TDD CA SSF Configuration

5G NR
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1

Per standard, is it allowed in TDD CA to have different SSF configuration in both TDD carriers?

1 Like
2

3GPP TS 36.211 version 15.8.1 4.2 Frame structure type 2

In case multiple cells with different uplink-downlink configurations in the current radio frame are aggregated and the UE is not capable of simultaneous reception and transmission in the aggregated cells, the following constraints apply:

  • if the subframe in the primary cell is a downlink subframe, the UE shall not transmit any signal or channel on a secondary cell in the same subframe

  • if the subframe in the primary cell is an uplink subframe, the UE is not expected to receive any downlink
    transmissions on a secondary cell in the same subframe

  • if the subframe in the primary cell is a special subframe and the same subframe in a secondary cell is a downlink subframe, the UE is not expected to receive PDSCH/EPDCCH/PMCH/PRS transmissions in the secondary cell in the same subframe, and the UE is not expected to receive any other signals on the secondary cell in OFDM symbols that overlaps with the guard period or UpPTS in the primary cell.

My understanding is: can be, but requires UE support and you will have some drawbacks.

3

Thanks @marcengo.
But precisely, my question is if pcell is with SSF conf 7 and scell SSF conf 5, then how aggregation will be performed?

4

My understanding is, for every SSF defined in 36.221 the SCell will not be scheduled.
But you are allowed to have.
It is not forbidden by spec, being the response to the original question.

5

Yes i agree with you. Thanks.
I observed , many devices are performing RRC Restablishment after being configured with scell having different ssf conf than pcell.
This is source of my query.

6

Interesting! The Reestab cause, I’m assuming is “reconfigurationFailure”, correct?
It would be cool to identify if this is related to a single OEM/device or spread across multiple.
Do you have tools for that?