Wcdma Kpi Optimization: Presented by Ahmed Aziz
October 8, 2022 | Author: Anonymous | Category: N/A
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Wcdma kpi OPTIMIZATION Presented by Ahmed Aziz
agenda DAY
1 WCDMA KPI OPTIMIZATION
– ACCESSIBILITY ACCESSIBILITY CS/PS – CS/PS – RETAINABILITY MOBILITY – INTEGRITY
WHY WE MEASURE NW PERFORMANCE › To check the cellular network is performing well. › A set of certain threshold is defined for measuring performance. performance. › To check the area where improvement required for improving NW/User perception. › Future requirement
3g kpi principle --- s.m.a.r.t.
WCDMA RAN Optimization WCDMA RAN Optimization process can be understood from following workflow. Performance
Performance
Recommendation
Verification
Measurement
Analysis
& Implementation
changes
accessibility Introduction
Accessibility is defined as the ability of a user to access the UMTS network successfully to utilize the available services.
MOC/MTC
The metrics within Ericsson RNC and OSS provide counters and KPI’s KPI’s that describe the behaviors and experience of the subscribers while accessing the UMTS network.
RRC Setup
problems
in Accessibility are occurring either due to problems in RRC (Radio Resource Control) connection, nas SIGNALING or due to problems with wit h establishment of RAB (Radio Access Access Bearer).
Accessibility = RRC × NAS × RAB
NAS
RAB Setup
accessibility .
accessibility divided into:
1.
admi ad miss ssio ion n Co Cont ntrrol
2.
Con onge gest stio ion n Con Contr trol ol
Both these services provide the efficient use of available resources. And ensure the services to costumer. Key Performance Indicators:
RRC connection setup Successful RAB establishment Paging success
ADMISSION CONTROL
Hardware;VSWR; Antenna alarms,
CS/PS Accessibility (RRC)
Admin Control Control
License
Node Blocking
1.Check Parameter settings for:
1. RBS specific parameters
a). Feeder length/TMA
2. Verify /correct individual licensed
b). OCNS c). Adm Control d). Check available resources (Downlink Tx power,, Channelization power codes).
capacity levels for the node. (via AMOS or SMO) 3.Check Channel elements usage trends
1. Check for node configuration error/mismatch, node limitations or transport network layer service unavailability.
Transport Blocking 1. Check for congestion on user plane (AAL2)/ control plane (UniSaal /SCTP) for Iub resources. 2. Expand TN bandwidth 3. Check IuCs / IuPs succ rate, affects all cells in RNC
RRC Succ rate could be low due to RF related issues also. (Poor RF in RACH, FACH) Investigate the t he RF using WMRR and trial maxfach1power and constantV c onstantValueCprach alueCprach
RRC Degradation
Hardware/Antenna alarms, VSWR
Congestion
CS/PS Accessibility (RAB)
Node Blocking 1. Check for node configuration error, node limitations or transport network layer service unavailability.
Transport Blocking 1. Check for congestion on user plane (AAL2)/ control plane (UniSaal/SCTP) for Iub resources. 2. Expand TN bandwidth (add T1s,define more Vc) 3. Check T1 Errors 4. Check Locked T1s 5. Check Iub/TD (Vc/Vp) Mismatches 6. Share Traffic with Nbrs(qoffset2sn) 7.Reduce CPICH or Tilt or qRxlevmin to take less traffic 8.Increase Directed Retry to Offload to GSM
RAB Degradation
RAB Degradation
CS/PS Accessibility (RAB)
Congestion DL Power 1.Check if Maximum Transmission Power is Transmission aligned with MaxDlCapability; 2. Check Maximum Transmission Transmis sion Power and CPICH ratio; 3. Reduce PwrOffset & Increase PwrAdm;
Code 1.Check dlCodeAdm values, if adjustment is still possible, 2.Reduce 384k Users on DL (sf8Adm), 3.Reduce HSPDSCH Codes,
4.Reduce HS-SCCH 4. Explore IFLS with other Codes Carrier;
ASE 1.Verify settings for dlASEAdm,UlAseAdm; 2.Check for R99 traffic load on the cell. 3. Trial higher value for releaseAseDlNg and releaseAseDl; 4. Optimize radio network to reduce interference/pilot pollution.
Hardware Resource 1. Check Locked TX/RAX Boards; 2. Check hanging CE (restart) 3.Check HS/EUL resource allocation (AMOS, UTRAN report) 4. ul/dlHwAdm parameter in Iublink; 5. Trial FIRS 16/16
5. Enable or Increase Directed Retry to GSM;
6. Trial Channel Type DCH to FACH
6. Reduce sf16Adm/sf8Adm
7. Reduce eulServing/NonServingAdm;
7.Consider 60W RU; changing to
8. Add,Replace RAX/TX Boards
8. Add another Carrier
Connection Limit 1. Verify Admission Admission settings/Usage trends for different SF RAB.
2. Fine tune parameter settings to maintain balance between Accessibility & throughput
CS/PS Accessibility (RAB)
Hardware Fault
UL RSSI
Errors/Crashes
T1 Errors
Alarms
Escalate
Escalate
1.Incorrect Attenuation/Losses 1. Restart Board 2. TMA UL Gain Parameter Check 3. Verify RFDS
2. Cold Restart Node 3.Verify SW on Node (Utran Report/OSS SMO)
4. External 4.Swap Cards/Boards Interference(UL RSSI problem 5. Replace Cards/Boards even during off-peak hours) 5. UL line physical problems (UL RSSI issue worst during peak hours)
Accessibility/Block Accessibility/B lock Reasons › Common Failure Reasons – Lack of DL Power – Lack of DL Code – Lack of UL/DL Hardware Resource – Exceed Connection Limits (for PS)
Mtilt & Etilt
– Iub Congestions – UL RSSI – HW or T1 Faults – Neighbor site/cell down
› Admission Control - Set of rules that determines whether whether a UE is granted access on making a connection request. request. Admission control is also used when adding a RAB , or a new RL via SHO or upswitch of services.
Congestion control Congestion situations are detected in the t he RNC by means of event based measurements of the Downlink Transmitted Carrier Power and the Uplink Received Re ceived Total Total Wideband Power ordered from the RBS. Two types from congestion control: co ntrol:
1- Downlink cell congestion detection 2- Uplink cell congestion detection
Downlink cell congestion detection
PwrHyst 300
Uplink cell congestion detection
Congestion – dl power › Align maximumT maximumTransmissionPower ransmissionPower with maxDlPowerCapability › Increase pwrAdm (but make sure that pwrAdm + pwrOffset is less than 100%) – Con: Less power available for SHO › Reduce sf16Adm/sf8Adm › Traffic balance between multicarrier using qOffset1sn/qOffset2sn) in idle mode. › Overshooter (propagationDelay/WNCS)? => Down-tilt – Con: Reduced coverage
› Enable or Increase Directed Retry to GSM › Consider changing to increasing the power license › Add another carrier
Congestion – dl codes › Increase dlCodeAdm › Reduce 384k Users on DL (sf8Adm)(default 8). › Reduce number of reserved (SF16) HS codes (numHsPdschCodes) › Reduce HS-SCCH Codes › Check if the site is over-propagating › Traffic balance between multicarrier using qOffset1sn/qOffset2sn) in idle mode. › Add another carrier
Congestion Hw limit › Increase ulHwAdm/dlHwAdm(default 100) range 0-100 › Check hanging CE (restart) › Check if the site is over-propagating › Increase CE licensing › Add DUW
› Traffic balance between multicarrier mul ticarrier using qOffset1sn/qOffset2sn) in idle mode. › Add another carrier
Accessibility Failures After Adm › › – –
– › – – –
›
Counter: pmNoFailedAfterAdm pmNoFailedAfterAdm The RRC and RAB fails after being admitted by the Admission Control. Possible Causes: 1.Iub Congestion: You can find out the RBS Link ID in OSS CEX/AMOS. Iub blockings can be caused by T1/IMA T1/I MA link link faults, mis-configurations or lack of Iub resource. Escalate to UTRAN or ML if you see lots of Iub blockings in these counters for further investigation. In the interim, suggest Coverage limiting (reduce CPICH, increase qrxlevmin) of traffic offloading (qoffset,) recommendations. 2. CE usage: Check the CE usage and suggest CE usage reduction either by traffic offloading or RAXB/TXB harvesting (exchanging from low traffic sites) 3. UL RSSI: Check the Quality Report for f or UL RTWP level. 4. HW or iub link Check alarms andissues: link error seconds/unavailability. seconds/unavailability. 5. Poor Radio: Check WMRR for signal level and quality distributions. Use GPEH or drive test to check pilot pollutions. Offload traffic to another Cell/Site (which has coverage overlap) with no problems in FailedAfterAdm Before spending too much time on a cell, check the t he cell availability of the neighbors. A major neighbor down or has T1 issue would impact the nearby sites. Also check RRC Reject due to MP Load.
BaSIC Accessibility parameter check Parameter Name
Default Value
Value Range
Resoluon
Unit
aseDlAdm
240
0...500
1
ASE
aseUlAdm
160
0…500
1
ASE
dlCodeAdm
80
0…100
1
%
pwrAdm
75
0…100
1
%
pwrAdmOset
10
0…100
1
%
sf8Adm
8
0…8
1
# no of radio links
sf16Adm
16
0…16
1
# no of radio links
sf32Adm
32
0….32
1
# no of radio links
ulHwAdm
100
0…100
1
%
dlHwAdm
100
0…100
1
%
primaryCpichPower
8-10% of maxTxPower
NA
1
dB
qQualMin
-18
-24…0
1
dB
qRxLevMin
-115
-25…-119
1
dBm
maxFach1Power
18
-350 ….150
0.1
dB
eulServingCellUsersAdm
64
0…96
1
Licensed dependent
hsdpaUsersAdm
64
0…128
1
Licensed dependent
Feature related to Accessibility License
FEATURE NAME
FROM
TO
FAJ 121 1334
Improved CE Ladder for E-DCH
OFF
ON
FAJ 121 406
Directed Retry to GSM
OFF
ON
FAJ 121 1356
Load based Handover
OFF
ON
FAJ 121 799
Service based Handover
OFF
ON
FAJ 121 1581
RNC RRC Load Control
OFF
ON
FAJ 121 977
Flexible Initial rate selection
OFF
ON
FAJ 121 435
Inter-Frequency Load Sharing
OFF
ON
FAJ 121 1593
Admission Block Redirection
OFF
ON
FAJ 121 1350
Improved RACH Coverage
OFF
ON
FAJ 121 2712
Service Differentiated RRC Admission
OFF
ON
RETAINABILITY Retainability
is defined as the ability of a user to retain its requested service once connected for the desired duration.
SOME
OF THE main FACTORS WHICH WHICH affect retainability include:
Handover
performance (soft/softer/HARD) and missing neighbor cell
INCORRECT
PARAMETER SETTINGS (POWER, ADMISSION, RELASE ETC.)
CONGESTION RADIO
ENVIRONMENT (POOR COVERAGE, PILOT POLLUTION, FAST EC/NO DROP ETC.)
NODE
HARDWARE FAILURES
TRANSMISSION
E1/T1 FAILURES/CONGESTION
RETAINABILITY
Drops
reasons based on counters:
Missing
SOFT
Neighbors DROPS
HANDOVER FAILURES DROPS
CONGESTION DROPS IRAT UL
DROPS
SYNC DROPS
OTHER
REASONS DROPS
CS/PS CS/PS Retainability
Missing Neighbor
Soft Handover
Uplink Sync
IRAT 1. Identify Identify the failing phase.
2. Add suggested suggested Nbrs with WNCS/GPEH/Drive Test data
2.Check T1 Errors
1. Investigating UE TxPwr by using Drive test data or WMRR
3.Check Cell Availability
2. Check parameter for UE TxPwr & maxSir
2. Audit the External GSMCell MO with latest 2G dump(BCC,NCC,
3. Analyze existing
4.Determine if the
3. Analyze cell
BSIC,etc)
neighbors with 3G-3G cell relation report
issue affects one cell or a only or RBS or or cluster
coverage by RF Planning tool or Drive test data
3. GSM coverage area verification for IRAT neighbors
4. Use GPEH to determine the number of Event 6a or number of Event 2d
4. Re-prioritization the neighbor list based on usage
1. Check neighbor cell availability
4. Analyze cell coverage by RF Planning tool /Drive Test data/PRACH Plots 5. Down tilts or other physical optimization
1.Check HW Alarms
5.Verify for SC Clashes
5. Check Cells due to RSSI Issues
Congestion 1. Check down switch counter for congestion reason. 2. Investigate the RRC Access failure due to lack of DL power & codes 3. Perform analysis of coverage area and reduce overshooting 4. Verify CE usage and HW allocation and dimensioning
Others 1. Transport Issue 2. RBS / RNC HW issue 3. RF issues outside of available counters 4. UE issues
Retainability Drops due to Missing Neighbors › Counter: pmNoSysRelSpeechNeighbr › Suggestions: › 1. Run WNCS and check Missing Neighbors. Check inter-site distance to determine if they need to be added. (Prioritize missing neighbors in the order of # of drops, # of events, distance, average av erage RSCP/EcNo) › Pay attention: Use SC(not cell name) to add missing neighbor neighbor.. › 2. Check PRACH Delay to assess if it is overshooting. › 3. Check neighbor cell availability. availability. If any of the neighbor cell is down, it can cause missing neighbor drops.
Retainability Drops due to Soft Handover Counter: pmNoSysRelSpeechSoHo pmNoSysRelSpeechSoHo This counter is pegged when the speech call release is due to inability to add a cell with or without relation into the active set. So it also includes the missing neighbor drops.
› Suggestions: › 1. Check 3G-3G Cell Relation Report on BO for both out-going and in-coming directions, to see which relation/direction is the cause; › 2. Check Hourly SHO stats. If occurring during busy hours, hours, identify the cause and relieve congestion on target cell; › 3. If SHO fails in off-peak hours then it is not lack of resource or Admission Control. Check cell availability/reserved, Iub configuration and UL RSSI for target cell. Check Alarms/T1/UL RSSI/HW/MP Load for the cell and its neighbors; › 4. Check Scrambling Code Collisions; › 5. Check for missing neighbors in WNCS as they will also contribute contr ibute to SHO Failures; › 6. If SHO fail rate is high on many relations, the issue could be with Source cell. Check admission control parameters such as: pwrAdm + pwrOffset, DLCodeAdm, UL/DL HWAdm HWAdm to see if there t here is sufficient margin available for SHO. Check SHO overhead with the admission control level. › 7. Trial IndividualOffset IndividualOffset to increase(faster HO) or decrease (delayed HO) SHO area with problem neighbor. › 8. Check CPICH Powers with the major neighbors. Keep the delta small (within 3 dB) to maintain UL
balance in SHO border.
Flowchart – drop due to Sho High number of Drops due to SoHo the issue could be with Source cell.Check admission control parameterss such as: pwrAdm, parameter DLCodeAdm, UL/DL HWAdm to see if there is sufficient resources available for SHO
Are missing Nbr drops also high
Several relations having moderate SHO fail rate
Cell maybe serving a RF area having sudden interference changes.
Yes
No
Check SHO Success rate per Nbr relation Identify some relations with high SHO fail rate
Is relation defined correctly in
High ASU failures
No
Yes
UtranRelation MO (Target RNC, RelationID = Target cellname) yes
Increase IndOffset expand HO area. Monitor powertoutilization to avoid Acc/Throughput issue
Check if Coverage overlap is sufficient. Increase footprint using Tilts or CPICH Is Nbr site having HW issues, UL RSSI,or Congestion due to Transport,pwr or other resources. Fix nbr site
Delete and re-define
Reduce interference with tilt or C CPICH PICH changes
Identify missing Nbrs with WNCS & add
Is it Inter-RNC relation? Check Iur Definitions & investigate other relations over same Iur.
Check for SC Collisions.
Retainability Drops due to speech congestion › Counter: pmNoOfTermSpeechCong › This counter is Incremented by one when the speech call release is due to congestion. The connection is terminated by RNC.
› Suggestions: › 1. Check admission admission counters (LackdlCode, (LackdlCode, lackdlpwr, lackdlpwr, UL/DLHwAdm) on RAB establishment to find out the resource bottleneck. › 2. Check for MPLoad. M PLoad. (Suggest temporary traffic-offloading) traffic-offloading) › 3. Check for Iub I ub congestion. (Suggest temporary traffic-offloading) › 4. Verify CE usage and HW allocation and dimensioning › 5. Check for special events (sports/festivals/holidays/accidents) or if a site nearby was down.
Retainability Drops due to UL Sync › Counter: pmNoSysRelSpeechUlSynch pmNoSysRelSpeechUlSynch › This counter is Incremented by one when the speech call release is due to the timer dchRcLostT expires.
› Suggestions: › 1. Resolve Missing Nbrs & SoHo issues, if any; › 2. Check Alarms/T1/UL RSSI/HW/MP Load for the cell; › 3. Check Propagation delay and WMRR for radio condition. If RSCP is bad, site needs to be optimized for coverage by uptilt(coverage hole); if EcNo is bad ,down tilt to reduce pilot pollution; › 4. Trial different cell designation (for instance, SHO to IRA IRAT/IFHO). T/IFHO). Lower the thresholds used to trigger IRAT/IFHO IRA T/IFHO (usedFreqThres2dEcno, usedFreqThresh2dRscp); › 5. Check IRAT failure rates. Audit Audit 2G (IRAT) neighbor list to see if there is missing 2G neighbors. This may be especially true for cells on the border of the 3G coverage area; › 6. Check for internal & External UL RSSI issues (neighbor cells); › 7. Trial minPwrMax minPwrMax (increase), minPwrRL(increase) to improve RL connection, constantly constant ly check for DL power congestion in these trials. › 8. Limit qRxlevmin to avoid taking far away samples (calls starting at low quality and dropping immediately). › 9. Check CPICH Powers with the major neighbors. Keep the delta small to maintain UL balance in SHO border. CPICH Power should be between 8-10% of maxTxPwr . › 10. Cell maybe serving a radio r adio environment with a relatively high number of UEs sudden interference changes (generally caused by bridges, buildings, tunnels, steep hilly experiencing terrain, etc). As a consequence of these changes, power utilization is higher. Trial minpwrlRL, minpwrlRL, Individualoffset but monitor
non-HS power utilization, and active set update failures.
Retainability Drops due to Others › KPI Formula:
› Drop Due to Other = pmNoSystemRabRe pmNoSystemRabReleaseSpeech leaseSpeech –pmNoSysRelSpeechUlSynch – pmNoSysRelSpeechSoHo pmNoSysRelSpeechSoH o - pmNoOfT pmNoOfTermSpeechCong ermSpeechCong › Basically all other speech drops which were not pegged in any of the speech drop counters described in the previous slides.
› Suggestions: › › › › › ›
1. Resolve missing nbrs, SoHo, UL sync issues if any before “other” drops 2. Check Alarms/T1/UL RSSI/HW/VSWR/MPLoad RSSI/HW/VSWR/MPLoad for the cell. 3. Check WMRR and Propagation Delay to improve radio condition and coverage range. 4. Assess the terrain profile and see if tilt can be adjusted. 5. Check Iub Congestions. 6. Check SHO/IRA SHO/IRAT/IFHO T/IFHO failure rates. Optimize the respective (SHO/IRA (SHO/IRAT/IFHO) T/IFHO) nbr list.
› 7. TrialinHOtype and Adjust 2d thresholds (usedFreqThresh2dRscp, usedFreqThresh2dEcNo) if coverage is weak the area. › 8. Check for RAX/TX board errors, may require a restart. › 9. Check Scrambling Code Collision. › 10. Check CPICH Power with the major neighbors. Keep the delta small to t o maintain UL balance in SHO border. CPICH Power should be between 8-10% of maxTxPwr. › 11. Restart the site if all the above has been checked and still cannot find out the problem. › Usually drops due to others are radio related(RU/CBU/FU). A site restart or HW replacement might be needed. Conduct drive test and record GPEH of the area for further investigation if necessary.
Solutions to control Drops due to ULsync & Others › Ideally, the drops due to ULsync & Others can be reduced by controlling the noise floor in the WCDMA cell, which can be done by the means of EDT or Layer Management ( Changing HOtype or relaxing 2d thresholds). If in some cases, tilting til ting & LM can’t be changed, the following set of parameters can also be tried: › 1. minpwrMax: › Defines the maximum power per Radio Link relative to CPICH power where Radio Link bit rates are equal to or below minimum Rate (15.9 Kbps). Increasing this parameter, provides more power for CS users on the cell c ell edge, at the expense of DL power. › Connections that fall into this range are: Signaling Radio Bearers (3.7 (3. 7 Kbps), Standalone Signaling Radio Bearers (14.8 Kbps), Conversational Circuit Switch Speech AMR 12.2 Kbps (15.9 Kbps).
› 2. minpwrRL: › By changing this parameter, the minimum power given per radio link is increased, therefore the starting point for power control ramping is higher, avoiding deep power decreases due to good RF conditions. Hence the radio link become now less sensitive to sudden RF conditions degradation.
› 3.rlfailureT: › Increasing the time before the radio link is considered out of sync, can lead to the signal recovering and the call being saved from being dropped.
› 4. noutsyncInd: › Increasing thestate consecutive error radio frames can lead to the delay in UE entering the “Out-of-Sync” and the number delay inof starting the rlfailureT timer.
BaSIC retainability parameter check Parameter Name
Default Value
Value Range
Unit
hoType
2
0,1,2
none
minPwrRl
-150
-350..150
dB
individualOffset
0
-100..100
dB
minPwrMax
-15
-350..150
dB
nOutSyncInd
10
0….500
Frame
rlFailureT
10
0..255
sec
reportingRange1a
4
0..29
dB
reportingRange1b
8
0..29
dB
timeToTrigger1a
10
0…15
ms
timeToTrigger1b
12
0…15
ms
usedFreqThresh2dEcno
-12
-24..0
dBm
usedFreqThresh2dRscp
-100
-115..-25
dBm
loadSharingGsmFraction
100
0..100
%
loadSharingGsmThreshold hsdschInactivityTimer inactivityTimer inactivityTimerPch downswitchTimer
95 -1 -1 -1 -1
0..100
% s s s s
-1..-1, 1..255
-1..-1 1..1440 -1..240 -1..-1 0..1000
Case study- SHO Parameter trial 1.- DESCRIPTION The feature enables tuning of intra-frequency mobility behaviour in high mobility areas, such as highways, in order to reduce the number of dropped calls in these areas. It is i s achieved by speeding up Radio Link additions to the Active Set and slowing down RL removals from the AS. AS. The feature can also be used in low mobility areas to limit the number of event 1a or event 1b occurrences .
2.- EXPECTED BENEFITS: Drop rate 3.- KPI TO EVALUA EVALUATE: TE: CS/PS Drop Rate, SHO Overhead, MP Load. Soft handover Success Rate. 4.- DETAILS: To change the paramet parameter er timeToTrigger1a 240- 200ms
timeToTrigger timeToT rigger1b 1b 640 1280ms (RNC)
Feature related to retain ability
Call Re-Establishment Inactivity Timers Timers on Cell Level Soft Handover Parameters on Cell Level
MOBILITY
Handover in WCDMA
Mobility/Handover is defined as the ability of a user to move between neighboring UMTS and GSM Cells and retain its requested service (CS or PS) once connected.
Soft/Softer Handover Inter-Frequency Handover Inter-Radio Access Technology (Inter-RAT) Handover
mobility Soft Handover In Soft Handover, Handover, the UE connection consists of at least two radio links l inks established with cells belonging to different Node-B. In Softer handover, handover, the UE connection consists of at least two radio links l inks established with cells belonging to the same Node-B.
Soft Handover is controlled through the events events 1a, 1b, 1c & 1d: 1a: A new candidate for the active set enters reporting range 1b: A cell in the active set leaves the reporting range 1c: A cell not in active set becomes stronger than a cell in the active set 1d: Any cell becomes better than the best cell in the active set Majority of the SOFT/SOFTER Handover failures include: Failures due to interference, poor areas of dominance Primary Scrambling Code collision Missing neighbors Neighboring sites Hardware issues
mobility I RAT Handover IRAT handover process includes the following two sub-processes: sub-processes : • Relocation preparation • Handover implementation Relocation preparation Failures are mainly due to following reasons: • The 2G resources are not enough. • The CN parameters are not configured reasonably. • The configurations of GSM neighboring cells are not consistent with actual parameters. Handover implementation failures are mainly due to following reasons: • Incorrect parameter configuration of neighboring 2G cells • There exists side-channel interference in 2G cells • Improper setting of neighboring threshold
mobility INTER FREQUENCY Handover Inter-Fr Inter-Frequency equency Handover allows continuation on dedicated channels when the UE is moving out of coverage of one WCDMA RAN frequency to an area where coverage on another WCDMA RAN frequency exists. IFHO can also be triggered when performing cell selection for a packet connection.
IF Hanover has following events : Event 2a: Change of best frequency Event 2b: The estimated quality of the currently used frequency frequency is below a certain threshold and the estimated quality of a non-used frequency frequency is above a certain threshold. Event 2c: The estimated quality of a non-used frequency is above a certain threshold Event 2d: The estimated quality of the currently used frequency is below a certain threshold (It is based upon Ec/No measurements and RSCP measurement) i.e. start of compression mode Event 2e: The estimated quality of a non-used frequency is below a certain threshold Event 2f: The estimated quality of the currently used frequency is above a certain threshold. i.e. stop of compression mode
Handover failures are mainly due to following reasons: • Incorrect parameter configuration of neighboring 3G cells
• •
Hardware issue on neighboring cells. Improper setting of neighboring threshold
3G-3G failures Troubleshooting
Possible Reasons for 3G-3G HO Failures
●
Interference
●
Pilot Pollution
●
Overshooting of nearby cells
●
Low coverage area
●
External Interference
●
PSC Collision
●
Two or more nearby Cells having same PSC
●
Missing Neighbour Definition
●
Improper cell relations resulting into failed HO
●
Neighbouring Site E1/Hardware Issue
●
E1/Hardware e issue Attempts to nearby site failing due to E1/Hardwar
●
Improper Definitions
●
Improper External Definitions in RNC/MSS
●
Congestion on neighboring site
●
Limited resource neighboring site will lead to failures
●
On Utran Cell Locked, Channels Unlocked
●
Attempts to the cell will take place based on unlocked cell, but will not succeed as cell is locked
Mobility SHO & Soho › 1. Incoming SHO SR (
= pmNoTimesRlAddToActSet /
(pmNoTimesRlAddToActSet + pmNoTimesCellFailAddToActSet)
)
› * Congestion (power, code, CE, etc); › * Overshooting › 2. Outgoing SHO SR (
=pmRlAddSuccessBestCellSpeech /
pmRlAddAttemptsBestCellSpeech )
› * With one specific cell or some cells; › * Dig into the root cause › (Wrong RNC info, overshooting, etc).
CS-IRAT failures Possible Causes & Counters
CS IRAT HO Failure
Preparation Failure Preparation failures pmNoFailOutIratHoSpeechGsmFail
Execution Failure Physical Channel Failure pmNoFailOutIratHoSpee chReturnOldChPhyChFai
not due to Physical Channel Failure pmNoFailOutIratHoSpee chReturnOldChNotPhyCh Fail
Failure due to UE rejection pmNoFailOutIratHo SpeechUeRejection
IRAT Check Checklist
Definition
External Cell Definition – Cell defined in RNC/BSC
●
Outer Definition – Cell defined in MSS/MSC
●
SGSN Definitions – LAC/RAC Def
●
RNC/MSS Definitions – Correct RNC/MSS(for new nodes)
●
Check
Hardware
●
Blocking
●
Hardware Failure
●
Poor GSM BCCH Channel quality
Check
●
E1 Issues
BaSIC mobility parameter check PARAMETER NAME
Object
Default
Recommended
Value Range
fddGsmHOSupp
RNC
TRUE
TRUE
0,1
hoType
Utrancell
GSM_PREFERRED
GSM_PREFERRED
0,1,2,
usedFreqThresh2dEcno
Utrancell
-12
-15
-24..0
usedFreqThresh2dRscp
Ut Utrancell
-100
-105
-115..-25
gsmThresh3a
RNC
-95
-92
-115..0
COEXUMTS
BSC
1 (ON)
1 (ON)
0,1
gsmAmountPropRepeat
RNC
4
1
0..25
gsmPropRepeatInterval
RNC
5
15
0..25
tmStopGsmMeas
RNC
20
20
1..60
ifhoAmountPropRepeat
RNC
4
4
0..25
ifhoPropRepeatInterval
RN R NC
5
5
0..25
fddIfhoSupp
RNC RN
1
1
0,1
RNC
0
0
-20..20
RNC
-1
0
-10..10
serviceOffset2dEcno utranRelThresh3aEcno
timeToTrigger3a
RNC
6
6
0..15
integrity Introduction
Service Integrity represents the quality experienced by the user during A call or session.
HSDPA & EUL throughput ARE used as MAIN Indicators FOR SERVICE INTEGRITY.
THROUGHPUT PERFORMANCE OF A NETWORK DEPENDS ON THE SPEEDS IN EITHER DOWNLINK AND/OR AND/OR UPLINK, EXPERIENCED BY THE END USER
LOW THROUGHPUT IS ONE OF THE MOST COMMON ISSUES OBSERVED IN THE NETWORK
troubleshooting flow chart
Low Throughput
Lack of Resources
Power
Code
Congestion
CE
High Iub Limiting Ratio
Incorrect Parameter Settings
Poor Radio Conditions
Poor Coverage/ Quality
Over shooting
Pilot Pollution
Low CQI
Higher Order Modulation License
Alarms & Outages
Transmission Errors
BaSIC intigrity parameter check MO
Parameter
MO
Parameter
max Hsrate
codeThresholdPdu656 NumHspdschcodes
hsMeasurementPowerOset
16 QAM 64 QAM HSDPA Dyanmic Code Allocation
Hsdsch
HSDPA flexischedular
Site Configuration
numHsPdschCodes
numHsScchCodes
Eul2msTti
eulMaxTargetRtwp
CQI
numEagchCodes
Hspower margin queueSelectAlgorithm
Eul numEhichErgchCodes
eulmaxshorate
maxTransmissionPower eulMaxOwnUuLoad
eulMaxRotCoverage
UtranCell eulServingCellUsersAdm
Case study- cqi ImprovementhsMeasurementPowerOffset 1.- DESCRIPTION t he P-CPICH that the UE shall use when calculating the assumed HS-PDSCH power in the Offset relative to the CQI estimation – Range: (0.. 200) – Default: 0 [0 dB] / 0.1 dB – Recommended: 80 [8 dB]
.The new recommended value is intended to shi the distribuon of reported CQI away from the lower edge, since CQI=0 will result in no scheduling and reduced throughput. Tuning of the parameter might sll be needed (considering the observed CQI distribuon), but the recommended value is a beer starng point for this tuning than the current default value.
•
The channel quality indicator is used by the UE to signal to the RBS it’s current radio condions. In fact it sends the RBS a number relang to the biggest transport block that the UE thinks it can successfully decode under the current condions.
•
The UE reports a number between 1 and 30 and this indicates a maximum transport block size depending on the UE category
2.- EXPECTED BENEFITS: User and reported CQI. 3.- DETAILS:
–Changing –Changing “hsMeasurementPowerOset ” from less than 80 to default value 80.
CQI Adjustment High number of NACKs
RBS throughput?
XXXXXX X High CQI reporng UE
√
= 10%
High retransmission rate cqiAdjustmentOn = TRUE => low throughput High number of ACKs
√ √ √ √ √ √ Low CQI reporng UE
Low ulizaon
Since the accuracy of the CQI reporng depends on the UE vendor and model, it is recommended to enable the CQI adjustment feature so that both cell and user throughput are maximized. This is parcularly important when proporonal fair or Max CQI is selected as scheduling
> low throughput
algorithm.
Case STUDY - ECiO IMPROVEMENT BY HSPOWERMARGIN 1.- DESCRIPTION In determining how much power can can be allocated allocated to HS-PDSCH, HS-PDSCH, the total transmit power (including all common channels, dedicated channels, HS-SCCH, HS-PDSCH and the Enhanced Uplink downlink control channels) is limited to the maximum downlink transmission power for the cell signaled from the RNC, minus the hsPowerMargin back off. P HS = P max - P non-HS - hsPowerMargin [dB],
2.- KPI TO EVALUATE: HS Throughput. 3.- EXPECTED BENEFITS:
EcIo. 4.- DETAILS: –Changing hsPowerMargin 02 –Changing
Case STUDY –Eul thput improvment 1.- DESCRIPTION
•
The maximum total interference tolerated is set by the parameter eulMaxRotCoverage. A high value of this parameter limits the cell coverage but increases EUL capacity. A low value increases coverage at the expense of cell capacity. capacity. The purpose of this estimate is to dynamically allow as much EUL throughput throughput as possible without compromising the planned cell coverage.
2.- KPI TO EVALUATE: Eul Througput,R Througput,RSSI SSI 3.- EXPECTED BENEFITS:
Eul Throughput . 4.- DETAILS: – Changing eulMaxRotCoverage 100 to 300 –
› › › ›
WCDMA Resources Code tree consumption The code tree consumption is measured in percentage of the total tree size by excluding the fixed codes allocated for
› HSDPA HSDPA (i.e. the higher the number of codes allocated for › HSDP HSDPA A the smaller will be the available tree and higher the
› relative consumption) › The admission limit is set by dlCodeAdm (as a percentage)
Admission Control: Counter flow Chart- RRC
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