4G Strategy : SFN to Improve Performance

Background:

    A single-frequency LTE network experiences very high interference, especially on cell edges. To reduce this interference, Huawei introduced SFN feature.

    This feature recommends 2 to 3 RF modules that provide coverage in different areas to serve one SFN cell, with the overlapping areas between non-SFN cells becoming part of the SFN cell center. Joint scheduling is thereby performed for all UEs in the SFN cell to reduce interference. When there are only a few users and low network load, this feature obviously improves user experience.

Analysis:

When common RRUs or RFUs are deployed in densely populated outdoor areas, the cell radius is small to ensure coverage, but this deployment leads to high interference between cells. If SFN is used, most of the overlapping areas between non-SFN cells become part of the SFN cell center. This change reduces interference.

Fact Finding:

 Some routes of VIP area have high interference between co-site cells which will lead to poor SINR and low throughput.

Pro :

•Reduces interference, Improve SINR .

•Improves user experience in the overlapping areas between physical cells.

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Cons :

•Capacity reduced 50% or 66% if implement 2 or 3 candidate SFN cells to 1 target SFN cell respectively.

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Execution Selection Criteria :

•The total PRB utilization rate of the candidate cells must be below 45%.

•There are high overlapping interferences between co-site cells.

 

 Parameter Setting

1	Deactivate cells 11 21 31
2	Remove sector equipment 11 from cell 11, 31 from cell 31
3	Turn off UlJointReceptionSwitch under Uplink Comp Switch in the CellAlgoSwitch
4	Change the Flag of Multi-RRU Cell parameter value of cell 21
5	Bind sector equipment 11 and 31 to cell 21
6	Changed the SRS configuration indicator.
7	Activate SFN cells

Result Summary :

DT:

•SFN benefit very limited when the coverage very poor;

•SFN benefit very obvious when coverage good and with large overlapping  area (high co-site interference) ;

OSS:

Handover attempts reduced, Average CQI, User DL Throughput and PRB

Utilizing Rate increased, while other KPI maintained.