GSM equipment
1
Reference
• Ericsson GSM RBS 2000 Basics (student
Text EN/LZT 123 3805 R2A)
• 遠傳電訊教育中心 GSM Basic Training
Material, http://www.fetec.org.tw
2
GSM System Structure
AUC
PSTN
PSTN
GMSC
ILR
SS
HLR
EIR
DTI
MSC/
VLR
MS
BSS
RBS
OMC
BSC
3
Radio Base Station
4
Radio Base Station
To BSC
Antenna
TRU
DXU
CDU
TRU
Main
supply
ECU
•
•
•
•
•
PSU
DXU: Distribution Switch Unit
TRU:Transceiver Unit
CDU:Combining and Distribution Unit
ECU: Energy Control Unit
PSU: Power Supply Units
Battery
supply
5
TRU:Transceiver Unit
• One TRU handle 8 air time slots
• Perform Channel Coding,
Interleaving, Ciphering, Equalization
• One transmit output, two receive
inlets
6
Transmission between RBS & BSC
• Enhancement of transmission network
RBS
RBS
BSC
BSC
7
Transmission between RBS & BSC
• Building access network is expensive
• Chain and Tree structures Vs. Ring and Mesh
RBS
RBS
Ring
Protection
BSC
BSC
8
Antenna
9
Omni-directional Antenna
GSM 1800
GSM 900
Lightning
conductor
10
Directional Antenna
Lightning
conductor
GSM 1800
GSM 900
11
Directional Antenna
12
Antenna Diversity
• Two independent
antennas receive the
same signal
• Space Diversity: Two
antennas are separated
in a certain physical
distance
• Polarization Diversity:
Two different
polarization arrays in
an antenna unit
Vertical
array
Horizational
array
13
Indoor Leakage
Coaxial Cable
Leakage coaxial cable
14
Indoor antenna
Directional patch antenna
Omni-directional antenna
15