Shadab Bsnl Report

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Training report-BSNL

External Guidance by: Mr. R.kumar Divisional Engineer (I/D)

Mr.R.M.Verma(S.D.E.)

InternalGuidanceby:

Mr.M.Gupta(Faculty)

Prof.M.Chhawta(H.O.D.)

Submitted By: Mohd.Shadab

B.tech(C.S.)

Roll.no.-0722010029

H.I.E.T.Gzb



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Acknowl nt

Success of every project depends largely on the SELF & encouragement

and guidance of many others. I take this opportunity to express my

gratitude to the people who have been instrumental in the successful

completion of this study project.

First of fall I would like to thank the M anagement at BSNLfor giving

me the opportunity to do my one-month project training in their

esteemed organization.

nt nal Gui f or provi ing me with valuable advice and endlesssuppl of new ideas and suppor t f or this project

I would like to thank Er. R. Kumar for providing practical exposure for the project and his valuable

guidance during the project work.

Mohammad Shadab

B.Tech C.S.)



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PREFACE

Since time immemorial, a man has tried hard to bring the world as close to himself as possible. His thirst for information is hard to quench so he has continuously tried

to develop new technologies, which have helped to reach the objective.

The world we see today is a result of the continuous research in the field of

communication, which started with the invention of telephone by Grahm Bell to the

current avtar as we see in the form INTERNET and mobile phones. All thesetechnologies have come to existence because man continued its endeavor towards

the

objective.

This project report of mine, STUDY OF TRE

DS TECH

O ¡ OGIES I

COMMU

ICATIO

A

D

ETWORKI

G has been a small effort in reviewing thetrends technologies prevailing. For this purpose, no organization other than BAHRAT

SANCHAR NIGAM LIMITED could have been a better choice.

Mohammad Shadab

B.Tech C.S.)



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Tabl¢

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f c£

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¤ ts

1.Acknowledgement 2.Preface

3.Tabl of contents

4.Introduction

5.making a telephone call6.About the exchange

a.computer unit

b.power plant c.central air conditioner

d.main distribution frame

7.V-SAT networka.Design aspects

b.Operational factors8.Types of access V-SAT networks

a.fixed assignment time division multiple access

(F-TDMA)b.Random access

c.Code division multiple access (CDMA)

9.The Internet a.Introduction

b.Internet connectivityc.OSI modeld.Communication b\w the layers

e.File transfer the internet f.National internet backbone

10.Wireless in local loop

a.Technical aspectsb. Advantages

11.3-G Mobile Communication12.Global system for mobile communication (GSM)



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A ¥ I ¥ t ¦

§

duct ̈

§

¥ :-

Today, BSNL is the No. 1 telecommunication company and the largest public sectorundertaking of India and its responsibilities includes improvement of the alreadyimpeccable quality of telecom services, expansion of telecom services in all villages

and instilling confidence among its customers.

Apart from vast network expansions, especial emphasis has given for introducing

latest technologies and new services like I -NET, INTERNET, ISDN (INTEGRATEDSERVICES DIGITAL NETWORK), IN (INTELLIGENT NETWORK), GSM and WLL

(WIRELESS IN LOCAL LOOP) services etc. Now BSNL has also entered in mobile

communication. BSNL has all the new services send technological advantages, whichare available with any well, developed Telecom network anywhere else in the

country.

Full credit for all above achievement goes to the officers and staff of the BSNL. The

administration is fully aware of the challenges lying ahead and quite committed to

provide the latest and best telecom services by their continued support and act iveco-operation.

© SNL Services:-

When it comes connecting the four corners of the country , and much beyond , one

solitary name lies embedded at the pinnacle - BSNL. A company that has gone past

the number games and the quest to attain the position of th e leader. It is workinground the clock to take India in to the future by providing excellent telecom services

for people of India.

Driven by the very best of telecom technology from global leaders, it connects eachinch of India to the infinite corners of the globe, to enable you to step in to

tomorrow.

The telecom services have been recognized the world over as an important tool forsocio-economic development for a nation and hence telecom infrastructure is treated

a crucial factor to realize the socio-economic objectives in India. Accordingly theDepartment of Telecom has been formulating developmental policies for the

accelerated growth of the telecommunication services in various cities. The

department is also responsible for frequency management in the field of radioconnection in close coordination with the international bodies.



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MAKING A TELEPHONE CALL

A telephone call starts when the caller lifts the handsets of the base. Once the dialtone is heard, the caller uses a rotary or a push button dial mounted either on thehandset or on the base to enter a sequence of digits, the telephone number of called

party. The switching equipment from the exchange removes the dial tone from the

line after the first digit is received and after receiving the last d igit, determines the

called party is in the same exchange or a different ones. If the called is in the sameexchange, burst of ringing current is applied to the called partys line. Each

telephone contains a ringer that responds to specific electric freque ncy. When the

called party answers the telephone by pocking up the handset, steady start to flow

in the called partys line and is detected by the exchange. The exchange than stopsapplying ringing and sets up the connection between the caller and the call ed party.

If the called party is in different exchange from the caller, the caller exchange set upthe connection over the telephone network to the called partys exchange. The

called party then handles the process of ringing, detecting an answer, and noti fyingthe calling and billing machinery when the call is completed. When conversation is

over, one or both parties hang up by replacing their handset on the base, stopping

the flow of current. The exchange when initiates the process of taking down theconnection, including notifying billing equipment of the duration of the call if

appropriate.

A OUT THE EXCHANGE

All telephone subscribers are served by automatic exchanges, which perform the

functions the human operator. The number being dialed is stored a nd then passedto the exchanges central computer, which in turns operates the switching to

complete the call or routes it a higher level switch for further processing. Todays

automatic exchanges uses a pair of computers, one running the program that provides services and the second monitoring the operation of the first, ready to take

over in a few seconds in the event of equipment failure.

Various exchanges present in BSNL are:

E-10B

OCB283EWSD

All exchange has some purposes and some basic structural units, which are:

1. subscribers connection unit

2. switching network (CX)



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3. control unit 4. OMC

For smooth working of an exchange following unit are very important: -

1. Computer Unit: - it deals with additional services of the exchange to thecustomers with the help of computers.

2. Power Plant:- to feed proper power supply to exchange

3. AC Plant: - to maintain the continuous temperature + or 2 degree Celsius to thedigital switch (exchange).

4. MDF: - to connect switch (exchange) with the external environment (subscriber)

i.e. it is the interface between subscribers and exchange.

C

mputer u

it

As the name specified it is the main part of the exchange that deals with the allservices provided by the exchange to the customers with the help of com puter. It

also provides the updated data to all other part of the exchange.

The customers are using the services of the exchange by using the internet also gets

connected to the main server present this room via an internet room.

It mainly consists of the servers that are providing the different services. The main

servers of this room are:-

IVRS is used for the change number services provided by the exchange.

CERS are provided by the exchange to avoid the problems that the users are facing

the repairing of telephone. In this system when the user enters its complained it

gets directly entered to the server and user is allotted with an id number.

LOCAL DIRECTORY ENQUIRY is another services provided by the exchange, by usingthis; subscribers calls the particular number and gets the directory enquiry. Theserver present in the main computer room provides this service.

INTERNET DIRECTORY ENQUIRY is the latest service by the exchange. In this type

of service makes it enquiry using the internet, which gets c onnected to the mainserver at the internet room in the exchange and further to the main server in thecomputer room.

POWERPL ANT

As we know that, the power is the main source or any organization. It is the case of



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E-10B exchange. That is the first requirement of any organization is the input.The main source of this exchange is AC supply. However, as soon as the power

supply is gone off, then what is source? No one think on this that the telephone is

always plays its role in the human life. Even if the po wer supply gone off. Thus theremust be adjustment source of power.

The main parts of the power room are:

Batteries: - these are the instant sources of the power as soon as power is gone off.

UPS (Uninterrupted Power Supply): - the UPS must give supply to the computer. As

we know there is some equipment which can withstand any type of power supply,but there are also some instruments which cannot withstand with this type of power

supply, even a microsecond delay will cause the loss of data.

Charging- Discharging Unit: - the batteries we are using in the power room needtimely charging. As soon as the AC power supply is on, we make use of the charging

unit present in the power room. The slowly charging of the batteries is known as thetrickle charging. But sometimes we need the BOOSTER charging. In this type of

charging awe take of the batteries from the load and charge separately, until it getsfully charged.

The main work of the discharging unit is to control the discharging of the batteries.

Inverter and Converter Unit: - the main use of this system is to change AC mains to

DC and vice versa as required by the parts of exchange.

Engine Room:-we know that the batteries are the instant source of supply but we

cannot use it for much larger time, thus for th is, we have an engine to generate thepower supply. They are of 885 KVA. Thus, this room controls the supply of theengine.

CENTRAL AIR CONDITIONER

For the function of electrical equipment, cooling system is basic requirement. The

basic advantages of cooling systems are following-It provides the thermal stability so that the temperature does not reach thetolerance limit of electronic equipment

It saves equipment from dust so to avoid malfunction of equipments.It protects equipment from excess humidity which can caused rusting of equipment.

The basic unit of measurement used in the industry is known as ton of refrigeration (TR) which is equivalent to the heat extracted in 24 hours for

converting thousands kg of liquid to ice at zero degree.

The compressor is the heart of the AC system and the costliest. It increases thepressure and temperature of the refrigerant gas coming from the evaporator coils by

compressing it.



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Compressor comes in various types. The most widely used is simple reciprocal type acylinder and piston arrangement. For capacity more than 120 TR, centrifugal

compressors are used. The condenser liquefies the refrigerant gas by a heat

exchange process. The capillary tube or the expansion valve pressurizes liquidrefrigerant and meters i t flows to the evaporator.

The refrigerant then passes trough the evaporator coils, which extract heat out of the ambience.

MAIN DISTRI UTION FRAME

The primary function of MDF is:The fault of telephone number is removed in the MDF; it is called as Fault Remove

Section.

For removing the fault of telephone number, we use the testing

These testing are T.T.Y. testing, Group testing, etc.For any type of testing firstly we need the vertical no. or the live tester, printer and

computer test N.E. number of that particular telephone number.The telephone numbers are also disconnected in the MDF because of some specific

reason.

ORGANIS ATION OF THE MDF

PARTS OF THE MDF

Horizontal side

Vertical side

HORIZONTAL SIDE:

It is again subdivided in to two parts

Exchange sideLine side

Description of the horizontal side:-

RACK: - On the rack, the tags are situated. One rack is having eight tags. Thecourting is done from up (0) to down (7).

TAG: - Each rack consists of eight tags.1 tag = 4 core

1 core = 4 bunch1 bunch = 2 line

N.E.:- The word NE stands for the NUMBER OF EQUIPMENT.

It is a 128 pair cable. The EWSD and MDF connected by NE.

WEDGE:-If we want to disconnect any two numbers then we insert a wedge



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between subscriber side and exchange side. Here wedge wo rks as insulator made of plastic.

VERTICAL SIDE:

The vertical aside connected to the underground cable. This cable is having 100pairs.These pair is distributed when we allot the telephone number to the subscriber.

Vertical side is again subdivided in t wo parts:

One part is connected with the horizontal side and another with the subscriber lineby using 100 pair underground cable.

This is how the present day telephone system works. Different exchanges have

different architectures of switching call rout ing and other features.

Now let us see how BSNL has kept up with the changing world and provided thesubscribers with the latest facilities technologies, which include the V -SAT network,

Internet, the WLL (wireless in local loop) and the GSM mobile.

V-S AT NETWORK

What is V-S AT?

It can be defined as a class of very small aperture Intelligent Satellite Earth Station

suitable for easy on-premise installation, usually operating in conjugation with alarge size HUB earth station. Capable of supporting a wide range of two ways

integrated Telecom Services.It has the following components:Micro Earth Station

Mini Earth StationPersonal Earth Station

Roof Top Terminal

Customer Premises Terminal

AD V ANTAGES OF V-S AT

Can be located in the user premises on roof top or backyard and hence eliminate last

mile problem.Superior quality satellite based data services.

Quick implementation time.Reliable communication.Broadcast feature on satellite communication.

Communication to different areas.

Flexibility for network and changes.Service in distance insensitive.

Low cost.



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REASON FOR V-S AT E VOLUTION

The main reason for V-SAT evolution is due to advances in following areas:

Packet transmission and switching.Efficient multiple access protocol.Powerful microprocessor.

KU and RF electronics.

Antennae miniaturization

Spread spectrum techniques.Protocol standardization and implementation.

LSI based FEC codec has and modems.

Higher power satellites.

CL ASSIFICATION OF V-S ATs

V-SAT can be classified as following:

1. Modulation type2. Application used for.

3. Transmission rate.

4. Cost.

CATEGORIES OF V-S ATs

1. Broadcast/ point to multipoint

Types of servicesa. Broadcast videob. Program quality audio.

c. Packetised data.In this mode of operation V-SATs transmit/receive data through a centralized HUB.

This type of network is called star network.

2. Point to point Types of services

a. Voiceb. Datac. Image

In this mode of operation, V -SATs transmit/receive data without the help of hubstation. This type of network is call ed a mesh network.

3. Two way interactiveTypes of servicesa. Voice

b. Data

c. ImageIn this configuration, V-SATs can communicate both on star as well as mesh

topology.



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DESIGN FACTORS FOR V-S AT S YSTEMS

The capabilities of V-SAT system depend upon the following factors.I. Satellite characteristics

II. Geographical and environmental factors.

III. Transmission link properties.

IV. Earth station characteristics. V. Information encoding and modulation.

VI. Total system operation.

When evaluating V-SAT system each of the above attributes should be givenattention. However, few of more important attributes are

Operational aspectsFrequency bands

Satellite access methods

OPERATION AL ASPECTS

Considering a V-SAT system from its operational aspects, there are five broad

functions that determines how the system works. These are:Bandwidth allocationMultiplexing

Network management Protocol handling

Transmission

TYPE OF ACCESS FOR V-S AT DATA NETWORK

There are three types access available for V -SAT data networks. They are:

1. Fixed assignment time division multiple access (F -TDMA)2. Random access

a. Pure alohab. Slotted alohac. Reservation

i. Implicit

ii. Explicit 3. code division multiple access (CDMA)



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FIXED ASSIGNMENT TIME DI VISION MULTIPLE ACCESS (F-TDMA)

In a fixed assignment TDMA, each frame is divided in to slots of fixed time durationsamong stations of network. The assignment of stations to slots is permanent similar

to TDMA system carrying digitalized voice except FTDMA does not have

synchronization. Packets are sent asynchronously, with no frame sync signals.

FEATURES

No inter modulation problems.

Transport utilization is better.Burst from different stations must arrive at satellite exactly in allocated slots.

Throughput is 70% to 80%Delay medium is too high.

Complexity-medium.

RANDOM ACCESS

With TDMA schemes, signals are transmitted by earth stations in a burst mode. If no

scheduling is provided b/w the transmitting station, this type of access is called time

random multiple access. This simplest method for the stations to transmit burst without regard for other station.

Random access id of two types:Pure aloha

Slotted aloha

PURE ALOHA

Pure aloha, also called unslotted aloha is the simplest form of random accessschema.In this form of access stations transmit packets\bursts randomly.

Packet from different stations may collide, thereby destroying information content.Station transmits the packet until they are received correctly.

The aloha channel throughout can be analyzed in terms of traffic offered throughthe following relationship:S=Ge-2g

Maximum throughput is 13% to 18%.

Delay- lowComplexity- very low



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SLOTTED ALOHA

The maximum throughput of an unslotted aloha channel is limited to 18% due tocollision.To reduce probability of each collision time slots are introduced so that the

transmission could only at the start of the slots.

The above network discipline reduces the rate of collision by half and hence

increases the maximum throughput efficiency of the channel.In S-Aloha, each station has 2 queues.

a. New packet queue

b. Retransmit packet queue.

Only if the retransmit packet queue is empty, a new packet queue is sent.The analysis of slotted aloha channel shows that

S = Ge2gMaximum channel throughput is 36%.

Delay- low.Complexity- low- medium.

Reservation

The low bandwidth utilization of pure aloha and the slotted aloha has led to manyproposals for increasing utilization by means of slot reservation schemes.

The object of slot reservation schemes is to rece ive a particular time slot for a givenstation. This ensures that no collision takes place.This scheme has a higher throughput than either S - Aloha or F-TDMA depending on

traffic.This increase in channel utilization efficiency is obtained at some overhea d either in

terms of allocation of bandwidth for reservation purposes and \or increased

complexity of the control mechanism in transmitting stations. All reservation methods use some form of framing approach and the reservation

scheme can be either implicit or explicit.The implicit reservation method involves reservation by use. This is done whenever astation successfully transmit in a slot; all the stations internally assign that slot in

sub-segment frames for exclusive use by the successful station. This is called R- Aloha. In this there is no way to prevent a station capturing most or all of the slots

in a frame for an indefinite time.The explicit reservation is a distinct and unique assignment of slots to a user by thenetwork scheduler.



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CODE DI VISION MULTIPLE ACCESS (CDMA)

With CDMA transmission from earth station are spread over the time frequencyplane by a code transformation. These techniques are referred to as Spread

Spectrum Systems. In addition to their multiple access capabilities, they are useful in

combating jamming, and are for this reason principally used in military systems.

Features

All stations operate on the same transponder frequency using a large bandwidth

than needed for the data rate.Network needs no time for frequency coo rdination.

Provide anti jam capabilities or protection against interference.Provide for a graceful degradation of network performance as the number of

simultaneous users increases.Low spectral density compared to conventional emissions.

It yields same capacity as FDMA.

Limitations of CDMA

Require large transponder ratio.

Due to imperfect code orthogonalities, expected simultaneous users may be limited.Requires a highly central earth station called HUB using star configuration.

VSAT technology using SSMA is presently available only for low bit rate application.

VS AT NETWORK IN DOT

Department of telecommunication entered the VSAT era in 1991 by commissioning

its first satellite based low bit rate network known as REMOTE AREA BUSINESSMESSAGE NETWORK (RABMN).This has been engineered for users located in remote areas for stable and reliable

data communication.This service envisages installation of very small aperture terminals (VSAT) to work

with satellite based pocket switched network.

It has 3 main components:-

A large master earth station (hub) A satellite transponder located in geo stationary orbit

A small micro earth station located at users premises



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SER VICES OFFERED Y RA M NETWORK:-

Data communication up to 1200 bps

Fax services.

Access to Public Telex Network

Access to international data network through VSNL gateway.

Tariff and billing:-

A RABMN customer availabling VSAT has to pay the following charges: -Registration charge Rs. 5000 per terminal

Cost of each VSAT Rs. 5.2 lakhsCost of each installation Rs. 15,000 per terminal

License fees Rs. 100 per terminalMaintenance charges Rs. 25,000 per terminal annually

Satellite access charges Rs. 5000 per month per terminal

Traffic charges Rs. 50 per kilo segment of data

Network users:

Some of the probable users are

Banking networkCivil aviation

Airlines\railwaysPublic\private sector industries

Meteorological department

Police department

RA MN NETWORK

Introduction

Satellite communication plays a vital role in long distance communicati on.Satellite medium offers high bandwidth making it suitable for data communicationand computer networking.

Satellite communication is of distance and cost effective.

Multi access nature of satellites.Provides two way communications.

Dynamic assignment of channels between geographically dispersed users.



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Satellite network provides point to point and point to multipoint communicationneeds.

Frequency division multiple access (FDMA):-

Bandwidth is split in to narrow frequency bands with multiple users eac h allocated afrequency range within the larger bandwidth.

Time division multiple access (TDMA):-

Each terminal is allotted a short time slot in which to transmit on a sequential basis.

This time slot is usually a fraction of a second.

Code division multiple access (CDMA)

Each terminal is allotted a unique encryption code. The transmitted signals areencoded and only the terminal intended to receive it, can decode it. This is also

known as Spread Spectrum Multiple Access.

Statistical time division multiplexing (STDM):-

In TDM, time slots are allotted to the multiplexed lines even if they have no data

transmit. In STDM, a time slot is allotted to the multiplexed line only if there is datato be sent. The multiplexed circuit is used more efficiently.

VS AT (very small aperture terminal)

It is also called Micro Earth Station or Personal Earth Station.

Its main features are as follows:-

Independent of terrain can be installed in hilly regions, islands and remote places.

Flexible service carrying data, Telex.

No last mile problems of cable pair\overhead lines.Interference immunity.

Data security

The main services offered by VSAT are as follows:-

Interactive data communication.Connection to public telex network.

Connection to Packet Switched Data Network INET.Connection to internat ional gateway packet switch.



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The different technologies used in VSAT are -

Satellite basedSpread spectrum

Packet switching

Tariffs:-

Cost of VSAT : about Rs. 7,00,000

Installation cost : Rs. 15,000Maintenance cost : Rs. 25,000

Satellite access charge : Rs. 5,000 per month

Charges for using VSAT are as follows:

Ø National : Rs. 50 per kilo segment of data: Rs. 10 per min in addition to vol. of telex

Ø International : Rs.200 per Kilo segment of data: Rs. 240 per hour duration.

Dialing codes for VSAT are as follows:

Within RABMN:o 12 digit code

o 4041xxxxxxxx

to other data networks:o I-NET

o 4043xxxxxxxx

o international networkso DNICxxxxxxxx

To telex networksNATIONAL

Q008/area code/telex number

INTERNATIONAL0009/country code/telex number

TELEX TO RABMIN

09841xxxxx (last 5 digits of telex number)



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Specifications for master earth station:

There are two types of master earth stations:

Outbound

Inbound

Outbound:

Each VSAT and host computer is allotted an HCL port

NPG polls HCL ports and generates a 153.6 Kbps demand based STDM data streamData stream contains variable length packets of data addressed to various VSATs

Outmux chips the data @1:16 resulting in 2.4576 MB stream.

BPSK modulator produced 5 MHz of spectrum

Upconvertor converts to 5GHz RFMes transmits 153.6KBps STDM/BPSK/SS carriers

NPG provides FEC encoding for outbound data

Inbound:

Inbound signals originates from VSATs

VSAT has a unique PN codeData spread by its PN code and transmitted to satellite in 6 GHz band

MES resolves the signal in 4 GHz band, converts to 70 MHz IF and sends to Demod

sectionDemod cards compare the pattern of the to other PN code for its associated VSAT.

When the correct pattern is detected, the original signal is ex tracted from the IFsignal and transmitted to INMUX NPG polls INMUX for I\C data packets and transmits the packets to HCL

VS AT specifications

Antennae module

Ø Reflector : 1.2M X 1.8MØ Weight : 60 KGsØ Tracking : fixed

Ø Amb. Temp : -40 to +50 deg. Cel.Ø Wind speed : operating 100 kmph

Controller module

Ø Size : 15 cm(h) x 43 cm(w) x 55 cm (d)

Ø Weight : 15 kgsØ Power supply : 220V\60Hz, 300 watts

Ø Oper. Temp. : -5 to 50 deg. Cel.



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Ø Humidity : up to 95%

Controller module :

Ø INPUT\OUTPUT PROCESOR· Converts raw data to packets· Customer protocol to network protocol

Ø NETWORK PROCESSOR

TRANS SIDE:· generates BFEC & FCS

· Retains packets in buffer until ACKs receives and transmits if required.

RECIEVER SIDE:· checks BFEC & FCS

· ACKs the packets and requests retransmission of missing packets

Ø SPACE PROCESSORTRANS SIDE

· Encodes the packets with PN sequence to 2.45MBps s tream

· BPSK modulation of IF

RECIEVER SIDE

· Demodulates IF signal to 2.45MBps· Dispreads to 153.6KBps stream

· Checks destination link address in the header· Discards packets addressed to other links.

Micro earth station transmits 1.2KBps\9.6KBps BPSK/CDMA carriers bursts inabsolutely random access mode in the same frequency.

INTERNET

Introduction:

The Internet is not a program, not software, not hardware or a big system. It is a

group of various co-operating computers worldwide interconnected by computerbased on TCP\IP communication protocols. People use it to get information over a

standard communication link. The hundreds or thousands or millions of computernetwork are connected to each other for exchanging the information which is basedon the unique identity and set of procedures. Internet is a series of interconnected

networks providing global link to inform ation.

GIAS: BSNL launched the Gateway Internet Access Service (GAIS) through dial

up/leased/ISDN network. Users can access GAIS from 99 cities in India by this



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means.

INTERNET CONNECTI VITY

INTERNET TECHNOLOGY

The basic function of Internet can be su mmarized as under-

Interconnecting of computers to form a network.Interconnecting of computers to form a network of networks.

To establish a communication link between two computers within as network.

To provide alternate communication link among the net works, even if one network is

not working. These are based on TCP/IP communications protocol.

Transfer of a file through Internet: -

Suppose a file is to be transmitted on Internet from one computer to other ones

Break the file in to small packets

Attached destination and source address in o packetsMultiplexed and transmit these packets

At destination de-multiplex the packetsRemove address bits from the packets and assemble the data in to the original fileMake source bits as destination address and send the acknowledgement in to the

source

Therefore, it is clear that network hardware sends the packets to specified

destination and network software reassembles of communications, the computernetwork performs the following functions-

Addressing and routingFragmentation and error correction

Data error checkingConnectivity control

Multiplexing and de-multiplexingData flow controlEnd users interface etc.

The data handling

A single module cannot handle the entire process. One that adopted as a standa rd is



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an open system interconnection (OSI) model.

OSI NETWORKING MODEL: The open systems interconnection model defines all

the methods and protocols needed to connect one computer to any other over anetwork.

The OSI model separates the methods and proto cols needed for a networkconnection in to seven different layers. Each higher layer relies on services provided

by a lower level layer.

The OSI model is sometimes called the seven layer model. It was developed by theInternational Standards Organizatio n (ISO) in 1983 and is documented as standard

7498.

Layers are:

Application layerPresentation layer

Session layerTransport layer

Network layer

Data link layerPhysical layer

PHYSICAL L AYER:

The physical layer defines the properties of the physical m edium used to make anetwork connection. It includes a network cable that can transmit a stream of bits

between nodes on the physical network. The physical connection can be either point to point or multipoint, and it can consist of either half duplex (one direction at a

time) or full duplex (both directions simultaneously) transmissions. Moreover, the

bits can be transmitted either in series or in parallel (most network use a serialstream of bits, but the standard allows for both serial and parallel trans mission). The

specification for the physical layer also defines the cable used, the voltages carriedon the cable, the timing of the electrical signals, the distance that can be run, and soon. For example, a NIC network interface network) is part of the p hysical layer.

DATA LINK L AYER: the data link layer, layer 2, defines standard that assignmeaning to the bits carried by the physical layer. It establishes a reliable protocolthrough the physical layer, so the network layer (layer 3) can transmit its d ata. The

data link layer typically includes error detection and correction to ensure a reliable

data stream. The data elements carried by the data link layer are called frames.Examples of frame types include x.25 and 802.x (802.x includes both Ethernet an d

Token Ring networks).



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The data link layer is usually subdivided in to two sub layers, called the Logical link

control (LLC) and Media Access Control (MAC) sub layers. The LLC sub layer

performs tasks such as call set up and termination and data transfer . The MAC sublayer handles frame assembly and disassembly, error detection and correction, and

addressing. The two most common MAC protocols are 802.3 Ethernet and 802.5Token ring .Other MAC protocols include 802.12 100 Base VBG, 802.11 Wireless, and802.7 Broadband.

Network Layer: The network layer, Layer-3, is where a lot of action goes on for

most networks. The network layer defines how data packets get from one point toanother on network. The Network layer is also known as packet layer, it defines

different packet protocols, such as Internet Protocol (IP) and Internet Protocol

Exchange (IPX). These packet protocols include source and destination routing

information. The routing information in each packet tells the network where to sendthe packets to reach its destination and tells the receiving computer from where the

packet originated.

Transport Layer: The Transport Layer, layer-4, manages the flow of informationfrom one network node to another. It identifies each computer or node on a network

uniquely. It ensures that the packets are decoded in the proper sequence and that

all packets are received. Transport layer protocols include Transmission ControlProtocol (TCP) and Sequenced Packet Exchange (SPX).Each is used in concert with

IP and IPX respectively.

Session layer: The session layer, layer-5, defines the connection from a user to anetwork server, or from a peer on a network to another peer. These virtualconnections are referred to as sessions. They include negotiation between the client

and the host, or peer and peer, on matters of flow and control, transaction -processing, transfer of user information, and authentication to the network.

Presentation Layer: The presentation layer, layer-6, takes the data supplied by

the lower level layer and transform so it can be presented to the system. ThePresentation layer can include data compression and decompression as well as dataencryption and decryption.

Application Layer: The Application layer, layer 7, controls how the operating

system and its application interact with network. As mentioned earlier, data flows from an application program or the operatingsystem, and then goes through the protocols and devices that make up the seven

layers of the OSI model one by one until the data arrives at the physical layer and is

transmitted over the network connection. The computer at the receiving endreverses this process. At each stage of the OSI model, the data is wrapped with

new control information related to the work done at the particular layer. This control



24

information is different for each layer, but it includes headers, trailers pre -ambles,and post-ambles.

Therefore, for example, when the data goes into the networking software and

components making up the OSI model, it starts at the applicati on layer and includesan application header and application data. Next, at the presentation layer, a

presentation header is wrapped around the data and it is passed to the sessionlayer, where a session header is wrapped around all the data, and so on, unt il it reaches the physical layer. At the receiving computer this process is reversed.

COMMON TERMINOLOGY USED IN INTERNET:

WWW:

World Wide Web (WWW) is a wide area hypermedia information retrieval aiming to

give universal access to a large universe of d ocuments.

HTTP:

Hyper text transmission Protocol (HTTP) is the communication protocol used totransfer documents from the server to client over the WWW (http:// www).

HTML:

Hyper Text Markup Language (HTML) is a system of marking or tagging the various

parts of web documents to tell the browser software how to display the document text, link graphics and link media.

ISDN:

Integrated Service Digital Network (ISDN) is a digital phone connection technologythat provides both voice and data services over the same connection.

ISP:

Internet Service Provider (ISP) is an agency that provides Internet access and othernet related services.

N ATION AL INTERNET ACK ONE (NI )

Networking is a key component of any Internet Services Provider (ISP) operations.The networking equipments like access servers, routers and modems are critical tothe successful functioning of ISP.

An ISP node where subscribers enter internet, consists of a set of equipments as

given below. Access server

Router



25

Modem bankLAN (Local Area Network) components

Security server

Rack, console & power supplyNetwork management agent.

Help desk

WIRELESS IN LOCAL LOOP (WLL) MO ILE

WLL is a communication system that connects customers to the Public Switch

Telephone Network (PSTN) using radio freque ncy signals as substitutes of conventional wires for all part of connection between the subscribers and the

telephone exchange. It works on CDMA technique. The local loop is access part of

telecommunication network i.e. the part between PSTN switch and sub scribers. WLL

network application involves uses of radio to replace of the wire link between PSTNswitch and subscriber. The radio technology is able to provide same quality of

services as that provided by the wires line. Application of wireless loop techn ologyhas just been started in the worldwide. There is no standard for this so far.

However, a number of national and international air interface standards for digitalcellular mobile telephone system are available.

TECHNICAL ASPECTS:

WLL is based on CDMA technique and is entirely different from GSM. The system forWLL services can be divided in to following parts: -

BSC (Base Switching Centre):- It provides links between BTS & BSM; it consists of different processors, in BSNL it is of SUN Polaris of LG Company. In LG 1 BSC can

have 48 BTS? In BSNL we have two types of BSC: -

V-5.2:- This type of BSC cannot switch by itself so it is dependent on local exchange / PSTN for switching and keeping records of billing etc. BSNL uses this type of BSC

for rural areas.

CCS-7 / R2:- These types of BSC are totally automatic it doesnt depend on localexchange for its functions, it is complete in itself. BSNL uses this type of BSC for

urban areas.

TS ( ase Transreceiver System):- As it is clear from its name it transmits as

well as receive signal, it works as an amplifier (router) to overcome the loss in signalin transmission.



26

BSM (Base Station Management):- It controls and manages the WLL services. It

can troubleshoot the problem; add new users as well as capa ble to block service

given to user. It is basically a computer system, which manages the whole processof WLL service. In BSNL BSM are two UNIX based computer system.

CODE DI VISION MULTIPLE ACCESS (CDMA):

CONCEPT OF MULTIPLE ACCESSES: - Multiple access system allows a large

number of users to share a common pool of radio telephone circuits, like sharing of

trunked radio facility. Multiple access radio has similarity to the LAN in which thecommon channel is available to all users. The circuits are demands assigned i.e.

assigned on demand first-cum-first-served basis. The provision of access to the radio

circuits methods of multiple accesses are:

CDMA: - Where large number of transmission are combined on the same channel at

the same time and separated by the codes.

FDMA (Frequency Division Multiple Access):- Where individual transmissionseparated by each other by the time.

WHAT IS CDMA?

CDMA, a cellular technology originally known as IS -95, competes with GSM

technology for dominance in the cellular worl d.There are now different variations, but the original CDMA is known as CdmaOne.

Latest CDMA global subscriber & operators numbers As of December 2002, there were 120 millions users worldwide, with 55 million of

these in the USA.See other cellular technology in the world.

We now have CDMA2000 and its variant like 1X EV, 1XEV -DO and MC 3X. The referof variant of usage of a 1.25 MHz channel. 3X uses a 5 MHz channel. Wide band

CDMA forms that the basis of UMTS 3G networks, developed originally byQualcomm, high capacity and small cell radius, employing spread -spectrumtechnology and special coding scheme characterized by CDMA.

The Telecommunication Industry Association (TIA) in 1993 adopted CDMA. May

2001 there were 35 million subscribers on cdmaOne syste m worldwide. Over 35countries have either commercial or trial activity ongoing. There were already 43WLL systems in 22 countries using cdmaOne technology.

Enhancing todays data capabilities is the 1XRTT CDMA standard this next

evolutionary step for cdmaOne operators will provide data rates up to 300 kbps,significant capacity increases as well as extended batteries life for handsets.

Worldwide resources are being devoted to roll out third generation CDMA



27

technology, including multi-carrier (cdmaOne2000 1xMC and HDR in 1.25 MHzbandwidth and 3xMC in 5 MHz bandwidth) and direct spread (WCDMA in 5 MHz

bandwidth).

This first phase of cdmaOne2000 variously called 1XRTT, 3G1X or just plain 1X isdesigned to double current voce capacity and support always on dat a transmission

speed 10 times faster than typically available today, some 153.6 kbps on both theforward and reverse links.

AD V ANTAGES OF WLL:

Country wide induction of WLL underway of areas than are non -feasible for thenormal network

Helping relieves congestion of connections in the normal cable / wire based network

in urban areas

Limited the mobility without any airtime chargesIt has improved signal and reducing the interference

Greater capacity than mobileProvides ease of operation, administration & maintenance at lower cost.

The telecommunication is the biggest factor in influencing the speed of life in themodern age. Today we can get connection with any corner of world through the

push button of computer; with the small mobile phone we can send no t only the

messages but also the secret document. As we know that there is positive viewbehind any mention that it should be helpful in the development of society. But

humans have diverted mentality some of them of positive view and some of them of

negative view. Where use any invention for the welfare of society but some uses forthe satisfaction their disturbed mentality and to earn more and more money whether

it may be harmful for the society. They infringe the norms of society and theirbehavior is condemned as antisocial, immoral and sinful.

CELLUL AR MOBILE SER VICES:

Cellular is one of the fastest growing and most demanding telecommunication

applications. Today, it represents a continuously increasing percentage of all newtelephone subscriptions around the world. Currently there are more than 45 million

subscribers in worldwide and nearly 50% of those subscribers are located in USA. It is forecasted that cellular system using a digital technology will become the universalmethod of telecommunications. By the year 2005, forecasters predict that there will

be more than 100 million cellular subscribers worldwide.



28



29

11- 3 G MOBILE COMMUNICATION

INTRODUCTION

y Wir eless Generations

y What is IMT-2000

y What IMT-2000 offer s

y K ey featur es and objectives

y Spectr um f or IMT-2000

y Technologies f or IMT-2000

y Migration pathsy Futur e T

WIRELESS GENERATIONS

1 G -analog (cellular r evolution) only mobile voice services2 G - digital ( br eak ing digital barr ier ) -mostly f or voice services & data deliver y possi ble

3 G - Voice & data ( br eak ing data barr ier ) Mainly f or data services wher e voice services will also be possi ble

Beyond 3G Wide band OFDM ?But sur ely higher data rates

11.1 LIMITATIONS OF 2ND GENERATION SYSTEMS

y No Global standards

y No common f r equency band

y Low inf or mation bit ratesy Low voice quality

y No suppor t of Video

y Var ious categor ies of systems to meet specif ic r equir ements



30

11.2 THIRD GENERATION (3 G ) STANDARD

y International mobile telecom 2000. imt-2000

y ITU¶s vision f or third generation mobile system

y a futur e standard in which a single inexpensive mobile ter minal can tr uly provide

communications any time and any wher ey Provisioning of these services over wide range of user densities and coverage ar eas.(in-

building , urban , su b-urban, global)

y Eff icient use of radio spectr um consistent with providing service at acceptable costly.

y IMT-2000 shall cover a pplication ar eas pr esently provided by seperately systems i.ecellular , cordless and paging etc.

y A high degr ee of commonality of design wor ldwide.

y A modular str uctur e which will allow the system to grow in size and complexity.

y Single unif ied standard (data & multimedia services)

y Anywher e, anytime communication

y Across network s, across technologies, seamless o peration using a small pock et ter minal

wor ldwide.y High speed access 144kb/s, 384 kb/s & 2m b/s f ast wir eless access to internet

y Full motion video phone

y Terr estr ial & satellite components

y Enhanced voice quality, u biquitous coverage and enable o perator s to provide service at r easonable cost

y Incr eased network eff iciency and ca pacity

y New voice and data services and ca pabilities

y An order ly evolution path f rom 2G to 3G systems to protect investments.

11.2.1 IMT TECHNOLOGIES

ITU has f inally narrowed down technology o ptions to the f ollowing f ive: 1. IMT -DS (Dir ect Spr ead) : W-CDMA UTR A FDD

2. IMT -MC (Multi Carr ier ) : CDMA 2000

3. IMT-TC ( Time Code) : TD -SCDMA UTR A TDD

4. IMT -SC ( Single Carr ier ) : UWC - 136

5. IMT-FT (Fr equency Time) : DECT

IMT-DS IMT-MC IMT-TC IMT-SC IMT-FT

WCDMA CDMA20001X/3X

CDMA-TDD UWC-136 FDMA/TDMADECT

IMT-2000 TERRESTRIAL

RADIO INTERFACES



31

11.2.2 IMT-2000 HARMONIZATION IS ON-GOING

IMT standards develo pment involves extensive collaboration between many differ ent

organizations

y Today¶s o perator s need seamless 2G 3G

y Many Focus groups have been established by industr yy 2 G o perator s GSM ; CDG ,UWCC, DECT f or um

y 3 G Groups UMTS For um , OHG

y Focus group f or IP- based 3G architectur e (3G. IP)

y SDOs cr eated 3G PP (Par tner shi p Projects)SDO Standards Develo pment

Organizations

11.3 MIGRATION PATH

y While a multi plicity of 2G standards have been develo ped and deployed, the ITU wanted

to avoid a similar situation to develo p f or 3G.

y

Hence, the ITU R adio communication Sector (ITU-R ) has elaborated on a f ramework f or a global set of 3G standards, which will f acilitate global roaming by o perating in a

common cor e spectr um and providing migration path f rom all the major existing 2G

technologies.

y The major 2G R adio access network s ar e based on either CDMA One or GSM

technologies and differ ent migration path is pro posed f or each of these technologies.

GSM GPRS EDGE

PDC

CdmaOne

DMA

IS-136

DMA/

GPRS

TDMA/

EDGE

Cdma 2000

CDMA

IMT-2000

CPA

LE

Y

TEM

2000 EVOLVED 2G

64-115 Kbps

TODAY 2G

19.2 Kbps

3G

115-384 Kbps 0.384-2 Mbps



32

Evolution from GSM to 3G

11.3.1 GSM EV L T

11.4 E GE (E E DATA FOR GSM EVOL T ON)

y Next step towards 3G for GSM/GPRS Networks

y Increased data rated up to 384 Kbps by bundling up to 8 c annels of 48 Kbps/c annel

y GPRS is based on modulation tec nique known as GMSK

y EDGE is based on a new modulation sc eme t at allows a muc ig er bit rate across t eair-interface called 8PSK modulation.

GS

2G

HSCS

GPR S

2.5G

EDGE

3G

GPRS200KHz carrier

115 Kbps peakdata rates

EDGE200KHz carrier

Data rates upto 384 Kbps

8-PSKmodulation

Higher symbol rate

UMTS5 MHz carrier

2 Mbps peakdata rates

New IMT-2000 2 GHz spectrum

GSM200KHz carrier

8 full-rate timeslots

16 half-rate timeslots

GSM GPRS EDGE UMTS

3G2.5G2G

HSCSD

HSCSD

Circuit-switched data

64Kbps peakdata rates



33

11.4.1 GSM TO UMTS

11.4.2 GSM TO GPRS TO EDGE TO 3G

y GSM can be upgraded for ig er data rate upto 115 Kbps t roug deploying GPRS(General Packet Radio Service) network.T is requires addition of two core modules

y

SGS N

(Serving GPRS Service N

ode)y GGS N (Gateway GPRS Service Node)

y GSM radio access network is connected to SGS N t roug suitable interfaces.

y GPRS p ase-II will support ig er data rates up to 384 Kbps t roug incorporatingEDGE

y ( En anced Data Rate for GSM Evolution).

SoftwareUpgrade

0101001010

BSC Upgr

d

NewSoftware

01010101

00

New Software

01010101

00

New Software0101001010

MSC

PST

BSC

BTS

SGSN

WWWEnt rpr Net or

VPN

IP

Backbone

GGSN

GPRS

Backbone

New

mod ! f ! edrouter

NewEqu ! pment

BSC

New

Ter minal

New cell sites(in some cases)

ModemPool

BTS

3G

GGSN

W-CDMA

BSC

3G

SGSN

NewEquipment& Softwar e

W-CDMA

BTS

New

Ter minal

Evolution To W-CDMA





35

11.6 FUTURE TRENDS (3 G TO 4G ONWARDS)

New data services, interactive TV and evolving Internet behavior will inf luence

mobile data usage. Long sessions in always-on mode will f orce a r e-think of radio access

technology to achieve the r equir ed but not easy to attain ca pacity (G bit/s/k m) at low cost.

The ideas pr esented in this ar ticle can incr ease ca pacity by a f actor of 500 with r egard to expected cellular deployments. Coverage will be based on large um br ella cells (3G, WiMAX)

and numerous Pico cells interconnected to provide the user with seamless high data rate

(several M bs) sessions. Scalable and progr essive deployments ar e possi ble while protecting

the o perator ¶s long-ter m investment. The 4G inf rastr uctur e o perator will mix several

technologies, each of which has its o ptimal usage. The connection to one of them will r esult

in a r eal-time trade-off which will offer the user the best possi ble service. Some tools that

genuinely improve the user ¶s multimedia quality of exper ience (availability, r esponse time,

def inition, etc) ar e also pr esented in this ar ticle.

11.7 4G MOBILE

4G will deliver low cost multi-megabit/s sessions any time, any place, using any

ter minal.

11.7.1 O eratio al Excelle ce

Voice was the dr iver f or second generation mobile and has been a considerable

success. Today, video and TV services ar e dr iving f orward third generation (3G) deployment and in the futur e, low cost, high speed data will dr ive f orward the f our th generation (4G) as

shor t-range communication emerges. Service and a pplication u biquity, with a high degr ee of per sonalization and synchronization between var ious user a ppliances, will be another dr iver .

At the same time, it is probable that the radio

access network will evolve f rom a central-ized architectur e to a distr i buted one.

11.7.2 Service Evolutio

The evolution f rom 3G to 4G will be dr iven by services that offer better quality (e.g.

video and sound) thank s to gr eater bandwidth, mor e so phistication in the association of a

large quantity of inf or mation, and improved per sonalization. Convergence with other network

(enter pr ise,f ixed) services will come about through the high session data rate. It will r equir e

an always-on connection and a r evenue model based on a f ixed monthly fee. The impact on

network ca pacity is expected to be signif icant. Machine-to-machine transmission will involve

two basic equi pment types: sensor s (which measur e parameter s) and tags (which ar e

generally r ead/wr ite equi pment). It is expected that user s will r equir e high data rates, similar

to those on f ixed network s, f or data and str eaming a pplications. Mobile ter minal usage(la pto ps, Per sonal digital assistants, hand-helds) is expected to grow ra pidly as they become

mor e user f r iendly. Fluid high quality video and network r eactivity ar e impor tant user r equir ements. K ey inf rastr uctur e design r equir ements include: f ast r esponse, high session

rate, high ca pacity, low user charges, ra pid r eturn on investment f or o perator s, investment that is in line with the growth in demand, and simple autonomous ter minals. The

inf rastr uctur e will be much mor e distr i buted than in curr ent deployments, f acilitating the



36

introduction of a new source of local traffic: machine-to-machine. Figure 1 shows one visionof how services are likely to evolve; most such visions are similar. Dimensioning targets A

simple calculation illustrates the order of magnitude. The design target in terms of radio performance is to achieve a scalable capacity from 50 to 500 bit/s/H /km 2 (including capacity

for indoor use), as shown in Figure 2. As a comparison, the expected best performance of 3G

is around 10 bit/s/H /km2

using High

Speed Down link Packet Access (HSDPA), Multiple-Input Multiple-Output (MIMO), etc. No current technology is capable of such performance.

Dimensioning ob jectives Based on various traffic analyses, the Wireless World Initiative

(WWI) has issued target air interface performance figures. A consensus has been reached

around peak rates of 100 Mbit/s in mobile situations and 1 Gbit/s in nomadic and pedestrian

situations, at least as targets. So far, in a 10 MH spec-trum, a carrier rate of 20 Mbit/s has

been achieved when the user is moving at high speed, and 40 Mbit/s in nomadic use. These

values will double when MIMO is introduced. Clearly, the bit rate should be associated with

an amount of spectrum. For mobile use, a good target is a network performance of 5 bit/s/H ,

rising to 8 bit/s/H in nomadic use.

Figure 1

Figure 2:Dimensioning examples



37

11.7.3 Multi-Technology A roach

Many technologies ar e competing on the road to 4G, as can be seen in F i$ % & ' 3. Thr ee

paths ar e possi ble, even if they ar e mor e or less specialized. The f ir st is the 3G-centr ic path,

in which CodeD

ivision Multi ple Access (CD

MA) will be progr essively pushed to the point at which ter minal manuf actur er s will give up. When this point is r eached, another technology

will be needed to r ealize the r equi-r ed incr eases in ca pacity and data rates. The second path is

the radio LA N one. Wide-spr ead deployment of WiFi is expected to star t in 2005 f or PCs,

la pto ps and PDAs. In enter pr ises, voice may star t to be car -r ied by Voice over Wir eless LA N

(VoWLA N). However , it is not clear what the next successful technology will be. R eaching a

consensus on a 200 M bit/s (and mor e) technology will be a lengthy task , with too many

pro pr ietar y solutions on offer . A third path is IEEE 802.16e and 802.20, which ar e simpler

than 3G f or the equivalent per f or mance. A cor e network evolution towards a broadband Next Generation Network ( NG N) will f acilitate the introduction of new access network

technologies through standard access gateways, based on ETSI-TISPA N, ITU-T, 3GPP,China Communication Standards Association (CCSA) and other standards. How can an

o perator provide a large num ber of user s with high session data rates using its existing inf rastr uctur e? At least two technologies ar e needed. The f ir st (called ³par ent coverage´) is

dedicated to large coverage and r eal-time services. Legacy technologies, such as 2G/3G and their evolutions will be complemented by WiFi and WiMAX. A second set of technologies is

needed to incr ease ca pacity, and can be designed without any constraints on coverage

continuity. This is known as picocell coverage. Only the use of both technologies can achieve

both targets ( F i$ % & ' 4). Handover between par ent coverage and pico cell coverage is differ ent

f rom a classical roaming process, but similar to classical handover . Par ent coverage can also

be used as a back -up when service deliver y in the pico cell becomes too diff icult.



38

11.8 Key 4G Technologies

Some of the key technologies required for 4G are briefly described below:

11.8.1 OFDMA

Orthogonal Frequency Division Multiplexing (OFDM) not only provides clear advantages for

physical layer performance, but also a framework for improving layer 2 performance by

proposing an additional degree of freedom (Pico cell). A ood example of a pico cell is a

WiFi coverage. By extension, a pico cell has a radius around 50 m and the associated base station is similar to a WiFi access point. It can be deployed indoors or outdoors.



39

Figure 4:Coverage performance trends

Using ODFM, it is possible to exploit the time domain, the space domain, the

frequency domain and even the code domain to optimi e radio channel usage. It ensures very

robust transmission in multi-path environments with reduced receiver com-plexity. As shown

in Figure 5, the signal is split into orthogonal sub carriers, on each of which the signal is

³narrow band´ (a few kH ) and therefore immune to multi-path effects, provided a guardinterval is inserted between each OFDM symbol. OFDM also provides a frequency diversity

gain, improving the physical layer performance. It is also compatible with other enhancement

technologies, such as smart antennas and MIMO. OFDM modulation can also be employed

as a multiple access technology (Orthogonal Frequency Division Multiple Access; OFDMA).

In this case, each OFDM symbol can transmit information to/from several users using adifferent set of subcarriers (subchannels). This not only provides additional flexibility for

resource allocation (increasing the capacity), but also enables cross-layer optimi ation of radio link usage.

11.8.2 Software Def ined Radio

Software Defined Radio (SDR) benefits from today¶s high processing power todevelop multi-band, multi-standard base stations and terminals. Although in future the

terminals will adapt the air interface to the available radio access technology, at present this isdone by the infra-structure. Several infrastructure gains are expected from SDR. For example,

to increase network capacity at a specific time (e.g. duringa sports event), an operator will reconfigure its net-work adding several modems at a given

Base Transceiver Station (BTS). SDR makes this reconfiguration easy. In the context of 4G



40

systems, SDR will become an enabler f or the aggr egation of multi-standard pico/micro cells.

For a manuf actur er , this can be a power ful aid to providing multi-standard, multi- band

equi pment with r educed develo pment eff or t and costs through simultaneous multi-channel

processing.

11.8.3 Multiple-Input Multiple-Output

MIMO uses signal multi plexing between multi ple transmitting antennas (space

multi plex) and time or f r equency. It is well suited to OFDM, as it is possi ble to process

independent time sym bols as soon as the OFDM wavef or m is corr ectly designed f or the

channel. This aspect of OFDM gr eatly simplif ies processing. The signal transmitted by m

antennas is r eceived by n antennas. Processing of the r eceived signals may deliver several

per f or mance improvements: range, quality of r eceived signal and spectr um eff iciency. In

pr inci ple, MIMO is mor e eff icient when many multi ple path signals ar e r eceived. The

per f or mance in cellular deployments is still su bject to r esearch and simulations. However , it is generally admitted that the gain in spectr um eff iciency is dir ectly r elated to the minimum

num ber of antennas in the link .

11.8.4 Software Define R a io

Sof twar e Def ined R adio (SDR ) benef its f rom today¶s high processing power to

develo p multi- band, multi-standard base stations and ter minals. Although in futur e theter minals will ada pt the air inter f ace to the available radio access technology, at pr esent this is

done by the inf ra-str uctur e. Several inf rastr uctur e gains ar e expected f rom SDR . For example,

to incr ease network ca pacity at a specif ic time (e.g. dur ing

a spor ts event), an o perator will r econf igur e its net-work adding several modems at a given

Base Transceiver Station (BTS). SDR mak es this r econf iguration easy. In the context of 4G

systems, SDR will become an enabler f or the aggr egation of multi-standard pico/micro cells.

For a manuf actur er , this can be a power ful aid to providing multi-standard, multi- band

equi pment with r educed develo pment eff or t and costs through simultaneous multi-channel

processing.

11.8.5 Multiple-Input Multiple-Output

MIMO uses signal multi plexing between multi ple transmitting antennas (space

multi plex) and time or f r equency. It is well suited to OFDM, as it is possi ble to process

independent time sym bols as soon as the OFDM wavef or m is corr ectly designed f or thechannel. This aspect of OFDM gr eatly simplif ies processing. The signal transmitted by m

antennas is r eceived by n antennas. Processing of the r eceived signals may deliver several per f or mance improvements: range, quality of r eceived signal and spectr um eff iciency. In

pr inci ple, MIMO is mor e eff icient when many multi ple path signals ar e r eceived. The

per f or mance in cellular deployments is still su bject to r esearch and simulations .However , it is generally admitted that the gain in spectr um eff iciency is dir ectly r elated to the minimum

num ber of antennas in the link .

11.8.6 Interlayer Optimization

The most obvious interaction is the one between MIMO and the MAC layer . Other

interactions have been identif ied



41

11.8.7 Handover and Mobility

Handover technologies based on mobile IP technology have been considered for dataand voice. Mobile IP techniques are slow but can be accelerated with classical methods

(hierarchical, fast mobile IP). These methods are applicable to data and probably also voice.In single-frequency networks, it is necessary to reconsider the handover methods. Several

techniques can be used when the carrier to interference ratio is negative (e.g. VSF-OFDM, bit

repetition), but the drawback of these techniques is capacity. In OFDM, the same alternative

exists as in CDMA, which is to use macro-diversity. In the case of OFDM, MIMO allows

macro-diversity processing with performance gains. However, the implementation of macro-

diversity implies that MIMO processing is centrali ed and transmissions are synchronous.

This is not as complex as in CDMA, but such a technique should only be used in situations

where spectrum is very scarce.

Figure 5:OFDM principles

11.8.8 Caching and Pico CellsMemory in the network and terminals facilitates service delivery. In cellular systems,

this extends the capabilities of the MAC scheduler, as it facilitates the delivery of real-time

services. Resources can be assigned to data only when the radio conditions are favorable.This method can double the capacity of a classical cellular system. In Pico cellular coverage,

high data rate (non-real-time) services can be delivered even when reception/transmission is

interrupted for a few seconds. Consequently, the coverage one within which data can bereceived/transmitted can be designed with no constraints other than limiting interference.

Data delivery is preferred in places where the bit rate is a maximum. Between these areas, the

coverage is not used most of the time, creating an apparent discontinuity. In these areas,

content is sent to the terminal cache at the high data rate and read at the service rate.

Coverages are ³discontinuous´. The advantage of coverage, especially when designed with

caching technology, is high spectrum efficiency, high scalability (from 50 to 500 bit/s/H ),high capacity and lower cost. A specific architecture is needed to intro-duce cache memory in



42

the net-work . An example is shown in F i( ) 0 1 8. At the entrance of the access network , lines

of cache at the destination of a ter minal ar e built and stor ed. When a ter minal enter s an ar ea

in which a transfer is possi ble, it simply ask s f or the line of cache f ollowing the last r eceived.

Between the ter minal and the cache. A simple, robust and r eliable protocol is used between

the ter minal and the cache f or ever y service deliver ed in this type of coverage.

11.8.9 Multime ia Service Delivery, Service Adaptation and R obust

Transmission

Audio and video coding ar e scalable. For instance, a video f low can be split into thr eef lows which can be transpor ted independently: one base layer (30 kbit/s), which is a robust

f low but of limited quality (e.g. 5 images/s), and two enhancement f lows (50 kbs and 200kbs). The f ir st f low provides availability, the other two quality and def inition. In a str eaming

situation, the ter minal will have thr ee caches. In Pico cellular coverage, the par ent coverageestablishes the service dialog and service star t-up (with the base layer ). As soon as the

ter minal enter s pico cell coverage, the ter minal caches ar e f illed, star ting with the base cache.

Video (and audio) transmissions ar e cur -r ently transmitted without error and without pack et loss. However , it is possi ble to allow error rates of about 10 -5 /10 ±6 and a pack et loss around

10 ±2 /10 -3 . Coded images still contain enough r edundancy f or error corr ection. It is possi ble to



43

gain about 10 dB in transmission with a r easonable incr ease in complexity. Using the

descr i bed technologies, multimedia transmission can provide a good quality user exper ience.

11.8.10 Coverage

Coverage is achieved by adding new technologies (possi bly in over lay mode) and progr essively enhancing density. Tak e a WiMAX deployment, f or example: f ir st the par ent

coverage is deployed; it is then made denser by adding discontinuous Pico cells, af ter which

the Pico cell is made denser but still discontinuously. Finally the pico cell cover -age is made

continuous either by using MIMO or by deploying another Pico cell coverage in a differ ent

f r equency band .Par ent coverage per f or mance may var y f rom 1 to 20 bit/s/Hz/k m?, while

Pico cell technology can achieve f rom 100 to 500 bit/s/Hz/k m?, depending on the complexity

of the ter minal hardwar e and sof twar e. These per f or mances only r efer to outdoor coverage;

not all the issues associated with indoor coverage have yet been r esolved. However , indoor coverage can be obtained by:

Di 2 3 ct penet 2 ation; this is only possi ble in low f r equency bands (signif icantly below 1 GHz)and r equir es an excess of power , which may raise signif icant inter fer ence issues.

Ind oo2

sho2

t r ange r ad io connected to the f ixed network . C onnection via a rel ay to a Pico cellular access point.

11.8.11 Integration in a Broadband NGN

The f ocus is now on deploying an architectur e r ealizing convergence between the f ixed and

mobile network s (ITU-T Broad- band NG N and ETSI- TISPA N). This gener ic architectur e

integrates all service enabler s (e.g. IMS, network selection, middle war e f or a pplications

provider s), and offer s a unique inter -f ace to a pplication service provider s.

GLOB AL S YSTEM FOR MOBILE COMMUNICATION (GSM)

The GSM Association is a unique organization, with a truly global reach, offering a

full range of business and technical services to its members. Now as the wirelessfamily unfolds the association is deriving forward its vision of seamless, limitless,

world of wireless communication.

Throughout the evolution of cellular telecommunications, various systems have beendeveloped without the benefit of standardized specifications. This presented many

problems directly related to compatibility, especially with the development of digital

radio technology. The GSM standard is intended to address these problems.Global system for mobile communication (GSM) is a globally accepted standard for

digital cellular communication. GSM is the name of a standardization groupestablished in 1982 to create a common European mobile telephone standard that

would formulae the specifications for a pan-European mobile cellular radio system

operating at 900 MHz. It is estimated that many country outside of Europe will jointhe GSM partnership.



Conclusion

The provision of megabit/s data rates to thousands of radio and mobile ter minals per squar e

k ilometer pr esents several challenges. Some k ey technologies per mit the progr essive

introduction of such network s without jeo pardizing existing investment. Disr uptive

technologies ar e needed to achieve high ca pacity at low cost, but it can still be done in a progr essive manner . The k ey enabler s ar e:

Suff icient spectr um, with associated shar ing mechanisms.

Coverage with two technologies: par ent (2G, 3G, WiMAX) f or r eal-time deliver y,

and discontinuous Pico cell f or high data rate deliver y.

Caching technology in the network and ter minals.

OFDM and MIMO.

IP mobility.

Multi-technology distr i buted architectur e.

Fixed-mobile convergence (f or indoor service). Network selection mechanisms.

Many other featur es, such as robust transmission and cross-layer o ptimization, will

contr i bute to o ptimizing the per f or mance, which can r each between 100 and 500 bit/s/Hz/k mThe distr i buted, full IP architectur e can be deployed using two main products: base stationsand the associated controller s. Ter minal complexity depends on the num ber of technologies

they can work with. The minimum num ber of technologies is two: one f or the radio coverageand one f or shor t range use (e.g. PA Ns). However , the pr esence of legacy network s will

incr ease this to six or seven.

At last, I would lik e to say thank s again all staff of the unit who hel ped me through my training per iod.

THAN S!

Mohammad Shadab

Final ear Computer Science & Engg.

HIET, Ghaziabad

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