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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!!!