After how many subframes in TDD LTE there is HARQ response?
Like for FDD it is after 4 subframes?
Depends on the subframe assignment
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.