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E3-E4 TELECOM FACTORY

Familiarisation with Telecom

Technologies


CFA Technology Overview-I

© For internal circulation of BSNL only

Public Switched Telephone Network (PSTN).

AGENDA

Next Generation Network (NGN)

Standalone Signal Transfer Point (SSTP)


Public Switched Telephone Network (PSTN)

The telephone network used for fixed line services

consist 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”.

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).


• 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

New Technology (NT) switching systems:


The total equipped capacity in BSNL as on 30thSept

2010 is about 6,21,98,000 (including WLL and DLC).

In the BSNL network about 30% of the total switching

capacity is on CDOT technology.


In the BSNL network about 38% of the total working

connection is on CDOT technology. The total

working connection in BSNL as on 30th Sept 2010 is

about 3,10,36,276.

The WLL FWT (Fixed wireless terminals and the

connection given over DLC are counted in Basic

service (Fixed Network).



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 ------- All the sites of Lev-I TAX .

SSTP ------- 24 locations



Why NGN?

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.

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>.



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.).

ETSI 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.



Generic diagram to depicts the concept of NGN

Interfaces

Switching

Call

Control

Call

Server

IP/MPLS

Gateways

SDH Transport

with Overlay

packets for data

Common IP MPLS

Transport over SDH/

DWDM/Fiber


• Packet-based transfer

• Separation of control functions among bearer capabilities,

call/session, and application/service

• De-coupling 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

• Interworking with legacy networks via open interfaces

• Generalized mobility

• Unfettered access by users to different service providers

Fundamental Aspects of NGN


• 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.

Strategy For Migration Towards NGN


Generic Reference Diagram For IP TAX


Soft Switch (or Call Agent or Call Server or Media

Gateway Controller) Functions:

• It is 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

• Interacts with application server to supply services not

hosted on soft switch

Soft Switch


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

Signalling Gateway (SGW)


Functions of Trunk Media Gateway (TMG)

• Voice Encoding & Compression

• Packetization of Voice Channels

• CNF (Comfort Noise Generation)

• VAD (Voice Activity Detection)

• Echo Cancellation

Trunk Media Gateway (TMG)


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.

Advantages of IP TAX Deployment:


Objectives of SSTP

• 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.

Standalone Signal Transfer Point


SSTP’s at BSNL Network

• 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

Standalone Signal Transfer Point


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

SSTP contd…..


Lawful Intercept (LI) of SMS

Mobile Number Portability (MNP)

Planned Applications on SSTP Network


CFA Technology Overview-II


Numbering Scheme in BSNL

AGENDA

Services offered by BSNL‟s Landline

Supplementary services in PSTN (phone plus services)

Services offered by ISDN

Landline VAS


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 .

Some special services like directory enquiry (197),

fault booking (198), railway enquiry (139) etc are

provided by these standard short codes.


Supplementary services in PSTN (phone plus services):

Abbreviated Dialing

Call Waiting

Hot Line

Call Transfer (Call Forward)

Automatic Wake-Up/Reminder Call Service

Number/Call Hunting Service

Calling Line Identification Presentation (CLIP)

Calling Line Identification (CLI) Announcement Service

Electronic Locking For STD/ISD ( Dynamic Locking Facility)

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

Services offered by BSNL’s Landline


Call Conferencing

Services offered by BSNL’s Landline contd…

Services Offered By ISDN:

Normal Telephone & Fax (G3) and G4 Fax

Digital Telephone -with a facility to identify the calling

subscriber number and other facilities.

Data Transmission at 64 Kbps with ISDN controller

card

Video Conferencing


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)


Landline Value Added Services (VAS)

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

Internet Facility:-

PSTN Dial Up Access

ISDN Dial Up Access

Account Free Internet Dial Up Access Based On CLI

Sancharnet Card

Broad Band Connection


© For internal circulation of BSNLonly © For internal circulation of BSNLonly

• 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.

• 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. A video

conference subscriber can schedule their video conferences

through the Web. The video conferencing service can be

availed by any user through IP or ISDN interface.



Online Billing Enquiry and Payment


Centrex Service:

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 may made by using a short

code consist of last 2- 6 digits (maxi.) of their

number. But all the calls made outside the group

will be charged at the normal applicable tariff.


• 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.




• 12555 Service:

Latest Bollywood songs

Old classic songs

Jokes

Horoscope

International/National news

Cricket news

Different contests

Finance/stocks related news

Travel information etc


• 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

Intelligent Network (IN) Services:


• MCIN is being used for Televoting and other IN services

except ACC

• New platforms have enhanced capacity for all IN services

Intelligent Network (IN) Services:

IN Services Offered By BSNL

Free-phone Service (FPH) or Toll Free Service (TFS)

(Access Code : 1800)

Virtual Card Calling services (VCC) or Universal India

Telephone Card(UITC)

(Access Code : 1802)

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

Virtual Private Networks (VPN) (Access Code: 1801)

Premium Rate Services (PRM) (Access Code: 1867)


Intelligent Network (IN) Services Contd…..

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

and

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

Tele-voting Services (VOT)

(Access code : 1803, 1861,1862)

Call Now Cards:

Personalised Ring Back Tone Service(PRBT):

Fixed Line Pre-Paid Telephone (FLPP)

(Access code: ,1805,1806)


Advantages of Fixed Line Pre Paid service:

• 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.

Intelligent Network (IN) Services Contd…..


CM Technology Overview

CDMA & WiMAX


Agenda

CDMA 2000 1x: Introduction

CDMA 2000 1x: Network Architecture

CDMA 2000 1x: Key Features & Additional Channels

CDMA 2000 1x EV-DO

Services in CDMA

WiMAX: Introduction

WiMAX Forum

WiMAX: Key Features

WiMAX: Network Architecture

BSNL Plans


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.



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.

A separate Packet Core Network (PS-CN) is provided to takes care of

data calls.

Enhancements of CDMA 2000 1x over IS-95 are

Enhanced Voice Capacity

Better handling of packet data



E1 Link

BTS

BTS FWT/HHT

BSC

BSC

BTS

BTS

MSC VLR

PSTN

Ex. FWT/HHT

HLR AUC

PDSN FA

AAA

Server

HA

HA

Internet

World

..

E1 Link

Packet Switch Core Network

Circuit Switch Core Network


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)



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)

HLR (Home Location Register)

VLR (Visitor Location Register)

AUC (Authentication Center)



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)

HA (Home Agent) Server

FA (Foreign Agent) Server

AAA Server


CDMA 2000 1x: Key Features

Some of the key features of CDMA 2000 are as follows.

Faster Forward Power Control

Variable length Walsh Codes

New Radio Configurations (RC)

Efficient use of spectrum

Seamless Evolution Path

High-Speed Data


CDMA 2000 1x: Additional Channels

In the Forward link Pilot, Sync, and Paging Channels are available in

CDMA 2000 1x same as in IS-95 systems. Several new channels are

added to provide more spectral efficiency, higher voice capacity & data

rate over the same RF bandwidth. Some of the new channels are as

follows.

Forward Fundamental Channel

Forward Supplemental Channel (valid for Radio Configuration 3

through 9)

Forward Quick Paging Channel (QPCH

Reverse Supplemental Channel (valid for Radio Configuration 3

through 6)


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 CDMA 2000 1x RTT.

CDMA 2000 1x EV-DO


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.

CDMA 2000 1x EV-DO


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.

Services in CDMA


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. WiMAX has become a “hot topic” in the wireless industry,

with visible and aggressive backing from INTEL, among others.

WiMAX is designed to provide “last-mile” or “backhaul” connectivity

using wireless.

WiMAX: Introduction


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.

WiMAX Forum


WiMAX Forum Profiles

WiMAX forum Profiles are defined by the following parameters:

•Spectrum band

•Duplexing-TDD/FDD

•Channel bandwidth

IEEE 802.16-2004 profile uses OFDM with 256 subcarriers and

802.16e profiles are based on Scalable OFDMA and supports

mobility.


WiMAX: Key Features

Some of the salient features supported by Mobile WiMAX are:

High Data Rates

Quality of Service (QoS)

Scalability

Security

Mobility



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.


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. NRM,

consisting of the following logical entities:

MS (Mobile Station)

Access Service Network (ASN)

Connectivity Service Network (CSN)



WiMAX Network Reference Model



BSNL PLANS


BSNL: Proposed WiMAX Network

FE

E1s

E1

STM 1

Tier 2/

Tier 1

SDH Ring

of the

BSNL

Circle

ASN FE

LAN

Switch

AS

N

Gate

wa

y

BTS FE

to

E1 / E3

Converter

FE

to

STM1

Converter

BTS

STM 1

OCLAN

(DSL)

BTS ETHERNET LINK ON MPLS

GE

CSN

HA

GE/FE

iManager

E1/ T1 TO FE

Convertor

FE

EMS AAA

AAA ALDAP DHCP DNS OM/ IM

OSS / BSS – Proj:3

Scenario -1

Scenario -2

Scenario -3


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

Rest of India 20 Mhz with TDD Mode

carrier frequency of 2645 Mhz.

BSNL: WiMAX Spectrum


BSNL has adopted different models for deployment of WiMAX

Services:

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

sharing agreement.

PB & KL Circle – Own deployment 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.

BSNL: WiMAX Models


BSNL: WiMAX Rural Project

Department of Information Technology (DIT) Project for wireless

Broadband connectivity to Community Service Centres (CSC‟s). STP

is the in-charge for Execution of the Project.

Rural Phase-I

•Approximately 11,666 CSC‟s for 1000 Blocks.

•PO to M/s HCL Infosystems Ltd. for North and East. PO to M/s Gemini

Communications Ltd. for South and West.

Rural Phase-II

•Approximately 51000 CSC‟s to be covered.

•Total 6863 BTS to be installated.


WiMAX Urban Project is for Kerala & Punjab Circle.

BSNL Will deploy its own WiMAX Network.

In Kerala the PO for supply of 450 BTS was awarded to M/s ICOMM.

In Punjab the PO for supply of 350 BTS was awarded to M/s Huawei

WiMAX urban service has been launched on 31.03.2010 in 22 cities

/towns of Punjab Circle.

BSNL: WiMAX Urban Project

CM Technology Overview

GSM & 3G

For internal circulation of BSNL only

Agenda

1.

Various sub system in GSM Technology

2.

GPRS and its function 3.

Requirement of 3G 4.

Why WCDMA ? 5.

Function of nodes


GSM Network Architecture- typical

B

T

S

B T S

Air interface

OSS

B T S BSC

HLR

MSC VLR

EIR

MSC VLR

(

AuC

PSTN ISDN

Data Networks

4/25/2011

4 For internal circulation of BSNL only

GSM Network Architecture- typical

OMC-R

MS

B

T

S

B T S

Air interface

BSS

B T S BSC

NSS

HLR

(

AuC

PSTN ISDN

MSC VLR Data

Networks

EIR

MSC VLR

4/25/2011


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 includes the equipments and

functions related to end-to-end call.

4. Operations and Maintenance subsystem includes

the operation and maintenance of GSM equipment for the radio and network interface.

4/25/2011


Mobile Station (MS)

Mobile Station consist of two units

Mobile Hand set

Subscriber Identity Module

SIM is a removable module goes into the mobile

Mobile Hand set is one of the most complicated GSM device. It provides user the access to the Network. Each handset has unique identity no. called IMEI.

handset. Each SIM has unique number called International Mobile Subscriber Identity (IMSI). It has built in Micro-computer & memory into it. It contains the ROM of 6 to 16KB,RAM of 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

4/25/2011


SIM •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.

4/25/2011


SIM •The SIM contains several pieces of information

- International Mobile Subscribers Identity ( IMSI ). This number identifies 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 Subsriber Directory Number

(MSISDN ) - This is the telephone number of the mobile.

4/25/2011


SIM

•Most of the 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.

4/25/2011

11


BSS


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.

4/25/2011


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.

4/25/2011


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.

4/25/2011


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).

4/25/2011


TRANSCODING

30 Timeslots 1 traffic channel / TS

64 Kbps / TS 4 E1 lines = 30 X 4

=120 Timeslots

MSC

Each Timeslot =16 X 4 = 64 Kb/s

30 timeslots = 30 x 4

=120 traffic channels XCDR BSC

Transcoded information from four calls

0

1

2

16

31

4/25/2011


NSS


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.

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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.

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Mobile Switching Centre (MSC)

• 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 − database management, − traffic metering and man machine interface − managing the interface between GSM & PSTN N/W.

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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 subscribers data may be accessed by the IMSI or

the MSISDN. 4/25/2011


HOME LOCATION REGISTER( HLR ) 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

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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.

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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.

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Equipment Identity Register ( EIR)

It 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.

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Equipment Identity Register ( EIR)

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OSS


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.

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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)

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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

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GPRS Architecture CS

MSC

BTS BSC

PSTN

INTERNET

GPRS Core Network

GGSN

GPRS Backbone

SGSN PS

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IP Network

32


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

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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

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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

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New air-interface in 3G

WCDMA

(Wide Band - Code Division Multiple Access)

It is the air -interface technology for the

UMTS systems

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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

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Main Network Elements…

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 )

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3G Network overview

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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

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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

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