Optimization Process Metrotelworks

METROTEL WORKS Company Confidential 1

OPTIMIZATION PROCESSOPTIMIZATION PROCESS IP data check.IP data check. Dump verification.Dump verification. KPI’s monitoringKPI’s monitoring Alarms checkAlarms check


Activity on the basis of checkActivity on the basis of check Raise CRF if any discrepancy in data.Raise CRF if any discrepancy in data. Send DT team in confirmation of Send DT team in confirmation of

Alarm removal.Alarm removal. Physical verification report.Physical verification report. DT file analysis.DT file analysis. Start fine tuning of parameter.Start fine tuning of parameter.


KPI’s to be monitorKPI’s to be monitor SD BlockingSD Blocking SD DropSD Drop TCH BlockingTCH Blocking TCH AssignmentTCH Assignment TCH DropTCH Drop HOSRHOSR


Reasons for SD BlockingReasons for SD Blocking High Utilization of SD.High Utilization of SD. Signaling load at LAC boundary.Signaling load at LAC boundary. Time slot faulty.Time slot faulty. Site location ( Airport, etc).Site location ( Airport, etc).


Solutions for removal of Solutions for removal of SD BlockingSD Blocking

Check the No. of SDCCH channel Check the No. of SDCCH channel Available, if less then increase SD channel Available, if less then increase SD channel taking care that there is no TCH Blocking.taking care that there is no TCH Blocking.

Check LAC boundary, If location update is Check LAC boundary, If location update is more then change the LAC of that site.more then change the LAC of that site.

Use of Dynamic SDCCH (It is a BSC Use of Dynamic SDCCH (It is a BSC parameter and will be applied on whole parameter and will be applied on whole BTS).BTS).

Hardware check / shift SD to new time slotHardware check / shift SD to new time slot


Reasons of SD DropReasons of SD Drop Wrong Parameter Planning.Wrong Parameter Planning. Hardware Fault.Hardware Fault. External Interference.External Interference. OvershootingOvershooting High TCH utilizationHigh TCH utilization


Check for Wrong Parameter Check for Wrong Parameter Planning.Planning.

Check the BCCH Plan (C/I or C/A).Check the BCCH Plan (C/I or C/A). Co-BSIC & Co BCCH.Co-BSIC & Co BCCH. LAC Planning.LAC Planning. If a cell is picking call from long distance, Check If a cell is picking call from long distance, Check

the sample log according to TA (using MMR).the sample log according to TA (using MMR). Cell orientation need to be define according to Cell orientation need to be define according to

clutter.clutter. Check the Timer T 3101, It should be 3.5 sec.Check the Timer T 3101, It should be 3.5 sec. Check the Timer T 200 (N 200 in Ericsson Check the Timer T 200 (N 200 in Ericsson

system), It should be 780 ms.system), It should be 780 ms.


Cure for SD Drops due to Low Cure for SD Drops due to Low Signal StrengthSignal Strength

If the drop call is due to low signal strength uplink, If the drop call is due to low signal strength uplink, check the receive path of this particular TRX. Check check the receive path of this particular TRX. Check receiver sensitivity, VSWR, feeder connection and etc. receiver sensitivity, VSWR, feeder connection and etc. Drops due to Low Signal StrengthDrops due to Low Signal Strength

If the drop call reason is due to low signal strength If the drop call reason is due to low signal strength downlink, then, check the transmit path. Check CDU, downlink, then, check the transmit path. Check CDU, RTX card, feeder and etc. Drops due to TCH Congestion.RTX card, feeder and etc. Drops due to TCH Congestion.

It is also possible to have a high percentage of drops on It is also possible to have a high percentage of drops on SDCCH but a low percentage of drops on TCH this could SDCCH but a low percentage of drops on TCH this could happen, for example, if the SDCCH were put on the happen, for example, if the SDCCH were put on the BCCH frequency, and the frequency plan were different BCCH frequency, and the frequency plan were different for the BCCH than for non-BCCH frequencies It is for the BCCH than for non-BCCH frequencies It is possible that the interference situation is worse on the possible that the interference situation is worse on the BCCH, thereby causing relatively high percentage of BCCH, thereby causing relatively high percentage of drops on SDCCH compared to TCH, To reduce this drops on SDCCH compared to TCH, To reduce this Shifting of SDCCH can also be done. This trick will be Shifting of SDCCH can also be done. This trick will be good to reduce CNDROPS from the cell but ICM will not good to reduce CNDROPS from the cell but ICM will not decrease too much.decrease too much.


Interference in the Transmission Interference in the Transmission frequenciesfrequencies

Solution: Interference due to Microwave frequencies is not Solution: Interference due to Microwave frequencies is not captured in the KPI’s , but if the drop due to other reasons are captured in the KPI’s , but if the drop due to other reasons are high than there is possibility of interference due to MW high than there is possibility of interference due to MW frequenciesfrequenciesCounters available for checking Transmission Counters available for checking Transmission related problems (Counters for LapD can be mapped).related problems (Counters for LapD can be mapped).


Reload of IDB/CF (for alarm 2A-53)Reload of IDB/CF (for alarm 2A-53)

At time DXU software gets hanged which results in At time DXU software gets hanged which results in failureTCHfailureTCH assignment assignment allocation. A reload of IDB at site allocation. A reload of IDB at site or CF reload clears this software hangingAudit of A-Ter or CF reload clears this software hangingAudit of A-Ter Link.Link.

Now the reason why this impacts the SDCCH drops other Now the reason why this impacts the SDCCH drops other is probably because TRA pool congestion and Ater is probably because TRA pool congestion and Ater congestion will lead to subscribers making repeated congestion will lead to subscribers making repeated attempts and no devices being available for them. One attempts and no devices being available for them. One may think that this should lead to SDCCH blocking more may think that this should lead to SDCCH blocking more than SDCCH drops ,other reasons. That is true but the than SDCCH drops ,other reasons. That is true but the thing of note here is that at the time of setup, on an thing of note here is that at the time of setup, on an average SDCCH (signaling) is there for a very less average SDCCH (signaling) is there for a very less duration (2/3 seconds MAX, as opposed to TCH drops) duration (2/3 seconds MAX, as opposed to TCH drops) and the congestion in Ater and TRA devices will lead to and the congestion in Ater and TRA devices will lead to further attempts and therefore drops which are pegged further attempts and therefore drops which are pegged as Other reasons. Moreover where are these drops as Other reasons. Moreover where are these drops taking place?-not at the BSC ,but at the Ater between the taking place?-not at the BSC ,but at the Ater between the BSC/RBSC and the transcoder,so logically all the above BSC/RBSC and the transcoder,so logically all the above will be known to the BSC as drops due to other reasonswill be known to the BSC as drops due to other reasons. .


SD Drop due to excessive TASD Drop due to excessive TA Use RNO specially MRR for coverage confinements and to find Use RNO specially MRR for coverage confinements and to find

bad BCCHs .it helps if Cell is over shooting or taking traffic bad BCCHs .it helps if Cell is over shooting or taking traffic from TA>40,this can considered for coverage confinement or from TA>40,this can considered for coverage confinement or will be suitable candidate for height reductions.will be suitable candidate for height reductions.

Cell OvershootingCell Overshooting For Example----For Example----

A% of Cell picking call from Distance Y------And Meeting KPI’s. A% of Cell picking call from Distance Y------And Meeting KPI’s. (% of A should be >95)(% of A should be >95) (100-A%) of Cell picking call beyond Distance Y----Not Meeting KPI’s(100-A%) of Cell picking call beyond Distance Y----Not Meeting KPI’s

Therefore Distance Y will confirms the Criteria of Distance of Therefore Distance Y will confirms the Criteria of Distance of Overshoot of a cell.Overshoot of a cell.


Hardware FaultHardware Fault Check Path Imbalance.Check Path Imbalance. VSWR of the Cell.VSWR of the Cell. Connector Connection.Connector Connection. TRX conditionTRX condition Mount position and Effective Tilt.Mount position and Effective Tilt.


External InterferenceExternal Interference May be due to CDMA or May be due to CDMA or

External/Unwanted resource.External/Unwanted resource. Check the ICM band value of that Check the ICM band value of that

site.site. It should be ideally 0.It should be ideally 0. Use BPF (Band pass filter).Use BPF (Band pass filter).


TCH BlockingTCH Blocking Implement half rate or Dual rate.Implement half rate or Dual rate. If Dual rate implemented already If Dual rate implemented already

then change the value of FRL and then change the value of FRL and FRU.FRU.

Add another TRX.Add another TRX. If TRX addition not possible, try to If TRX addition not possible, try to

share the traffic of that cell with the share the traffic of that cell with the neighboring cell by changing tilt or neighboring cell by changing tilt or orientation.orientation.


TCH AssignmentTCH Assignment For improving assignment, remove For improving assignment, remove

TCH Blocking.TCH Blocking. Check TRX condition.Check TRX condition. Path Imbalance.Path Imbalance. VSWR.VSWR. Connection from CDU and TRX.Connection from CDU and TRX. Connector connection.Connector connection.


See…See… TCH attempt=TCH Block+TCH TCH attempt=TCH Block+TCH

Allocated.Allocated. TCH Allocated=TCH miss (may be TCH Allocated=TCH miss (may be

block or SD Drop) +TCH Assigned.block or SD Drop) +TCH Assigned. It is not necessary that total TCH It is not necessary that total TCH

allocated will be assigned.allocated will be assigned.


Reasons for TCH DropReasons for TCH Drop Wrong Parameter Planning.Wrong Parameter Planning. Hardware Fault.Hardware Fault. External Interference.External Interference.


Wrong Parameter Planning.Wrong Parameter Planning. Check the BCCH Plan (C/I or C/A).Check the BCCH Plan (C/I or C/A). Co-BSIC & Co BCCH.Co-BSIC & Co BCCH. Check Co-BCCH.Check Co-BCCH. If a cell is picking call from long distance, Check If a cell is picking call from long distance, Check

the sample log according to TA.the sample log according to TA. Check the Timer T 100(RLT). It should be 20.Check the Timer T 100(RLT). It should be 20. Check the Neighbor Plan.Check the Neighbor Plan. Site Orientation and Tilt.Site Orientation and Tilt.


TCH Drop Reason, Low SS DL (%)TCH Drop Reason, Low SS DL (%)

If the drop call reason is due to low signal If the drop call reason is due to low signal strength downlink, then, check the strength downlink, then, check the transmit path. Check CDU, RTX card, transmit path. Check CDU, RTX card, feeder and etc.feeder and etc. Drops due to TCH Drops due to TCH Congestion.Congestion.

Check the proper coverage of the cell, Check the proper coverage of the cell, may be far off village getting the week may be far off village getting the week coverage. Avoid week coverage area. coverage. Avoid week coverage area. Coverage of the cell should be limited at Coverage of the cell should be limited at the point where there is no population.the point where there is no population.


TCH Drop Reason, Low SS UL (%)TCH Drop Reason, Low SS UL (%)

If the drop call is due to low signal If the drop call is due to low signal strength uplink, check the receive path strength uplink, check the receive path of this particular TRX. Check receiver of this particular TRX. Check receiver sensitivity, VSWR, feeder connection and sensitivity, VSWR, feeder connection and etc. Drops due to Low Signal Strength.etc. Drops due to Low Signal Strength.

Check whether main lobe of the cell is Check whether main lobe of the cell is not out of clutter, change the orientation.not out of clutter, change the orientation.

Use of TMA, while installing TMA it should Use of TMA, while installing TMA it should be properly check whether the cabling of be properly check whether the cabling of Bias Injector is done properly at BTS end.Bias Injector is done properly at BTS end.


Drop Reason, Bad Quality DL (%)Drop Reason, Bad Quality DL (%)

Go for BCCH and TCH Plan check.Go for BCCH and TCH Plan check. Site covered area…may be the Site covered area…may be the

populated area is suffering for High populated area is suffering for High C/I or C/A.C/I or C/A.

Check the Hopping plan.Check the Hopping plan. Check VSWR, Path imbalance.Check VSWR, Path imbalance.


Drop Reason, Bad Quality UL (%)Drop Reason, Bad Quality UL (%)

In addition to above , please check In addition to above , please check the ICM band condition. the ICM band condition.


Drop Reason, Suddenly Lost Drop Reason, Suddenly Lost Connections (%)Connections (%)

if drops are only on one site, then go for a if drops are only on one site, then go for a check for that particular even attach with check for that particular even attach with that site.that site.

If drops are on all sites connected to a If drops are on all sites connected to a single link, then check the slip or single link, then check the slip or interference on that Abis interface.interference on that Abis interface.

If Drops are distributed on all site of the If Drops are distributed on all site of the BSC, then check the slips on Ater.BSC, then check the slips on Ater.

Down Time of the cell.Down Time of the cell. TRX condition.TRX condition. BTS should not getting the temperature BTS should not getting the temperature

alarm continuously.alarm continuously.


Drop Reason, Excessive TA (%)Drop Reason, Excessive TA (%) Proper tilting required considering all Proper tilting required considering all

hot spots are covered.hot spots are covered. Effective tilt should be check…Effective tilt should be check… Mount position should be check. Mount position should be check.


Drop Reason, Other (%)Drop Reason, Other (%) Check Path Imbalance.Check Path Imbalance. VSWR of the Cell.VSWR of the Cell. Connector Connection.Connector Connection. TRX conditionTRX condition Mount position or Effective Tilt.Mount position or Effective Tilt.


HOSRHOSR Neighbor Planning should be good.Neighbor Planning should be good. In city neighbor should be planned to 2In city neighbor should be planned to 2ndnd layer, layer,

But in new town try to restrict to 1But in new town try to restrict to 1stst layer. layer. If reversion rate is high, check the hardware If reversion rate is high, check the hardware

condition, quality and Congestion on target cell.condition, quality and Congestion on target cell. If handover failure is due to low signal strength, If handover failure is due to low signal strength,

change the handover margin and also check the change the handover margin and also check the VSWR of source and target cell.VSWR of source and target cell.

If handover failure is due to bad signal quality, If handover failure is due to bad signal quality, check the C/A or C/I. In addition to this please check the C/A or C/I. In addition to this please check the hardware fault of that site. check the hardware fault of that site.

If there is lot of Ping-pong handover in the cell If there is lot of Ping-pong handover in the cell avoid overlapping cell by tilting the cell.avoid overlapping cell by tilting the cell.


Attention….Attention…. If Intra Handover failure is occurring, Check If Intra Handover failure is occurring, Check

the hardware and Blocking of all the sec.the hardware and Blocking of all the sec. Case I- If there is Path Imbalance in sec B, Case I- If there is Path Imbalance in sec B,

then there is possibility that there will be then there is possibility that there will be handover failure from A-handover failure from A-B and C-B and C-B. And B. And there will be also intra cell handover failure in there will be also intra cell handover failure in sec B whenever call will be transfer to Faulty sec B whenever call will be transfer to Faulty TRX.TRX.

Case II- If there is Blocking in sec B, then there Case II- If there is Blocking in sec B, then there is possibility that there will be handover failure is possibility that there will be handover failure from A-from A-B and C-B and C-B. B.

Please check Co-BSIC & Co-BCCH.Please check Co-BSIC & Co-BCCH. And Co-BCCH during Neighbor Planning.And Co-BCCH during Neighbor Planning.


Other Criteria’s Can be kept in Other Criteria’s Can be kept in mind.mind.

MBC SynchronizationMBC SynchronizationComments : If the site is MBC than at Comments : If the site is MBC than at

times it happens that MBC cabinet times it happens that MBC cabinet goes out of sync bue to faulty ESB goes out of sync bue to faulty ESB cable, thus TCH cable, thus TCH assignment assignment allocation allocation on MBC doesn't happen which results on MBC doesn't happen which results in high SD drops due to other reasons. in high SD drops due to other reasons.


SDCCH drop can be triggered during an Assignment SDCCH drop can be triggered during an Assignment Failure alsoFailure also

There are a few cases where an assignment failure, which is There are a few cases where an assignment failure, which is indicated by the formula (1 - (TFCASSALL / TASSALL)), would indicated by the formula (1 - (TFCASSALL / TASSALL)), would be accompanied by an SDCCH drop (CNDROP).be accompanied by an SDCCH drop (CNDROP).

Case-I: if Congestion on TCH if there is congestion on TCH, the Case-I: if Congestion on TCH if there is congestion on TCH, the mobile will eventually be cleared from the SDCCH channel (case: mobile will eventually be cleared from the SDCCH channel (case: No Assignment Command, abnormal release, unspecifiedNo Assignment Command, abnormal release, unspecified), and ), and so CNDROP and CNRELCONG will be stepped.so CNDROP and CNRELCONG will be stepped.

Case-II: If NO Establishments on TCH or Fails to Case-II: If NO Establishments on TCH or Fails to return,----return,----Another case occurs when the mobile station never Another case occurs when the mobile station never establishes itself on the TCH and fails to return to SDCCH establishes itself on the TCH and fails to return to SDCCH (Unsuccessful Assignment on TCH, abnormal release (Unsuccessful Assignment on TCH, abnormal release unspecified). After a time-out in the BSC, the call is released by unspecified). After a time-out in the BSC, the call is released by sending a Channel Release (sending a Channel Release (cause: abnormal release cause: abnormal release unspecifiedunspecified).).

Case-III: if TCH Assignment failed---Case-III: if TCH Assignment failed---Another case can occur Another case can occur when the assignment to TCH failed, but the mobile succeeded to when the assignment to TCH failed, but the mobile succeeded to return to the old SDCCH. After a time-out, the system return to the old SDCCH. After a time-out, the system disconnects the call and sends a Channel Release with the cause disconnects the call and sends a Channel Release with the cause “abnormal release, unspecified.”“abnormal release, unspecified.”


CBCH Impact on Data & SDCCH UtilizationCBCH Impact on Data & SDCCH Utilization

Check for SDCCH Utilization, proper re-dimensioning should Check for SDCCH Utilization, proper re-dimensioning should be done for effective SDCCH use, though it will be helpful for be done for effective SDCCH use, though it will be helpful for reducing SDCCH Congestion, if any but at the same time if reducing SDCCH Congestion, if any but at the same time if SDCCH are getting hanged then you will not be short to SDCCH are getting hanged then you will not be short to SDCCH SDCCH

If you use CBCH, change to SDCCH/8 config, since GPRS has If you use CBCH, change to SDCCH/8 config, since GPRS has more system information to transmit over BCCH and it is more system information to transmit over BCCH and it is advisable to keep like this.advisable to keep like this.


High RACH FailuresHigh RACH Failures

Other reasons look for Random access statistics, if there is a Other reasons look for Random access statistics, if there is a lot of random access failures try to check hardware too. It lot of random access failures try to check hardware too. It includes thorough hardware audit including CF Reloading, IDB includes thorough hardware audit including CF Reloading, IDB Setting and reloading, Software synchronization ,filter check Setting and reloading, Software synchronization ,filter check etcetc))


DTAP IssueDTAP Issue Solution : Check for Connection refused messages sent Solution : Check for Connection refused messages sent

by MSC (before Setup message)by MSC (before Setup message) Comments : The losses due to DTAP issues may also be Comments : The losses due to DTAP issues may also be

result of subscriber related issues like faulty handsetresult of subscriber related issues like faulty handset))


Alarms DescriptionAlarms Description

For various alarms go though the attach Doc.


Internal BTS ConnectionInternal BTS Connection

2206 2964


Some timers…..Some timers….. T3212T3212 ---Time between periodic update of MS. ---Time between periodic update of MS.

SET by the MML command RLSBC. The value is SET by the MML command RLSBC. The value is sent to the MS in system information. The MS will sent to the MS in system information. The MS will do periodic update, if it is residing in the same do periodic update, if it is residing in the same location area at a time interval exceeding location area at a time interval exceeding T3212 T3212 . If the MS is roaming to a new location . If the MS is roaming to a new location area, update will be done anyway and the time to area, update will be done anyway and the time to next periodic update will start counting from zero next periodic update will start counting from zero again. again.

T3101T3101 ---Guard time for Immediate Assign. ---Guard time for Immediate Assign. Started as 'IMM_ASS_CMD' is sent to BTS and Started as 'IMM_ASS_CMD' is sent to BTS and stopped by reception of 'EST_IND' from BTS. The stopped by reception of 'EST_IND' from BTS. The allocated channel will be released at timer expiry. allocated channel will be released at timer expiry.


Ericsson Optimization ToolsEricsson Optimization Tools Winfoll.Winfoll. RNO--RNO--

(NCS,FAS,MRR,MTR,CTR,RIR,ABAL,O(NCS,FAS,MRR,MTR,CTR,RIR,ABAL,OMS,STS etc).MS,STS etc).

BO (Business Object).BO (Business Object).


WinfollWinfoll It is online status It is online status

tool, with the help tool, with the help of this tool you can of this tool you can directly login to directly login to any BSC and check any BSC and check and change the and change the status of any cell.status of any cell.

Command use to Command use to access the various access the various parameter are parameter are attach below.attach below.


RNORNO NCS-Neighboring Cell SupportNCS-Neighboring Cell Support

Neighboring Cell Support feature is to help the operator Neighboring Cell Support feature is to help the operator optimize neighboring cell lists in the network. This is optimize neighboring cell lists in the network. This is done by collecting data recorded from measurement done by collecting data recorded from measurement reports and handover statistics. In the BSC, this is reports and handover statistics. In the BSC, this is handled by the feature Active BA-list Recording. handled by the feature Active BA-list Recording. Neighboring Cell Support is operated through the Neighboring Cell Support is operated through the Operation and Support System (OSS).Operation and Support System (OSS).

This feature is load regulated, partly by the 3% rule, This feature is load regulated, partly by the 3% rule, partly by low-priority Base Level Load Control. The total partly by low-priority Base Level Load Control. The total load from this feature should not exceed 6% when there load from this feature should not exceed 6% when there is a shortage of CP capacity. Load peaks may occur at is a shortage of CP capacity. Load peaks may occur at BA-list reconfiguration, when test frequencies in BA-list BA-list reconfiguration, when test frequencies in BA-list are changed. In order to decrease CP load from this are changed. In order to decrease CP load from this feature, the number of cells can be reduced.feature, the number of cells can be reduced.


Continue…Continue… FAS- Frequency Allocation SupportFAS- Frequency Allocation Support

The purpose of Frequency Allocation The purpose of Frequency Allocation Support (FAS) is to facilitate the frequency Support (FAS) is to facilitate the frequency planning for the operator. The uplink planning for the operator. The uplink interference level for specified frequencies interference level for specified frequencies and cells are recorded by the feature Radio and cells are recorded by the feature Radio Interference Recording. After a recording is Interference Recording. After a recording is completed the results can be presented to completed the results can be presented to the operator via the OSS user interface.the operator via the OSS user interface.


Continue…Continue… MRR: Measurement Result RecordingMRR: Measurement Result Recording

MRR is an OSS tool for measuring and analyzing radio MRR is an OSS tool for measuring and analyzing radio characteristics. The feature makes it possible to extract characteristics. The feature makes it possible to extract information from the measurement results that are sent information from the measurement results that are sent from the base stations to the BSC. This feature is load from the base stations to the BSC. This feature is load regulated, partly by the 3% rule, partly by low-priority regulated, partly by the 3% rule, partly by low-priority Base Level Load Control.Base Level Load Control.During the recording, the collection and accumulation of During the recording, the collection and accumulation of measurement data is done in the TRH and the impact on measurement data is done in the TRH and the impact on CP load is therefore limited. In live tests no extra basic CP load is therefore limited. In live tests no extra basic load or load peaks have been observed from this load or load peaks have been observed from this feature. Some CP load increase is however likely at feature. Some CP load increase is however likely at activation and deactivation of the feature.activation and deactivation of the feature.Although actions should not be needed to reduce CP Although actions should not be needed to reduce CP load from this feature, the amount of data to collect load from this feature, the amount of data to collect (number of cells) can be limited to minimize load if (number of cells) can be limited to minimize load if desired.desired.


BO (Business Object).BO (Business Object). With the help of this tool, we can With the help of this tool, we can

generate the stats of the site before generate the stats of the site before four hour of fetching.four hour of fetching.

We can generate the stats Cell We can generate the stats Cell wise ,or BSC Wise hourly or for whole wise ,or BSC Wise hourly or for whole day.day.

BO generate the KPI’s only with other BO generate the KPI’s only with other related counters.related counters.


ConcludingConcluding Optimization start at very basic level, Optimization start at very basic level,

so the ground things need to be so the ground things need to be check.check.

Drive test to be done with proper Drive test to be done with proper guidance of Optimization Engg.guidance of Optimization Engg.


ThanksThanks Any further valuable addition will be Any further valuable addition will be

appreciated………..appreciated………..

Optimization Process Metrotelworks

Documents

low signal

frequency

wrong parameter

check receiver

neighboring

abnormal release

tch drop reason

drop call