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Investigation Flow Chart

Drop Call, Congestion, Handover Analysis & Procedure

Vendor: Ericsson

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Table of Contents

Investigation Flow Chart ....................................................... 1 I. Scope Of Work......................................................... 4

II. Introduction.......................................................... 4

III. Investigation Flow Chart ......................................... 4

IV. Drop Call Analysis .................................................. 5

V. Network Congestion ............................................. 13

VI. Handover Analysis ............................................... 15

VII. Metrica Related Reports ........................................ 26

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I. Scope Of Work

This document describes the procedure for investigating and diagnosing the performance-related network problems and recommends solutions and a checklist to identify and cease the causes thus improving network performance. Since RF parameters, counters, and tools are Vendor-Specific, the analysis described in this document is applicable only to Ericsson equipment. II. Introduction

The network’s key RF performance indices are drop call, congestion, and handover performance. In order to minimize the RF drop rate, resolve network congestion, and improve handover performance, a logical investigation flow chart is proposed in order identify the network faults and eliminate them. Recommendations, parameter check list is also proposed. III. Investigation Flow Chart The flow chart depicted in Fig-1 illustrates the methodology and the procedure used to identify the possible network problem and propose a check list to enable the RF engineer diagnosing the network performance degradation.

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Parameters set according to Best

Practices ?

Current Market Status:- KPI-Traffic

RN Database Audit

Correct Database Parameters

CNA (OSS) Consistency

Check

Any Inconsistencies

?

Correct InconsistenciesCongestion Audit

- Do Capacity Upgrade- Check CLS Parameters- Check Network Availability and Radio Blocked Resources

Any Congestion?

Drop Call Reason Analysis

Note: These steps can be done in parallel

Drops Other>10%, High Sudden Loss

Drops?

Low SS_UL Drops High?

O&M-Check H/W, T1s

Check for Faulty RBS H/W- Alarm Supervision- MRR

Identify cells needing TMAs(Using Stats and Link Budget)

Low SS_BL Drops High?

- Identify areas need Power Increase:TCC, S/W Power Boost, New Sites, High Gain Antennas, TDU

- Neighbor Optimization using NCS & Neighbor relations check

Quality Drops High?

Identify:- Boomer Sites- Areas with Bad Frequency Plan

Propose Solutions:- Power Decrease- Frequency Retunes- Antenna Downtilts- Antenna Changes- Antenna Height (RAD) Changes- BCCH in OL- AMR Parameter retune

Does Market meet KPI and Coverage Targets?

Performance Analysis using:- Metrica- Drive Test- MRR- NCS/NOX/FAS/FOX

Identify Worst Performing Cells

EXIT/FA

Possible Solutions:- Power Increase/Decrease- Frequency Retunes- Antenna Downtilts- Antenna Changes- Neighbor Addition/Deletion- Parameter retune

Investigation Flow Chart

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Yes

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No

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Fig-1 Investigation Flow Chart

IV. Drop Call Analysis

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Drop Call Reasons……… Low SS-UL Only Parameter Parameter Name MML Command Parameter Description

SSOFFSETULAFR RLIHP UL offset for signal strength in Db in AFR

SSDESULAFR RLAPP Signal strength for the UL AMR FR. Numeral 47 - 110

LOWSSUL RAEPP UL low SS limit used for counter – not used in HO algorithm

RLINKUP RLLDP Radio Link Timeout counter value on the uplink

SSDESUL RLPCP UL signal strength

SSLENUL RLPCP UL length of signal strength filter

Counter Counter Name Object Type Counter Description Metrica Report Heading

TFDISSUL CLTCHDRF Total No of dropped TCH-FR connections due to low SS on UL

CELLTCHD R1_30MIN

THDISSUL CLTCHDRF Total No of dropped TCH-HR connections due to low SS on UL

CELLTCHD R1_30MIN

TFDISSULA CLTCHDRF Total No of dropped AMR-FR TCH connections due to low SS on UL

CELLTCHD R1_30MIN

TFHISSULA CLTCHDRF Total No of dropped AMR-HR TCH connections due to low SS on UL

CELLTCHD R1_30MIN

TFNDROP CELTCHF Total No of dropped FR TCH in UL subcell.

CELLTCHF 1_30MIN

THNDROP CELTCHF Total No of dropped HR TCH in UL subcell.

CELLTCHF 1_30MIN

TFCASSALL CELTCHF No. of assignment complete messages on TCH-FR for all MS power classes.

CELLTCHF 1_30MIN

Low SS-DL Only Parameter

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Parameter Name Ass. MML CommandParameter Description

SSOFFSETDLAFR RLIHP DL offset for signal strength in dB in AFR

SSDESDLAFR RLAPP Signal strength for the DL AMR FR. Numeral 47 - 110

LOWSSDL RAEPP DL low SS limit used for counter – not used in HO algorithm

RLINKT RLSSP Radio link Timeout counter value for MS (D/L)

SSDESDL RLBCP Downlink desired signal strength at MS

REGINTDL RLBCP Downlink Power control regulation interval/period

SSLENDL RLBCP Length of Signal Strength averaging filter D/L DPC

BSPWRMIN RLBCP Minimum DL dynamic power level

MSTXPWR RLCPP Max. MS power while maintaining a TCH connection

BSPWRB RLCPP Base Station output power in dBm for the BCCH RF channel number.

BSPWRT RLCPP Base Station output power in dBm for the non-BCCH RF channel numbers.

BSPWR RLLOP Tx power on BCCH carrier (at reference point)

BSTXPWR RLLOP Tx power on non-BCCH carrier (at reference point)

Counter Counter Name Object Type Counter Description Metrica Report Heading

TFDISSDL CLTCHDRF Total No of dropped TCH-FR connections due to low SS on DL

CELLTCHD R1_30MIN

THDISSDL CLTCHDRF Total No of dropped TCH-HR connections due to low SS on DL

CELLTCHD R1_30MIN

TFDISSDLA CLTCHDRF Total No of dropped AMR-FR TCH connections due to low SS on DL

CELLTCHD R1_30MIN

TFHISSDLA CLTCHDRF Total No of dropped AMR-HR TCH connections due to low SS on DL

CELLTCHD R1_30MIN

TFNDROP CELTCHF Total No of dropped FR TCH in UL subcell.

CELLTCHF 1_30MIN

THNDROP CELTCHF Total No of dropped HR TCH in UL subcell.

CELLTCHF 1_30MIN

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TFCASSALL CELTCHF No. of assignment complete messages on TCH-FR for all MS power classes.

CELLTCHF 1_30MIN

Low SS-BL Parameter Parameter Name MML Command Parameter Description

BSRXMIN RLLOP Min. SS at BTS to consider n-cell a h/o candidate

MSRXMIN RLLOP Min. SS at MS to consider n-cell a h/o candidate

HIHYST RLNRP SS hysteresis when evaluating high SS cells

LOHYST RLNRP SS hysteresis when evaluating low SS cells

BSRXSUFF RLLOP Sufficient SS at a BTS to consider cell for PL rank

MSRXSUFF RLLOP Sufficient SS at MS to consider cell for PL ranking

SSEVALSD RLLFP RxLev averaging filter type on TCH

SSRAMPSD RLLFP Time to ramp up N-cell measurements on TCH

SSLENSD RLLFP Length of RxLev average. filter for SSEVALSD = 6 - 9

SSLENSI RLLFP Length of RxLev average filter for SSEVALSI = 6 - 9

MSTXPWR RLCPP Max. MS power while maintaining a TCH connection

BSPWRB RLCPP Base Station output power in dBm for the BCCH RF channel number.

BSPWRT RLCPP Base Station output power in dBm for the non-BCCH RF channel numbers.

BSPWR RLLOP Tx power on BCCH carrier (at reference point)

BSTXPWR RLLOP Tx power on non-BCCH carrier (at reference point)

Counter

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Counter Name Object Type Counter Description Metrica Report Heading

TFDISSBL CLTCHDRF Total No of dropped TCH-FR connections due to low SS on BL

CELLTCHD R1_30MIN

THDISSBL CLTCHDRF Total No of dropped TCH-HR connections due to low SS on BL

CELLTCHD R1_30MIN

TFDISSBLA CLTCHDRF Total No of dropped AMR-FR TCH connections due to low SS on BL

CELLTCHD R1_30MIN

TFHISSBLA CLTCHDRF Total No of dropped AMR-HR TCH connections due to low SS on BL

CELLTCHD R1_30MIN

TFNDROP CELTCHF Total No of dropped FR TCH in UL subcell.

CELLTCHF 1_30MIN

THNDROP CELTCHF Total No of dropped HR TCH in UL subcell.

CELLTCHF 1_30MIN

TFCASSALL CELTCHF No. of assignment complete messages on TCH-FR for all MS power classes.

CELLTCHF 1_30MIN

Bad RXQual-UL Only Parameter Parameter Name MML Command Parameter Description

QLIMUL RLLUP RxQual threshold on uplink (at BTS) for h/o. Lower threshold used for cells hopping over 6 or more frequencies

QLIMULAFR RLLUP Quality limit UL for handover. Numeral 0 - 100

QOFFSETULAFR RLIHP UL offset for quality in dtqu in AFR

QDESULAFR RLAPP Quality for the UL AMR FR. Numeral 0 - 70

QDESUL RLPCP Desired RxQual at BTS Rx QLENUL RLPCP Length of UL quality filter

BADQUL RAEPP UL BQ limit used for urgency counter – not used in HO algorithm

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Counter Counter Name Object Type Counter Description Metrica Report Heading

TFDISQAUL CLTCHDRF Total No of dropped TCH-FR connections due to bad quality on UL.

CELLTCHD R2_30MIN

THDISQAUL CLTCHDRF Total No of dropped TCH-HR connections due to bad quality on UL.

CELLTCHD R2_30MIN

TFDISQAULA CLTCHDRF Total No of dropped AMR-FR TCH connections due to bad quality on UL.

CELLTCHD R2_30MIN

THDISQAULA CLTCHDRF Total No of dropped AMR-HR TCH connections due to bad quality on UL.

CELLTCHD R2_30MIN

TFNDROP CELTCHF Total No of dropped FR TCH in UL subcell.

CELLTCHF 1_30MIN

THNDROP CELTCHF Total No of dropped HR TCH in UL subcell.

CELLTCHF 1_30MIN

TFCASSALL CELTCHF No. of assignment complete messages on TCH-FR for all MS power classes.

CELLTCHF 1_30MIN

Bad RXQual-DL Only Parameter Parameter Name MML Command Parameter Description

QLIMDL RLLUP

RxQual threshold on downlink (at MS) for h/o. Lower threshold used for cells hopping over 6 or more frequencies

QLIMDLAFR RLLUP Quality limit DL for handover. Numeral 0 - 100

QOFFSETDLAFR RLIHP DL offset for quality in dtqu in AFR

QDESDLAFR RLAPP Quality for the DL AMR FR. Numeral 0 - 70

QDESDL RLBCP Desired Qual in DL

BADQDL RAEPP DL BQ limit used for urgency counter – not used in HO algorithm

Counter Counter Name Object Type Counter Description Metrica Report Heading

TFDISQADL CLTCHDRF Total No of dropped TCH-FR connections due to bad quality on DL.

CELLTCHD R2_30MIN

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THDISQADL CLTCHDRF Total No of dropped TCH-HR connections due to bad quality on DL.

CELLTCHD R2_30MIN

TFDISQADLA CLTCHDRF Total No of dropped AMR-FR TCH connections due to bad quality on DL.

CELLTCHD R2_30MIN

THDISQADLA CLTCHDRF Total No of dropped AMR-HR TCH connections due to bad quality on DL.

CELLTCHD R2_30MIN

TFNDROP CELTCHF Total No of dropped FR TCH in UL subcell.

CELLTCHF 1_30MIN

THNDROP CELTCHF Total No of dropped HR TCH in UL subcell.

CELLTCHF 1_30MIN

TFCASSALL CELTCHF No. of assignment complete messages on TCH-FR for all MS power classes.

CELLTCHF 1_30MIN

Bad RXQual-BL Parameter Parameter Name MML Command Parameter Description

BQOFFSETAFR RLNRP Signal strength corridor in dB for bad quality urgency handover. Numeral 0 - 63

BQOFFSET RLNRP Bad RxQual h/o corridor or negative hysteresis

DMQB RLDMP Quality based switch from HR ->FR allow switch

DMQBAMR RLDMP Bad radio quality threshold to trigger for an IHO HR ->FR

DMQG RLDMP Quality based switch from FR ->HR allow switch

QEVALSD RLLFP RxQual averaging filter type on TCH

QLENSI RLLFP Length of RxQual average filter for QEVALSI = 6 - 9

QLENSD RLLFP Length of RxQual average filter for QEVALSD = 6 - 9

TINIT RLLBP Min. time before handover after call init. or handover

Counter Counter Name Object Type Counter Description Metrica Report Heading

TFDISQABL CLTCHDRF Total No of dropped TCH-FR connections due to bad quality on BL

CELLTCHD R2_30MIN

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THDISQABL CLTCHDRF Total No of dropped TCH-HR connections due to bad quality on BL

CELLTCHD R2_30MIN

TFDISQABLA CLTCHDRF Total No of dropped AMR-FR TCH connections due to bad quality on BL

CELLTCHD R2_30MIN

THDISQABLA CLTCHDRF Total No of dropped AMR-HR TCH connections due to bad quality on BL

CELLTCHD R2_30MIN

TFNDROP CELTCHF Total No of dropped FR TCH in UL subcell.

CELLTCHF 1_30MIN

THNDROP CELTCHF Total No of dropped HR TCH in UL subcell.

CELLTCHF 1_30MIN

TFCASSALL CELTCHF No. of assignment complete messages on FR-TCH for all MS power classes.

CELLTCHF 1_30MIN

Excessive TA Parameter Parameter Name MML Command Parameter Description

MAXTA RLLDP

Maximum timing advance permitted before disconnection. Normal cell can work to 63. RBS200 Xrange cell with SPP cards can work to 133 and new RBS2000 extended range hardware can work to 219.

TALIM RLLUP Timing advance threshold for handover

TAAVELEN RLLBP Timing Advance (TA) averaging window length

PTIMTA RLLPP Duration of penalty PSSTA for TA h/o

PSSTA RLLPP SS penalty on cell from which h/o occurs (TA)

Counter Counter Name Object Type Counter Description Metrica Report Heading

TFDISTA CLTCHDRF Total No of dropped FR TCH connections at excessive TA.

CELLTCHD R1_30MIN

THDISTA CLTCHDRF Total No of dropped HR TCH connections at excessive TA.

CELLTCHD R1_30MIN

TFDISTAA CLTCHDRF Total No of dropped AMR-FR TCH connections at excessive TA.

CELLTCHD R1_30MIN

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THDISTAA CLTCHDRF Total No of dropped AMR-HR TCH connections at excessive TA.

CELLTCHD R1_30MIN

TFNDROP CELTCHF Total No of dropped FR TCH in UL subcell.

CELLTCHF 1_30MIN

THNDROP CELTCHF Total No of dropped HR TCH in UL subcell.

CELLTCHF 1_30MIN

TFCASSALL CELTCHF No. of assignment complete messages on TCH for all MS power classes, FR-UL.

CELLTCHF 1_30MIN

Sudden Loss Parameter

Check the MAIO Assignment, HSN, Freq. Allocation of the DCHNO's, T1 and/or Radio Outages, DXU Faults, etc. Run RXMFP on the CF for faulty H/W, and run DTQDP on the DIP for T1 outages and slip freq errors.

Counter Counter Name Object Type Counter Description Metrica Report Heading

TFSUDLOS CLTCHDRF Sudden loss of FR-TCH connections.

CELLTCHD R1_30MIN

THSUDLOS CLTCHDRF Sudden loss of HR-TCH connections.

CELLTCHD R1_30MIN

TFSUDLOSA CLTCHDRF Sudden loss of AMR-FR TCH connections.

CELLTCHD R1_30MIN

THSUDLOSA CLTCHDRF Sudden loss of AMR-HR TCH connections.

CELLTCHD R1_30MIN

TFNDROP CELTCHF Total No of dropped FR TCH in UL subcell.

CELLTCHF 1_30MIN

THNDROP CELTCHF Total No of dropped HR TCH in UL subcell.

CELLTCHF 1_30MIN

TFCASSALL CELTCHF No. of assignment complete messages on TCH for all MS power classes, FR-UL.

CELLTCHF 1_30MIN

V. Network Congestion Feature/Parameter Cell Load Sharing Parameter Name MML Command Parameter Description

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CLSSTATE RLLCI/E Cell load sharing

active/inactive for a cell

HOCLSACC RLLCP

Enable/disable acceptance of incoming h/o due to Load Sharing

CLSLEVEL RLLCP

% Idle channel free level at which shedding of calls is started

CLSACC RLLCP

% Idle channel free level, below which no shedded call is accepted by target cell

RHYST RLLCP

Hysteresis reduction factor (how much of hysteresis zone is used for call shedding)

CLSRAMP RLLCP Time interval in which

hysteresis is ramped down Load Distribution SCLD RLLLC Subcell load distribution

SCLDLL RLLLC Subcell Load Distribution

Lower Limit

SCLDUL RLLLC Subcell Load Distribution Upper Limit

AMR DMQGAMR RLDMP Bad Radio Quality threshold to trigger for an IHO HR->FR

DMSUPP RLDMP

Switch to activate Dynamic allocation of HR & FR Codec Sets

DTHAMR RLDHP Packing threshold for AMR

HR Calls. Counters Counter Name Object Type Metrica Report Heading Counter Description

CCONG CLSDCCHO CELLSDCC H2_30MIN Congestion counter for UL subcell. Stepped each time an allocation attempt fails due to SDCCH congestion.

CTCONGS CLSDCCH CLSDCCH Congestion time counter for UL subcell. Stepped each second all available SDCCH channels are busy.

CNRELCONG CLSDCCH CELLSDCC H3_30MIN

Number of released connections on SDCCH due to TCH or Transcoder (TRA) congestion.

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TFNRELCONG CELTCHF CELLTCHF 2_30MIN

Number of released TCH-FR signaling connections due to transcoder resource congestion during immediate assignment on TCH.

THNRELCONG CELTCHF CELLTCHF 2_30MIN

Number of released TCH-HR signaling connections due to transcoder resource congestion during immediate assignment on TCH.

TFCONGSAS CELTCHF CELLTCHF 2_30MIN

Number of congestion at TCH-FR assignment or immediate assignment in UL subcell.

THCONGSAS CELTCHF CELLTCHF 2_30MIN

Number of congestion at TCH-HR assignment or immediate assignment in UL subcell.

TFCONGSHO CELTCHF CELLTCHF 2_30MIN Number of congestion at incoming handover in UL subcell- for TCH-FR

THCONGSHO CELTCHF CELLTCHF 2_30MIN Number of congestion at incoming handover in UL subcell- for TCH-HR

TFTCONGS CELTCHF CELLTCHF 2_30MIN Soft Congestion time counter for UL subcell- for TCH-FR

THTCONGS CELTCHF CELLTCHF 2_30MIN Soft Congestion time counter for UL subcell- for TCH-HR

TFTHARDCONGS CELTCHF CELLTCHF 2

Hard congestion time counter for UL subcell. The counter starts to increment only when it has not been possible to allocate a channel with the help of any type pf pre-emption.

VI. Handover Analysis

General HO Problems

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Internal HO Check List- Actions

Interference

Check the results from Co-Channel interference and Drop Call Analysis

Wrong Neighboring Cell Definition & Faulty Exchange Properties

Check the results from the radio related data check

Faulty Parameter Settings related to HO Check the results from the radio related data check

Too many Measurement Frequencies (more than 16) in theActive BA list

This can result in fewer samples per frequency and less accurate HO decision

Too few (or even too many) defined neighboring cells Check the results from the radio related data check

Software problems such as Congestion. Check the results from the SAE & EOS Analysis

Faulty H/W Check the faults by running the RXMFP on the TG

External HO & Inter MSC HO Check List- Actions

MSC Definition

The MSC's to which Inter-MSC HO shall be performed have to be defined as neighboring MSC.

Address Definition

The address definitions have to be consistent in all MSC's

Software Routes

SW Routes for the inter MSC HO have to be defined properly

C7 Links The C7 Link performance shall be checked

BSC Definition The BSCs have to be defined properly in the MSCs

Investigation Analysis Rules Description

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Rule # 1

The worst cell analysis is based on internal incoming HO on cell level

Rule # 2 The problem with HO can be traced on the target cell

Rule # 3

The worst cell analysis should not include cells with extremely low HO rates- At least 50 HO attempts..!

Worst Cell Analysis on Cell Level Check List- Actions

Follow the General Procedure described above Shown under "General HO Problems"

HO Reversion Rate

If the HO Reversion rate is high (>5-6%), for a cell, and there is no strong indication of interference problem in the target cell => Check the BTS error log and a site visit need to be scheduled to check the antenna and its near parts.

HO Lost calls

Check the HO lost of total dropped calls in the cell. If too many calls are dropped during HO=> Check the drop call report.

Congestion

Check the area around the investigated cell for cells with congestion (see the TCH and SDCCH analysis reports). Congestion in surrounding cells can lead to that a bad HO candidate has to be selected.

Worst Cell Analysis on Cell relation Level Check List- Actions

HO Behavior

Check the HO behavior for concerned cell relations (both ways); e.g. the number of HO decisions leading to HO attempts.

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HO reasons

Check the HO reasons related to HO decisions (bad quality, signal strength, etc) for concerned cell relations (both ways).

HO successful rates

Check the rate of successful HO back to old cell within 10 seconds for the concerned cell relations

Coverage Maps

Look for areas with bad coverage. Low signal strength during HO will make the MS more sensitive for UL- and DL interference.

Cell Map

Study the cell map. Check if there is any neighboring cells close to the concerned cell which are missing in the cell relation statistics of have low number of HO commands registered.

Results and Recommendations Actions

Missing Neighbors Cell Relations are found Add neighbors and/or run NCS reports

BTS Sites which are suspected to have H/W issues Recommend site visits and Field test=> contact FOPS

Faulty Parameter Settings affecting the HO performance

Recommend parameter changes- check the HO parameters and compare to the standard parameter settings

Too many Measurement Frequencies in the active BA list

Remove unnecessary cell relations and recommend fewer measurement frequencies

Coverage Holes are affecting HO performance Expand with more cells in affected areas.

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Problems with Congestion

Recommend expansion with more TRX's in affected cells or recommend cell splits, micro cells or new sites (This should be associated with the TCH/SDCCH analysis

Interference affecting the HO performance in specific areasBCCH Frequency change/retune

Troubleshooting Too Few Handover Attempts or No Handovers Possible Reasons Troubleshooting Cell Split Layout- Distance between cells or antenna directions Natural reasons

TCH Congestion- for Target Cell

Check HO congestion report and HO decision successful rate

Parameter settings: for CO-BCCH/CO-BSIC in 2 ncells Change BSIC for one or more ncells

Parameter settings: Missing MBCCHNO Add missing MBCCHNOs

Parameter settings: Too many MBCCHNO Remove unnecessary MBCCHNOs

Parameter settings: Too high hysteresis Adjust the hysteresis to lower value

Parameter settings: Low O/P Power in target cell Increase BTS Output Power

Parameter settings: NCCPERM wrong Add missing NCC to NCCPERM

HW-Errors: TRU/CDU error in target cell Check BTS Error Log- Site visit if necessary

HW-Errors: Antenna/Feeder installation error Check BTS Error Log- Site visit if necessary

HW-Errors: Synchronization problems Drive test- Site Visit HW-Errors: Target cell blocked by buildings Site visit

Interference: Target cell BCCH is interfered Frequency planning and drive test

Unsuccessful (Lost) Handovers Possible Reasons Troubleshooting

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Cell Split layout: The neighboring cell is far away

Investigate the ncell relation if it is possible to remove the relation

Congestion: High congestion in target cell may lead to dragged calls and unsuccessful HO's

Check TCH Congestion rate in target cell and/or HO decision success rate. Additional TCH capacity required. Short term solution is to activate the cell load sharing and/or use offsets to move the cell borders.

Interference: DL Interference in serving and/or target cell results in lost HO's

Check reasons for HO, check HO reasons for target cell in opposite direction. Check frequency plan. Run CTR or perform drive test using TEMS

Too many Measurement Freqs.

MBCCHNOs >16 will decrease the accuracy of the mobile measurements to locate the best 6 servers. Many measurement freqs mean fewer samples per frequency and problem for mobiles o decode the BSIC. Check the number of MBCCHNOs

Unbalanced Power Link Budget

DL is stronger than UL in serving cell. The MS cannot receive the HO command message. Drop call due to Low SS or handover lost as result. Too high BTS output power. Run CTR and/or MRR

Handover Reversions Possible Reasons Troubleshooting

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UL Interference in target cell

Check drop reasons for target cell. Check HO reasons for target cell. Run MRR and/or CTR. Check ICM band in target cell. Measure with spectrum analyzer on site for possible (external) source.

DL interference in Serving Cell- The MS cannot detect the HO Command Message

Check drop call reasons for serving cell. Check the HO reasons for serving cell. Run MRR and/or CTR. Check Freq Plan.

Unbalanced Link Power Budget- DL is stronger than UL in target cell

Too high BTS O/P Power. Too low MS power settings. Run MTR, CTR and/or MRR to check power balance.

Lower Power on TCH than on BCCH in Target Cell Check power parameter settings. Check BTS error Log

Receive Antenna Problems- Only if separate TX/RX antennas are installed

Run MTR/CTR and/or MRR to check power balance. Check antenna installation on site.

Co-BCCH/BSIC in two ncells- The MS measures BCCH from wrong cell

Run Consistency Check in OSS. Check BCCH/BSIC Plan

Co-BCCH/TCH & Co-BSIC in two ncells

The MS measures a strong TCH and detect BSIC from a weak BCCH in another ncell. Check the freq/BSIC plan and run CTR

Ping-Pong Handovers Possible Reasons Troubleshooting

Wrong Parameter Settings

Hysteresis can be too low. Urgency HO can be triggered too early. Check hysteresis parameters. Check HO reasons

Lower O/P Power on TCH than BCCH Check power parameter settings. Check BTS error log

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Coverage Holes

Coverage holes can lead to ping pong HOs especially for slow moving mobiles. The coverage problem might be shadowing by high buildings and straight streets with good coverage from another nearby BTS. Run CTR, MRR or drive test by TEMS. Reduce the Hysteresis and shorten the signal strength filters. Long term solutions is to add coverage.

No Dominant Server

Several possible equal signals from two or more base stations might lead to a Ping Pong effect. This is valid for slow moving vehicles. Often, this situation also causes bad quality and finally a high ratio of dropped calls. Long term solution is to add sites. A short term solution might be is to re-direct the antennas, change antenna types or tilt, to get sharper borders.

Parameters

Parameter Name MML Command Parameter Description

IBHOASS RLLBP Flag to enable assignment to another cell inter-BSC

IBHOSICH RLLBP Flag to enable SDCCH handover inter-BSC

IHOSICH RLLBP Flag for enabling intra-cell handover on SDCCH

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HOCLSACC RLLCP Enable/disable acceptance of incoming h/o due to Load Sharing

SCHO RLLCP Flag to enable SDCCH handover

EXTPEN RLLCP Flag to enable penalty "transfer" for inter-BSC h/o

HYSTSEP RLLCP SS separator for HIHYST and LOHYST

IHO RLIHP Flag enabling intra-cell handover on a sub-cell

MAXIHO RLIHP

Max. no. of consecutive intra-cell handovers allowed. For OL / UL cells it must always be less than the no of CHGR in the subcell

TMAXIHO RLIHP

Maximum time between intra-cell handovers to consider them as consecutive.

TIHO RLIHP Time for which intra-cell h/o inhibited

SSOFFSETUL RLIHP Offset FQSS function along RxLev axis (uplink)

SSOFFSETDL RLIHP Offset FQSS function along RxLev axis (downlink)

QOFFSETUL RLIHP Offset FQSS function along RxQual axis (uplink)

QOFFSETDL RLIHP Offset FQSS function along RxQual axis (downlink)

SSOFFSETULAFR RLIHP UL offset for signal strength in Db in AFR

QOFFSETULAFR RLIHP UL offset for quality in dtqu in AFR

SSOFFSETDLAFR RLIHP DL offset for signal strength in dB in AFR

QOFFSETDLAFR RLIHP DL offset for quality in dtqu in AFR

KHYST RLNRP Hysteresis applied when both cells ranked on SS

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KOFFSET RLNRP Offset applied when both cells are ranked on SS

LHYST RLNRP Hysteresis applied when both cells ranked on PL

LOFFSET RLNRP Offset applied when both cells are ranked on PL

TRHYST RLNRP Hysteresis when in transition between K and L

TROFFSET RLNRP Offset when in transition between K and L

AWOFFSET RLNRP Assignment to worse cell negative hysteresis

BQOFFSETAFR RLNRP

Signal strength corridor in dB for bad quality urgency handover. Numeral 0 - 63

BQOFFSET RLNRP Bad RxQual h/o corridor or negative hysteresis

LOHYST RLNRP SS hysteresis when evaluating low SS cells

HIHYST RLNRP SS hysteresis when evaluating high SS cells

OFFSET RLNRP SS offset

CAND RLNRP

Candidate type: Identifier AWN (assignment to worse cell), NHN (normal handover) or BOTH

SSRAMPSD RLLFP Time to ramp up N-cell measurements on TCH

SSRAMPSI RLLFP Time to ramp up N-cell measurements on SDCCH

QLIMULAFR RLLUP Quality limit UL for handover. Numeral 0 - 100

QLIMDLAFR RLLUP Quality limit DL for handover. Numeral 0 - 100

TALIM RLLUP Timing advance threshold for handover

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PTIMHF RLLPP Duration of penalty PSSHF for handover failure

PTIMBQ RLLPP Duration of penalty PSSBQ for RxQual h/o

PTIMTA RLLPP Duration of penalty PSSTA for TA h/o

PSSHF RLLPP SS penalty applied to a cell to which h/o fails

PSSBQ RLLPP SS penalty on cell from which h/o occurs (RxQual)

PSSTA RLLPP SS penalty on cell from which h/o occurs (TA)

PSSTEMP RLLHP Size of temp. penalty on meas. From new n-cells

PTIMTEMP RLLHP Time of temp. penalty on meas. From new n-cells

Counters

Counter Name Counter Description

HOVERCNT No of HO commands sent to the MS

HOVERSUC No of successful HO's to the neighboring cell

HORTTOCH

No of HO's that result in a return to the old channel after a failure of a HO attempt to a neighboring cell

HODUPFT

No of successful HO's back to the old cell within 10 seconds.

HOTOKCL HO attempts made to better K-Cell. (This is for Ericsson-1 Alg.

HOTOLCL HO attempts made to better L-Cell.

HOTOHCS HO attempts due to HCS

HODWNQA No of HO attempts due to bad DL quality

HOUPLQA No of HO attempts due to bad UL quality

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HOEXCTA No of HO attempts due to excessive TA

HOASBCL No of assignment attempts to better cell

HOASWCL No of assignment attempts to worst cell

HOSUCBCL No of successful assignment attempts to better cell.

HOSUCWCL No of successful assignment attempts to worst cell.

HOATTLSS No of HO attempts when the serving cell is a Low SS cell.

HOATTHSS No of HO attempts when the serving cell is a High SS cell.

HOATTHR No of HO attempts at high handover rate.

HOSUCHR No of successful HO's at high handover rate.

VII. Metrica Related Reports

Drop Call Analysis

Metrica Reports

Drop Call Analysis/Daily Reports/ Ericsson Drop Analysis Report

AMR Reports/Reports/Ericsson AMR Cell Drop Report

AMR Reports/Reports/Ericsson AMR BSC Drop Report

AMR Reports/Summary Reports/Ericsson AMR MOUs Per Drop calls Report

AMR Reports/Summary Reports/Ericsson AMR BSC MOUs Per Drop calls Report

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Congestion

Metrica Reports Radio Network BSS/Daily Reports/Cell TCH Traffic Report

Radio Network BSS/Summary Reports/Cell TCH Traffic

Radio Network BSS/Summary Reports/BSS Cell TCH

Radio Network BSS/Summary Reports/Cell Blocking BSS TCH Availability/Reports/BSS Avail Cell Report BSS TCH Availability/Reports/BSS Avail BSC Report AMR Reports/Reports/Ericsson AMR Cell Reports AMR Reports/Reports/Ericsson AMR Traffic Cell Report AMR Reports/Reports/Ericsson AMR Traffic BSC Report Radio Network BSS/Daily Reports/Cell SDCCH Traffic Report

H/O Analysis

Metrica Reports Radio Network BSS/Daily Report/Cell Handover

Radio Network BSS/Summary Reports/Cell Handover

Radio Network BSS/Summary Reports/HO Trending Report