gsm global system for mobile communication b89902008 徐士璿 b89902014 陳致穎 b89902015...
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GSM Global System for Mobile communication
B89902008 徐士璿B89902014 陳致穎B89902015 江致和
Shih-hsuan Hsu. NTU CSIE, 2003 Spring
History
GSM Global System for Mobile communication
1982 by ETSIanalog => digital
solve the compatibility problem
released to market in 1991
TDMA、 FDMA
Shih-hsuan Hsu. NTU CSIE, 2003 Spring
Components
Mobile Station- SIM、Mobile phone
Base Station System- receiver
Mobile-service Switching Center- the heart of the network
Shih-hsuan Hsu. NTU CSIE, 2003 Spring
Features
International Roaming Increase in capacity
- frequency hopping
Security- frequency hopping、 TDMA
- SIM (Subscriber Identity Module)
Digital Service Communication- mobile data
Shih-hsuan Hsu. NTU CSIE, 2003 Spring
Telecom & Datacom
Circuit switch
Packet switch
MSCMS1 MS2
Internet
PC
PC
1 2 3
1 2 3
123 123
Shih-hsuan Hsu. NTU CSIE, 2003 Spring
Basic concept
GSM 900/1800- bandwidth: 890~960MHz/1710~1880MHz
- 0.2MHz per frequency carrier
- what’s different?
。 distance
。 power
。 number of BS
Shih-hsuan Hsu. NTU CSIE, 2003 Spring
Basic concept
EM spectrum- GSM:
900/1800 MHz
- Bluetooth:
2.4 GHz
UV
Visible
IR
Fibre communication
SatelliteRadar
UHFMobile communication
AMRadioFM
telephony
Wave length Frequency
0.47m
0.76m
1cm
10cm
1m
10m
100m 1km
10km
100km
1015Hz
100GHz
1014Hz
10GHz
1GHz
100MHz
10MHz
1MHz
100KHz
10KHz
1KHz
GSM. Bluetooth
Shih-hsuan Hsu. NTU CSIE, 2003 Spring
FDMA
Frequency Division Multiple Access
0.2MHz ......
124 carriers
0.2MHz 0.2MHz
890MHz 915MHz
0.2MHz ......
124 carriers
0.2MHz 0.2MHz
935MHz 960MHz
Uplink
Downlink
Guard band
Frequency carrier
Shih-hsuan Hsu. NTU CSIE, 2003 Spring
TDMA
Only 124 people can access concurrently?!
Time Division Multiple Access- 8 time slots per frequency carrier
f
time
‧‧‧‧‧1 2 3 4 1 2 3 4
Shih-hsuan Hsu. NTU CSIE, 2003 Spring
Cellular Telecommunications
124 * 8 = 992 connections are NOT enough! Cell structure
36~ 53
1 ~ 17
18~ 35
36~ 53
1 ~ 17
18~ 35
Shih-hsuan Hsu. NTU CSIE, 2003 Spring
Communication system
BS3BS1
BS2MSC
MSC
LSC
LSC
CSIE
CCBS3
BS1BS2
Mobil telecom network Public telecom network
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