Sequence number expansion

This disclosure provides systems, methods and apparatus, including computer programs encoded on computer storage media, for identifying frames or packets of data that were received in error (such as incorrectly decoded or not received at all) by a receiving device for purposes of retransmission. In one aspect, a wireless device may form a number of frames for wireless transmission. Each of the frames may include a frame header and may be associated with a unique sequence number. In some implementations, for each of the frames, the wireless device may embed at least a portion of the unique sequence number into a portion of a control field or a delimiter field of the frame header. In some other implementations, for each of the frames, the wireless device may signal at least a portion of the unique sequence number using bit locations unassociated with a sequence number field of the frame header.