BLOCK DIAGRAMS OF MS, BTS, MSC ECE 2526 MOBILE COMMUNICATION - - PowerPoint PPT Presentation
BLOCK DIAGRAMS OF MS, BTS, MSC ECE 2526 MOBILE COMMUNICATION Friday, 15 March 2019 GSM SM ESS SSENTIAL COMPONENTS To fixed network OMC (PSTN, ISDN, PDN) GMSC EIR AUC HLR VLR MSC MS Mobile Station BSC BTS Base Transceiver
ECE 2526 – MOBILE COMMUNICATION Friday, 15 March 2019
GSM SM ESS SSENTIAL COMPONENTS
BTS BTS BTS BTS BTS BSC BSC MSC VLR HLR AUC EIR GMSC
To fixed network (PSTN, ISDN, PDN)
OMC
MS Mobile Station BTS Base Transceiver Station BSC Base Station Controller MSC Mobile Switching Center GMSC Gateway MSC OMC Operation and Maintenance Center EIR Equipment Identity Register AUC Authentication Center HLR Home Location Register VLR Visitor Location Register
MS
GSM SM SIG SIGNALS: SO SOURCE C CODING & CHANNEL CODING
Speech decoding Channel decoding De-interleaving Burst Formatting De-ciphering
Demodulation
Modulation Ciphering Burst Formatting Interleaving Channel Coding Speech coding
Radio Interface
Speech Speech
13 Kbps 22.8 Kbps 22.8 Kbps 33.6 Kbps 33.6 Kbps 270.83 Kbps
GSM SPEECH CODİNG
RPE-LTP Regular Pulse Excited - Long Term Prediction used to reduce the digital speech rate to 13kbps A-law PCM conversion PCM encoder using linear quantization (with companding) at 13 bits/sample.
WHAT IS IS TR TRANSMITTED FOR VOIC ICE IN IN GSM SM?
5
Best coefficients are selected get the best approximation of the 20mS sample Low order coefficients are coded as 6-bit while Higher order are coded as 3-bit 20ms of 104 Kbps stream = 2080 kbits
Output filter Input Filter 925-960 MHz Transmitter 880 – 915 MHz Receiver Slow freq. Hopping TRX Digital Signal Processing Transmission System
Operation and Maintenance Functionality/clock distribution Abis Interface (to BSC) Um Interface (to MS)
Um-Interface Protocol GSM uses Regular Pulse Excited-Long Term Prediction (RPE-LTP) coder for voice data between the mobile device and the BSS E1
1. The functions of a Base Station Controller are:
a) It acts as a concentrator where many different low capacity connections to BTSs (with relatively low traffic) become reduced to a smaller number of connections to the MSC. b) It switches traffic from the MSC to the BTSs c) It allocates radio channels, d) It receives measurements from the mobile phones, e) It controls handoffs/handovers from BTS to BTS (except in the case of an inter-BSC handover in which case control is in part the responsibility of the anchor MSC).
2. Therefore networks are structured to have BSCs distributed into regions near their BTSs (originally called area switching centres) which are then connected to large centralised MSC sites.
BSC To MSC (Typically E1) BTS
switch BTS-1 BTS-2 BTS-K
DB
From/to MSC Database BSC database contains