CELL PCH Feature Implementation Guild in 3G Network

CELL-PCH Feature Guild in 3G Network

2012-4-12

Issue

1.00

Date

2011-10-27

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About This Document Author Prepared by

Jiapengyu

Reviewed by

Date

2011-10-22

Date

Reviewed by Approved by

Date

Summary This document includes the Cell PCH feature launching guild and issue handling.

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Content Author............................................................................................................................................................................2 Summary........................................................................................................................................................................2

1. Introduction of Cell-PCH.................................................................4 1.1. Benefit of Cell _PCH feature in current 3G network..............................................................................................4 1.2. Cell-PCH Feature Introduction................................................................................................................................4 1.2.1. CELL-PCH Fefination.......................................................................................................................................4 1.2.2. CELL-PCH working algraithm.........................................................................................................................4

2. Data Configuration of CELL_PCH......................................................6 2.1. RNC Configuration..................................................................................................................................................6 2.2. CELL Configuration................................................................................................................................................7 2.3. Reserved Parameter Configuration..........................................................................................................................8

3. Feature Testing and Verification....................................................10 3.1. Test case.................................................................................................................................................................10

4. KPI Impact after CELL_PCH Enabled...............................................11 4.1. KPI Impact and Degradation.................................................................................................................................11 4.1.1. Relocation Preparation Success Rate Decreased.............................................................................................11 4.1.2. PS Idle Mode Paging Degradation..................................................................................................................12 4.1.3. RNC HSDPA D2H Incereased When RNC is R12SPC5xx............................................................................13 4.1.4. RNC Call Drop Rate Degradation...................................................................................................................14 4.2. KPI Formula Change after CELL-PCH Implementation......................................................................................15

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1. Introduction of Cell-PCH 1.1. Benefit of Cell _PCH feature in current 3G network The RNC and core capacity is changeling with signaling storm risks which is caused by the quickly growing smart phones in 3G network. When the application is in use, sometimes the user is doing nothing at all. (For example, waiting for message coming when using MSN). During the time described as above, UE will send “Heart Beat” message to inform the AP server that the application is still on. To solve this risk, 3G RAN part can enable Cell-PCH to reduce the signaling load and meanwhile, reduce the SPU and GOU board load.

1.2. Cell-PCH Feature Introduction. 1.2.1. CELL-PCH Fefination In 3GPP, there are four RRC connected states for UE including URA_PCH, CELL_PCH, CELL_FACH, and CELL_DCH. Normally Cell-PCH mode is optional for 3G network, Below is basic information of CEL-PCH: CELL_PCH (Paging Channel). This is an optional RRC state. If there are downlink packets for the terminal, the terminal will be paged. In this state, the terminal is not able to send or receive packets, but the terminal will have to enter either the CELL_DCH or CELL_FACH state to send or receive. Not all network implementations currently use the CELL_PCH state.

1.2.2. CELL-PCH working algraithm Cell update procedure is required for CELL_PCH mode to keep RRC connection alive. 2012-4-12

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Whenever UE need to do a cell update RACH will be used (CELL UPDATE Message will send using common channels). If UE need to transfer data, the Cell Update message will send to with update reason “Uplink data Transmission” The RNC will send the CELL_UPDATE_CONFIRM message to reconfigure the RB to enter the UE to CELL_FACH mode to transfer UL data. If there any data transfer on DL, the Network will inform by PICH to make a cell update and the update reason is Paging Response. The RNC will send the CELL_UPDATE_CONFIRM message to reconfigure the RB to enter the UE to CELL_FACH mode to transfer DL data to UE. In CELL_PCH mode UE is known to Cell level in RNC, so all the paging messages will send to particular cell only ( Not to whole LAC as in Idle mode). So RNC should know if UE change camping cell by cell reselection procedure. To inform the new cell camped, UE will send Cell Update message with update reason “Cell Re-selection”. Below is status transmitting diagram of CELL PCH and CELLFACH, CELL-DCH.

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2. Data Configuration of CELL_PCH 2.1. RNC Configuration Below is the configuration in RNC side. 1. Run the ADD TRMFACTOR and MOD ADJMAP commands in sequence to change the Iu-PS activation factor. The recommended value for the activation factor is 10%. If the configured Iu-PS activation factor is smaller than 10%, retain the configured value. To avoid the admission failure on the Iu-PS interface due to the increase of UEs in CELL_PCH or URA_PCH state, change the Iu-PS activation factor. ADD TRMFACTOR: FTI=19, REMARK="IUPS", PSCONVDL=10, PSCONVUL=10, PSSTRMDL=10, PSSTRMUL=10, PSINTERDL=10, PSINTERUL=10, PSBKGDL=10, PSBKGUL=10, HDSRBDL=10, HDSIPDL=10, HDVOICEDL=10, HDCONVDL=10, HDSTRMDL=10, HDINTERDL=10, HDBKGDL=10, HUSRBUL=10, HUSIPUL=10, HUVOICEUL=10, HUCONVUL=10, HUSTRMUL=10, HUINTERUL=10, HUBKGUL=10; MOD ADJMAP: ANI=1400, ITFT=IUPS, TMIGLD=30, TMISLV=30, TMIBRZ=30, FTI=19; MOD ADJMAP: ANI=1401, ITFT=IUPS, TMIGLD=30, TMISLV=30, TMIBRZ=30, FTI=19; 2. Enable the DCCC and state transit switch SET UCORRMALGOSWITCH: DraSwitch=DRA_DCCC_SWITCH1&DRA_HSDPA_STATE_TRANS_SWITCH-1&DRA_HSUPA_STATE_TRANS_SWITCH1&DRA_PS_BE_STATE_TRANS_SWITCH-1; 3.Set H2F/D2F/F2P timer SET UUESTATETRANSTIMER: BeD2FStateTransTimer=4, BeF2PStateTransTimer=6, BeH2FStateTransTimer=4, BeE2FStateTransTimer=4; 4.Set PS Inactive timer SET UPSINACTTIMER: PsInactTmrForInt=1800, PsInactTmrForBac=1800; 5. Set F2D 4A Threshold SET UUESTATETRANS: BeF2DTvmThd=D2k,BeF2HTvmThd=D2k, BeF2ETvmThd=D2k;

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2.2. CELL Configuration Once CELL-PCH enabled, lots of the users will be transmit to PCH channel. Congestion might be happened. Additional SCCPCH is mandatory required for all the cells to expand the PCH and FACH capacity before enable Cell-PCH and EFD feature Below is the script for cell SCCPCH addition. Step1.Deactive Cell •

DEA UCELL: CellId=XXXX;

Step2.Remove exist SCCPCH • • • • • • • • • •

DEA USCCPCH: CellId=XXXX, PhyChId=8; RMV UPCHDYNTFS: CellId=XXXX, TrChId=3, RLCSize=240; RMV UPCH: CellId=XXXX, TrChId=3; RMV UPICH: CellId=XXXX, PICHId=10; RMV UFACHLOCH: CellId=XXXX, TrChId=4; RMV UFACHDYNTFS: CellId=XXXX, TrChId=4, RLCSize=168; RMV UFACHDYNTFS: CellId=XXXX, TrChId=5, RLCSize=360; RMV UFACH: CellId=XXXX, TrChId=4; RMV UFACH: CellId=XXXX, TrChId=5; RMV USCCPCH: CellId=XXXX, PhyChId=8;

Step3.Add SCCPCH for PCH • ADD USCCPCHBASIC:CELLID=XXXX, PHYCHID=8, TFCIPRESENCE=EXISTS, SCCPCHOFFSET=50, SCRAMBCODE=0, STTDIND=FALSE, CTFCSIZE=BIT4, SLOTFORMAT=D8, MBMSCHIND=COMMON; • ADD USCCPCHTFC:CELLID=XXXX, PHYCHID=8, CTFC=0; • ADD USCCPCHTFC:CELLID=XXXX, PHYCHID=8, CTFC=1; Step4.Add PCH and Active it • ADD UPICH:CELLID=XXXX, PICHID=10, PHYCHID=8, PICHMODE=V36, STTDIND=FALSE; • ADD UPCH:CELLID=XXXX, TRCHID=3, PHYCHID=8, RATEMATCHINGATTR=230, TOAWS=35, TOAWE=10, PCHPOWER=-20; • ADD UPCHDYNTFS:CELLID=XXXX, RLCSIZE=240, TRCHID=3, TFSNUMBER=D2, TBNUMBER1=0, TBNUMBER2=1; • ACT USCCPCH:CELLID=XXXX, PHYCHID=8; 2012-4-12

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Step5.Add SCCPCH for FACH • ADD USCCPCHBASIC:CELLID=XXXX, PHYCHID=9, TFCIPRESENCE=EXISTS, SCCPCHOFFSET=100, SCRAMBCODE=0, STTDIND=FALSE, CTFCSIZE=BIT4, SLOTFORMAT=D8, MBMSCHIND=COMMON; • ADD USCCPCHTFC:CELLID=XXXX, PHYCHID=9, CTFC=0; • ADD USCCPCHTFC:CELLID=XXXX, PHYCHID=9, CTFC=1; • ADD USCCPCHTFC:CELLID=XXXX, PHYCHID=9, CTFC=2; • ADD USCCPCHTFC:CELLID=XXXX, PHYCHID=9, CTFC=3; Step6.Add FACH Sig channel and User channel • ADD UFACH:CELLID=XXXX, TRCHID=4, PHYCHID=9, RATEMATCHINGATTR=220, MAXCMCHPI=D15, MINCMCHPI=D14, SIGRBIND=TRUE, CHCODINGTYPE=CONVOLUTIONAL, CODINGRATE=D1/2, TOAWS=35, TOAWE=10, MAXFACHPOWER=10; • ADD UFACH:CELLID=XXXX, TRCHID=5, PHYCHID=9, RATEMATCHINGATTR=130, MAXCMCHPI=D13, MINCMCHPI=D0, SIGRBIND=FALSE, CHCODINGTYPE=TURBO, TOAWS=35, TOAWE=10, MAXFACHPOWER=10; • ADD UFACHDYNTFS:CELLID=XXXX, TRCHID=4, RLCSIZE=168, TFSNUMBER=D3, TBNUMBER1=0, TBNUMBER2=1, TBNUMBER3=2; • ADD UFACHDYNTFS:CELLID=XXXX, TRCHID=5, RLCSIZE=360, TFSNUMBER=D2, TBNUMBER1=0, TBNUMBER2=1; • ADD UFACHLOCH:TRCHID=4, CELLID=XXXX, • ACT USCCPCH:CELLID=XXXX, PHYCHID=9; Step.7Active Cell •

ACT UCELL:CELLID=XXXX;

Step.8Check Cell status and SCCPCH availability status •

DSP UCELL:CELLID=XXXX;

2.3. Reserved Parameter Configuration There are two reserved parameter need to be modified to avoid CS RAB SSR degradation issue: SET URRCTRLSWITCH: RsvdPara1=RSVDBIT1_BIT21-0; SET URRCTRLSWITCH: RsvdPara1=RSVDBIT1_BIT20-0; 2012-4-12

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After the CELL_PCH state is activated, the CS RAB assignment fails under the following condition: A UE transits from the CELL_PCH state to the CELL_FACH state before setting up an AMR service. When the UE in the CELL_FACH state starts the AMR service setup, the UE transits from CELL_FACH state to CELL_DCH state. During the AMR service setup, the RNC receives from the UE a CELL UPDATE message with a cause value of "cell reselection" after sending the UE a RADIO BEARER SETUP message. The RNC then sends the CN an RAB ASSIGNMENT RESPONSE message, notifying the CN that the AMR service setup fails. When the cell update procedure with the cause value of "cell reselection" occurs in the AMR service setup procedure, the RNC stops the AMR service setup procedure and sends an RAB ASSIGNMENT RESPONSE message to the CN, and then the RNC starts to process the cell update procedure. The AMR service setup fails when the cell update procedure with the cause value of "cell reselection" occurs in the AMR service setup procedure. 1. If the UE transits from CELL_FACH state to CELL_DCH state when setting up AMR services, ensure that the RNC stops the AMR service setup after receiving the CELL UPDATE message with a cause value of "cell reselection", and continues the AMR service setup after the CELL UPDATE message is processed. The preceding function is disabled by default. To enable this function, run the following command: SET URRCTRLSWITCH: RsvdPara1=RSVDBIT1_BIT21-0; 2. If a UE in CELL_PCH state sends a CELL UPDATE message with a cause value of "Originating Conversational Call" or "Emergency Call" to the RNC when setting up AMR services, ensure that the RNC notifies the UE to transit from CELL_PCH state to CELL_DCH state. In this way, the two procedures are not crossed. The preceding function is disabled by default. To enable this function, run the following command: SET URRCTRLSWITCH: RsvdPara1=RSVDBIT1_BIT20-0;

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3. Feature Testing and Verification 3.1. Test case There are some test case in RNC acceptance guild, below is detail:

Test Case Descri pt i on. doc

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4. KPI Impact after CELL_PCH Enabled 4.1. KPI Impact and Degradation After CELL –PCH enabled in live network, there are many KPI will be degraded. But most of the KPI degradation are not impact customer experience, the local engineer must explain the possibility sequence to customer before implementation to avoid the complaint.

4.1.1. Relocation Preparation Success Rate Decreased While TRNC enabled Cell_PCH function, SRNC PS and CS SRNC relocation preparation success rate decreased sharply. Below is a example in live network:

Root cause: From signaling message there are two reason caused this degradation: - Failure message1” message-not-compatible-with-receiver-state” - Failure message 2” relocation-failure-in-target-CN-RNC-or-target-system" After Cell-PCH launched, to a certainty, users in Cell-FACH and Cell-PCH state increased. That will lead to combined service of CS&PS increased too. And current IUR don’t support CCH, so this scene appeared. Since the reason of relocation prepare stage failure is caused by user behavior after Cell PCH feature enabled in live network, and there is no any abnormal in RNC processing. Also this issue is not affect user experience, so no need to enable CCH over Iur to solve this issue. 2012-4-12

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Immediate action and Solution: No need take action for this KPI degradation.

4.1.2. PS Idle Mode Paging Degradation While TRNC enabled Cell-PCH function, the success rate of PS idle mode paging was degraded, below is the KPI:

Root cause:

The root cause of this idle paging degradation is due to user behavior changing after cell-pch implemented in whole network. Normally there are two kind of PS users in mobile network: high active users and low active users. The high active users are who using PS service frequently, for example the facebook, pushmail, MSN users. When those user making service, normally they are always choosing good coverage area to use PS service; and when they are come to bad coverage area, after a few time’s failure they will give up the service. Also the application server considered this user is offline already after service failed, it will not call this user for a certain time. So that the high active users are always has good paging/call success rate. But the low active users are always has lower paging/call success rate because that those users are not initiative to make PS service: they normally to receive ps call/paging passivity so that the possibility of their PS service in good and poor coverage area is same. 2012-4-12

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After cell-PCH feature enabled, the high active users are always stay in PCH status; but the low active users will be in idle mode because they are not make service frequently. That’s why the idle mode paging is degraded. Immediate action and Solution: No need take action for this KPI degradation.

4.1.3. RNC HSDPA D2H Incereased When RNC is R12SPC5xx While TRNC enabled Cell-PCH function, SRNC PS and CS SRNC relocation preparation

Root cause - The version V900R012ENGC01SPH5xx has an inner arithmetic correction, which makes the online time calculation of CELL_PCH user more accurate then makes CELL_PCH user number increase a lot. - For the UE of R5 and below R5, if its state is CELL_PCH and setup a CS RAB, then there will be a scenario of D2H. 2012-4-12

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- The length of PS inactive timer is configured very long on current network (600 seconds) and the CELL_PCH user number increase a lot, then the D2H scene above increased a lot. - Most UEs in du are under R6 device; - The UE under R6 in CELL_PCH state will trigger D2H when setup CS RAB. All the reasons above make the D2H increased a lot, which is normal Immediate action and Solution: No need take action for this KPI degradation

4.1.4. RNC Call Drop Rate Degradation RNC call drop rate will be degraded after CELL-PCH feature launched. PS Call Drop Ratio = PS RAB abnormal release times/(PS RAB abnormal release times+ PS RAB normal release times) After CELL_PCH or EFD feature enable, The PS inactive timer will extend then whole network “PS RAB Normal Release Times” will reduce, further “PS Call Drop Ratio” will increase. More PS user will keep in CELL_FACH, the CELL_FACH call drop will increase a little higher than CELL_DCH. the “PS RAB Abnormal Release Times” will increase a little bit probably. The reason of “PS Call Drop Ratio” increase is the “PS RAB normal release times” decline, So that the user perception is still normal.

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4.2. KPI Formula Change after CELL-PCH Implementation It is recommended to change the PS CDR formula to exclude the drops which is happened in PCH or FACH after cell-PCH launched. Below is the KPI formula which is used in E operator.

Table 1．

PS R99 CDR(Cell－PCH)

Counter & Formula

·

PS R99 Call Drop Ratio with PCH (Cell)= [(VS.RAB.AbnormRel.PSR99VS.RAB.AbnormRel.PS.PCHVS.RAB.AbnormRel.PS.R99D2PVS.RAB.AbnormRel.PS.F2P)/ (VS.RAB.AbnormRel.PSR99+ VS.RAB.NormRel.PSR99VS.RAB.AbnormRel.PS.PCHVS.RAB.NormRel.PS.PCH+ VS.HSDPA.F2H.Succ+ VS.HSDPA.D2H.Succ+ VS.PSR99.D2P.Succ+ VS.DCCC.Succ.F2P)]*100%

Scope

Table 2．

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PS HSDPA CDR(Cell－PCH)

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Counter & Formula

·

HSDPA Service Drop Ratio with PCH(Cell)= [(VS.HSDPA.RAB.AbnormRelVS.HSDPA.RAB.AbnormRel.H2P)/ (VS.HSDPA.RAB.AbnormRel+ VS.HSDPA.RAB.NormRel+ VS.HSDPA.HHO.H2D.SuccOutIntraFreq+ VS.HSDPA.HHO.H2D.SuccOutInterFreq+ VS.HSDPA.H2D.Succ+ VS.HSDPA.H2F.Succ+ VS.HSDPA.H2P.Succ)]*100%

·

HSDPA Service Drop Ratio with PCH(RNC)= [(VS.HSDPA.RAB.AbnormRel+ VS.RAB.AbnormRel.HSDPA.IurVS.HSDPA.RAB.AbnormRel.H2P)/ (VS.HSDPA.RAB.AbnormRel+ VS.RAB.AbnormRel.HSDPA.Iur+ VS.RAB.NormRel.HSDPA.Iur+ VS.HSDPA.RAB.NormRel+ VS.HSDPA.H2D.Succ+ VS.HSDPA.H2F.Succ+ VS.HSDPA.HHO.H2D.SuccOutIntraFreq+ VS.HSDPA.HHO.H2D.SuccOutInterFreq+ VS.HSDPA.H2P.Succ)]*100%

Scope

Table 3．

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PS HSUPA CDR(Cell－PCH)

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Counter & Formula

HSUPA Call Drop Ratio with PCH (Cell)= [(VS.HSUPA.RAB.AbnormRelVS.HSUPA.RAB.AbnormRel.E2P)/ (VS.HSUPA.RAB.AbnormRel+ VS.HSUPA.RAB.NormRel+ VS.HSUPA.HHO.E2D.SuccOutIntraFreq+ VS.HSUPA.HHO.E2D.SuccOutInterFreq+ VS.HSUPA.E2F.Succ+ VS.HSUPA.E2D.Succ+ VS.HSUPA.E2P.Succ)]*100%

HSUPA Call Drop Ratio with PCH (RNC)= [(VS.HSUPA.RAB.AbnormRel+ VS.RAB.AbnormRel.HSUPA.IurVS.HSUPA.RAB.AbnormRel.E2P)/ (VS.HSUPA.RAB.AbnormRel+ VS.HSUPA.RAB.NormRel+ VS.RAB.AbnormRel.HSUPA.Iur+ VS.RAB.NormRel.HSUPA.Iur+ VS.HSUPA.HHO.E2D.SuccOutIntraFreq+ VS.HSUPA.HHO.E2D.SuccOutInterFreq+ VS.HSUPA.E2F.Succ+ VS.HSUPA.E2D.Succ+ VS.HSUPA.E2P.Succ)]*100%

Scope

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