MAC-level partial checksum for H.264 video transmission over 802.11 ad hoc wireless networks

We present a technique to enhance real-time video transmissions over 802.11-based ad hoc networks. We propose to limit the coverage of the error detection mechanism to the most error sensitive bit class contained in video packets. Packets are retransmitted only if errors affect those bits, instead of retransmitting all corrupted packets irrespective of error positions. The expectation was that the negative effects of errors in the less sensitive bits should be more than adequately counterbalanced by the lower number of discarded video packets. Moreover, the lower number of retransmissions should reduce network load, with positive effects on all the transmissions. We simulated the transmission of H.264 video over an ad hoc scenario with a varying number of relay nodes using ns with experimental bit error traces. Results show consistent video quality improvements (up to 1 dB PSNR) as well as network load reduction with respect to state-of-the-art techniques, such as unequal error protection based on different retry limits.