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RNO Wind Part II.

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Presentation on theme: "RNO Wind Part II."— Presentation transcript:

1 RNO Wind Part II

2 Part II - Content Retainability Compress Mode IRATHO
Drop cause relevance Compress Mode CM Time IRATHO Adjg Optimization Failure analisys

3 Retainability

4 Retainability Drop call (from 3G RNC side) can occur when UE is leaving the 3G layer (during inter-system HO) or in 3g layer. It is not easy to find clear relationship between drop call in 3g layer and active set size or SHO success rate. Considering WCELs with high permanence in “one cell in active state” (greater than 90% weighted value) no more than 50% suffer drop call value greater than 1% and increasing to higher value statistical data does not confirm the cause – effect relationship. Same behaviour is revealed for SHO success rate KPI. At the same way is not possible to find direct relationships between intersystem mobility failure procedure and high value of drop call. The reason for that has to be seek in the masking effect of the counters involved either SHO or Active Set Size or in the IRATHO success rate KPIs Drop call analisys have to be performed with a second level analisys taking into count that an averall improvement should come from ADJS and ADJG optimization

5 RAB & RRC Active Failures
RAB and RRC active failure reasons: RNC Internal BTS UE (for user perspective) Radio Interface Iur Iu RAB and RRC normal release: RAB active complete Pre-emption SRNC Relocation Unspecific error in CN (RAS05.1) UE RNC RAB Assignment Request (setup) CORE Radio Bearer Setup RAB Assignment Response Radio Bearer Setup Complete RAB Assignment Request (release) Iu Release Command Iu Release Request

6 RAB & RRC Active Failures
By a RNO point of view the drop due to lack of radio resources are the most important. Iu, Iur and RNC failure causes are neglected because the dimensioning should assure about it and out of RNO scope Fail due to congestion has to be intended as caused by shortage of resources or not appropriate air interface. In the following two KPIs to evaluate the drop cause that can be optimized:

7 RAB & RRC Active Failures
The retainability KPI does not take into account RRC-connections that move successfully through the cell, they only count drop ratio of RRCs that were released in the cell. In this way the drop KPI shows a bit too high values. Generic Drop Call KPI does not take into count the following scenario: To overcome this problem, new counters are implemented in RAS05.1 that are updated when the reference cell changes In this context term “reference cell change” means the cell that e.g. M1006 RRC counters are updated and that is used as stop_bts when pmi_ticket In Cell-FACH state the reference cell is the cell in which the UE is listening to the FACH channel RRC Drop here causes RRC_CONN_ACT_FAIL_xx to be incremented and not RRC_CONN_ACT_COMP is incremented Successful RRC Setup -> RRC_CONN_ACC_COMP is updated M1001C443 RRC_CONN_OUT_REF_CELL - The number of RRC Connections that have left from the old reference cell M1001C466 RRC_CONN_IN_REF_CELL - The number of RRC connections that enter a new reference cell

8 RAB & RRC Active Failures
Separating the numerator it is possible to have two separate KPIs for radio and BTS. This allows to differentiate the action required: Radio coverage plot , dominance must be verified indication from UL/DL Load KPI (see PartI) BTS HW & CE resource must be checked using KPI for CE and codes Start DC due to congestion Yes RNP data anlisys Load analisys Radio? Yes BTS? CE upgrade HW check End

9 Compress Mode

10 Compressed Mode Selection
CM is used to create idle periods (gaps) in the transmission during which ncell measurements on another system can be made Gaps can be created using single or double frame approach (Nokia supports both) Because same data amount is sent in a shorter time => affects WCDMA coverage Fast Power control information might be lost during the gap => higher Eb/No => affects WCDMA capacity Compressed frames may be lost if power control is not set correctly => affects WCDMA quality CM methods are Spreading Factor Halving and Higher Layer Scheduling Measurement gap Compressed Mode Power / Data Rate Normal fra\\me Normal frame Normal frame Compressed mode is not ideal from a “spectral efficiency point of view” only used when necessary Spreading Factor Halving: like switching temporarily from ISDN64kbit to ISDN128kbit to transmit more data. Then use the time to carry out more measurements)

11 Compressed Mode Selection
Selection of the compressed mode method is performed in the following way: AMR, RT PS or CS data service SF/2 used for both UL and DL Transmission Gap Pattern: Single frame: 7 slot gap, variable # of normal frames NRT PS data service Higher layer scheduling is Used for both UL and DL # of normal frames Double frame: 7 slot gap, Selection between HLS ½ and HLS ¾

12 CM Time The following counters are available for the CM procedure monitoring M1002C437 ALLO DURA FOR COM MODE UL USING SF/2 METHOD IN SRNC / M1002C433 ALLO FOR COM MODE UL USING SF/2 METHOD IN SRNC M1002C438 ALLO DURA FOR COM MODE DL USING SF/2 METHOD IN SRNC / M1002C434 ALLO FOR COM MODE DL USING SF/2 METHOD IN SRNC M1002C440 ALLO DURA FOR COM MODE DL USING HLS METHOD IN SRNC / M1002C436 ALLO FOR COM MODE DL USING HLS METHOD IN SRNC M1002C439 ALLO DURA FOR COM MODE UL USING HLS METHOD IN SRNC / M1002C435 ALLO FOR COM MODE UL USING HLS METHOD IN SRNC Dividing the duration by the respective allocation is possible to have an estimation of the CM Time The approaching of the limit GSMMeasRepInterval * GSMMaxMeasPeriod can be considered as an indication for the tunig of the related parameters Time for cell search and for CM can be tuned as well

13 CM Time RNC GSMRepInterval * GSMNcellSearchPeriod
After HO triggering condition is fulfilled a RRC message ”Measurement Control” is sent to UE containing details of the measurement that the UE must execute. RRC: ”Measurement control ” message (GSM RSSI measurements) RNC UE The neighbour cell search is regulated by the GSMNcellSearchPeriod period parameter. ISHO is not allowed until the are enough measurement reports given by this parameter (O means that only 1 measurement result is enough for decision making) Duration of the cell search period is calculated by: GSMRepInterval * GSMNcellSearchPeriod

14 CM Time GSMMeasAveWindow RNC GsmMeasRepInterval
Upon reception of the measurements reported by the UE, RNC applies a sliding averaging window to theRXLEV measurements. The averaged levels are used as input to the IS-HO decision algorithm. GSMMeasAveWindow is Measurement Averaging Window size, sliding window is used RNC UE The first measurement report has info from the best GSM cell: BCCH freq & RSSI, no filtering used in UE RRC: ”Measurement report” GsmMeasRepInterval is the interval between measurement reports, which are sent to BTS RRC: ”Measurement report” RXLEV measurements are reported through ”Measurement report” messages

15 CM Time WBTS RNC GSMMinMeasInterval
In case of an unsuccessful IS-HO attempt, the network will deactivate compressed mode for a time period given by GSMMinMeasInterval WBTS RNC NBAP: Compressed Mode Command GSMMinMeasInterval This is Minimum Measurement Interval, wait time when the following CM starts. NBAP: Compressed Mode Command If the RNC is not able to execute an inter-system Handover, it shall stop the inter-system measurements after the UE has sent the predefined number of measurement reports to the RNC, given by GSMMaxMeasPeriod The Maximum allowed duration of the inter-system measurement is calculated: GSMMeasRepInterval * GSMMaxMeasPeriod [ es:0.5*20 =10s,]

16 CM Time The CM time should never approach the max limit stated by
Start The CM time should never approach the max limit stated by GSMMeasRepInterval * GSMMaxMeasPeriod The best cndition is to perform the IS with the minimum time GSMRepInterval * GSMNcellSearchPeriod without failure. In the other cases ADJG optimzation or tunig of parameters are required Yes CM Time approach max? CM Time approach min? System stable Yes Verify # No Cell Found Yes Yes High # No Cell Found? New ADJG availale? Add ADJG CM tuning 1E/1F tuning


18 IRATHO As M1013 described in PartI, M1015 return statistic for intesystem HO. The filtering criteria can be replicated with the exception of ping-pong Filtering criteria: Major - High number of failures for a defined out-going adjg (failure ADJG) - high number of fail for a defined source (failure WCEL) Minor - very low number of attempt with failure (low used adjg) - zero number of attempt for declared adjs– stabilized value (no adjg) - high number of attempts for an out-going adjs (unbalanced ADJG) out-going condition is sufficient - high number of attempts for a defined source (unbalanced WCEL) Same procedures can be applied to the case considering that the event related are 1E and 1F

19 1E/1F Events for CPICH Ec/No and RSCP
HHoEcNo(RSCP)Threshold determines the absolute CPICH Ec/No threshold which is used by the UE to trigger the reporting event 1F. When the measured CPICH Ec/No of all active set cells has become worse than or equal to the threshold in question, the RNC starts inter-frequency or inter-RAT (GSM) measurements in compressed mode for the purpose of hard handover. HHoEcNo(RSCP)Cancel Defines the threshold of Ec/No(RSCP) that must be exceeded by a measurement of an active set cell to be canceled the event 1F related Cell 1 Cell 2 e.g. P-CPICH Ec/No Cell 3 1F 1E time HHoEcNo(RSCP)CancelTime determines the time period during which the CPICH RSCP of the active set cell must stay better than the threshold HHoRscpCancel before the UE can trigger the reporting event 1E. HHoEcNo(RSCP)TimeHysteresis determines the time period during which the CPICH Ec/No of the active set cell must stay worse than the threshold HHoEcNoThreshold before the UE can trigger the reporting event 1F.

20 IRATHO – Triggering reason
1. Low measured absolute CPICH Ec/No, event 1E/1F FMCG: GSMcauseCPICHEcNo 2 . Low measured absolute CPICH RSCP, events 1E/1F FMCG: GSMcauseCPICHrscp Triggering reason gives an indication 3. UE Tx power approaches its maximum allowed power, event 6A/6D FMCG: GSMcauseTxPwrUL 4. DL DPCH approaches its maximum allowed power FMCG: GSMcauseTxPwrDL 6 . Others - Load and Service based HO - IMSI based HO - Emergency ISHO 5. Quality deterioration report from UL outer loop PC FMCG: GSMcauseUplinkQuality GSMcauseX These parameters indicates whether a handover to GSM caused by low measured absolute CPICH Ec/No of the serving cell is enabled (1)

21 IRATHO – Triggering reason
It’s important to know which is the most frequent triggering reason: It’s possible to diffentiate between quality and coverage reasons and understand the network limiting factors: CPICH coverage Pilot pollution UL/DL Service coverage In actual case is possible to dsciminate between low CPICH coverage triggered by high# RSCP attempts or probable pilot pollution triggered by high # Ec/No attempts A KPI that gives reason for that is

22 IRATHO – Triggering reason
Enabling all the causes a screaning on the network is returned individuating the limiting factor and the required action. Start Yes High # Ec/No? DL Qual limiting DL interference/ Pollution should be evaluated DL Yes High # RSCP? DL level limiting CPICH power analisys/ new site required This condition should be the dominannt one without associated failure Yes High # UE Tx pwr? New site required or new Parametrization for IRATHO UL level limiting UL Yes Load analisys and UL interference evaluation High # UL Qual? UL qual limiting End Yes High # DL DPCH? Service limiting New planning for service is required

23 IRATHO - Failure Failure can happen at different point:
CN UE Node B RNC RRC: Measurement Control Failure can happen at different point: Before decision - Before CM - During CM - Measuring GSM cell After decision - Drop Utran and ue have to treated as particular case ISHO triggering (5 reasons are possible) RRC: Measurement Report NBAP: Radio Link Reconfiguration Prepare NBAP: Radio Link Reconfiguration Ready Initial Compressed Mode Configuration NBAP: Radio Link Reconfiguration Commit RRC: Physical Channel Reconfiguration RRC: Physical Channel Reconfiguration Complete NBAP: Compressed Mode Command RRC: Measurement Control GSM RSSI Measurement RRC: Measurement Report RRC: Cell Change Order from UTRAN RANAP: SRNS Context Request RANAP: SRNS Context Response RANAP: SRNS Data Forward Command RANAP: IU Release Command RANAP: IU Release Complete

24 Admission Control check for CM
CM not possible RNC UE RRC: Measurement Report (3,4,5) RRC: Measurement Control BTS Admission Control check for CM NBAP: Radio Link Reconfiguration Prepare NBAP: Radio Link Reconfiguration Ready NBAP: Radio Link Reconfiguration Commit RRC: Physical Channel Reconfiguration RRC: Physical Channel Reconfiguration Complete NBAP: Compressed Mode Command RRC: Measurement Report BSIC verification phase for target cell RX Level measurement phase for all ISHO neighbours AC is responsible for checkiing if CM is possiblle If CM fails one of the following mus be checked: Not enough resources – AC reject CM. Evaluate interference Expand capacity (see PartI) The following KPI gives an indication of the number of CM procedure not started Considering that M1010C2 (INTER SYST COM MOD STA NOT POS FOR RT) is updated if it is not possible to start inter-system compressed mode measurement due to radio resource congestion, BTS- or UE-related reasons to have a better insight on radio congestion it could be better to use, e.g. for UL the M1002C361 REQ FOR COM MODE UL REJECT TO INT SYST HHO IN SRNC and the M1002C357 REQ FOR COM MODE UL TO INT SYST HHO IN SRNC and use the following : M1002C361/M1002C357

25 NO Cell Found … measurement fail … measurement not fail No Cell Found
Compressed Mode start No Cell Found Counters HHO Attempt NO Cell Found means: there is no suitable gsm target cell in terms of RX Level OR the target gsm is suitable but its BSIC verification fails AND the maximum number of measurement reported are received maximum measurement interval is not expired … measurement not fail The following KPI gives an indication of the number of GSM cell not found Missing ADJG could be the reason or a dedicated parameter tuning for the 1F event. The KPI can be madified taling care of the WO_CMOD events

26 NO Cell Found Start High # NO Cell? End Yes Yes New site required
GSMCause=Ec/Nol? Pollution evaluation Reduce “Cancel” Increase “Time hysteresis” Verify ADJG Good GSM coverage in the far field? ADJG Addition? Coverage anlisys Good GSM coverage in the near field? Yes Yes Reduce “thershold” End

Optimization for unsuccess is not possible because the reason are: - physical channel failure (the UE is not able to establish the phy. - Protocol error - Inter-Rat protocol error - Unspecified Drop are related to drop call occurred during the procedure UTRAN Failure Counter UE Failure Counter ISHO Unsuccess Counters HHO Attempt Counters ISHO Success Counters In this case the optimization is required and pass through the evaluate of GSM and 3G plot coverage. Optimize If necessary number of ADJG or NWP parameters otherwise tune RNW parameters. Thresholds can be relaxed to favourite an early exit from 3G layer RRC Drop Counters

28 3G –> 2G Unbalancing This topic present the inherent problem due to the fact that the 2G layer is not involved in the analisys. Few consideration can be performed under some assumption: The following KPIs used over a cluster for CS voice service gives the percentage of the CM started over all the RAB, giving an idea of the attempted mobility procedure requested for a cluster where the 3G coverage should be assured Better to use completes: failures, normal & SRNC reloc on denominator and use the KPI inside the 3G cluster or difining a polygon where 3G service is required Once Correlated with voice drop due to radio link failure and rrc drop during ISHO, the KPI can help operator in understand the ISHO strategy. Similar KPI is possible for PS Threshold to shrink the HO area or inhibit the procedure has to be setted

29 How to use Nokia core and secondary colors
Nokia secondary color palette (secondary blue, secondary neutrals, secondary brights) can only be used in charts and shapes, in addition to core colors. Nokia blue Nokia green Nokia secondary blue Nokia secondary colors for charts & shapes R 000 G 051 B 204 R 068 G 165 B 028 R 175 G 212 B 240 R 235 G 233 B 216 R 191 G 215 B 218 R 230 G 192 B 031 R 175 G 148 B 023 R 206 G 150 B 032

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