What happens if two LTE TDD cells are configured with different special subframe SSP5 and SSP7?


What happens if two LTE TDD cells are configured with different special subframe ssp 5 and ssp7?

How can interference occur although in both config ULpts size is 2?

SSF5 has a longer guard time Just before UL expected slot begins.

This is set for cells with long RTD and TA.

DL slots from SSF7 may interfere in UL bits from far UE, besides increasing noise floor at SSF5 eNB.

This is my guess, others can comment.

Why after changing one NBR cell to be SSP5 and have close NBR have cell SSP7 - although according to below - there are no overlap between DwPTS of cell_A and UpPTS for cell_B?


Hope this help:

Thanks! :clap:

So you mean UL interference will be effective from SSP7 on SSP5 due to beyond attempt out of cell radius for SSP7 cells so this will overlap with ulpts for ssp5 hence ssp5 more affected?

Please correct me if I am wrong…

SSP7 to SSP5 conversion is done to mitigate the effect of ducting interference.
By Ducting interference we mean that Aggressor cell impacts the far-away neighbor beyond normal cell range. These faraway neighbors can be beyond 150kms also.
So, if we change the the Special Subframe from SSP7 to SSP5, the guard duration will be increased & thus there is chances that the ducting impact can be reduced.
When we change from SSP7 to SSP5 there is ~18% reduction in the cell capacity as during this, Guard period duration is increased & there is no transmission on DL duration.
So, returning to your original question, there will not be any impact if two neighboring cells are configured with different SSP patterns apart from capacity reduction as there will not be any overlapping of DL & UL duration as suggested above also.
Hope this will help you.