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.

Wireless communication involves the transmission of information over a distance without the help of wires, cables or any other forms of electrical conductors.

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.

Features of Wireless Communication
The evolution of wireless technology has brought many advancements with its effective features.

The transmitted distance can be anywhere between a few meters (for example, a television's remote control) and thousands of kilometers (for example, radio communication).

Wireless communication can be used for cellular telephony, wireless access to the internet, wireless home networking, and so on.

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

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

3. Why “Cellular”?

4. Three Generations
AMPS
NMT
TACS
HCMTS
GSM
GPRS
WCDMA
CDMA2000
TD SCDMA
2G 3G1G

5. 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

6. 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

7. FDMA

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

9. 2G
Start early 90’s
Digital technique
GSM : Global System of Mobilephone
GPRS : General Packet Radio Service
D-AMPS : Digital AMPS

10. 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

11. FD / TDMA

12. Network Structure

13. 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

14. 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)

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

16. GPRS

17. 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

18. 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

19. 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

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

21. 3G

22. 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

23. 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

24. CDMA

25. 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