8T8R LTE Soft Split Resource Duplex Configuration

[arian.jumaa]

Hi everyone,

has anyone of you experience or recommendation for 8T8R LTE Soft Split Resource Duplex Configuration

[rimoucha]

Hello,

We tried it without the support of huawei (Huawei recommendation is needed using the "softsplit design tool" ) and we had a severe degradation of CQI and many users complaints so we rollbacked.

BR

[arian.jumaa]

I have done below change for enabling it, would you check if there there are other switch or change need to be done for enabling SSRD

MOD CELLALGOSWITCHOCALCELLID=X,BFALGOSWITCH=BfSwitch-1,MUBFALGOSWITCH=MuBfSwitch-0,SSRDALGOSWITCH=Ssrd8T8RAlgoSwitch-1;




MOD CELLBFOCALCELLID=x,MAXBFRANKPARA=SINGLE_LAYER_BF;
MOD EUCELLSECTOREQMOCALCELLID=0,SECTOREQMID=0,WEIGHTNO=0;
MOD BFANTEVICENO=X,CRSSPLITBEAMINDICATOR=0;
MOD BFANTEVICENO=X,MODELNO="Soft_Split_Beam_Common";
MOD BFANTEVICENO=x,BEAMWIDTH=65;
MOD CELLOCALCELLID=X,ULCYCLICPREFIX=NORMAL_CP,DLCYCLICPREFIX=NORMAL_CP,FDDTDDIND=CELL_TDD,SUBFRAMEASSIGNMENT=SA2,EUCELLSTANDBYMODE=ACTIVE,HIGHSPEEDFLAG=LOW_SPEED,MULTIRRUCELLFLAG=BOOLEAN_FALSE,CRSPORTNUM=CRS_PORT_2,TXRXMODE=8T8R,MULTICELLSHAREMODE=SPLIT;


ADD SSRDCELLGROUP:PRIMARYLOCALCELLID=X,SSRDLOCALCELLID=Y;
MOD ENODEBALGOSWITCH:SSRDALGOSWITCH=IFSSFuncSwitch-1&SsrdSchOptSwitch-1&SsrdDlPwrShareSwitch-1&SsrdMultiBeamMeasSwitch-1&SsrdPdcchAllocOptSwitch-1;

[subway]

Unless you can keep the soft split duplexed neighbor cells on a different frequency (inter freq. soft splitting), you are effectively doubling the number of cell boundaries on your enodeb, which means twice as much area for self-interference. And this is the biggest limitation of this technology. I guess most of your clients do not support TM9. In that case I would recommend doing TM9 with CRS2 and feedback, instead of soft splitting.

Do you have the feature description for SSRD from Huawei? If not, I can upload it for you.

[arian.jumaa]

I have feature description but its not include all configuration , if you have applied it in your network would you please share the steps

[subway]

After we investigated how it works, we decided not to implement it due to the expected double cell edge situation, and we continued on the beamforming path, but I am honestly not very happy with that either. It is more and more seems to me, that on LTE the whole BF thing was "hacked" into the protocol which was originally not designed for the efficient multi-beam design. And that is the root cause of the poor performance. It is also true that we "stuck" on SRAN12, so maybe on SRAN13 or 15, the LTE BF might work better.

[subway]

What is not clear to me about soft splitting is the CPRI usage after the soft split is done.

Huawei claims soft splitting is "Just software upgrade, No changing antenna, RRU, etc., No special requirement to UE"

But the soft split document tells a bit otherwise:

The following capacity licenses can be applied for only based on the primary cell. Other
capacity licenses need to be applied for based on the split cell.

- UBBP First-Mode License(LTE TDD)
- RF Output Power (per 20W)(TDD)
- RF Transmit Channel (per Channel)(TDD)
- RF Receive Channel (per Channel)(TDD)

That means if I split a primary cell to two split cells, I doubled the cell number, so I need twice as many cell level licenses and therefor double the amount of CPRI bandwidth?

But if I read forward, I find this: "The CPRI compression bandwidth requirements do not change after intra-frequency split."

So do I need more CPRI bandwidth after soft splitting on intra-freq or not??

The same question is for inter-freq split:

"To implement inter-frequency split, a cell needs to be added on the RRU serving the original cell." and "The number of cells doubles after a split."

But nothing about the CPRI requirements.

[rimoucha]

Hello,

We activated the softsplit feature (Intra-freq) without any additional licences or BBP card or CPRI bandwidth but as i mentioned we rollbacked as there is a severe impact on quality.
Below is the activation script, hope this helps:

deactivate original cell



DEA CELL: LOCALCELLID=xx;


Change MultiCellShareMode of original cell

MOD CELL: LOCALCELLID=xx,MULTICELLSHAREMODE=SPLIT;

ADD the split cell


ADD CELL: LocalCellId=yy, CellName="mmmmmmmmm", NbCellFlag=FALSE, FreqBand=42, UlEarfcnCfgInd=NOT_CFG, DlEarfcn=zzzzz, UlBandWidth=CELL_BW_N100, DlBandWidth=CELL_BW_N100, CellId=yy, PhyCellId=499, FddTddInd=CELL_TDD, SubframeAssignment=SA2, SpecialSubframePatterns=SSP7, EuCellStandbyMode=ACTIVE, RootSequenceIdx=190, CustomizedBandWidthCfgInd=NOT_CFG, EmergencyAreaIdCfgInd=NOT_CFG, UePowerMaxCfgInd=NOT_CFG, CRSPORTNUM=CRS_PORT_2,TxRxMode=8T8R, MultiCellShareMode=split;


Activate weight database file


ACT BFANTDB: OPMODE=SWFILE;

Add beamforming antenna (To check DEVICENO and MANUFACTORY)

ADD BFANT: DEVICENO=11, MANUFACTORY=HuaweiAgisson, CONNSRN=60, MODELNO="Soft_Split_Left_BandD2",TILT=2,BAND=42;
ADD BFANT: DEVICENO=12, MANUFACTORY=HuaweiAgisson, CONNSRN=60, MODELNO="Soft_Split_Right_BandD2",TILT=2,BAND=42;

Add both cells to the same sector equipment and add weight numbers


ADD EUCELLSECTOREQM: LOCALCELLID=71, SECTOREQMID=12, WEIGHTNO=12, CELLBEAMMODE=NORMAL;
MOD EUCELLSECTOREQM: LOCALCELLID=51, SECTOREQMID=12, WEIGHTNO=11;

Add both cells to the same SSRD cell group

ADD SSRDCELLGROUP: PrimaryLocalCellID=51, SsrdLocalCellID=71;
Adding operator information of the new cell

ADD CELLOP: LocalCellId=71, TrackingAreaId= 60013, MMECfgNum=CELL_MME_CFG_NUM_0;

Turning off the quick channel calibration switch
MOD CELLALGOSWITCH: LOCALCELLID=51, EnhChnCalSwitch=QUICK_CHN_CAL_SWITCH-0;
MOD CELLALGOSWITCH: LOCALCELLID=71, EnhChnCalSwitch=QUICK_CHN_CAL_SWITCH-0;
Activating the split cell and then the primary cell. Two cells generated after a split are served by the same RRU. You are advised to activate the primary cell immediately after activating the split cell. This ensures that the split takes effect immediately in two cells :
ACT CELL: LOCALCELLID=yy;

ACT CELL: LOCALCELLID=xx;


MOD CELLALGOSWITCHOCALCELLID=xx,BFALGOSWITCH=BfSwitch-1,SSRDALGOSWITCH=Ssrd8T8RAlgoSwitch-1;

MOD CELLALGOSWITCHOCALCELLID=yy,BFALGOSWITCH=BfSwitch-1,SSRDALGOSWITCH=Ssrd8T8RAlgoSwitch-1;

MOD ENODEBALGOSWITCH:SSRDALGOSWITCH=SsrdSchOptSwitch-1&SsrdDlPwrShareSwitch-1&SsrdMultiBeamMeasSwitch-1

MOD CELLALGOSWITCH: LocalCellId=xx, IrcSwitch=PucchIrcSwitch-1;

MOD CELLALGOSWITCH: LocalCellId=yy, IrcSwitch=PucchIrcSwitch-1;

[subway]

Hello,

We activated the softsplit feature (Intra-freq) without any additional licences or BBP card or CPRI bandwidth

Do you use normal CPRI compression already, or did it worked after the split without any CPRI compression?

Also, can you share the antenna type?

[rimoucha]

Hello,

We use normal compression by default.The antenna type is Huawei ATD4516R8.