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This Interface located between MS and BTS (also called the Radio interface) has these features: • Totally normalized. • Full inter-operability between Mobile Stations and infrastructure from different manufacturers. Organized in 3 levels: • Level 1 physical support: - Time Division Multiple Access (TDMA) frame and FDMA. - Logical channel multiplexing. • Level 2 LAPDm Protocol (modified from LAPD): - No flag. - No error retransmission mechanism due to real time constraints (window = 1). • Level 3 Radio interface layer (RIL3) Protocol involves three sub-layers: - Radio Resource Management (RR): paging, power control, ciphering execution, handover. - Mobility Management (MM): security, location, IMSI attach/detach. - Connection Management (CM): Call Control (CC), Supplementary Services (SS) Short Message Services (SMS), Dual Tone Multi Frequency (DTMF) facilities.
Each SI Type contains different elements among those described below: • information identifying the current network, the location area and the cell, • information for cell measurements for handover and cell selection procedures, • information about the current control channels structure, • information for the random access channel use, • information about different options of the cell, • information about the neighboring cells BCCH allocation. • Information about the UTRAN neighboring cells. • Information about the ongoing voice group Call in the cell
SYS INFO Type 1 to 4 & 7 to 8 messages are regularly broadcast by the network on the BCCHs. Each message uses the 4 TSs allocated for BCCH on a 51-multiframe. Each multiframe num gives a cyclic value (called TC: Transmission Cycle) between 0 and 7 in order to rule the sending of each SYS INFO message. TC value is obtained as a division remain of multiframe num by 8 (=[multiframe num] mod 8). Some SYS INFO messages are only sent if necessary and on their own multiframe defined by the TC value: • System Information Type 1 need only to be sent on TC=0 if frequency hopping is in use, • System Information Type 2 is always sent on TC=1, • System Information Type 2bis sending on TC=5 is indicated in SYS INFO Type 2 message, • System Information Type 2ter is sent on TC=4 if System Information Type 2bis also needs to be sent and on TC=5 else. Its sending is indicated in SYS INFO Type 3 message, • System Information Type 2quater is sent if needed and follow the same rules as System Information Type 2ter on BCCH Norm. If sent on BCCH Ext it is sent at each occurrence of TC=5 • System Information Type 3 is always sent on TC=2 and 6, • System Information Type 4 is sent on TC=3 and 7, • System Information Type 7 is sent on TC=7 if SYSINFO Type 4 doesn’t contain all info needed for cell reselection. • System Information Type 8 is sent on TC=3 if SYSINFO Type 4 doesn’t contain all info needed for cell reselection. • System Information Type 13 is sent on TC=4 of BCCH or on TC=0 of extBCCH. This is the minimum scheduling specified in the GSM Rec05.02.A supplementary scheduling is optionally transmitted on SYSINFO 9.
REDUCED TDMA FRAME STRUCTURE. T1 = SUPERFRAME NUMBER T2 = 26 FRAME MULTIFRAME NUMBER T3` = IS THE REDUCED 51 FRAME MULTIFRAME 3 . ACTUAL 51 FRAME VALUE IS = T3`*10+1
Paging type 1: can page 2 subscribers using imsi/tmsi Paging type 2: can page 3 subscribers – 2 by timsi and 1 by imsi Paging type 3: can page 4 subscribers by timsi
Asif HaiderHabib Awan
OPTIMIZATIONOptimization is intended to provide the best network quality using available resources as efficiently as possible
INTRODUCTION TO TEMS• Drive testing is the most common and maybe the best way to analyze Network performance.• Drive testing is basically recording measurement data which can also be analyzed afterwards.• It gives idea about what’s happening with a subscriber point of view.
CONTENTS The information provided by TEMS is displayed in status windows. This information includes• cell identity, base station identity code, BCCH carrier ARFCN, mobile country code, mobile network code and the location area code of the serving cell.• There is also information about RxLev, BSIC and ARFCN for up to six neighboring cells;
CONTENTS• channel number(s), timeslot number, channel type hopping channel indication, mobile allocation index offset and hopping sequence• RxLev, RxQual, FER, DTX down link, TEMS Speech Quality Index (SQI), timing advance (TA), TX Power, radio link timeout counter and C/A• parameters for the radio environment.• The signal strength, RxQual, C/A, TA, TX Power, TEMS SQI and FER of the serving cell and signal strength for two of the neighboring cells can also be displayed graphically in a window.
ANALYSIS OF LOG FILESAnalysis is the most important part. Lets look at some of the cases.• Dropped call - Nbr not defined• Dropped call – RL Timer expires• HO Failure
Lack of Dominant ServerSignals of more than one cell can bereaching a spot with low level causing pingpong handovers. This might happenbecause the MS is located on the cellborders and there is no any best server tokeep the call.
Drop Call due to Bad Coverage• Call is dropped because of poor coverage.• The signal level goes down below the minimum signal level that system could carry on
Bad Quality due to Signal Strength• FER is Bad• FER is good implies no obviuos interference in the area.