1. GSM Traffic Statistics Analysis
ZTE university

2. Course Target When you finish studying this course，you can：
Master ZTE traffic statistic
Master the meaning of parameter items of common-used traffic statistic
Master the methods to analyze and position the problems making use of traffic statistic

3. Contents ZTE Traffic Statistic Overview
Definitions Of Main Traffic Statistic Parameters
Position And Analyze Problems Making Use Of Traffic Statistic
Traffic Statistic Analysis Cases 3

4. Traffic statistic analysis
ZTE Traffic Statistic Overview--The Function Of Traffic Statistic Analysis
Optimization scheme
Traffic statistic analysis
Data collection
Know network performance index
Provide clients with quantitative service guidelines
Monitor network performance
Position and analyze network problems
Improve network running quality
Radio Network Optimization
Light adjustment solution and evaluation
optimization scheme implementation

5. ZTE Traffic Statistic Overview--ZTE Traffic Statistic Introduce

6. ZTE Traffic Statistic Overview-- Traffic Statistic Index
Original traffic statistic index
SDCCH congestion rate
SDCCH assignment success rate
SDCCH call drop rate
TCH congestion rate
TCH assignment success rate
TCH call drop rate
Handover success rate
Random access success rate
Paging success rate (correlative index)
Synthetical traffic statistic index
Traffic-to-drop ratio
Worst cell ratio
TCH assignment success rate (China Union definition)
Radio connection rate

7. ZTE Traffic Statistic Overview --CS Traffic Basic Measurement1
CS traffic basic measurement
Basic measurement task is the measurement which produces basic performance report，including resource status、service status、channel quality etc.，can reflect the total network status more roundly. ２
Carry out statistic according to the modules，mainly including assignment and handover, and the load of CPU. Statistic is mainly responsed to RMM, and SMM is used to measure cpu's burthen.
Q3 module measurement ３
Measure BTS power、Rx_level、Rx_quality and TA in terms of cells, then accumulate the measurement values got from TRX power control counter and report the statistic.
　Q3 cell BTS measurement counter

8. ZTE Traffic Statistic Overview --BTS Measurement1
　Power control measurement
BTS decides whether to control MS’s(or BTS’s) power or not based on Rx_lev or Rx_qual in measurement report ,and carries out statistic according to different power control factor.
　Carrier frequency service measurement ２
It’s to measure whether channel activation、assignment、handover are successful with carrier frequency as unit, and measure carrier frequency interference bands、MAX and MIN uplink/downlink signal level. ３
Paging measurement
Carry out statistic paging drop and the length of queue with carrier frequency as unit. ４
　 Carrier frequency basic measurement
Measure carrier frequency’s service occupation times and occupation time about TCH and SDCCH.

9. ZTE Traffic Statistic Overview-- Radio measurement1
　Cell radio measurement
Measure interference and Qos of per channel which is occupying and idle state. ２
　Radio access measurement
Measure MS’s radio random access process, including access trying times、processing times 、successful times with different reason. ３
　SDCCH measurement
Measure success times and success rate about SDCCH assignment, allocation& occupation etc., reflect service of SDCCH. ４
Measure success times and success rate about TCH/F assignment, allocation& occupation etc. ,which is based on configure channels and adjust parameter.
　 TCH/F measurement ５
　SAPI3 measurement
Measure connection times、 receive times and transmitting times of point to point SMS.

10. ZTE Traffic Statistic Overview-- Radio measurement６
　 RMM assignment measurement
Describe RMM assignment, including assignment attempt、executing and queue with every reason. ７
　 RMM call drop measurement
Describe all kinds of channel in signaling flow、RMM call drop times、call drop reason etc.. ８
　Handover reason measurement
Carry out statistic on every handover(out) attempt according to every reason. ９
　Handover common measurement
Carry out statistic handover process with every reason,including attempt、executing、success and fail times,reflect handover success rate. １０
Handover synchronization measurement
Carry out statistic all kinds of synchronism handover times.

11. ZTE Traffic Statistic Overview-- Radio measurement１１
　Neighboring cell handover measurement
Carry out statistic on mutual handover by selecting some cells and their neighboring cells. １２
　Paging measurement
The meaning and measurement point of paging measurement counter. １３
　Abis interface signaling statistic
Carry out statistic on all kinds of signaling numbers transmitted in Abis interface. １４
　Radio resource usability measurement
Measure usage of each cell radio channel resource. １５
It’s added HR basic measurement according to subscriber’s need, mainly describe resource status, service status and dynamic changeover status of TCH/H
　HR statistic measurement

12. ZTE Traffic Statistic Overview --A Interface Measurement1
A interface signaling statistic measurement
carry out statistic on signaling numbers of BSC production 、forwarding and reception based on signaling name and signaling type.
　A interface assignment、call drop、handover statistic measurement ２
Carry out statistic on assignment 、call drop and handover times of A interface, carry out statistic and classify on failure status, it’s helpful to position and solve problem.
　SCCP connection measurement and ground circuit resource usability measurement ３
Measure SCCP links’ establish status and usability of ground relay circuit resource.

13. ZTE Traffic Statistic Overview --Resource Occupation Measurement1
　 TRX LAPD link measurement
Carry out statistic on signaling alternant of each LAPD signaling link which connecting TRX when it’s transmitting and receiving messages via LAPD board ,with TRX LAPD link as unit. ２
Carry out statistic on signaling alternant of each O&M LAPD signaling link which connecting TRX when it’s transmitting and receiving messages via LAPD board ,with TRX O&M LAPD link as unit.
　 O&M LAPD link measurement ３
　SCCP link measurement
Carry out statistic on signaling alternant of each SCCP link with SCCP link as unit. ４
　 Processor load measurement
Carry out statistic on CPU load 、internal memory 、service load and file system load of each SMM and RMM module, with module as unit.

14. ZTE Traffic Statistic Overview --PS Service Measurement1
It measures PS basic performance report, including resource status 、 service status and channel quality etc., can reflect comprehensively total PS network performance.
　PS basic measurement ２
　NS measurement
Carry out statistic on BSVC links’ data transmition 、signaling alternant and abnormal reason etc. with single NSVC as measurement entity. ３
　 BSSGP measurement
Mainly measure messages transmitting and receiving in Gb interface on BSSGP layer of GPRS service. ４
NSE measurement
Carry out statistic on paging 、status indication message 、BVC signaling reset times etc. with single NSE as measurement entity.
Nsvc NS Virtual Circuit NS虚电路 ５
　PS traffic statistic and resource management measurement
PS traffic statistic measure cell services. Resource management mainly measure BSC system resource usage.

15. Contents ZTE Traffic Statistic Overview
Definitions Of Main Traffic Statistic Parameters
Position And Analyze Problems Making Use Of Traffic Statistic
Traffic Statistic Analysis Cases 15

16. Definitions Of Key Traffic Statistics Indicators -- SDCCH blocking rate
KPI name
SDCCH blocking rate
definition
Number of SDCCH blockings*100%/Number of SDCCH call attempts
V3 (6.20)
(C C C )*100 %/(C C C )

17. Definitions Of Key Traffic Statistics Indicators --Signaling statistical point of SDCCH blocking

18. Definitions Of Key Traffic Statistics Indicators -- TCH blocking rate
KPI name
TCH blocking rate
Definition
Number of TCH blockings *100%/ Number of TCH call attempts
V3 (6.20)
(C C C C )*100%
/(C C C C )

19. Definitions Of Key Traffic Statistics Indicators --Signaling statistical point of TCH blocking

20. Definitions Of Key Traffic Statistics Indicators --TCH assignment success rate
KPI name
TCH assignment success rate
Definition
Number of TCH assignment successes*100/(Number of TCH assignment successes + Number of TCH assignment failures)
V3 (V6.20)
((C C C C
C C )*100/(C
C C C C
+C C C C
C C C )

21. Definitions Of Key Traffic Statistics Signaling statistical point of TCH assignment success rate

22. Definitions Of Key Traffic Statistics -- Signaling statistical point of TCH assignment failure
MS sends Assignment Failure to BSC after the assignment fails.
After T3107 expires, BSC counts assignment failure for one time.

23. Definitions Of Key Traffic Statistics --TCH call drop rate
KPI name
TCH drop rate / Call drop rate
Definition
Number of TCH call drops*100%/Number of TCH assignment successes
V3 (V6.20)
(C C )*100/(C C
+C C )

24. Definitions Of Key Traffic Statistics Indicators—Signaling statistical point of radio call drops

25. Definitions Of Key Traffic Statistics Indicators—Signaling statistical point of call drops due to handovers
Call drop due to intra-cell handover
Call drop due to inter-BSC handover
The signaling statistical point for call drops due to all kinds of handovers is A2, which means after the timer expires due to handover failure, BSC clears the channels and counts one time of call drop due to handover failure.
Call drop due to inter-BSC handover

26. Definitions Of Key Traffic Statistics --TCH handover success rate
KPI name
Handover success rate
Definition
Number of busy-hour handover successes*100%/ Number of busy-hour handover requests
V3 (V6.20)
(C C C )*100/(C
+C C C C
C C C C )

27. Definitions Of Key Traffic Statistics Indicators -- Signaling statistical point of TCH handover success rate
The signaling statistical point of intra-cell handover request is C1, and that of handover success is C3, which means Assign Complete message is received by BSC after the handover is completed successfully.

28. Definitions Of Key Traffic Statistics Indicators --Signaling statistical point of TCH handover success rate
The signaling statistical point of intra-BSC handover request is A4, which means the message received by BSC is incoming handover request. The signaling statistical point of handover success is A6, which means the Handover Complete message is received after the handover is completed successfully.

29. Definitions Of Key Traffic Statistics Indicators -- Signaling statistical point of TCH handover success rate
The signaling statistical point of inter-BSC handover request is D1, which means the handover request message sent by MSC is received. The signaling statistical point of handover success is D3, which represents that Handover Complete message is received.

30. Definitions Of Key Traffic Statistics Indicators -- DL TBF establishment success rate
KPI name
DL TBF establishment success rate
Definition
（Number of GPRS DL signaling TBF establishment + Number of GPRS DL data TBF establishment + Number of EGPRS DL signaling TBF establishment + Number of EGPRS DL data TBF establishment ）*100% / Number of DL packet channel requests （V3）
V3 (V6.20)
(C C C C )*100/
(C C C C
C C C C )

31. Definitions Of Key Traffic Statistics Indicators -- Signaling statistical point of DL TBF establishment success rate
Statistical point of DL TBF establishment before T3192 expires: A
Statistical point of DL TBF establishment with existing resource: A
The signaling statistical point of DL TBF establishment usually consists of three flows: DL TBF establishment before T3192 expires; DL TBF establishment during DL TBF; DL TBF establishment on the PACCH of UL TBF.
Statistical point of DL TBF establishment on the PACCH of UL TBF: A2

32. Definitions Of Key Traffic Statistics Indicators—UL TBF establishment success rate
KPI name
UL TBF establishment success rate
Definition
（Number of GPRS UL signaling TBF establishment + Number of GPRS UL data TBF establishment + Number of EGPRS UL signaling TBF establishment + Number of EGPRS UL data TBF establishment ）*100% / Number of UL packet channel requests （V3）
V3 (V6.20)
(C C C C )*100/(C C C C
C C C C )

33. Definitions Of Key Traffic Statistics Indicators—Signaling statistical point of UL TBF establishment success rate
UL TBF establishment consists of two modes: one-phase access (left figure) and two-step access (right figure); the statistical point of access success is A1.

34. Contents ZTE Traffic Statistic Overview
Definitions Of Main Traffic Statistic Parameters
Position And Analyze Problems Making Use Of Traffic Statistic
Traffic Statistic Analysis Cases 34

35. Traffic Statistic Analysis Content
Position And Analyze Problems with Traffic Statistics-- Traffic Statistic Analysis Content
Call Drop Problems Analysis
TCH congestion problems analysis
Handover problem analysis
Traffic Statistic Analysis Content
SDCCH congestion problems analysis
TCH assignment problems analysis
SDCCH assignment problems analysis

36. Position And Analyze Problems with Traffic Statistics
Whole Principle of Traffic Statistic Analysis
Whole Principle：From whole problem to the particular problem, from one-day network index observation to one-week network index, from single index to their correlation, from the key cells to subordinate cells.
Before Traffic Statistic Analysis：Collect overall data, including all kinds of performance reports and measurement data, and need to know such basic information as networking structure.
Carry out Traffic Statistic Analysis ：Based on the principle of “grasp the situation macroscopically, handle it microscopically” and characteristics of traffic statistic data, traffic statistic analysis is a process from the whole network performance measurements to the cells performance measurements, and a gradual process from the main index to subordinate index. It analyzes network performance index first, with a clear grasp of the whole network index, then determines which index are worse, finally analyzes the main cells which cause worse index.
Combine with other network optimization tools：During traffic statistic analyzing, it needs to combine with other network optimization tools to position and analyze problems.

37. Position And Analyze Problems with Traffic Statistics
TOP Analyze Method
Description of TOP 10 Method: Use data sort and filter functions of EXCEL or other software tools to sort each data from bad to good. Thus facilitate connecting each data ,finding the rules and locating problems more easily.
Carry out studying and contrastive analysis on the sub-item’s statistic function of BSC-level traffic statistic report.
If certain important index (such as call drop rate、successful handover rate) are found abnormal in BSC-level traffic statistic report, then carry out cell-level traffic statistic to analyze its more detailed content.
Check the cells which single index is abnormal and has more absolute times of failure (call drop、congestion、handover failure, etc) .
Combine the two parameters, percentage and absolute times of failure (call drop、congestion、handover failure, etc), to decide whether it needs to adopt further measures.

38. Position And Analyze Problems with Traffic Statistics--Traffic Statistic Analysis General Idea
BSC Level
Report
话统分析总体思路

39. The other optimization methods
Position And Analyze Problems with Traffic Statistics--Traffic Statistic Analysis General Idea
The other optimization methods
DT：Simulate Subscriber make calls in moving state, Analyze coverage、quality、handover、signaling.
CQT：make a great deal of calls in different place
Signaling Trace：Collecting signaling through signaling tool or OMCR signaling trace function.

40. Individuality Problems
Position And Analyze Problems with Traffic Statistics--Index Analysis Filter Method
First Commonness Second Individuality
Commonness Problems
Individuality Problems
Equipment hardware problems
Interference problems
Coverage problems
Handover problems
Other radio parameters problems
。。。

41. Position And Analyze Problems with Traffic Statistics
Commonness factors lead to bad KPI
Equipment hardware problems
Interference problems
Coverage problems
Other factors

42. Position And Analyze Problems with Traffic Statistics —Common Problems

43. Traffic Statistic Analysis Method of Position and Resolve
Position And Analyze Problems with Traffic Statistics--Common Problems
Equipment Hardware Problems
Traffic Statistic Analysis
Method of Position and Resolve
CELL performance report：SDCCH and TCH usable rate abnormal，< 100%，High TCH assignment failure rate ，especially > 10%；
BTS measurement：position call drop and assignment failure of TRX level；
Alarm statistic: find hardware problems；
Dynamic channel observation：carrier frequency occupying abnormally；
NMS measurement：SDCCH/TCH channel occupation time；
Check clock problems；
Monitor transmission ：find transmission problems；
The hardware problems of transmission error code and stability 、REPEATER self-excitation、tower top amplifier yawp etc. .
Target cell channel activation NACK or TIMEOUT；
High group link call drop times；
Synchronize CLOCK；
Position range of hardware problems according to left analysis，judging whether TRX , CMM and TIC problem, whether power of power amplifier too low, combiner, divider, REPEATER problem etc..

44. Traffic Statistic Analysis Method of Position and Resolve
Position And Analyze Problems with Traffic Statistics--Common Problems
Interference
Traffic Statistic Analysis
Method of Position and Resolve
CELL traffic statistic：Analyze interference bands level
CS basic measurement：Analyze discipline of interference bands appears：change with time and traffic capacity
BTS measurement：Position TRX level interference bands；
Handover reason measurement：The ratio of UL/DL RQ handover to all handover；
Cell radio measurement：Analyze level and quality status of cells.
Abis interfaces signaling trace：Analyze cells and TRXs with interference.
Frequency check：Analyze inner interference within same or adjacent frequency point；
Sweep frequency test：search external interference；
DT：Check interference and signal quality status of the problem section ;
Adjust BTS’s transmit power of correlative cells、antenna downtilt or frequency point etc. to avoid interference;
Enable function of HP，DTX，DPC etc. ;
Resolve equipment problems (such as: TRX board self-excitation、antenna intermodulation).

45. Position And Analyze Problems with Traffic Statistics-- Common Problems
Coverage Problems
Traffic Statistic Analysis
Method of Position and Resolve
Cell traffic statistic: Worse UL/DL RQ and KPI;
Power control performance measurement: average of UL/DL signal level is too low;
Cell radio measurement: Times of low RX-Level have higher percentage;
Handover reason measurement: Times of rescue UL/DL Rx-lev handover has higher percentage;
DT in weak coverage area;
Adjust network parameters according to DT result;
BTS transmitting power, antenna downtilt and height, Rxlev_ACCESS_MIN_MS, the neighbor relation, RXLEV_ACCESS_MIN of handover candidate cell.
Adjust coverage, avoid over-coverage、owe-coverage and alone island phenomenon;
Add BTS.

46. Position And Analyze Problems with Traffic Statistics--Call Drop Analysis
Call Drop Type
Radio Link Failure call drop
Handover Failure call drop
LAPD call drop

47. Confirm TRX level call drop Analyze call drop factors
Position And Analyze Problems with Traffic Statistics--Call Drop Analysis
Analysis Frame 1 2 3 4 5
Confirm higher
call drop cell
Confirm call drop type
Confirm TRX level call drop
Analyze call drop factors
Solve Call
drop problems
BSC Level performance report
CELL level performance report
CELL Level performance report
CS basic measurement
Alarm statistic
BTS measurement
Cell radio measurement
Common problems analysis
Individuality problems analysis
Alarm analysis
Traffic statistic analysis
Signaling analysis
Other optimization methods
From whole to particular
Easy to position and analyze
Carrier frequency level
First commonness then individuality
Execute and solve problems

48. Common causes of call drop
Position And Analyze Problems with Traffic Statistics--Call Drop Analysis
Common causes of call drop
Handover parameters setting problems
Equipment hardware problems
UL/DL imbalance
Call Drop
Setting of other parameters is irrationality
Interference
Coverage Problems
Common Problems already analyzed

49. Traffic Statistic Analysis
Position And Analyze Problems with Traffic Statistics--Call Drop Analysis
Improper setting of handover parameters
Traffic Statistic Analysis
Resolve Methods
Add neighbor relation in reason;
Adjust handover parameters.
Check handover parameters, find unreasonable parameters setting;
Handover common measurement, check handover out failure status;
Handover common measurement, check handover reason and percents of each kind of handover;
Adjacent cell handover statistic measurement: low success rate of handover out （aim at certain cell），find target cell with low handover success rate and looking for cause;
CS basic service measurement: handover times/call times ＞3）

50. Traffic Statistic Analysis
Position And Analyze Problems with Traffic Statistics--Call Drop Analysis
UL/DL Imbalance (Tower top amplifier、HPA、Antenna azimuth)
Traffic Statistic Analysis
Resolve Methods
CS basic service measurement: Analyze UL/DL Average_Rx_Lev;
Abis interface signaling trace: Analyze UL/DL Rx_Lev;
Cell radio measurement: Analyze UL/DL Rx_Lev distributing.
Check tower top amplifier、CDU、RDU、BTS boards and RF feeder;
Check antenna feeder. Check antenna azimuth and downtilt whether according with design criterion; check antenna feeder, jumper feeder is connected rightly and connecters are connected tightly, feeder is undamaged, make sure standing wave rate under normal range.

51. Traffic Statistic Analysis
Position And Analyze Problems with Traffic Statistics--Call Drop Analysis
Improper setting of other parameters
Traffic Statistic Analysis
Resolve Methods
Check radio parameters: adjust irrational parameters;
irrational RLT and Rx_lev_Min;
Amend irrational parameters.

52. Position And Analyze Problems with Traffic Statistics—Handover Problems Analysis
Handover Analysis Idea
切换问题分析

53. Position And Analyze Problems with Traffic Statistics—Handover Problems Analysis
General Analysis Idea
Cells with handover problems: All cells or individual cell.
Handover direction of problem cells : Handover out cell failure or in cell handover failure;
Object of handover failure: Between service cell and multi-cell or individual cell.
MSC1
BSC1
BSC2
BSC3
MSC2 1 2 3

54. Checking Handover Index
Position And Analyze Problems with Traffic Statistics—Handover Problems Analysis
Checking Handover Index
Check cells with lower handover success rate;
Check cells with much handover failure times
Analyze handover out/in failure times, find out main factors of handover failure;
Register out/in cells handover performance;
Observe trait of handover failure: For all adjacent cells or individual adjacent cell、all conditions or part condition lower handover success rate.

55. Lead Low Handover Success Rate
Position And Analyze Problems with Traffic Statistics—Handover Problems Analysis
Possible Factors influencing Handover Success Rate
Common Problems already analyzed
Handover Parameters Irrationality
UL/DL Imbalance
Coverage
Lead Low Handover Success Rate
Equipment Problem
Interference

56. Traffic Statistic Analysis
Position And Analyze Problems with Traffic Statistics—Handover Problems Analysis
Improper setting of handover parameters
Traffic Statistic Analysis
Resolve Methods
Cell performance report: Low handover success rate, more handover failure times;
BTS measurement: filter TRXs with more handover failure times.
Basic measurement: analyze every handover factors percent, PBGT handover percent too high or too low;
Handover statistic handover: find out two cells lead to handover failure.
Check PBGT、rescue handover etc. handover level threshold, setting of handover function switch whether correct.
Result of handover times vs TCH call occupation success times is disproportion. If handover/call＞3，Ping-pong handover exist in all probability, should check handover parameters setting and adjust (least time space of inter-cell, PBGT HoLevThs etc.)
PBGT 50%以上

57. Traffic Statistic Analysis
Position And Analyze Problems with Traffic Statistics—Handover Problems Analysis
Comprehensive analysis
Traffic Statistic Analysis
Resolve Methods
Performance report of cells level: target cell congestion;
CS basic measurement: low handover in success rate, maybe handover in cell hardware problems or has interference etc.;
Low handover success rate: maybe target cell congestion or handover parameters setting is irrationality;
Check neighbor relation: whether have omitted neighbor,single or redundant neighbor;
Check exterior cell: setting of exterior cell parameters error.
Extend capacity of target cell or traffic proportion;
Check hardware;
Adjust handover parameters;
Optimize adjacent cells;

58. Position And Analyze Problems with Traffic Statistics—Handover Problems Analysis
Other
After eliminate commonness problems, optimize parameters of adjacent cells, analyze and resolve UL/DL balance problems of adjacent cells,

59. Position And Analyze Problems with Traffic Statistics-- Analysis Of TCH Blocking
Possible causes of TCH blocking
Shortage of system capacity or traffic imbalance
Antenna and feeder system problem
Interference
TCH Blocking
Parameters setting problem
Coverage problem
Data configuration problem
Common Problems already analyzed

60. Position And Analyze Problems with Traffic Statistics-- Analysis Of TCH Blocking
Lack of system capacity or unbalanced traffic
Judging Method
Solution
Too high traffic capacity in TCH (Traffic per channel>0.6)；
Too much overflow times, system busy for a long time;
Traffic imbalance (three cells of one BTS traffic imbalance, or several BTS traffic imbalance;
Analyze out serious congestion from performance reports.
Extend capacity, or adjust configuration of busy and idle carrier cells;
Adjust coverage (adjust transmit power of BTS, antenna azimuth, downtilt, height etc.);
Adjust main parameters (CRO, Rxlev_access_Min_MS, enable trafficHo function);
Adjust priority level and handover parameters of cells.

61. Antenna and feeder problem
Position And Analyze Problems with Traffic Statistics-- Analysis Of TCH Blocking
Antenna and feeder problem
Judging Method
Solution
Frequency point scanning: results to same frequency point through main and secondary diversity antenna measuring;
Cell radio measurement: signal level, quality disturbing;
Signaling tracing: measurement report analysis.
Check antenna azimuth, downtilt, connection of antenna and feeder system.

62. Position And Analyze Problems with Traffic Statistics-- Analysis Of TCH Blocking
Improper setting of parameters
Judging Method
Solution
Performance statistics report: judging TCH congestion;
Alarm information statistic：BTS or TRX problem;
BTS measurement: check TRXs;
Check parameters: RxLev_Access_Min_MS, cell reselect parameters.
Adjust irrationality parameters setting;
Solve problems.

63. Position And Analyze Problems with Traffic Statistics-- Analysis Of SDCCH Blocking
Causes of SDCCH blocking
引起SDCCH 拥塞率高的几 个主要因素：
Interference
Parameters problem
SDCCH Congestion
Capacity
LAC Partition
Common Problems already analyzed

64. Position And Analyze Problems with Traffic Statistics-- Analysis Of SDCCH Blocking
Improper setting of parameters
Judging Method
Solution
Basic measurement: judging reasons for SDCCH congestion；
Radio access measurement: immediate assignment success times/immediate assignment times>85％；
Parameters checking: parameters of correlative with radio access;
Low usability rate SDCCH.
Adjust parameters (random access error level threshold, RACH access level threshold), Maximum retransmission times, Extend Transmission distributed timeslots );
Adjust location update parameters;
Adjust parameters of the dual-band network.

65. Position And Analyze Problems with Traffic Statistics-- Analysis Of SDCCH Blocking
Insufficient system capacity
Judging Method
Solution
Performance report: TCH and SDCCH both congested;
Performance report: TCH don’t congest but SDCCH is congested seriously;
Parameters adjusting: traffic hinge, such as aviation hinge, railway station etc., has lots of location updates;
SMS leap.
Extend network capacity;
Add SDCCH;
Adjust T3122、T3212、RACH parameters etc. ；
Adjust other parameters.

66. Position And Analyze Problems with Traffic Statistics-- Analysis Of SDCCH Blocking
Improper LAC division
Judging Method
Solution
Performance report: SDCCH congested badly;
Basic measurement: percent of location update too high;
LAC partition: business area, LAC areas are crossed badly;
Adjust CRH；
Adjust cell reselect parameters；
Adjust T3212；
Adjust other parameters.

67. Position And Analyze Problems with Traffic Statistics-- Analysis Of SDCCH Blocking
Existence of interference
Judging Method
Solution
RACH level threshold is lower, at the same time has interference, system mistake for having lots of SDCCH occupation requests.
Performance report: SDCCH congested badly;
Basic measurement: more useless SDCCH access ;
Check and adjust frequency point;
Solve interferences;
Adjust access parameters.

68. TCH Channel Assignment TCH Channel Allocation
Position And Analyze Problems with Traffic Statistics—Analysis of TCH Assignment Problems
TCH Channel Analysis Process 3
TCH Channel Assignment 2
It is carried out between BSC and MS. BTS just transmits commands transparently. Then it is a channel assignment attempt. When BSC receives BTS’s feedback message Establish Indication, it is considered assignment is successful.
TCH Channel Allocation 1
BSC sends Channel Activation FOR TCH command to BTS，that is TCH channel allocation attempt. BSC receives BTS’s feedback message Channel Activation ACK, then allocation has been done.
Channel Occupation
After the system receives CHANNEL REQUIRE command, it will inquire channel resources in MP database.

69. Causes of TCH Assignment Failure
Position And Analyze Problems with Traffic Statistics—Analysis of TCH Assignment Problems
Causes of TCH Assignment Failure
Hardware problems：TRX、CDU、loose panel cables；
Interference：co-channel/ adjacent-channel interference/ external interference;
Antenna problems: damaged antenna feeder, uni-polarized antenna azimuth, inconsistence between down-tilt and antenna type, high VSWR, crossed or misconnected antenna feeders;
Unreasonable parameter configuration：improper setting of HF parameters, T3107 value is set too small, inconsistence between data configured at OMCR and the data planned, etc.;
Coverage problem：weak signal or uplink &downlink imbalance ;
Repeater problem: uplink/downlink interference or imbalance of uplink/downlink;
Other reasons：soft & hardware versions of the system、signaling cooperation between BSC and MSC;

70. Position And Analyze Problems with Traffic Statistics—Analysis of TCH Assignment Problems
Analysis of traffic statistics
Judging Method
Solution
Performance report：find out cells with TCH assignment failure;
Basic measurements：judge interference band、call drop、handover、uplink& downlink RQ value;
Alarm statistics：hardware problems
BTS measurements：position TCH assignment failure of carrier frequency level
NMS：judge whether carrier frequency occupation is normal by occupation time of TCH and SDCCH;
Parameter configuration：unreasonable dynamic SDCCH parameter configuration.
Check whether radio parameters of the cell is reasonable;
Check BER、idle interference band level index, decrease radio interference;
Check hardware of the cells;
Check transmission problems;
DT analysis;
Check BSC and base station versions to avoid unmatched versions leading to TCH assignment failure.

71. Contents ZTE Traffic Statistic Overview
Definitions Of Main Traffic Statistic Parameters
Position And Analyze Problems Making Use Of Traffic Statistic
Traffic Statistic Analysis Cases 71

72. Phenomenon Description
Cases of Call Drop
Phenomenon Description
On 16, March, from OMCR BAM statistic, I10 of Station 3 of BSC 80 in PAKTEL network had much more call drop rate suddenly, with its rate more than 7%. Call drop times increased a lot.
Problem Analysis
Through carrying out statistic on detailed performance data, checking call drop types, we found radio link failure accounted for great part of call drop;
Through carrying out statistic on the interference band of the cell, we found 3-level or above interference band accounted for higher percentage;
We doubted first that the station had interference. After checking frequency planning, we found there was no neighboring interference with adjoining cells. Through BTS measurements, we found the second and third carrier frequency of the station had a higher failure rate
From alarm statistics, this station had no hardware alarms, no adjacent cells missed in configuration, handover parameters are reasonable. However, it’s found that the MAIOs of the second and third TRXs are the same.

73. TCH in call drop rate(%)
Cases of Call Drop
Solution
After adjusting MAIO of the third carrier frequency from 8 to 10, the interference disappeared, call drop times decreased greatly and call drop rate restored to normal.
Region
Cell Name
BSC ID
CELL ID
DATE
TCH in call drop rate(%)
Remark
NORTH
I102 80
50022
8.17
Before
Adjustment
7.74
7.53
7.97
1.03
After
0.94
0.85
0.76

74. Phenomenon Description
Cases of TCH Handover Problems
Phenomenon Description
In Tong Ning Road Elementary School BTS of Ge Er Mu Mobile company, during DT(site:32, S465,C1:50251/50252/50253), we found the station can not handover among three cells, but can handover (out/in) with neighboring cells normally. No problems can be detected just from BTW traffic statistic because each index is in normal state. Only by DT can we found problems. We analyzed Lay 3 signaling via DT, and found MS hardly received handover command which was sent out from the system until the vehicle left, then it handover with other neighboring cells.

75. Cases of TCH Handover Problems Problem Analysis
Checked parameters of BAM in the station, and the configuration is ok;
Then checked station hardware and it is normal;
Resetting the station can not solve the problem.
reconfigure the base station data can not either.
Front and back platform ZDB files are consistent
Solution
After resetting MP, handover
restored to normal.
BSC No.
SITE No.
CELL No,
Adjoining Cell CI
11101(successful handover out attempts to the adjoining cell)
11102(successful handover out attempts to the adjoining cell) 1 32
50252 77
Other adjacent Cell 53 48 2
50251
100 63 59 3 57
335
295

76. Phenomenon Description
Cases of TCH Blocking
Phenomenon Description
On 21, December, we carried out statistic from BAM, and found TCH traffic of the third sector of No. 106 station in BSC8 under Libyan network is very congested suddenly. TCH congestion rate（exclude handover）arrived at higher than 30%.
Problem Analysis
Before, this sector wasn’t congested, but this time was in sudden TCH traffic congestion. After implementing statistic on the performance report and alarm statistic of the surrounding cells, we found the reason for congestion was that No.127 station corresponding with this cell had broken, thus the neighboring traffic had been absorbed by the third sector of No, 106 station.
Solution
After coordinating with the office, commission the No.127 station in time. Then TCH traffic congestion of the third sector of N had been cleared.

77. Cases of TCH Blocking A Contrast Before &After Optimization
BSC-SITE ID-BTS
Cell and Location Area Cell(LAC-CI)
SDCCH in congestion rate(%)
TCH in congestion rate(exclude handover)(%)
TCH overflow total number(exclude handover)
Bsc8-Site106-Bts1
LAC8198-CI11061
Bsc8-Site106-Bts2
LAC8198-CI11062
Bsc8-Site106-Bts3
LAC8198-CI11063
0.04
30.24
936
After Adjustment

78. Phenomenon Description
Cases of SDCCH Blocking
Phenomenon Description
In September, after No.61 new station had been commissioned, SDCCH channel of the third cell congested suddenly and its congestion rate was as high as 35%.
Problem Analysis
Through analyzing the basic measurement of the cell, we found the reason for SDCCH congestion in the third cell was that there existed a great amount of positions to be updated. After checking plan data and LAC division, we didn’t find unreasonable points. Thus we analyzed that this new station had certain mistaken data during commissioning.
Solution
After checking, we found LAC No. of the third cell in the station is 8198, while LAC No. of other two cells of the station is It is confirmed that during commissioning the new station, LAC No. of the third cell was input 8198 mistakenly. It should be Thus caused a great amount of positions to be updated. Through readjustment, SDCCH congestion rate restored to normal.

79. Cases of TCH Assignment
Phenomenon Description
In the third cell of No.1 station of PHO, its call drop rate arrives at 6.9% ,successful handover in rate is only 68.38%, while handover out rate is 91.31%.
Problem Analysis
TCH assignment rate is morn than 10%, from which we excluded the interference problem and make sure that the cell has hardware problems. After analyzing BTS measurements of the cell, we found that TCH assignment failure rate of the second carrier frequency in the cell is very high, arriving at 30%. And during on-site testing, we found that after occupying this carrier frequency, the signal level is 20dB less than BCCH carrier frequency level.
Solution
After changing carrier frequency, each parameter restores to normal.

80. Cases of TCH Assignment
A Contrast Before &After Optimization
BSC -SITE ID-BTS
Cell and Location Area Cell(LAC-CI)
TCH in call drop rate(include handover)(%)
TCH dropped call total number
TCH assign failure rate(%)
Handover in success rate(%)
Handover out success rate(%)
Bsc80-Site1-Bts3
LAC1003-CI50003
6.9 98
12.28
68.38
91.31
After Adjustment
0.9 5
2.28
92.38
92.89