8/3/2019 A Case for Tch Drop Analysis

1/4

SH NPI BIWEEKLY REPORT 1 (4)

Prepared (also subject responsible if other) No.

201108

Approved Checked Date Rev Reference

2011-08-11 A

1.1.1 D68E01A Hight drop rate deal

Description of the phenomenon: Observed from the statistics,cell D68E01A with high TCHdrop times recently,TCH drop times is more then fifty times at busy hour,drop rate isnear 10%, Cell d68e01a become worst cell more then eight times for one day, This hasseriously affected the performance of the BSC.

Analysis:From STS analysis ,almost all the TCH drop calls due to sudden lost.Weinitiallysuspectedhardware devicesfailures, butfound nowarningon theOSS system, and replacedmost of the hardwarebase stationequipment, dropped callsproblem remainsunresolved.

AndresidentialD68E01Acover the same areaofhighresidentialD68354Aalsoremain highrate ofdropped calls and the mainreason fordropped calls is also suddenly droped.droppedcallsduring the daysessionfocused onworking hours, dropped calls, and wedeterminetheinitialdevice-independent, D68E01A statisticalindicators are as follows:

TIME CELL

TCHdroptime

s

TCHTraffic

TCHdroprate

Sudden lostdroptimes

Sudden lostdrop /Totaldrop times

2011/8/2 09:00:00D68E01A

7 8.66 1.11% 7 100.00%

2011/8/2 10:00:00D68E01A

14 11.79 1.78% 14 100.00%

2011/8/2 11:00:00D68E01A

24 15.01 2.47% 24 100.00%

2011/8/2 12:00:00D68E01A

2 8.29 0.41% 2 100.00%

2011/8/2 13:00:00D68E01A

22 7.28 4.42% 22 100.00%

2011/8/2 14:00:00D68E01A

80 7.97 12.36% 79 98.75%

2011/8/2 15:00:00D68E01A

102 9.28 14.96% 101 99.02%

2011/8/2 16:00:00D68E0

1A81 10.38 11.46% 76 93.83%

2011/8/2 17:00:00D68E01A

69 7.95 12.61% 69 100.00%

2011/8/2 18:00:00D68E01A

0 0.14 0.00% 0 0.00%

2011/8/2 19:00:00D68E01A

0 2.07 0.00% 0 0.00%

2011/8/2 20:00:00D68E01A

2 19.1 0.18% 0 0.00%

2011/8/2 21:00:00D68E01A

2 21.21 0.21% 0 0.00%

CQT test on site Not find problems, Downlink signal level and downlink quality is good.MRR Statistics found that up-110dBm signal level ratio of more, MRR diagram is as follows

8/3/2019 A Case for Tch Drop Analysis

2/4

SH NPI BIWEEKLY REPORT 2 (4)

Prepared (also subject responsible if other) No.

201108

Approved Checked Date Rev Reference

2011-08-11 A

Figure1UP and down signal distribution

CTR analysis found that the main cause of dropped calls is the measurement report(Measure Report) lost and dropped calls T200 timeout:

Time CseCd3TA

RxLSbUL

RxQSbUL

RxLSbDL

RxQSbDL

11:01:58

Too many measurement generations missing1 -110.5 7 -77.5 4

11:03:55

T200 expired (N200+1) times~ abnormalrelease 1 -110.5 7 -79.5 0

11:06:2

7 Too many measurement generations missing 2 -110.5 7 -69.5 011:16:5

9Too many measurement generations missing

2 -110.5 7 -80.5 411:16:5

0T200 expired (N200+1) times~ abnormal

release 2 -110.5 7 -79.5 011:16:4

3T200 expired (N200+1) times~ abnormal

release 1 -110.5 7 -79.5 411:18:0

0Too many measurement generations missing

- -110.5 7 - -11:18:1

2Too many measurement generations missing

- -110.5 7 - -11:21:3

8T200 expired (N200+1) times~ abnormal

release 2 -110.5 7 -82.5 511:23:2

0 Too many measurement generations missing 2 -110.5 7 -81.5 011:27:0

2Too many measurement generations missing

2 -110.5 7 -78.5 411:40:5

3Too many measurement generations missing

2 -110.5 7 -68.5 011:47:3

5T200 expired (N200+1) times~ abnormal

release 1 -110.5 7 -79.5 7

8/3/2019 A Case for Tch Drop Analysis

3/4

SH NPI BIWEEKLY REPORT 3 (4)

Prepared (also subject responsible if other) No.

201108

Approved Checked Date Rev Reference

2011-08-11 A

11:50:4

1

T200 expired (N200+1) times~ abnormal

release 2 -110.5 7 -74.5 611:53:0

6T200 expired (N200+1) times~ abnormal

release 2 -110.5 7 -74.5 011:54:0

8Too many measurement generations missing

2 -110.5 7 -72.5 0

Table 2D68E01A CTR dropped calls reanson statistics for a period of time

2D68E01A DE- _1 CTR

Through the CTR analysis, the down up signal and quality are good before call drop. then

the signal suddenly interrupted ,after a timeout until RLT, BSC release the connection,recorded as a sudden dropped calls. If it is not covered by the elevator or into the tunnelsignal should be decreased gradually rather than suddenly interrupted.For traffic restrictions on D68E01A, dropped calls transferred to the same to the district:G68E29A, two residential weekends dropped calls while indicators are normal, ruled out ahardware problem high dropped calls:

TIME CELLTCHtraffic

TCHdroptimes

sudden los

CELLTCHtraffic

TCHdroptime

s

sudden los

2011/8/2 11:00:00D68E01A 15.01 24 24

G68E29A 8.04 0 0

2011/8/2 12:00:00D68E01A

8.29 2 2G68E29A

5.83 2 2

2011/8/2 13:00:00D68E01A

7.28 22 22G68E29A

4.47 1 1

2011/8/2 14:00:00 D68E0 7.97 80 79 G68E2 6.06 0 0

8/3/2019 A Case for Tch Drop Analysis

4/4

SH NPI BIWEEKLY REPORT 4 (4)

Prepared (also subject responsible if other) No.

201108

Approved Checked Date Rev Reference

2011-08-11 A

1A 9A

2011/8/2 15:00:00 D68E01A

9.28 102 101 G68E29A

7.98 3 3

2011/8/2 16:00:00D68E01A

10.38 81 76G68E29A

6.76 2 2

2011/8/2 17:00:00D68E01A

7.95 69 69G68E29A

11.82 1 1

2011/8/2 18:00:00D68E01A

0.14 0 0G68E29A

17.12 114 112

3D68E01A DE-_1GE-_1

Dropped calls caused by the transfer of traffic restrictions and comprehensive analysis to

the CTR, we suspected group call equipment problems or mobile terminal stores, mobilephone chip makers abnormal test (Call directly unplug the power) lead to high droppedcalls. After signaling track, we find D68E01A event of dropped calls are almost 10086.According to statistics IMEI, found that more than one terminal replacing the number thatdial 10086 appear constantly dropped calls. Specific statistics are as follows

D68E01A signaling device to track a call drop event

Solution: existence of unusual call in the cell, further investigation can go base on the tracked number