There seems not to be a relation with poor SCC success and HSDPA retainability.
SCC success rate for HSDPA and HSUPA is not very accurate in cell level as denominator is incremented in the source cell (old serving cell) and numerator is incremented in the target cell (new serving cell).
REASONOTHERSTARTEDSCCUPDSETACTIVESTARTEDSCC ERRORSIRULSTARTEDSCCECNOCPICHSTARTEDSCC SUCCESSFULBTSINTERSCCSUCCESSFULBTSINTRASCC ARNC
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100%733_
No-- SHO_Adjacencies(46)--neighbor add/delete, Soft_Handover_Performance(28), Active_Set_Size_for_NRT-RT_Traffic--active set update fails-- check ad/delete/replacement window From cell level report
Check SHO Overhead (RNC_79b) to see how big is SHO area, if it is too small SHO may fails and if too big capacity is wasted
SHO success rate KPI (RNC_195a) is informing how many successful Active set updates we will have, compared to initial Addition/Replacement/Deletion requests.
RT Update % - 1a,1b,1c, NRT Update % - 1a,1b,1c, Events Ratio RT+NRT, HSUPA SHO Success Rate, CPICH EcNo Report(in % & no.) - Excellent, good, Acceptable, Poor, Bad SHO adjacencies are checked to increase SHO Success Rate, Target cells without neighbors are checked with their attempts & SR, Also their Avg. EcNo & RSCP shown their,
then decide whether neighbor is to be added or not.---- ADJs addition & deletion of neighbors with no share
HO success rate per adjacency counters-- delete/create them again,
Audit Adjacent sites for Alarms/capacity/traffic and visualization check with map
(Active_Set_Size_for_NRT-RT_Traffic Report)
Link is unbalanced--- do CPICH Optimization
REASONOTHERSTARTEDSCCUPDSETACTIVESTARTEDSCC
If UL interference----load optimization/External Interferer
No exact value can be given.
–If UL SRB becomes overloaded, it can cause:
§Delayed HOs -> decreased KPIs
§NAS signaling problems
§RRC signaling problems
•These problems can be avoided by optimizing the following parameters:
–Increasing ReplacementWindow –Increasing ReplacementTime
–Changing the interval of the periodical reports
New value for ReplacementWindow for Event 1C must be set in relation to events 1A and 1B
•FMCS: increase ReplacementWindow
–The amount of the ReplacementWindow increase depends on AddWindow and DeletionWindow sizes
•FMCS: increase ReplacementTime to 640ms
–UE measures CPICH Ec/N0 internally every 200ms
–Therefore practical ReplacementTime parameter values are 0ms, 240ms, 640ms and above to optimally utilize averaging in the UE
§Other values just cause delay (for example 320ms compared to 240ms means extra 80ms delay)
•Reporting happens on occasions 0, 200, 400, 600 –This is valid also for event 1A and 1B
•Periodical reporting parameters –AdditionReportingInterval –ReplacementReportingInterval
–DropReportingInterval (RU10 parameter)
•Increase the interval of the periodical measurements or disable periodicity to make reporting event based –Event 1C measurements are long, each occupying 160-200ms air interface time
–If the measurement interval is too short, the whole UL SRB bandwidth will be easily fully occupied by long measurement reports –Recommended way is to increase the interval from 0.5s to 1.0s
REASONOTHERSTARTEDSCCUPDSETACTIVESTARTEDSCC
AC rejects CM request due to Interference(UL/DL)
Radio Link(or physical channel) re-configuration failure--due to BTS/UE reasons--- ISHO is parallel procedure at the same time
y
2. 2G neighbors BCCH/BSIC collision chk ISHO KPI can be spitted in RT and NRT parts
1. CM start possible?--No( Chk Admission Control rejection--> PRxTotal, PTxTotal)
Yes-- ISHO measurement Success?
1. missing ADJG/bad performing neighbors(SR/Adjacency)-- ISHO Adjacencies report
REASONOTHERSTARTEDSCCUPDSETACTIVESTARTEDSCC ERRORSIRULSTARTEDSCCECNOCPICHSTARTEDSCC SUCCESSFULBTSINTERSCCSUCCESSFULBTSINTRASCC ARNC
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100%733_
3. Alarm of reference clock in 3G or in 2G
4. TCH Blocking/TCH congestion( target GSM cell is fully Loaded)/TCH failures/2G traffic/2G Hardware Alarm 5. Compressed mode parameter set checking
7. Strict ADJG minimum threshold
ADJG RxlevMinHO--(here set as -95dbm) 8. Poor GSM Coverage
If RRC connection drops during ISHO… TRelocOverall timer expires[8sec](in case of RT); RRCtmriRCCl timer expires[8sec](in case of NRT);
If No cell found ratio is>90% & enough ADJGs--- Wrong reference Clock tuning( 10MHz tunning)
TCH Blocking/TCH congestion/TCH failures/2G traffic/2G coverage & Interference
GsmMeasRepInterval= 0.5sec GsmMaxMeasPeriod= 6
6. Too low ISHO triggering threshold
If No cell found ratio >40%-- 3G cell at inter-RNC border/ 3G cell covers a coverage hole---- RF & ISHO neighbor optimization
The inter-system measurement phase takes a few seconds and during that time the conditions in the WCDMA layer may change => Cancellation
AS Update (1A or 1C) can also cancel ISHO in case of RSCP or Ec/No triggered ISHO
If the CPICH Ec/No or the CPICH RSCP of this cell is found to be greater than or equal to the threshold for event 1E
maximum number of ISHO cancellations per UE and per active set
-- BSIC Identification of max. 3 GSM carriers simultaneously
HandOver to GSM is close to typical value of 10 sec (GsmMeasRepInterval * GsmMaxMeasPeriod); visible benefit in reducing CM.
REASONOTHERSTARTEDSCCUPDSETACTIVESTARTEDSCC
3. Force Decode BSIC feature for NRT--> •ISHO success rate improved a lot -> ISHO cell found ratio decrease 4. Missing ADJG/bad performing neighbors(SR/Adjacency)-- ISHO Adjacencies report---> to be defined & corrected
--->
--->
If Max. Output power of UE is < value of AdjgTxPwrMaxTCH parameter; RNC adds Power diff(db) to AdjgRxLevMinHO -- 0...43 dBm, step 1 dBm ( set as 30dbm in TMO) GSM neighbor cell must exceed the RSSI level of AdjgRxLevMinHO-- for a handover to be possible--- ( set as -95dbm in TMO)
kitni measurement report se RNC avg GSM RSSI value for handover nikallegi---- 1...32 MeasRep, step 1 MeasRep, (6 in TMO
3. Decision Algorithm
max three GSM carriers simultaneously.
If the ISHO attempt to the best neighbour cell fails, a new attempt to the other cell can be started without new inter-system measurements in compressed mode.
(according to the GSM RSSI measurements) fails, or the target GSM cell is fully loaded.
Instead of waiting the penalty period and then retrying the HO with new CM measurements, the BSIC identification for more than one GSM cell is performed.
and allows another handover attempt to the second or third best cell without repetitive GSM measurements if the first handover attempt fails.
Multiple BSIC identification can be enabled with The MultipleBSICIdent parameter which must be set to ‘on’ to enable the feature across an RNC
The MaxBSICIdentTime parameter limits the maximum time for BSIC identification measurements per cell. If during this time no handover succeeded the handover attempt to GSM is finished.
•The MaxBSICIdentTime parameter must be configured with a value of greater than 0
•Suggested valued for testing of MaxBSICIdentTime is 3 or 4 seconds if the overall procedure of HandOver to GSM is close to typical value of 10 sec (GsmMeasRepInterval * GsmMaxMeasPeriod); visible benefit in reducing CM.
•Feature is applicable to both CS and PS connections so parameter is applicable in both RT and NRT FMCG parameter sets (although BSIC verification is not always required for PS connections)
REASONOTHERSTARTEDSCCUPDSETACTIVESTARTEDSCC ERRORSIRULSTARTEDSCCECNOCPICHSTARTEDSCC SUCCESSFULBTSINTERSCCSUCCESSFULBTSINTRASCC ARNC
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100%733_
SCC success rate for HSDPA and HSUPA is not very accurate in cell level as denominator is incremented in the source cell (old serving cell) and numerator is incremented in the target cell (new serving cell).
###
Determine SCC success rate, SCC failure rate and failure cause distribution
###
Check target cells HSDPA Setup performance (M1002C401 – M1002C428) if source cells SCC failure rate is high
###
•To find out which target cells are causing the SCC failure
•Check target cells M1000C22 AVE_PTXTOT_CLASS_4 and M1000C20 AVE_PTXTOT_CLASS_3 if SCC failures due to the lack of DL power (SCC_Failed_due_to_AC) – this is not visible in HSDPA accessibility KPI
•Check target cells number of simultaneous active HSDPA users
•Check target cells M1002C416/424 SETUP_FAIL_BTS_HS_DSCH_XXX
•Check target cells CE resource utilisation at BH using M5001 counters for lack of UL return channel resource
•Check NBAP Radio Link Reconfiguration Failure rate
•Check SHO overhead – all branches must have enough CE capacity if UE is in SHO when HS-DSCH allocation is started
•Check target cells M1002C415/423 SETUP_FAIL_UE_HS_DSCH_XXX
•Check RB reconfiguration Failure rate
•Require ICSU troubleshooting for UE types monitoring 6.If high SCC_FAILED_due_to_TRANS
•Check target cells of M1002C414 SETUP_FAIL_IUB_MAC_D_INT or M1002C422 SETUP_FAIL_IUB_MAC_D_BGR
•Evaluate number of reconfiguration failure due the transmission
•Check M1005C128 CANC_ADD_SRNC_TRAN_STP_FAIL
•Check M1001C531-C533 RAB_STP_FAIL_XXX_IUB_AAL2 7.If high SCC_FAILED_due_to_Others
•Check RNC internal transport resources usage (DMPG)
•Require ICSU troubleshooting
No-- SHO_Adjacencies(46)--neighbor add/delete, Soft_Handover_Performance(28), Active_Set_Size_for_NRT-RT_Traffic--active set update fails-- check ad/delete/replacement window
HSUPA SHO Success Rate, CPICH EcNo Report(in % & no.) - Excellent, good, Acceptable, Poor, Bad SHO adjacencies are checked to increase SHO Success Rate, Target cells without neighbors are checked with their attempts & SR, Also their Avg. EcNo & RSCP shown their,
Delayed HOs -> decreased KPIs
RRC signaling problems
These problems can be avoided by optimizing the following parameters:
Changing the interval of the periodical reports
New value for ReplacementWindow for Event 1C must be set in relation to events 1A and 1B
The amount of the ReplacementWindow increase depends on AddWindow and DeletionWindow sizes
UE measures CPICH Ec/N0 internally every 200ms
practical ReplacementTime parameter values are 0ms, 240ms, 640ms and above to optimally utilize averaging in the UE Other values just cause delay (for example 320ms compared to 240ms means extra 80ms delay)
Reporting happens on occasions 0, 200, 400, 600
Increase the interval of the periodical measurements or disable periodicity to make reporting event based Event 1C measurements are long, each occupying 160-200ms air interface time
If the measurement interval is too short, the whole UL SRB bandwidth will be easily fully occupied by long measurement reports Recommended way is to increase the interval from 0.5s to 1.0s
BSIC decoding need to be done in target GSM cell for RT BSIC decoding is not needed for NRT
No Cell found ratio-- should not be greater than 40-50%.
Radio Link(or physical channel) re-configuration failure--due to BTS/UE reasons--- ISHO is parallel procedure at the same time Cell found ratio for RT tells how easily target cell is found
Admission Control rejection--> PRxTotal, PTxTotal)
1. missing ADJG/bad performing neighbors(SR/Adjacency)-- ISHO Adjacencies report
4. TCH Blocking/TCH congestion( target GSM cell is fully Loaded)/TCH failures/2G traffic/2G Hardware Alarm
FMCS parameter set
MaxBSICIdent= 3sec ); visible benefit in reducing CM.
Force Decode BSIC feature for NRT
parameter; RNC adds Power diff(db) to AdjgRxLevMinHO -- 0...43 dBm, step 1 dBm ( set as 30dbm in TMO) GSM neighbor cell must exceed the RSSI level of AdjgRxLevMinHO-- for a handover to be possible--- ( set as -95dbm in TMO)
kitni measurement report se RNC avg GSM RSSI value for handover nikallegi---- 1...32 MeasRep, step 1 MeasRep, (6 in TMO)
•RAS06 ED2.1 feature
•ISHO success rate improved a lot -> ISHO cell found ratio decrease
parameter which must be set to ‘on’ to enable the feature across an RNC
parameter limits the maximum time for BSIC identification measurements per cell. If during this time no handover succeeded the handover attempt to GSM is finished.
must be configured with a value of greater than 0
if the overall procedure of HandOver to GSM is close to typical value of 10 sec (GsmMeasRepInterval * GsmMaxMeasPeriod); visible benefit in reducing CM.
Feature is applicable to both CS and PS connections so parameter is applicable in both RT and NRT FMCG parameter sets (although BSIC verification is not always required for PS connections)
Determine SCC success rate, SCC failure rate and failure cause distribution
Check target cells HSDPA Setup performance (M1002C401 – M1002C428) if source cells SCC failure rate is high To find out which target cells are causing the SCC failure
Check target cells M1000C22 AVE_PTXTOT_CLASS_4 and M1000C20 AVE_PTXTOT_CLASS_3 if SCC failures due to the lack of DL power (SCC_Failed_due_to_AC) – this is not visible in HSDPA accessibility KPI Check target cells number of simultaneous active HSDPA users
Check target cells M1002C416/424 SETUP_FAIL_BTS_HS_DSCH_XXX
Check target cells CE resource utilisation at BH using M5001 counters for lack of UL return channel resource Check NBAP Radio Link Reconfiguration Failure rate
Check SHO overhead – all branches must have enough CE capacity if UE is in SHO when HS-DSCH allocation is started
Check target cells M1002C415/423 SETUP_FAIL_UE_HS_DSCH_XXX Check RB reconfiguration Failure rate
Require ICSU troubleshooting for UE types monitoring
Check target cells of M1002C414 SETUP_FAIL_IUB_MAC_D_INT or M1002C422 SETUP_FAIL_IUB_MAC_D_BGR Evaluate number of reconfiguration failure due the transmission
Check M1005C128 CANC_ADD_SRNC_TRAN_STP_FAIL Check M1001C531-C533 RAB_STP_FAIL_XXX_IUB_AAL2 Check RNC internal transport resources usage (DMPG)
FMCG parameter set
30dbm in TMO)
GsmMaxMeasPeriod); visible benefit in reducing CM.
Check target cells M1000C22 AVE_PTXTOT_CLASS_4 and M1000C20 AVE_PTXTOT_CLASS_3 if SCC failures due to the lack of DL power (SCC_Failed_due_to_AC) – this is not visible in HSDPA accessibility KPI
If no planned value exists for a parameter, it can be compared to NSN default value or to the most common value in the network.
Discrepancy check can be limited to the most important objects WBTS licenses
Check allocation of local cell groups:
Non-optimal LCG allocation can cause unnecessary blocking due to lack of baseband capacity in LCG or reduced HSUPA performance if unused baseband capacity is allocated to other LCG.
Usually operator maintains a list of planned values.
ØTarget is to find and correct discrepancies in the parameter settings.
-Baseband capacity (license controlled in FlexiBTS up to HW limit)
Number and type of HSDPA schedulers-- HSDPA shared schedular(in TMO)--HSDPA 48 Users per Cell Number of HSUPA schedulers-- (HSUPA Basic 24 users per BTS enabled in TMO)
-Local cell grouping and capacity allocation between local cell groups -Cell maximum RF power
-Antenna line properties (MHA gain, feeder loss, RX diversity branch,…)
• number of cells per LCG
• baseband allocation per LCG
• Is HSUPA enabled in the LCG
•If shared scheduler is used, the number of schedulers depend on Tcell parameter settings on the site.
Tcell (Frame timing offset of a cell)-- WCEL parameter
Each cell in a BTS uses a BTS Frame Number (BFN) counter, which is delayed by a number of chips defined by the value of Tcell.
Group 1: Tcell values 0 (0 chips), 1 (256 chips) and 2 (512 chips) Group 2: Tcell values 3 (768 chips), 4 (1024 chips) and 5(1280 chips) Group 3: Tcell values 6 (1536 chips), 7 (1792 chips) and 8 (2048 chips) Group 4: Tcell values 9 (2304 chips)
Cells composing a Dual Cell HSDPA cell pair must have the same Tcell value.
Tcell is used for defining the start of SCH, CPICH, Primary CCPCH and DL Scrambling Code(s) in a cell relative to BFN. The main purpose is to avoid having the overlapping SCHs in different cells belonging to the same BTS. An SCH burst is 256 chips long.
UE classes –HSDPA category
Majority of the HSDPA UEs are still category 1-6 five code UEs having max 3.6 Mbps throughput
UE classes –HSUPA category
For HSUPA, the majority of the Ues in our Example are Category 5 UEs supporting 2Mbps throughput and 10 ms TTI.
Less than 30% of the UEs are category 6 UEs supporting higher uplink bitrates with 2ms TTI.
Propagation delay counters
Three main counters/KPIs was used for selecting the candidates for tilt:
Overshooting WCEL was found based on monitoring the three main KPIs.
Then decide whether it needs to be dowtilted or neighbor relations needs to be modified.
WCEl parameter-- Cell range- 5000, 10000, 20000 (mts) If Cell range is= 5000;
PRACH Propogation Delay report If Cell range is= 10000
PRACH Propogation Delay report-- can be used to evaluate how far UEs are from the cell
•Can be used to detect overshooting sites
M1006C169 PRACH_DELAY_RANGE_VALUE Counter can be used to monitor value of WCEL parameter PRACHDelayRange when the last RRC Connection Request or Cell Update of the measurement interval was received.
WCEL parameter PRACHDelayRange
•1 (5 km), 2 (10 km), 3 (20 km), 4 (60 km), 5 (180 km)
Example: Antenna Tilt Excercise – KPIs Used
•1) PRACH_distance > 10 km
•2) CSSR_CS (Call set-up success ratio)
•3) RAB_CS_DR (RAB CS drops)
Class 0 to Class 20 tak hoti hai If Cell range is= 20000;
PtxCellMax 43 dbm 40 dbm 40 dbm
PtxCPICH 33 dbm 30 dbm 33 dbm
CCCH total 35.5 32.5 35.5
Available HSDPA pwr (W) 16.4 8.2 6.5
Gammafactor 0.5 0.5 0.5
Ptx_Allowed HSDPA (W) 8.2 4.1 3.2
MPO, dB (calculated) 6.1 6.1 2.1
MPO from Nemo 6 6 2
•Reported CQI can be improved by optimisation on DL RF quality and level
–Reported CQI can not be improved by direct parameter changes in NSN RAN
If no planned value exists for a parameter, it can be compared to NSN default value or to the most common value in the network.
Any errors or mismatches between planned setup, configured setup, and actual hardware on site may lead to performance degradation.
WBTS configuration can be checked using WBTS site manager:
Collecting the data takes quite long time as the tool automatically logs to every WBTS to copy the data, but it can collect all the files in background without user interaction.
Example script for WBTS xml file mass analysis:
Output data includes:
BTS configuration (cells, carriers, HSDPA/HSUPA schedulers, …) BTS HW (system modules, radio modules, WSPx/WPAx/WTRx cards) BTS licenses
Local cell group configuration MHA and antenna line data
Check HSDPA scheduler type and number:
HSDPA scheduler type is defined in WBTS commissioning phase or by HSDPA shared scheduler license
Wrong scheduler type may cause HSDPA setup problems due to too many users, or waste baseband capacity if schedulers are underutilized.
HSDPA 48 Users per Cell WBTS configuration files can also be collected using a tool such as FileCollectorTool:
https://twiki.inside.nokiasiemensnetworks.com/bin/view/SEM/CommandlineTools
It collects site configuration data (including commissioning data and licenses) to xml files which can be mass post-processed.
•If shared scheduler is used, the number of schedulers depend on Tcell parameter settings on the site.
•If shared scheduler is used, the number of schedulers depend on Tcell parameter settings on the site.
Each cell in a BTS uses a BTS Frame Number (BFN) counter, which is delayed by a number of chips defined by the value of Tcell.
defining the start of SCH, CPICH, Primary CCPCH and DL Scrambling Code(s) in a cell relative to BFN. The main purpose is to avoid having the overlapping SCHs in different cells belonging to the same BTS. An SCH burst is 256 chips long.
Majority of the HSDPA UEs are still category 1-6 five code UEs having max 3.6 Mbps throughput
For HSUPA, the majority of the Ues in our Example are Category 5 UEs supporting 2Mbps throughput and 10 ms TTI.
Less than 30% of the UEs are category 6 UEs supporting higher uplink bitrates with 2ms TTI.
Classification criterias in the below table.
Overshooting WCEL was found based on monitoring the three main KPIs.
Then decide whether it needs to be dowtilted or neighbor relations needs to be modified.
If Cell range is= 5000; 5000 21 238.09m 1 class=238.09m
If Cell range is= 10000 10000 21 476.19m 1 class=476.19m
-- can be used to evaluate how far UEs are from the cell
can be used to monitor value of WCEL parameter PRACHDelayRange when the last RRC Connection Request or Cell Update of the measurement interval was received.
If Cell range is= 20000; 20000 21 952.38m 1 class=952.38m
Impact of PtxCPICH power tuning
EcNo degraded
•UE estimates CQI using available information on the channel quality.
–RSCP –Ec/N0
–HSDPA transmit power (signalled to UE) –Retransmission rate
–Etc.
Under isolated cell without any other traffic. HSDPA 15 code, 64QAM enabled, Category14 – 64QAM HSDPA UE used
•Both PtxCPICH 33 dBm and PtxCPICH 30 dBm measured. All other parameter remains untouched (PtxCellMax was 40 dBm in both cases)
•While decreasing CPICH tx power by 3 dB (from 33 dBm to 30 dBm) –Ave reported EcNo decrease ~ 2.5 - 3 dB
–Ave reported CQI increases only by ~ 1 - 1.5
Reported CQI can not be improved by direct parameter changes in NSN RAN
Any errors or mismatches between planned setup, configured setup, and actual hardware on site may lead to performance degradation.
Collecting the data takes quite long time as the tool automatically logs to every WBTS to copy the data, but it can collect all the files in background without user interaction.
HSDPA scheduler type is defined in WBTS commissioning phase or by HSDPA shared scheduler license
Wrong scheduler type may cause HSDPA setup problems due to too many users, or waste baseband capacity if schedulers are underutilized.
FileCollectorTool:
https://twiki.inside.nokiasiemensnetworks.com/bin/view/SEM/CommandlineTools
(including commissioning data and licenses) to xml files which can be mass post-processed.
If shared scheduler is used, the number of schedulers depend on Tcell parameter settings on the site.
to avoid having the overlapping SCHs in different cells belonging to the same BTS. An SCH burst is 256 chips long.
when the last RRC Connection Request or Cell Update of the measurement interval was received.
HSDPA 15 code, 64QAM enabled, Category14 – 64QAM HSDPA UE used
measured. All other parameter remains untouched (PtxCellMax was 40 dBm in both cases)
same BTS. An SCH burst is 256 chips long.