Gsm, Gprs,Cdma

7/29/2019 Gsm, Gprs,Cdma

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COMPARATIVE STUDYON

GSM,GPRS&

CDMATECHNOLOGY

PREPARED BY :

PAVANI MAGOO

KANIKA


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Clamshell handheldsTablets

Netenabled mobile phones

Palm-sized

Laptop computers


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First-generation: Analog cellular systems (450-900 MHz) Frequency shift keying; FDMA for spectrum sharing NMT (Europe), AMPS (US)

Second-generation: Digital cellular systems (900, 1800 MHz) TDMA/CDMA for spectrum sharing; Circuit switching GSM (Europe), IS-136 (US), PDC (Japan)


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Single hop wireless connectivity Space divided into cells Abase station is responsible to communicate with

hosts in its cell

Mobile hosts can change cells while communicating Hand-offoccurs when a mobile host starts

communicating via a new base station

Factors for determining cell size No. of users to be supported Multiplexing and transmission technologies


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Limited number of frequencies => limited channels

High power antenna => limited number of users Smaller cells => frequency reuse possible => more users

Base stations (BS): implement space division multiplex Cluster: group of nearby BSs that together use all available channels

Mobile stations communicate only via the base station FDMA, TDMA, CDMA may be used within a cell

As demand increases (more channels are needed) Number of base stations is increased Transmitter power is decreased correspondingly to avoid interference


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Each cell is served by a base station (BS)

Each BSS is connected to a mobile switching center(MSC) through fixed links

Each MSC is connected to other MSCs and PSTN

MSC MSC

HLR

VLR

HLR

VLR

To other

MSCs

PSTNPSTN


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INTRODUCTION

GSM is a mobile telephony network based on the cellular

concept.

Users can place and receive calls without being fixed to a

specific location or wired to a physical connection.

To supply this capability, a GSM network consists of four

Basic components:

The Mobile Station (MS).The Base Station Subsystem (BSS).

The Network and Switching Subsystem (NSS).

The Operation and Support Subsystem (OSS).

Global System for Mobile Communications (GSM)


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1) Mobile Station- A Mobile Station consists of two main

elements i.e mobile equipment or terminal and

Subscriber Identity Module (SIM).

2) The Base Station Subsystem -The BSS connects the Mobile

Station and the NSS.

3)The Network and Switching Subsystem-Its main role is to

manage the communications between the mobile users and

other users, such as mobile users, ISDN users etc.

4) The Operation and Support Subsystem (OSS)-The OSS is

connected to the different components of the NSS and to

the BSC, in order to control and monitor the GSM system.


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FUNCTIONS

1)Transmission.

2)Provides higher digital voice quality .

3)Provides roaming services.

4)Communication Management (CM).

5)Operation, Administration andMaintenance (OAM).

6) Low cost alternative.


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INTRODUCTION

GENERAL PACKET RADIO SERVICE (GPRS)

General Packet Radio Services (GPRS) is a standardized

packet switched data service for GSM.

The GPRS provides us with:

1) Fast coverage rollout, adding packet switching nodes to an

existing GSM network.2) Efficient use of scarce radio resources


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GPRS design is to support burst data transfer.

Two new elements are added to keep packet data traffic

separated from traditional GSM voice and data.

i.e. a) The Serving GPRS Support Node (SGSN)

b) The Gateway GPRS Support Node (GGSN).

The migration path from GSM to GPRS requires:

a) Additional packet switching nodes

b) Software upgrades in the base station subsystemc) Transmission links can be reused

d) Station Controllers (BSCs) for both GSM and GPRS.


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Radio resources are allocated for only one or a fewpackets at a time, so GPRS enables many users to share radio resources, and allow efficient

transport of packets connectivity to external packet data networks volume-based charging

High data rates (up to 171 kbps in ideal case)

GPRS carries SMS in data channels rather thansignaling channels as in GSM


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Requires addition of a new class of nodes called GSNs(GPRS Support Nodes) SGSN: Serving GPRS Support Node,

GGSN: Gateway GPRS Support Node

BSC requires a PCU (Packet Control Unit) and variousother elements of the GSM n/w require softwareupgrades

All GSNs are connected via an IP-based backbone.

Protocol data units (PDUs) are encapsulated andtunneled between GSNs


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ADVANTAGES

Faster Data Transfer Rates

Always-On Connection

Robust Connectivity

Broad Application Support

Security Support


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Time Time Time

Freq Freq Freq

PN Code

FDMA TDMA CDMA


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In FDMA, the entire allocated cellular frequencyspectrum is divided into a number of 30-kHzchannels .

The power transmitted by a cell is only large

enough to communicate with mobile stationslocated near the edge of the cells coverage area.

The radius of a cell might be one mile or less-referred to as a small cell.


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FDMA Overview

A A

B B

CC

Frequency

Time

f2

f1

f0


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TDMA is a digital wireless air interface .

It divides each carrier frequency into a number oftime slots, each of which constitutes an

independent telephone circuit.


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TDMA Overview

C B A C B A C B A C B A

C

A

B

Time

f0

Frequency


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CODE DIVISION MULTIPLE ACCESS (CDMA)

INTRODUCTION

CDMA is a "spread spectrum" technology, allowing many

users to occupy the same time and frequency allocations ina given band/space.

The spectral spreading of the transmitted signal gives to

CDMA its multiple access capability.

CDMA is a form of Direct Sequence Spread Spectrum

communications


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A digital multiple access technique specified bythe Telecommunications Industry Association(TIA) as "IS-95."

One of the unique aspect of CDMA is that while

there are certainly limits to the number of phonecalls that can be handled by a carrier, this is nota fixed number .

Code division multiple access (CDMA) is a

digital air interface standard, claiming eight tofifteen times the capacity of analog.


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What is CDMA ?

Sender Receiver

Code A

A

Code B

B

AB

A

BC

BC

A

Code A

A

BC

Time

Frequ

BC

B

A

Base-band Spectrum Radio Spectrum

spread spectrum


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Classification of CDMA Systems

CDMAone

CDMA2000

IS95 IS95B JSTD 008

Narrow Band

Wide Band

CDMA SYSTEMS


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Concept of CDMAo Users share same

bandwidtho User axis shows

cumulative signal strengthof all users

Code 1

Code2

Code 3

Code 4

Freq

User


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General Architecture Of CDMA

ME

SIM

BTS

BTS

BSC

BSC

MSC

VLR

EIR

HLR

AuC

AUm

Abis

PSTN,ISDN

Mobile

station

Base Station

Subsystem

Network

Subsystem

MS BSS NS


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Mobile Station (MS): Two Blockso Mobile Equipment (ME)o Subscribers Identity Module (SIM)

Function of Mobile Station:1. Personal Mobility2. IMEI (International MobileEquipment Identity)

3. IMSI (International MobileSubscriber Identity)


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Base Station Subsystem (BSS)o Base Transceiver Station (BTS)o Base Station Controller (BSC)

BSC


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BSC

BTS : Base Tranceiver station1. It defines the cell .2. It handles the radio linkprotocol with the mobile station

BSC: Base station Controller1. It manages radio resources forone or more BTS.2. Allocation and Deallocation of

channels.3. Transmitter power control.4. Handoff control


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Network Subsystemo MSC: Mobile Switching Center

o HLR: Home Location Registero VLR: Visitor Location registero AuC: Authentication Centero EIR: Equipment Identity Register

BS

C

MSC

VLR

EIR

HLR

AuC

PSTN,ISDN


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Mobile Switching center:(MSC)1 Call set up/supervision/release2 Call routing3 Billing information collection

4 Mobility management5 Paging, Echo cancellationconnection to BSC, other MSC and other local exchangenetworks6 Access to HLR and VLR


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Home Location Register (HLR)1 One HLR per CDMA operator2 Contains permanent M database of all thesubscribers in the network

3 Contains MSRN(mobile station routing no.)4 It is reffered for every incomming call


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Visitor Location Register(VLR)1. Temporary visitors database2. One VLR per MSC

Authentication Center(AuC)

1. Provides security2. Authentication and encryption

Equipment Identity Register:1. Contains IMEI


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Handoff

BSCBSC BSC

MSC MSC

GMSC

Handoff is of3 types

1. Intra BSC

2 Inter BSC3. Inter MSC


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BSC

BSC

MSC

MSC

VLR

VLR

HLRGMS

C

PSTN.

ISDN

LocationUpdate


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Comparison between CDMA andTDMA/FDMA: In TDMA Band width available for transmission

is small which leads to compromise in quality oftransmission. Whereas in CDMA systems entirespectrum is used which enhances voice quality.

In TDMA/FDMA, cell design requires morefrequency planning which is tough job. Whereas

in CDMA frequency planning is minimal. TDMA is Band limited system. CDMA is Power

limited system


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Some Pics Of BSC


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Some Pics Of BTS


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CDMA

ADVANTAGES OF CDMA Increased Cellular Communication Security.

Soft Handoff Because Of Same Carrier Frequency Increased Efficiency, Meaning That The Carrier Can Serve

More Subscriber.

Smaller Phones.

Low Power Requirements And Little Cell-to-Cell Coordination

Needed By Operators.

Extended Reach - Beneficial To Rural Users Situated Far FromCells.


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CDMA

DISADVANTAGES OF CDMA

NEAR FAR PROBLEM.

CDMA IS RELATIVELY NEW, AND THE NETWORK IS NOT AS MATURE ASGSM.

CDMA CAN NOT OFFER INTERNATIONAL ROAMING, A LARGE GSMADVANTAGE.


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CONCLUSION

GSM has been the catalyst in the tremendous shift in

traffic volume from fixed networks to mobile networks.

GPRS cost is less than circuit- switched services since

communication channels are being used on a shared basisand also the packets are need-based rather than dedicated

only to one user.

CDMA, for Code Division Multiple Access, is differentthan those traditional ways in that it does not allocate

frequency or time in user slots but gives the right to use

both to all users simultaneously.


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Thank you!!!

Documents

Gsm, Gprs,Cdma