Download - Gsm vs Cdma Presentation
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Presentation on
GSMand
CDMA
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What is GSM ?
Global System for Mobile (GSM) is a
second generation cellular standarddeveloped to cater voice services and
data delivery using digital modulation
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CellularNetworking technology
that breaks geographicarea into cells shapedlike honey comb
Cell
is the radio coveragearea of one basetransceiver station
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GSM ConceptsCellular Structure
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GSM in World
Figures: March, 2005
37%
1%4%43%
4%
3%
3%
3% (INDIA)
3%
Arab World
Asia Pacific
AfricaEast Central Asia
Europe
Russia
India
North America
South America
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GSM in India
Figures: March 2005
Bharti
27%
BSNL
22%
Spice
4%
IDEA13%
Hutch
19%
BPL
6%
Aircel4%
Reliance
3%MTNL
2%
Bharti
BSNL
Hutch
IDEA
BPL
Aircel
Spice
Reliance
MTNL
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GSM Services
Tele-services
Bearer or Data Services
Supplementary services
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GSM System Architecture
BSC
BSC
MSC
MS
MS
MS BTS
BTS
BTS
GMSC
PSTNISDNPDN
EIRAUC
HLR
VLR
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GSM Actors
PublicSwitchedTelephoneNetwork
BTS
BSS
BSC
Fixed subscriberMobile subscriber
AUC
HLRVLR
MSC
NSS
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GSM System Architecture-I
Mobile Station (MS)Mobile Equipment (ME)
Subscriber Identity Module (SIM)
Base Station Subsystem (BSS)
Base Transceiver Station (BTS)
Base Station Controller (BSC)
Network Switching Subsystem(NSS)
Mobile Switching Center (MSC)
Home Location Register (HLR)
Visitor Location Register (VLR)
Authentication Center (AUC)
Equipment Identity Register (EIR)
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System Architecture
Mobile Station (MS)
The Mobile Station is made up of two entities:
1. Mobile Equipment (ME)
2. Subscriber Identity Module (SIM)
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System Architecture
Mobile Station (MS)
Mobile Equipment
Portable,vehicle mounted, hand held device Uniquely identified by an IMEI (International Mobile
Equipment Identity) used to identify stolen orfraudulently altered phones.
Voice and data transmission
Monitoring power and signal quality of surrounding cellsfor optimum handover
Power level : 0.8W20 W
160 character long SMS.
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System Architecture
Mobile Station (MS) contd.
Subscriber Identity Module (SIM)
Smart card contains the International Mobile SubscriberIdentity (IMSI) used to identify each home user.
Allows user to send and receive calls and receive othersubscribed services
Encoded network identification details
- Key Ki,Kc and A3,A5 and A8 algorithms
Protected by a password or PIN
Can be moved from phone to phonecontains keyinformation to activate the phone
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System Architecture
Base Station Subsystem (BSS)
Base Station Subsystem is composed of two parts that
communicate across the standardized Abis interface allowing
operation between components made by different suppliers
1. Base Transceiver Station (BTS)
2. Base Station Controller (BSC)
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System Architecture
Base Station Subsystem (BSS)
Base Transceiver Station (BTS):
Encodes,encrypts,multiplexes,modulates and feeds the
RF signals to the antenna.
Frequency hopping Communicates with Mobile station and BSC
Consists of Transceivers (TRX) units
Mobile Handoff: B/w two BTSs under the control of the
same BSC, greatly reduces switching burden of MSC.
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System Architecture
Base Station Subsystem (BSS)
Base Station Controller (BSC)
Manages Radio resources for BTS
Assigns Frequency and time slots for all MSs in its area
Handles call set up
Handover for each MS
Radio Power control
It communicates with MSC and BTS
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System Architecture
Network Switching Subsystem(NSS)
Mobile Switching Center (MSC)
Heart of the network
Manages communication between GSM and other networks Call setup function and basic switching
Call routing
Billing information and collection
Mobility management
- Registration
- Location Updating
- Inter BSS and inter MSC call handoff
MSC does gateway function while its customer roams to other networkby using HLR/VLR.
In NSS, there are three different databases called HLR, VLR &
AUC.
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System Architecture
Network Switching Subsystem
Home Location Registers (HLR)
- permanent database about mobile subscribers in a large servicearea(generally one per GSM network operator)
- database contains IMSI,prepaid/postpaid,roamingrestrictions,supplementary services.
Visitor Location Registers (VLR)
- Temporary database which updates whenever new MS enters its area,by HLR database
- Controls those mobiles roaming in its area
- Reduces number of queries to HLR
- Database contains IMSI,TMSI,Location Area,authentication key.
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System Architecture
Network Switching Subsystem
Authentication Center (AUC)
- Protects against intruders in air interface
- Maintains authentication keys and algorithms and provides
security triplets ( RAND,SRES,Kc) >>- Generally associated with HLR and AUC consists of EIR.
Equipment Identity Register (EIR)
- Database that is used to track handsets using the IMEI(International Mobile Equipment Identity)
- Made up of three sub-classes: The White List, The BlackList and the Gray List >>
- Only one EIR per PLMN ( public land mobile network)
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Security Triplets :
RAND : is 128-bit random challenge
generated by the Home Location Register.
SRES : is the 32-bit Signed Responsegenerated by the Mobile Station and the
Mobile Services Switching Center.
Kc : is the 64-bit ciphering key used as aSession Key for encryption of the over-the-
air channel.
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The EIR contains three lists of IMEIs in its
database
white list (handsets allowed to access thenetwork)
grey list (handsets to be observed)
black list (handsets to be barred from
network)
EIR LISTS :
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Radio Link Aspects From Speech to RF Signal
Blah Blah Blah...Blah... Blah... Blah...Digitizing andSource Coding
Channel Coding
Interleaving
Ciphering
Burst Formatting
Modulating Demodulating
Burst De-formatting
Deciphering
De-interleaving
Channel Decoding
Source Decoding
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Characteristics of GSM Standard
Fully digital system using 900,1800 MHz frequency band. TDMA over radio carriers(200 KHz carrier spacing.
8 full rate or 16 half rate TDMA channels per carrier.
These rates are GSM traffic channels & carry digitized
speech or user data.
User/terminal authentication for fraud control.
Full international roaming capability.
Low speed data services (upto 9.6 Kb/s). Compatibility with ISDN (Integrated Services Digital
Network) >>
Support of Short Message Service (SMS).
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Advantages of GSM over Analog system
Capacity increases
Reduced RF transmission power and longer battery life.
International roaming capability due to wide N/w. Better security against fraud (through terminal validation
and user authentication).
Encryption capability for information security and privacy.
Compatibility with ISDN, leading to wider range ofservices & for simultaneous digitaltransmission of voice,
video, data, and other network services over the traditional
circuits of the public switched telephone network.
http://en.wikipedia.org/wiki/Digitalhttp://en.wikipedia.org/wiki/Transmission_(telecommunications)http://en.wikipedia.org/wiki/Public_switched_telephone_networkhttp://en.wikipedia.org/wiki/Public_switched_telephone_networkhttp://en.wikipedia.org/wiki/Transmission_(telecommunications)http://en.wikipedia.org/wiki/Digital -
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GSM Applications
Mobile telephony
GSM-R (railway)
-. A sub-system ofEuropean Rail Traffic ManagementSystem (ERTMS), it is used for communication
between train and railway regulation control centers.
Telemetry System
- Fleet management- Automatic meter reading
- Toll Collection
Value Added Services
http://en.wikipedia.org/wiki/European_Rail_Traffic_Management_Systemhttp://en.wikipedia.org/wiki/European_Rail_Traffic_Management_Systemhttp://en.wikipedia.org/wiki/Trainhttp://en.wikipedia.org/wiki/Trainhttp://en.wikipedia.org/wiki/European_Rail_Traffic_Management_Systemhttp://en.wikipedia.org/wiki/European_Rail_Traffic_Management_System -
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Future Of GSM
2nd Generation GSM -9.6 Kbps (data rate)
2.5 Generation ( Future of GSM)
HSCSD (High Speed ckt Switched data)Data rate : 76.8 Kbps (9.6 x 8 kbps)
GPRS (General Packet Radio service)
Data rate: 14.4 - 115.2 Kbps
EDGE (Enhanced data rate for GSM Evolution)
Data rate: 547.2 Kbps (max)
3 Generation
WCDMA(Wide band CDMA)
Data rate : 0.3482.0 Mbps
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Multiple Access Techniques for WirelessCommunications
Multiple Access:
Enable many mobile users to share simultaneously radio
spectrum.
Provide for the sharing of channel capacity between a number
of transmitters at different locations.
Aim to share a channel between two or more signals in such
way that each signal can be received without interference from
another.
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Types of Multiple Access Techniques
Time Division Multiple Access (TDMA)
Code Division Multiple Access (CDMA)
Frequency Division Multiple Access
(FDMA).
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Each signal is modified by multiplying with a large BW
called a spreading signal.
This spreading occurs by combining the transmitter signal
with a spreading sequence which is known as Pseudo noise(PN) sequence, with higher chip rate compared to data rate
of message.
Hence, its a kind of spread spectrum technique.
Spread spectrum multiple access in which each channel isassigned a unique PN code which is orthogonal to PN codes
used by other users.
Code Division Multiple Access (CDMA)
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Code Division Multiple Access (CDMA)
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Features of CDMA
Many users of a CDMA system share the same
frequency.
Due to high data rates the symbol (chip) duration
is very short and usually much less than the
channel delay spread.
The multipath fading is substantially reduced
because the signal is spread over large spectrum.
Code Division Multiple Access (CDMA)
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Advantages of CDMA
Increased cellular communications security.
Simultaneous conversations.
Low power requirements and little cell-to-cell coordination needed by operators.
Extended reach - beneficial to rural users
situated far from cells. It provides soft Handoff which can
simultaneously monitor a particular user
from 2 or more Base stations.
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Disadvantages of CDMA
Unlike TDMA, it has soft capacity limit .
i.e. System performance ::1/no. of users.
CDMA is relatively new, and the network is
not as mature as GSM.
CDMA cannot offer international roaming,
a large GSM advantage.
Self jamming & near- far problems.
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What interested military for CDMA ?
CDMA, incorporating spread-spectrum, works by
digitizing multiple conversations, attaching a code
known only to the sender and receiver, and thendicing the signals into bits and reassembling them.
The military loved CDMA because coded signals
with trillions of possible combinations resulted in
extremely secure transmissions.
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Advantages of GSM
GSM is already used worldwide with over 450 million
subscribers.
International roaming permits subscribers to use one phone
throughout Western Europe. CDMA will work in Asia, but not
France, Germany, U.K. and other popular Europeandestinations.
GSM is mature, having started in the mid-80s. This maturity
means a more stable network with robust features. CDMA is still
building its network. GSM's maturity means engineers cut their teeth on the
technology, creating an unconscious preference.
The availability of smart cards (SIM) that provide secure data
encryption give GSM m-commerce advantages.
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Conclusion:
Today, the battle between CDMA and GSM is
muddled. Where at one point Europe clearly
favored GSM and North America, CDMA, the
distinct advantage of one over the other hasblurred as major carriers like AT&T Wireless
begin to support GSM, and recent trials even
showed compatibility between the two
technologies.
GSM still holds the upper hand however. There's
the numerical advantage for one thing: 456 million
GSM users versus CDMA's 82 million
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CDMA GSM
Global market
share: 18% 82%
Storage Type: Internal Memory SIM (subscriber identitymodule) Card
Dominance: Dominant standard in the U.S. Dominant standard worldwideexcept the U.S.
Stands for: Code Division Multiple Access Global System for Mobilecommunication
Comparison chart
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Thanks !
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Questions ?