NETWORK SOLUTIONS SERVICES SOLUTIONS PACKAGES 2G ACCESSIBILITY RETAINABILITY 2G MOBILITY Gprs/edge 2G MOBILITY Basic Sanity Check [L1] PARAMETER RECOMMENDATIONS [L2] NEW FEATURES [L3] MOBILITY Mobility is defined as the ability of a user to move between neighboring GSM Cells and retain its requested service once connected Definition: The Change of dedicated Radio Channel (SDCCH or TCH) when an active RR Connection exists between MS & BTS major component of mobility IS Handover Success Rate HANDOVER IS A PROCESS IN WHICH, THE SERVICE TO THE SUBSCRIBER IS TRANSFERRED FROM THE SERVING CELL TO ANOTHER CELL, DURING THE ACTIVE MODE OF MS AND THE CALL WILL CONTINUE, TILL THE MS DISCONNECTS THE CALL Ericsson Internal | 2012-06-22 | Page 5 MOBILITY CALCULATION COUNTER a. Mobility counters: › › › › › › SUMOHOSUCC SUMEOHOSUCC SUMOHOATT SUMEOHOATT SUMOHOLOST SUMEOHOLOST B. Mobility formula Handover Success Rate: › PERCENTAGE SUCCESSFUL HANDOVERS. SUMMED UP FOR ALL EXTERNAL AND INTERNAL CELL RELATIONS H_SUC=100*[(SUMOHOSUCC + SUMEOHOSUCC) / (SUMOHOATT + SUMEOHOATT)] Handover LOST rate: › PERCENTAGE MS LOST AT HANDOVERS. SUMMED UP FOR ALL EXTERNAL AND INTERNAL CELL RELATIONS H_LOST=100*[(SUMOHOLOST+SUMEOHOLOST) /( SUMOHOATT+SUMEOHOATT)] Ericsson Internal | 2012-06-22 | Page 6 Mobility failureS POSSIBLE REASONS Possible Causes for Handover Failures › › › › › › › › Missing Neighbors. Co-BCCH/BSIC. TCH Congestion at Target. Swapped Sectors. BCCH / TCH interference. Weak Cell Boundary. Too Many Neighbors. Incorrect Handover Parameters. Recommendations for improvement: › Use of planning tool and drive tests to identify and add missing neighbors. › Audit of the co BCCH/BSIC allocation › Antenna implementation check. › Bringing down the average neighbor count per cell. › Optimization of handover parameters Ericsson Internal | 2012-06-22 | Page 7 MOBILITY FLOW CHART Cell Mobility issueS Dragged Ping Pong Missing SWAPPED Handover effect Neighbor SECTOR Check Check for AUDIT AND parameters Check cable Rf coverage OVERLAP ADD NEIGHBOR feeder issues connections Check traffic volume handover H/W PROBLEM Parameter Check missing neighbors optimization HANDOVER Power control optimization Ericsson Internal | 2012-06-22 | Page 8 PARAMETERS Layer1 troubleshooting process – BASIC Sanity check [L1] Sanity is the level one check where parameter values are audited to make sure they are set to the recommended values. If any discrepancies are observed then those must be corrected MO ACCESS Parameter SSDESUL CRO LCOMPUL ACCMIN QCOMPUL CCHPWR SSLENUL Power Control(MS) INILEN HOP QLENUL HSN QDESUL PSSBQ INIDES PSSTA REGINTUL QLIMDL SSDESDL QLIMUL QDESDL QOFFSETDL LCOMPDL QOFFSETDLAFR QOFFSETUL POWER CONTROL (Bs) Parameter ACC CRH HANDOVER MO Power Control (BS) QCOMPDL REGINTDL QOFFSETULAFR SSLENDL SDCCHREG QLENDL Note: detailed explanation mentioned in attached excel. Ericsson Internal | 2012-06-22 | Page 9 Layer 2 troubleshooting process – parameter RECOMMENDATIONS [L2] CONTD… FOLLOWING SET OF Parameters can be CONSIDERED FOR IMPROVING THE Mobility performance Ericsson Internal | 2012-06-22 | Page 10 Parameter Default BQOFFSET 3 BSRXSUFF - KHYST 3 KOFFSET 0 LHYST 3 LOFFSET 0 LOHYST 3 MSRXSUFF - OFFSET 0 PSSBQ 10 PSSTA 63 QLIMDL 55 QLIMUL 55 TRHYST 2 TROFFSET 0 MOBILITY improvement – NEW FEATURES [L3] FOLLOWING SET OF FEATURES can be CONSIDERED FOR IMPROVING THE MOBILITY PERFORMANCE LICENSE FEATURE NAME FAJ 122 625 Enhanced Handover Success Rate FAJ 122 181 Handover of Traffic at Channel Blocking FAJ 122 429 Handover Power boost Ericsson Internal | 2012-06-22 | Page 11 MOBILITY IMPROVEMENT - CASE STUDY 1 - Dragged handover A Quality handover should happen earlier Ericsson Internal | 2012-06-22 | Page 12 MOBILITY IMPROVEMENT - CASE STUDY 2 - MISSING NEIGHBORS Ericsson Internal | 2012-06-22 | Page 13 MOBILITY IMPROVEMENT CASE STUDY 3 - BCCH COLLISION Ericsson Internal | 2012-06-22 | Page 14