After how many subframes in TDD LTE there is HARQ response?

4G LTE
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1

Hi All,
After how many subframes in TDD LTE there is HARQ response?
Like for FDD it is after 4 subframes?

2

Depends on the subframe assignment

3

FDD, each DL slot has 1 corresponding UL slot, so HARQ timing can be fixed.
TDD, for example DDDSU: all DL slot 0,1,2,3 can have ack/nack in slot 4, or even in slot 9 of next uplink.

4

In LTE TDD UL/DL Config #2 (DSUDDDSUDD), the UE transmits the ACK/NACK in subframe ‘n’ for the PDSCH received in subframe ‘n-4’, ‘n-6’, ‘n-7’ and ‘n-8’. For e.g. , the UE will transmit ACK/NACK in subframe 2 of radio frame ‘N+1” for the PDSCH received in subframe 8, 6, 5 and 4 of previous radio frame N.
Similarly, if the UE transmit the PUSCH in subframe ‘n’, the corresponding ACK/NACK is transmitted in subframe ‘n+6’. For e.g., when the UE transmits PUSCH in subframe 2, the eNB will send the ACK/NACK in
subframe 8 using PHICH.