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 Station BSC Base Station Controller BTS MSC Mobile Switching Center GMSC Gateway MSC BTS BTS OMC Operation and Maintenance Center EIR Equipment Identity Register BSC BTS AUC Authentication Center HLR Home Location Register BTS VLR Visitor Location Register MS

GSM SM SIG SIGNALS: SO SOURCE C CODING & CHANNEL CODING Speech Speech Speech decoding Speech coding 13 Kbps Channel Coding Channel decoding 22.8 Kbps Interleaving De-interleaving 22.8 Kbps Burst Formatting Burst Formatting 33.6 Kbps Ciphering De-ciphering 33.6 Kbps Radio Interface Demodulation Modulation 270.83 Kbps

GSM SPEECH CODİNG RPE-LTP A-law PCM conversion Regular Pulse Excited - Long Term Prediction PCM encoder using linear quantization used to reduce the digital speech rate to (with companding) at 13 bits/sample. 13kbps

WHAT IS IS TR TRANSMITTED FOR VOIC ICE IN IN GSM SM? 20ms of 104 Kbps stream = 2080 kbits Best coefficients are selected get the best approximation of the 20mS sample Low order coefficients are coded as 6-bit while Higher order are 5 coded as 3-bit

BLOCK DIAGRAM OF BASE TRANSCEIVER STATION (BTS) Um-Interface Protocol GSM uses R egular P ulse E xcited- L ong T erm P rediction (RPE-LTP) coder for voice data between the mobile device and the BSS Abis Interface (to BSC) Output filter 925-960 MHz Transmission U m Interface E1 Slow freq. Transmitter Hopping TRX System (to MS) Digital Signal 880 – 915 MHz Processing Input Receiver Filter Operation and Maintenance Functionality/clock distribution

BASE STATION CONTROLLER 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. To MSC b) It switches traffic from the MSC to the BTSs (Typically E1) c) It allocates radio channels, d) It receives measurements from the mobile phones, BSC 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). BTS 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.

Database BSC database contains 1. -state information for all BSS BTS-1 - BTS software DB BTS-2 X From/to MSC switch BTS-K