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54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
54600526 drive-test-logs-analysis
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54600526 drive-test-logs-analysis

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  • 1. August 11, 2000 Jim Luan, Lin Mubao
  • 2. Drive Test Procedure Preparation Drive Test FICS Netplan VOT/GEP Statistics Analysis Problem Finding 12/31/13 2
  • 3. Preparation (1) • Definition File – Without it, it is impossible to observe overshooing neighbors – GenDef7.exe can convert FP to definition file Neighbor list with definition file 12/31/13 Neighbor list without definition file 3
  • 4. Preparation (2) • • • • • • Frequency Plan & Configuration map Software:TEMS, FICS, GEP, VOT Hardware: TEMS, GPS, Portable PC Test Problem Sheet Route Map 12/31/13 4
  • 5. Drive Test • For Benchmark – 2 minutes per call – 10 – 15 minutes a log files – Force to appropriate band (GSM only, DCS only or Dual) • For Special Problem – Planning route – No limitation 12/31/13 5
  • 6. TEMS Introduction • Interface • Functions 12/31/13 6
  • 7. Log File Process TEMS Log File FICS .FMT Excel VB .NP/.TXT NetPlan Route Map 12/31/13 .CSV .STA Much shorter cycle time by VOT and GEP. VOT/GEP 7
  • 8. TEMS .log file Analysis Below lists common problems which can be observed from Drive Test Log. • • • • • • • • • Undecoded BCCH BSIC Undecode in Other Site No Handover Delay Handover Ping Pong Handover Negative Handover Overshooting High Overlapping No Dominant Server 12/31/13 • • • • • • • • • Poor Coverage Unreasonable Serving Area Interference Handover Failure Handover Loss UL Drop Drop Call Sudden Power Drop MS Power Rapid Increase 8
  • 9. Undecoded BCCH (1) Description: – BSICs can’t be decoded in 5s – Usually consider 3 strongest neighbors Reason: – GCLK shift, only decode same site BSICs – Channel interference – Non-BCCH carrier, no dedicated spectrum for BCCH 12/31/13 9
  • 10. Undecoded BCCH (2) 12/31/13 10
  • 11. BSIC Undecode in Other Site Description: – BSIC in same site can be decoded but not for other sites – Handover can only happen in intra-site basis – It is similar to former Undecoded BCCH case Reason: – GCLK shift • GCLK recalibration is required • No one monitors OMC-R alarms 12/31/13 11
  • 12. No Handover (1) Description: – Neighbor BSIC is decoded and COMMON handover requirement is fulfilled but there is never a handover Reason: – Missing neighbor • No such neighbor in CM database – Incorrect external neighbor • Target cell’s LAC/BCCH/BSIC in add_neighbor is different from those in equip_rtf • Engineer modifies external neighbor at MMI, not through GUI • Never use OMC-R Proxy Cell to propagate external neighbor information – – – – N < hreqt. Great HO_MARGIN. Improper algorithm 1-7 setting Missing_rpt =1 Serving cell overshoots/covers too far away Refer to GSM BSS Statistics Analysis Handbook 12/31/13 12
  • 13. No Handover (2) 12/31/13 13
  • 14. Delay Handover (1) Description: – Neighbor BSIC is decoded but handover occurs in much later time Reason: – All possible neighbors suffer blocking – Large hreqt * hreqave – qual_power_flag is enabled, full BTS/MS power must be reached before handover – Large handover_recognized_period and bssmap_t7 setting – Refer to GSM BSS Statistics Analysis Handbook 12/31/13 14
  • 15. Delay Handover (2) 12/31/13 15
  • 16. Ping Pong Handover (1) Description: – Lot of handovers between cells – “Time between Handover” is around hreqt*hreqave of such HO cause Reason: – – – – – Improper hardware calibration Hardware fault UL/DL interference Negative handover Different coverage footprint for antennas of a cell 12/31/13 16
  • 17. Ping Pong Handover (2) 12/31/13 17
  • 18. Negative Handover (1) Description: – Serving cell hands over to a weaker neighbor Reason: – ho_only_max_power is enabled – qual_margin_flag is disabled – ho_margin_usage_flag is enabled with negative ho_margin_rxqual/rxlev – Negative HO_MARGIN – Micro-cellular algorithms are enabled, especially type 5 12/31/13 18
  • 19. Negative Handover (2) -59dBm before HO 12/31/13 -66dBm after HO 19
  • 20. OverShooting (1) Description: – Cell shoots at far distance but that location has closer cells around Reason: – – – – Overshooting cell has small downtilt, 0 degree! Overshooting cell has too high altitude Closer cells have overshooting as well BSIC of closer cells can’t be decoded 12/31/13 20
  • 21. OverShooting (2) 12/31/13 21
  • 22. High Overlapping (1) Description: – Cells have major rxlevel difference within ±5dB Reason: – Overshooting – Too many cells in that area – Poor antenna downtilt 12/31/13 22
  • 23. High Overlapping (2) -65dBm -65dBm Over Lapping Area -65dBm 12/31/13 -65dBm 23
  • 24. No Dominant Server (1) Description: – Rxlevel of best neighbors are close to that of serving cell Reason: – Poor antenna downtilt – Lack of near-by site 12/31/13 24
  • 25. No Dominant Server (2) 12/31/13 25
  • 26. Poor Coverage (1) Description: – – – – Low rxlevel with rxquality In rural area, rxlevel is less than 15 (-95dBm) In city center, rxlevel is less than 35 (-75dBm) Different location has different threshold, noise level is the key point Reason: – – – – Lack of cell site BSIC of dominant server can’t be decoded Dominant server has blocking or cell-bar Handover problem. E.g. missing & incorrect neighbor, negative handover, no & delay handover 12/31/13 26
  • 27. Poor Coverage (2) 12/31/13 27
  • 28. Unreasonable Serving Area (1) Description: – Coverage area of the cell is incoherent to the antenna direction Reason: – Wrong cable connection to antennas – Incorrect record of antenna orientation – Incorrect ANTENNA_SELECT 12/31/13 28
  • 29. Unreasonable Serving Area (2) Cell ID:101 BCCH: 35 Cell ID:102 BCCH: 40 12/31/13 Cell ID:103 BCCH: 45 29
  • 30. Interference (1) Description: – High rxlevel with rxquality Reason: – – – – Channel interference Not using dominant server No handover Turn the corner with delay handover 12/31/13 30
  • 31. Interference (2) 12/31/13 31
  • 32. Handover Failure (1) Description: – MS fails to reach target cell, so return to source cell – MS sends HO FAILURE and UL-SABM to source cell and there is response Reason: – – – – Channel interference Poor coverage External interference at UL, like wideband repeator Refer to GSM BSS Statistics Analysis Handbook 12/31/13 32
  • 33. Handover Failure (2) 12/31/13 33
  • 34. Handover Loss (1) Description: – MS fails to reach target cell, but can’t return to source cell – MS sends HO FAILURE and UL-SABM to source cell but no response Reason: – – – – Channel interference Poor coverage External interference at UL, like wideband repeator Refer to GSM BSS Statistics Analysis Handbook 12/31/13 34
  • 35. Handover Loss (2) 12/31/13 35
  • 36. UL Drop (1) Description: – BSS doesn’t receive UL SACCH for link_fail times – BSS stops transmitting DL power Reason: – – – – External interference Channel interference Faulty ancillary. UL path loss >>> DL path loss Refer to GSM BSS Statistics Analysis Handbook 12/31/13 36
  • 37. UL Drop (2) 12/31/13 37
  • 38. Drop Call (1) Description: – DL case: Radio_link_timeout counter decreases to 0 – UL case: link_fail counter decreases to 0 – Layer 2: BSS/MS send SABM/DISC in every T200 for N200+1 times, and no response from recipient Reason: – All cases in this presentation – Refer to GSM BSS Statistics Analysis Handbook 12/31/13 38
  • 39. Drop Call (2) 12/31/13 39
  • 40. Sudden Power Drop (1) Description: – Dedicated ARFCN has significant non-power control rxlevel difference from rxlevel of BCCH Reason: – – – – No/improper TX power calibration Faulty ancillary. E.g. combiner, filter.. Different cable lengths from BTS to antennas Due to air combing, so antennas have different coverage footprints 12/31/13 40
  • 41. Sudden Power Drop (2) 12/31/13 41
  • 42. MS Power Rapid Increase (1) Description: – MS rapidly increases its TX power due to • Optimised Power Control or • UL SACCH multiframes aren’t received for link_fail link_about_to_fail times Reason: – Sudden UL interference, e.g. wideband repeator, channel interference – Too much rapid power down – l_rxlev_ul_p is too small 12/31/13 42
  • 43. MS Power Rapid Increase (2) UL power rapid increase from 19 to 5 suddenly 12/31/13 43
  • 44. How GEP Help? Help to identify below problem in VISUAL basis • Co-channel interference • Adjacent-Channel interference • Mutual neighbor • Missing neighbor • Unreasonable neighbor • Incorrect external neighbor 12/31/13 44
  • 45. How VOT Help? Help to identify below problem in VISUAL basis • Ping pong HO • Overshooting • No dominant server • Poor coverage • Unreasonable serving area • Interference • HO failure • HO loss • Drop call 12/31/13 45
  • 46. How CM Extractor Help? Extract most BSS parameter for reference • Cell – e.g. hreqave,hreqt,N,P… • BTS – e.g. antenna_select… • RTF – check any incorrect external neighbor • Neighbor – e.g. ho_margin, delay_timer… 12/31/13 46
  • 47. How NPM Help? • Provide cell statistics for VOT display • Provide BSS and system level 23 key statistics • Provide detail troubleshooting statistics 12/31/13 47

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