1.Wireless Communication System_Wireless communication is a broad term that incorporates all procedures and forms of connecting and communicating between two or more devices using a wireless signal through wireless communication technologies and devices.

The Wireless Communication
System
T.JEYA.,ASSISTANT PROFESSOR.,
DEPARTMENT OF COMPUTER SCIENCE,
SAC WOMEN’S COLLEGE,CUMBUM.

Wireless Communication
 Cellular phone system
 Cordless telephone system
 Bluetooth
 Infrared communication
 Microwave communication
 IEEE Wireless LANs (Wi-Fi)
 Satellite communication

Three Generations
AMPS
NMT
TACS
HCMTS
GSM
GPRS
WCDMA
CDMA2000
TD SCDMA
2G 3G
1G

1G
 Start early 80’s
 Analogue technique
 AMPT (Advanced Mobile Phone System): North America
 NMT (Nordic Mobile Telephony): North Europe
 TACS (Total Access Communication Service): Europe, China
 HCMTS (High Capacity Mobile Telephone System): Japan

FDMA
 Frequency Division Multiple Access
 Different carrier frequencies are assigned to
different traffic channels(speech)
 One carrier frequency can only carry one
single speech channel at one time

Shortage
 Voice information only
 Unsafe （eavesdropping）
 Waste of frequency resource

2G
 Start early 90’s
 Digital technique
 GSM : Global System of Mobilephone
 GPRS : General Packet Radio Service
 D-AMPS : Digital AMPS

GSM
 TD/FDMA: A mix of FDMA and TDMA
 The whole useable spectrum was divided to
many 200k Hz carrier frequencies —FD
 Each carrier was divided into 8 timeslots (burst)
—TD
 Each burst is assigned to a user(a logical traffic
channel)
 One carrier frequency can carry up to 8 logical
traffic channels (voice or data) at the same time
 The maximum data communication rate is 14.4
kbps

BTS,BSC and MSC
 BTS & BSC: Base Transceiver System and
Base Station Controller. Radio signal
transceiver, a connection between
handset and MSC
 MSC: Mobile services Switching Center,
switching center of the GSM network,
and connect to other networks

Databases
 HLR : Home Location Register, contains static
information of subscribers and location update
data
 VLR : Visitor Location Register, embedded in MSC
to avoid delay, contains current location
information of handsets
 AUC : Authentication Center, stores secret keys
for authentication and encryption of the
radio channel
 EIR : Equipment Identity Register, contains a list
of all valid mobile equipment in the network,
by its International Mobile Equipment Identity
(IMEI)

GPRS
 Upgrade of existed GSM network
 Improves the data communication ability

Network nodes
 GGSN: Gateway GSM Support Node,
 Protocol transferring, data encapsulation, a
connection to external networks
 SGSN: Service GSM Support Node,
 Communicate with HLR and mobile
handsets, authorization and admission
control, charging, mobility management

Data communications
 In GSM, one user occupies one traffic channel to
exchange voice/data information
 In GPRS, up to 8 traffic channels(a whole carrier)
can be dynamically combined together for one
data communication application
 The theoretically maximum data transmission rate:
14.4k bps * 8 = 115.2k bps

Advantages of GPRS
 Higher data rate
 Seamless connection to internet
 Packet switching rather than circuit switch,
bandwidth is only used when the data is
actually used, even though it is always
connected
 A primary step to 3G

shortage
 Not fast enough for the multimedia service
 The data rate falls when the network is busy
 Upgrade of handset

3G-Standards
 Three CDMA standards approved by ITU:
 Direct Spread CDMA(WCDMA) : Europe,
Japan
 Multi-Carrier CDMA(CDMA 2000) : North
America
 TD-Synchronous CDMA(CDMA TDD) :
Europe, China

3G-CDMA
 Code Division Multi Address
 Spread spectrum technology
 Each single traffic channel occupies the
whole spectrum, but distinguished by a
unique digital code
 Walsh code: an orthogonal 64 bit pattern,
unique in the network

Features
 Better voice quality
 Up to 2 Mbps data communication rate
 Increase battery life
 Soft hand-off
 Excellent data safety
 More effective spectrum usage than 2G

1.Wireless Communication System_Wireless communication is a broad term that incorporates all procedures and forms of connecting and communicating between two or more devices using a wireless signal through wireless communication technologies and devices.

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