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GBO_011_E1_1 Network quality evaluation ZTE University GSM-BSS D&T Team.

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Présentation au sujet: "GBO_011_E1_1 Network quality evaluation ZTE University GSM-BSS D&T Team."— Transcription de la présentation:

1 GBO_011_E1_1 Network quality evaluation ZTE University GSM-BSS D&T Team

2 Objectives At the end of this course, you will be able to:  State the concept and content of network evaluation  Grasp test methods of DT and CQT  Grasp evaluation test result analysis

3 Contents Network evaluation overview Network evaluation test Test result and analysis

4 Concepts of network evaluation Simulate subscribers calling process. Choose representative test samples Test on Um interface Test methods :DT and CQT Network evaluation overview

5 Network quality is the chief factor to win the competition. Why network test evaluation? Discover network problems, GSM network evaluation include:  MSC statistic analysis  Radio network evaluation analysis Network evaluation overview

6 Probably problems in radio network Limited frequency resource Unreasonable engineering parameters Unreasonable radio parameters Unreasonable site location Unfavorable coverage in important area and scenery spots Weak indoor coverage in big buildings Voice quality problems such as cacophony, intermittence, etc. Network evaluation overview

7 Significance of network evaluation Get to know the status of our own network and other operator’s network comprehensively Discover network problems Propose optimization suggestions Build high quality and stable network Network evaluation overview

8 Contents Network evaluation overview Network evaluation test Test result and analysis

9 Network evaluation flow Network evaluation test

10 Main contents of test Select test route and venue Test items  Cell coverage range  co-channel and adjacent channel interference  TCH inspection  Inter cell handover  layer 3 signaling trace  customer complaints Confirm test time, personnel and schedule

11 Network evaluation test Test schedule TIMETEST SCHEDULE WEEK1WEEK2 MissionMONTUEWEDTHRFRISATSUNMONTUEWEDTHRFRI Prepare documents Driving Test CQT Test analysis KPI collection KPI analysis Evaluation report Summary

12 Test and evaluation methods DT ( DRIVE TEST ) CQT ( CALL QUALITY TEST ) Network evaluation test

13 key points in DT Prepare documents for DT Prepare DT instruments Select representative test route Choose proper test time (generally busy hour) Reasonable test method Offer abundant test analysis report

14 Digital map (MAPINFO, etc.) Network evaluation test Main documents for DT

15 Network evaluation test Main documents for DT Site and cell data  Site name, frequency, antenna data, neighbor cell, longitude, latitude …

16 Network evaluation test Main documents for DT Traffic data in 24 hours

17 Network evaluation test Main documents for DT GPS, Test handset, DT software, SIM card, vehicle, power, laptop …

18 Network evaluation test DT route selection Highway from airport to downtown Traffic trunks in the city Other sections with lots of customer complaints High traffic area, roads around important areas

19 Network evaluation test DT time selection DT shall be carried out on busy hours according to traffic statistics, such as:  AM 9:00-12:00  PM 16:00-18:00

20 Network evaluation test Test method of DT Vehicle speed:  Downtown area: 30km/h  Common urban: 40km/h  Suburb, railway: 50km/h Test methods:  Automatic calling, each call lasts 60s, interval 10s, MS calls fixed phone Vehicle loss : 6 to 10dB

21 Network evaluation test DT items BCCH coverage test TCH coverage test Handover test on cell borders Interference test Indoor coverage test in special locations Call quality test Complaints test ……

22 DT Index Coverage rate ( SUB )  Rx-Lev (>=-94dbm )/ Total samples×100 % Call completion rate  Call completion rate = Success call / Call attempts×100 % Call drop rate  Call drop rate = Call drop number/ Success number×100 % Voice quality ( SUB )  Quality=0-4 level/ total samples×100 % Network evaluation test

23 DT for data service WAP test FTP test Network evaluation test

24 Test mode Idle mode: Cell selection and reselection, coverage Automatic calling: Downlink level, quality and call completion rate Manual calling:  Frequency locking : Cell coverage and cell status  Compelling handover: Check whether handover can be carried out among cells

25 Network evaluation test DT examples-1 Get network running status and each radio parameters through continuous setting up calls. Commonly recorded parameters include BCCH, TCH, Rx Level, Rx Qual, Tx Power, Time Advance, Time slot, BSIC, Cell ID and adjacent cell BCCH, RxLevel. Diagrams and tables to facilitate the analysis of network.

26 Network evaluation test DT examples-2 Analyze handover according to RxLevel, RxQual and adjacent cell environment, to check Pingpong handover and lonely island Location and analysis of some practical events (such as call drop, handover, etc.),

27 Network evaluation test DT examples-3 Cell coverage range test  Lock frequency of test mobile phone Interference test  Scanning receiver, calculate C/I, C/A. Network borderland test  Handover strip, the change of BISC or LAC.

28 Network evaluation test DT examples-4 Dual-band network reselection and handover  Cell reselection relationship on idle status  Handover relationship on busy status Indoor coverage test  Portable DT device for indoor coverage test.  Ping-pong handover caused by nearby macro-cells

29 Network evaluation test DT analysis result RXLEV distribution chart and table RXQUAL distribution chart and table TA distribution chart and table Interference from adjacent channel distribution chart Main server area chart Handover distribution chart Location update distribution chart ……

30  Hello ! Speak louder ! Too much noise! 0063 goes up again… Network evaluation test Brief description of CQT Call quality test, that is to choose a certain amount of spots, and set up some calls in each spot. Test items include call completion rate, call drop rate, silent call, call quality, etc.

31 Network evaluation test Principles for CQT CQT test spots shall be as comprehensive as possible  Political hotspots: authority office, power building, etc.  Economic hotspots: shopping mall, office building, hotel, restaurant, stock exchange, etc.  Cultural hotspots: exhibition, museum, theatre, scenic spot, entertainment place, etc.  Transportation junction: airport, railway station, port, etc. At least 80% indoor test

32 Network evaluation test CQT KPI Call completion ratio  Call completion ratio=total successful call / total call set up *100% Call drop rate  Call drop rate = total call drop / total successful call * 100% Voice intermittence rate  Voice intermittence rate= total voice intermittency / total successful call * 100% Silent call rate Echo and background noise ratio Cross talk ratio

33 Network evaluation test CQT data test items Attach  Attach length, Attach success rate PDP activation success rate  Activation length, activation success rate WAP test  Homepage display time, WAP success rate Ping test  Average time delay, ping success rate FTP download  Download speed, RLC average throughput

34 Network evaluation test CQT data test table

35 Network evaluation test CQT mode Generally, carry out MOC and MTC 10 times each and every call lasts 1 minute Test spots shall be even-distributed in test area Two testers can call each other at the same place Carry out data service test according to customer’s demand Record each test and fill them into tables

36 Contents Network evaluation overview Network evaluation test Test result and analysis

37 Evaluation result of network test Network KPI DT result CQT result Test instance analysis Network development suggestion

38 Test result and analysis Network KPI Call drop rate Handover success rate TCH assignment success rate Call drop rate of traffic Radio access rate Bad cell proportion

39 Cells’ names Voice channel congestio n rate Voice channel overflow times Total traffic of voice channel Traffic in each channel Total number of configured voice channel Carrier number Cell2, Taxiu Cell1, Hebei village, Tongde Guide,Laxiwa Cell1,Guinan county Cell1,Douhoulo u Test result and analysis Congestion cells Traffic in each channel is larger than 0.5 Erl

40 Coverage analysis signal sample numberProportion -75 to % -85 to % -95 to % -110 to % other00.00% area proportion whose signal strength is higher than % Test result and analysis DT result-Coverage

41 Voice analysis Error rate sample numberProportion % % % % % % % % Proportion of voice quality higher than % Test result and analysis DT result-Voice quality

42 Test result and analysis CQT result Voice test result

43 Test items Test result EricssonZTE Transformer substation, Xuefu Educational building, Bayi Agriculture University Longhu harbor1 Longhu harbor2 Attach test GPRS Attach average time1656ms1619ms2454ms2468ms GPRS Attach success rate(%) 100% PDP activation test PDP activation time609ms630ms790ms876ms PDP activation success rate(%) 100% Ping test Ping package size300 bytes128 bytes 300 bytes Average time delay2070ms835ms1162ms1840ms Success rate100% FTP testAverage download speed3.63 KB/S3.60 KB/S3.57KB/S3.60KB/S Test result and analysis CQT result Data test result

44 Test result and analysis Test instance analysis-1 Signal strength is weak in the red circle where has high bit errors.  BTS antenna is very high  In addition, phoenix trees flourish in these areas too

45 Test result and analysis Test instance analysis-2 Signal strength is weak in the red circle where has high error rate, call drop is induced there.

46 Test result and analysis Test instance analysis-3 Signal strength is very low there and BSIC can’t be decoded.

47 Test result and analysis Test instance analysis-4 Generally, in dense urban, it is reasonable if TA value is lower than 2; overshooting may happen if TA value is too high.

48 Test result and analysis Test instance analysis-5 Handover requiring times: 167 Handover success times: 166 Handover failure times:1 Handover success rate: 99.40% Frequent handover occurs in many places of the figure

49 Test result and analysis Test instance analysis-6 Reason 1 for frequent handover: handover threshold is set improperly.

50 Test result and analysis Test instance analysis-7 Reason 2 for frequent handover: signal strengths of adjacent cells are close to each other in areas where frequent handover occurs

51 Test result and analysis Test instance analysis-8 Effective neighbor cell means cells that can be tested BISC can be decoded. We shall check places whose effective neighbor cell is zero.

52 Co-channel interference analysis Test result and analysis Test instance analysis-9 On RXLEV and RXQUAL figure Good receiving signal level but bad voice quality.

53 Test result and analysis Suggestions for network development Collect and classify each chart, table Propose suggestions of optimizing adjustment after comprehensive analysis  Engineering parameter adjustment  Frequency, neighbor cell adjustment  Radio parameter adjustment  …… Suggestions for network development  Cell capacity expansion  Indoor distributed suggestion  Newly-built site suggestion New round of network evaluation and optimization

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