technical study case sharing_ver0

HUAWEI TECHNOLOGIES CO., LTD. Huawei Confidential

Simple Case Study Sharing

Compiled byAdriansyah Putra TaufikSenior RNPO EngineerHuawei Indonesia NIS

[email protected] / [email protected]


Case Type

Performance Analysis

Alarm Analysis

Drive test Analysis

Configuration Analysis

HISILICON SEMICONDUCTORHUAWEI TECHNOLOGIES CO., LTD.

Case 1 : Late 2G Cell Reselection

Country I Project A Region W City B Technology : 2G Vendor : Huawei Case Type : Drive Test Analysis – Configuration analysis Description : Improper 2G Idle Parameter make bad coverage in several spot Keyword : Rx Lev Access Min Conclusion : Too high Rx Lev Access Min make limited coverage for selected cell



We found problem during FAC test , which have late cell reselection so Rx Level can not achieve and make bad spot

Cell KB054GB did not want to cell reselection to Cell BD022GA , even the distance nearest from BD022GA and have good signal. Also we must take analysis for this cell selection reselection. Please see BD022GA have better Rx Level , but have worse C1 and C2 from KB054GB



So based on Cell Reselection criteria and formula ,we can check parameter which have improper settingLike : Rx Lev_Access_Min , MS_TXPWR_MAX_CCH,CRO , TO and PT


Case 1 : Late 2G Cell Reselection After we do parameter checking , we found improper RxLev_Access_min in Cell BD022GA [25] , so we roll back again into default value [8]

Parameter Explanation


Case 1 : Late 2G Cell Reselection After parameter roll back (Rx lev_access_min) into default value in Cell BD022 , cell reselection process become normal, and coverage bad spot become better


Case 2 : Wrong TRX Parameter

Country I Project A Region W City C Technology : 2G Vendor : Huawei Case Type : Performance Analysis – Configuration Analysis Description : Improper 2G TRX Parameter make performance degradation Keyword : TRX – Receive Mode and Send Mode – BTS 3012 Conclusion : 2G TRX Parameter must be audited (for Huawei BTS 3012 Series) for periodically to avoid

performance degradation because wrong parameter


Case 2 : Wrong TRX ParameterWe found a cell which have many Handover fail count day per day and make high CDR and low HOSR. After we review Neighbor List relationship is normal , Handover parameter is default. No alarm or hardware issue. Then we check TRU Configuration for that cell and for receive mode is independent receiver (it must be dividing receiver)

TRX / TRU Parameter must be following this rule


Case 2 : Wrong TRX Parameter

Page 11

After revise TRU / TRX Configuration parameter in Cell KC020GA from independent receiver into dividing receiver , there is KPI OSS improvement in CDR and HOSR

KC020GA TCH Drop Rate Vs Number of TCH Drop

0.00%1.00%2.00%3.00%4.00%5.00%6.00%7.00%8.00%

0

5

10

15

20

25

30

TCH Drop Rate

#Drop TCH

KC020GA HOSR Vs Fail Intra BSC HOSR

75.00%

80.00%

85.00%

90.00%

95.00%

100.00%

105.00%

01020304050607080

HOSR Total

#Fail IntraBSC14 April date to changeparameter



Country I Project A Region W City T Technology : 2G Vendor : Huawei Case Type : Drive Test Analysis – Configuration Analysis Description : Improper 2G Idle Parameter make bad coverage in several spot Keyword : CRO Conclusion : CRO value parameter can make selected cell more aggressive or less aggresive



Page 13

We found a not good coverage (Rx Level in idle) in Cell TS022GB and very late to cell reselection to TS018GA (even already very near distance to TS018G) , so we do some method (check 2G idle parameter related)

Cell TS022GB did not want to cell reselection to other cell which have better Rx Level. After Check idle Parameter , because Cell TS022GB have CR0(2dB) : 1


Case 4 : Failed Inter BSC Handover

Country I Project A Region W City S Technology : 2G Vendor : Huawei Case Type : Performance Analysis – Configuration analysis Description : Failed Inter BSC Handover in border between Vendor Huawei with Vendor Ericsson Keyword : Inter BSC Handover - Invalid Cell Conclusion : Before analyze Inter BSC HOSR, please ensure neighbor in source BSC and Destination / Target

BSC and also every LAC CI in border must be registered in MSC


Case 4 : Failed Inter BSC Handover We found BG405GC have very bad Inter BSC HOSR value in daily , so we try to analyze (This site is border to Ericsson). So We try check via passive measurement counter (M2000) and 2G LMT tracing

After check via PM counter (M2000) , we can see almost handover request is fail


Case 4 : Failed Inter BSC Handover From tracing file we can get cause value is invalid cell , so we must create cell / define cell in the Destination BSC and ensure LAC CI already registered in MSC

Check Contain Message from LMT Tracing


Case 5 : BTS3900 Series Power Test

Technology : 2G Vendor : Huawei Case Type : Configuration Analysis Description : BTS3900 Power Test to ensure “Zero Traffic” / “Silent Cell” Keyword : BTS3900 - Zero Traffic – Forward Power / Back Power Conclusion : We can get actual value for Forward and Back Power remotely for BTS 3900 Series


Case 5 : BTS3900 Series Power TestOne of method to check TRX Quality / Performance / working condition for BTS3900 Series is with Test Site Performance in BSC6000 and test BTS Performance test with MML command in BSC6900.

Press CTRL+Shift+F12 to enter super admin mode so we can get site

performance test in BTS Performance – Internal Maintenance

– Test Site Performance

Result

Sample

Site Performance Test in BSC6000

systemFrom TRX Site Performance Test we can get

actual value for Forward Power / Back Power and power level. If Forward / Back Power value is zero

mean Module is faulty / problem


Case 5 : BTS3900 Series Power TestTo test BTS Site Performance in BSC6900 (MML Based), first is to write MML Command TST BTSPERFTEST then press “Generate Input interface” then wait for a moment then add BTS ID and TRX ID based on id type.

From TRX Site Performance Test we can get actual value for Forward Power / Back Power and power level. If Forward / Back Power value is zero mean

Module is faulty / problem

Site Performance Test in BSC6900

using MML Command


Case 6 : BTS3900 Problem

Country I Project A Region W City K Technology : 2G Vendor : Huawei Case Type : Performance Analysis – Drive Test Analysis – Configuration Analysis Description : BTS3900 Problem make “Zero Traffic” / “Silent Cell” Keyword : BTS3900 - Zero Traffic – Forward Power / Back Power Conclusion : To ensure whether there is Zero Traffic / Silent Cell we can analysis with these step :

a. Traffic Data from performance measurement

b. Call Attempt from performance measurement

c. Drive test check

d. Power Test (Internal maintenance)


Case 6 : BTS3900 ProblemWe found 2 cell no serving during drive test , these two cells is BTS3900 , se we check site status , The sites look normal (With “Green” indicator) and no alarm found.


Case 6 : BTS3900 ProblemAfter we check that 2 cells have no TCH traffic and no call seizures (K3013A). So we check alarm again , there is no major alarm.Also we check parameter and the all parameter is default. So suspect must be TRX. So we do internal maintenance – site performance


Case 6 : BTS3900 ProblemWe do a site performance test . And the result for cell which can not serving is has back power 0 dBm , it means TRX faulty. So the problem found because DRFU Faulty (Hardware Faulty).


Case 7 : Power Level make Coverage Degradation

Country I Project A Region W City K Technology : 2G Vendor : Huawei Case Type : Drive Test Analysis – Configuration Analysis Description : Power Level Parameter impact to coverage degradation Keyword : Power Level Conclusion : Greater Power Level parameter value can make transmit power reduce by 2 dB for every add 1

level value


Case 7 : Power Level make Coverage DegradationWe found coverage degradation in K area, even customer declare there is new site on air in K area. So we must verify Actual data configuration whether there is new site and check bad spot / problem to analyze

Problem 1

Problem 2

Problem 3

Coverage Before Coverage After


Case 7 : Power Level make Coverage DegradationFirst we must ensure from actual data configuration – LMT BSC6000 for new site information based on customer information, after check for sites with red circle still off air

Problem 1

Problem 2

Problem 3

Verify site

information via

LMT BSC

Based on LMT BSC, all sites with red circle is still off air, but the problem , why the coverage is still degraded ? Please see

next slide


Case 7 : Power Level make Coverage DegradationProblem Area 1 : We found coverage degradation in problem area 1, then we compare 2 data configuration (parameter consistency check) then we found parameter change in power level, for the newer data configuration power value is 1 which mean BTS transmit power decrease by 2 dB

From Old data we found “0” Power level

value

From New data we found “1” Power level

value




value


value


Case 7 : Power Level make Coverage Degradation

Power Level Parameter

Explanation


Case 8 : Site Audit Founding (1)

Country I Project A Region W City C Technology : 2G Vendor : Huawei Case Type : Drive Test Analysis Description : Improper Feeder Type and limitation antenna installation make coverage not optimal Keyword : Azimuth – Feeder Type


Case 8 : Site Audit Founding (1)Our team found bad coverage even already optimize power level and power type, but bad coverage still occur. So we proposed to site audit. Then from site audit found discrepancy feeder type and antenna limitation because using “Mobile BTS” for tower structure.

From site audit , we found feeder type is 7/8 “ but in design and planning data

it must be 5/4 “

Also we found antenna

limitation Coverage not optimal

because these two factor : discrepancy feeder type and antenna limitation


Case 9 : Site Audit Founding (2)

Country I Project A Region W City C Technology : 2G Vendor : Huawei Case Type : Drive Test Analysis Description : Improper antenna installation make coverage not optimal Keyword : Antenna azimuth installation


Case 9 : Site Audit Founding (2)Our team found bad coverage even already optimize power level and power type, but bad coverage still occur. So we proposed to site audit. Then from site audit found improper antenna installation

From site audit , we found antenna limitation so

coverage can not optimum to serve in several / selected

area


Case 10 : Can Not Access 2G PS

Country I Project A Region W City T Technology : 2G Vendor : Huawei Case Type : Drive Test Analysis – Performance Analysis – Configuration Analysis Description : NSVC Parameter not defined in PCU outer make all user in one city can’t access 2G PS. Keyword : PCU – TBF – NSEI Conclusion : To verify 2G PS Access Parameter can be check :

a. PS Drive Test

b. PS Cell Check (PTPBVC)

c. NSEI Check

d. Gb (From BSC to SGSN) Performance measurement check

e. Pb (From BSC to PCU) Performance measurement check (If the PCU is “separated” or “not integrated” with BSC


Case 10 : Can Not Access 2G PSBefore we analyze, better we must know some parameter in 2G PS

1.Pb Interface : Interface between BSC to PCU

2.Gb Interface : Interface between BSC to SGSN

3.NSVC : Virtual Connection between the BSC and the SGSN

4.PCU : Packet Control Unit

5.PTPBVC: Same like Cell in GSM but use in GPRS

6.TBF: Kind of physical connection used for the transmission of the

data between the MS RR entity and the BSS RR entity. It exist during

data transmission only


Case 10 : Can Not Access 2G PSWe get complaint by customer, one city can’t access 2G PS for several days. So we do Drive test and performance analysis in this area.

We try 2G PS Test in Cell A Site A, then we found PS Access Failure which have message

“The PPP Link Control Terminated”

Also we try 2G PS Test in Cell B Site B, then we found same event RAS Error with PS Access Failure which have same message “The PPP

Link Control Terminated”


Case 10 : Can Not Access 2G PSAfter we get 3 sample cell to do PS Test and we check radio condition, we can temporary summarize the problem is not in Radio Part

Finally we try 2G PS Test in Cell C Site C, then we found same event RAS Error with PS

Access Failure which have same message “The PPP Link Control Terminated”

Based on coverage Drive Test (Rx

Level) , there is no radio problem in

Cell C Site C


Case 10 : Can Not Access 2G PSFrom Pb Interface performance analysis, we get all counter related to resource blocking (Blocked circuit) and resource problem (faulty circuit and maintenance problem) have “zero” counter. So we can temporary summarize there is no problem between PCU to BSC interface


Case 10 : Can Not Access 2G PSFrom Gb interface performance analysis using TBF establishment analysis, we can see in chart whether there is problem in Gb Link because there is “zero” downlink TBF establishment attempts meanwhile there is number in uplink TBF establishment attempt.

From TBF establishment analysis, we can conclude whether there is problem in Gb link because there is no

TBF establishment in DL which mean there is no

data transmission between PS domain to Mobile Station Side direction


Case 10 : Can Not Access 2G PSSo next step we check PCU (PCU Outer Model) Data Configuration for every cell (PTPBVC) status like activation and normal state. And as we can see the result is normal and active, so the PTPBVC / cell run normal

From PTP BVC (Cell in PS domain) in PCU data

Configuration check all Cell active and normal.


Case 10 : Can Not Access 2G PSSo next step is to check NSVC Status to check NSEI (Like LAC in 2G CS). From all PCU Outer only PCUTS01 doesn’t have NSVC and NSEI definition which is have complaint in one city and zero downlink TBF establishment attempt.

For every PCU Outer status in W Region, only PCUTS01 doesn’t have NSEI Table definition which inline with problem in one city can not

access 2G PS.

Actual Data Capture in PCU show NSVC Status in PCUTS01

has empty table which mean NSEI

didn’t define

Actual Data Capture in PCU show NSVC Status in other PCU

has NSEI Table define


Case 10 : Can Not Access 2G PSConclusion : Based on Drive Test Result, we found event RAS Error with PS Access Failure which message “The PPP Link Control Terminated” and also founding based on performance measurement data there is “zero” data for downlink TBF establishment attempt . Then based on data configuration as we can see there is no NSEI (like LAC in 2G CS) definition so this make can not access 2G PS


Case 11 : Power Control Parameter Set Too Aggressive Make Degradation Coverage during Dedicated Mode

Country I Project A Region W City C Technology : 2G Vendor : Huawei Case Type : Drive Test Analysis – Configuration Analysis Description : During drive test in dedicated mode, we get degradation if we compare to idle mode, after we check

data configuration – we found power control parameter too aggressive so for temporary solution we disable power control to ensure there is no coverage reduction during dedicated

Keyword : Huawei Power Control II Conclusion : If we set power control parameter threshold too aggressive can make coverage reduction due to

decrease step level from power control adjustment in action zone.


Case 11 : Power Control Parameter Set Too Aggressive Make Degradation Coverage during Dedicated Mode (HW PC II Intro)

Before we enter to analysis, better we must know Huawei Power Control II Method. As Per chart below, power control can be applied / start / works whether entering area / criteria of UL/DL Qual Upper – Lower Threshold and area / criteria of UL/DL RX_Lev Lower - Upper threshold. Then action it’s depend by it criteria it self

Action Zone

Receive Level



Below picture are RX level threshold parameter explanation for power control parameter “windowing” / prerequisite for action zone



Below picture are RX qual threshold parameter explanation for power control parameter “windowing” / prerequisite for action zone



We get Rx Level much reduce during drive test in dedicated mode compare to idle mode in several cells.

Idle mode Dedicated mode



Also snapshot below show there is much reduce for Rx level during dedicated mode compare to idle mode.

Idle mode Dedicated mode



Then we try to temporary disable downlink power control to ensure there is problem in power control algorithm. So we conclude there is “improper” power control threshold like DL/UL Lower – Upper Level / qual threshold which make power control start in good Rx Level / Rx Qual and also maybe power control action like reduction step level is too much (like 8 dB to decrease)

Dedicated Mode with power control enable

Dedicated mode with power control disable

Downlink power control disabled


Case 12 : 2G Ping-Pong Handover (Too frequent Handover)

Country I Project A Region W City T Technology : 2G Vendor : Huawei Case Type : Drive Test Analysis Description : During drive test we get bad Rx Qual, after do RF analysis we get one cell overshoot and serving

site azimuth is not to wide only 30 degree Keyword : Rx Qual - Ping Pong HO Conclusion : To ensure good RX Qual beside we must consider good ARFCN Plan – other cell/site overshoot, is

to check actual site / cell azimuth/ bearing whether difference between one sector to other sector is too tight or not to wide



Problem Spot 1

Problem Spot 2

Problem Spot with many Ping Pong HO

Happened



Problem Spot 1

Ping-pong HO happened becauseCM035 Sector A overshoot

This problem spot area must be serve by CM035 Sector B not

Sector A, so next step is to do site audit to check azimuth and tilting



Site ID Problem Date Of OptimizationAzimuth Mechanical Electrical

before after before after before after

CM043GA All DT Item (Change Route) 30-Apr-09 35 20 0 4 0 0

CM043GB All DT Item (Change Route) 30-Apr-09 170 170 0 4 0 2

CM043GC All DT Item (Change Route) 30-Apr-09 335 335 0 0 0 0

Ping Pong HO happened because Sector separator too close for CM043GC and CM043GA (Only 35 degree)

Suggestion make CM043GCAzimuth around 300-315 or CM043GA azimuth around 35-45


Case 13 : External Interference (Uplink Interference) Problem make Call Drop degradation

Country I Project T Region E Technology : 2G Vendor : Huawei Case Type : Configuration Analysis – Performance Analysis Description : We found call drop degradation in BSC and in one area, after we check there is increase number

interference band in several cell in same area which mean indicate there is external interference Keyword : Interference Band Conclusion : One of way to analyze to check call drop rate degradation is to check interference band (SDCCH-

TCHH-TCHF)



2G Interference Band Explanation



There is TDR,HOSR and There is TDR,HOSR and SDSR degradation from 22 SDSR degradation from 22

December in December in BSC_jemberbukit4BSC_jemberbukit4



There is CM330 (Call Drop There is CM330 (Call Drop on radio interface in stable on radio interface in stable

state) and CM331 (Call state) and CM331 (Call Drop on radio interface in Drop on radio interface in handover state) increase handover state) increase number in 22 December number in 22 December

2010 and lead to KPI 2010 and lead to KPI DegradationDegradation



There is H3028Ca (Failed internal intra-cell handovers) number increase and lead to CM331 Increase, also there is M3201A (Call drop There is H3028Ca (Failed internal intra-cell handovers) number increase and lead to CM331 Increase, also there is M3201A (Call drop due to Connection fail) number increase and lead to CM330 Increasedue to Connection fail) number increase and lead to CM330 Increase



There is no related alarm to KPI degradation in 22 december 2010, in 23 December 2010 there is alarm related to transmission.There is no related alarm to KPI degradation in 22 december 2010, in 23 December 2010 there is alarm related to transmission.So we can conclude there is no related alarm to this case (Call Drop Degradation)So we can conclude there is no related alarm to this case (Call Drop Degradation)



- Interference Band give related analysis about interference which is related to SDCCH Success Rate- Interference Band give related analysis about interference which is related to SDCCH Success Rate- There is no degradation in In SDCCH/TCHF/TCHH Interference Band Percentage for Band 1+2+3, but there is degradation for Band 1+2 inThere is no degradation in In SDCCH/TCHF/TCHH Interference Band Percentage for Band 1+2+3, but there is degradation for Band 1+2 in 22 December 201022 December 2010



-- We make problem cell list based on TDR Performance , so we calculate number of call drop count after 22 december 2010 (when the - We make problem cell list based on TDR Performance , so we calculate number of call drop count after 22 december 2010 (when the performance degraded) and before 22 december 2010performance degraded) and before 22 december 2010



64

Highlight : (Find from cell which have high different call drop count from 23 Dec until 21 Dec)Highlight : (Find from cell which have high different call drop count from 23 Dec until 21 Dec)-There is main or diversity average RSSI around -92 dBm in Pakusari-1 And Unmuh Jember-0There is main or diversity average RSSI around -92 dBm in Pakusari-1 And Unmuh Jember-0- Both Pakusari-1 and Unmuh Jember-0 have high different call drop between 23 december and 21 decemberBoth Pakusari-1 and Unmuh Jember-0 have high different call drop between 23 december and 21 december

Scan Frequency Result In Pakusari-1 and Unmuh Jember-0 (Problem Cell)



65

Highlight : (Find from cell which have high different call drop count from 23 Dec until 21 Dec)Highlight : (Find from cell which have high different call drop count from 23 Dec until 21 Dec)-There is main or diversity average RSSI around -92 dBm in Arjasa Jember-2 and Jelbuk-2There is main or diversity average RSSI around -92 dBm in Arjasa Jember-2 and Jelbuk-2- Both Arjasa Jember-2 and Jelbuk-2 have high different call drop between 23 december and 21 decemberBoth Arjasa Jember-2 and Jelbuk-2 have high different call drop between 23 december and 21 december

Scan Frequency Result In Arjasa Jember-2 and Jelbuk-2 (Problem Cell)



66

Highlight : (Find from cell which have no or low different call drop count from 23 Dec until 21 Dec)Highlight : (Find from cell which have no or low different call drop count from 23 Dec until 21 Dec)-There is main or diversity average RSSI around -102 dBm in perum alfa-0 and sukorambe relok jember-0There is main or diversity average RSSI around -102 dBm in perum alfa-0 and sukorambe relok jember-0- Both perum alfa-0 and sukorambe relok jember-0 have low or no different call drop between 23 december and 21 decemberBoth perum alfa-0 and sukorambe relok jember-0 have low or no different call drop between 23 december and 21 december

Scan Frequency Result In Perum Alfa-0 and Sukorambe Relok Jember-0 (Normal Cell)



67

Highlight : (Find from cell which have no or low different call drop count from 23 Dec until 21 Dec)Highlight : (Find from cell which have no or low different call drop count from 23 Dec until 21 Dec)-There is main or diversity average RSSI around -102 dBm in Jelbuk-0There is main or diversity average RSSI around -102 dBm in Jelbuk-0- Jelbuk-0 has low or no different call drop between 23 december and 21 decemberJelbuk-0 has low or no different call drop between 23 december and 21 december

Scan Frequency Result in Jelbuk-0 (Normal Cell)



68

Highlight :Highlight :- Interference Band give information about interference which is related to SDCCH Success Rate- Interference Band give information about interference which is related to SDCCH Success Rate- There is degradation in In SDCCH/TCHF/TCHH Interference Band Percentage for Band 1+2 fromThere is degradation in In SDCCH/TCHF/TCHH Interference Band Percentage for Band 1+2 from 22 December 201022 December 2010

Interference Band Percentage In Pakusari-1 (Problem Cell)



69


Interference Band Percentage In Unmuh Jember-0 (Problem Cell)



70


Interference Band Percentage In Arjasa Jember-2 (Problem Cell)



71

Highlight :Highlight :- Interference Band give information about interference which is related to SDCCH Success Rate- Interference Band give information about interference which is related to SDCCH Success Rate- There is no degradation in In SDCCH/TCHF/TCHH Interference Band Percentage for Band 1+2 fromThere is no degradation in In SDCCH/TCHF/TCHH Interference Band Percentage for Band 1+2 from 22 December 201022 December 2010

Interference Band Percentage In Jelbuk-0 (Normal Cell)



72

Highlight :Highlight :- Interference Band give information about interference which is related to SDCCH Success Rate- Interference Band give information about interference which is related to SDCCH Success Rate- There is no degradation in In SDCCH/TCHF/TCHH Interference Band Percentage for Band 1+2 fromThere is no degradation in In SDCCH/TCHF/TCHH Interference Band Percentage for Band 1+2 from 22 December 201022 December 2010

Interference Band Percentage In Jelbuk-0 (Normal Cell)



73

From analysis chart we can conclude there is TDR and HOSR Degradation meanwhile we found increase number of interference band in several cell



74

From analysis chart we can conclude there is SDSR and EMD (Erlang Minute Drop) Degradation meanwhile we found increase number of interference band in several cell which mean “indicate” external interference in some cell


Case 14 : Call Drop Due To Equipment Failure because Alarm in A Interface Board

Country I Project T Region E Technology : 2G Vendor : Huawei Case Type : Configuration Analysis – Performance Analysis Description : We found call drop degradation in BSC and in one area, after we check there is increase number

interference band in several cell in same area which mean indicate there is external interference Keyword : Call Drop due to Equipment Failure Conclusion : One of way to analyze to check call drop rate degradation is to check interference band (SDCCH-

TCHH-TCHF)

technical study case sharing_ver0

Documents

diversity

sdcch success

event ras

ps access

scan frequency

access 2g

dedicated

sukorambe