/* old feedbacks we missed: mark for retransmission */
while(harq->feedback_frame!=frame
while((harq->feedback_frame-frame+1024)%1024>512// harq->feedback_frame < frame, distance of 512 is boundary to decide if feedback_frame is in the past or future
/* feedbacks that we wait for in the future: don't do anything */
if(harq->feedback_slot>slot){
if((frame-harq->feedback_frame+1024)%1024>512// harq->feedback_frame > frame, distance of 512 is boundary to decide if feedback_frame is in the past or future