including database

management, traffic metering and man machine interface & managing the

interface between GSM & PSTN N/W.

HOME LOCATION REGISTER (HLR) The HLR contains the master database of all subscribers in the PLMN.

This data is remotely accessed by the MSC´´s and VLRs in the network. The

data can also be accessed by an MSC or a VLR in a different PLMN to allow

inter-system and inter-country roaming.


A PLMN may contain more than one HLR, in which case each HLR contains

a portion of the total subscriber database. There is only one database record

per subscriber.

The subscriber‟s data may be accessed by the IMSI or the MSISDN.

The parameters stored in HLR are

• Subscribers ID (IMSI and MSISDN )

• Current subscriber VLR.

• Supplementary services subscribed to.

• Supplementary services information (e.g. Current forwarding address).

• Authentication key and AUC functionality.

• TMSI and MSRN

VISITOR LOCATION REGISTER (VLR)

The VLR is a local subscriber database, holding details on those

subscribers who enter the area of the network that it covers.

The details are held in the VLR until the subscriber moves into the area serviced by another VLR.

The data includes most of the information stored at the HLR, as well as more precise location and status information.

The additional data stored in VLR are :

• Mobile status ( Busy / Free / No answer etc. )

• Location Area Identity ( LAI )

• Temporary Mobile Subscribers Identity ( TMSI )

• Mobile Station Roaming Number ( MSRN )

• The VLR provides the system elements local to the subscriber, with

basic information on that subscriber, thus removing the need to access

the HLR every time subscriber information is required


Authentication Centre ( AuC)

The AUC is a processor system that perform authentication function.

It is normally co-located with the HLR.

The authentication process usually takes place each time the subscriber initializes on the system.

Each subscriber is assigned an authentication key (Ki) which is stored in the SIM and at the AUC.

A random number of 128 bits is generated by the AUC & sent to the MS.

The authentication algorithm A3 uses this random number and authentication key Ki to produce a signed response SRES( Signed Response ).

At the same time the AUC uses the random number and Authentication algorithm A3 along with the Ki key to produce a SRES.

If the SRES produced by AUC matches the one produced by MS is the same, the subscriber is permitted to use the network.

Equipment Identity Register ( EIR)

The Equipment Identity Register (EIR) contains a centralized database for

validating the international mobile station equipment identity, the IMEI. The database contains three lists:

• The white list contains the number series of equipment identities that

have been allocated in the different participating countries. This list

does not contain individual numbers but a range of numbers by

identifying the beginning and end of the series.

• The grey list contains IMEI‟s of equipment to be monitored and

observed for location and correct function.

• The black list contains IMEI‟s of MS‟s which have been reported

stolen or are to be denied service.

The EIR database is remotely accessed by the MSC‟s in the Network and can

also be accessed by an MSC in a different PLMN.


OSS(Operations and Maintenance subsystem)

Operation And Maintenance Centre (OMC) The OMC controls and monitors the Network elements within a region.

The OMC also monitors the quality of service being provided by the Network.

The following are the main functions performed by the OMC

The OMC allows network devices to be manually removed for or

restored to service. The status of network devices can be checked from

the OMC and tests and diagnostics invoked.

The alarms generated by the Network elements are reported and logged at the OMC.

Maintenance personnel monitor and analyze these alarms and take appropriate action .

The OMC keeps on collecting and accumulating traffic statistics from the network elements for analysis.

Software loads can be downloaded to network elements or uploaded to the OMC.

What is GPRS?

GPRS is a new non-voice value added service that allows Mobile Phones to be

used for sending and receiving data over an IP based network. GPRS as such is a data bearer that enables wireless access to data networks

like Internet , enabling user to access E-mails and other Internet applications

using Mobile phones.

With GPRS we can enjoy a continuous wireless connection to data networks (Internet)

GPRS Network Elements:- GPRS Architecture is same as GSM except few hardware modifications :

GPRS includes GSNs in NSS

• SGSN : Serving GPRS Support Node

• GGSN : Gateway GPRS Support Node


Serving GPRS Support Node (SGSN):- Delivers data packets to mobile stations & vice-versa.

Detect and Register new GPRS MS in its serving area.

Packet Routing, Transfer & Mobility Management.

Authentication, Maintaining user profiles.

Its location register stores location info. & user profiles.

Gateway GPRS Support Node (GGSN):-

Interfaces GPRS backbone network & external packet data networks

Converts the GPRS packets from SGSN to the PDP format

Converts PDP addresses change to GSM addresses of the destination user

Stores the current SGSN address and profile of the user in its location register

Performs authentication

Many-to- many relations among SGSNs & GGSNs.

KEY REQUIREMENTS OF 3G Improved system capacity

Backward compatibility with second generation ( 2G ) systems

Multimedia support

High speed Packet data services

Data Rates

• up-to 2 Mbps – for fixed or Indoor environments


• up-to 384 kbps – for pedestrian or urban environments

• up-to 144 kbps – for wide area mobile environments

New air-interface in 3G WCDMA WCDMA stands for Wide Band – Code Division Multiple Access

It is the air –interface technology for the UMTS (UNIVERSAL MOBILE TELECOMMUNICATION SYSTEM) systems.

Why WCDMA …. ?????????? WCDMA for high speed data access up to 384 Kbps - 2 Mbps

Demand for high Speed Data Access

• Streaming

• Video on Demand

• Video Telephony Data Revenue is becoming significant

Operators World wide have shown inclination to introduce WCDMA

Main Network Elements in WCDMA New Core Network-

• MSC-MGW (CS)

• SGSN-GGSN(PS)

[Same for GSM (2G) and UMTS(3G)] Radio Network-

• GSM: BSC, BTS and

• UMTS: RNC, Node B

[All other network element are common for 2G as well as 3G]


3G Network overview

© BSNL India For internal circulation only

RNC : Main Functionalities

Manage and secure an optimal usage of the radio resources of the

radio access network

Control the mobility and handover within the radio access network

RNC provide Handover functions between WCDMA RAN and GSM, and Cell Change between WCDMA RAN and GSM/GPRS

Support radio access bearer (RAB) services with: Circuit Switched and Packet Switched data

Node B : Main Functionalities:-

Provides radio interface to the UE.

Transceiver Units and Dedicated Power Amplifiers for every sector.

Executes power control to minimize interference.

Date post:	01-Mar-2021
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