Cross-layer frame synchronization for H.264 video over WIMAX

In the WIMAX (802.16e) standard several small medium access control (MAC) packets may be aggregated to form a MAC burst, forwarded to the physical (PHY) layer [1] The burst transmission is a mechanism to allow multiple MAC protocol data units (PDUs) belonging to the same video channel to be transmitted / received in an aggregated way, in order to enable power saving at the mobile station, by putting the transceiver in sleep mode during off-burst interval. As a consequence of it, at the receiver side individual packets should be isolated within a burst, i.e. frame synchronization should be performed. We propose here to forward soft values from the PHY to the MAC layer, and to use our previous results on frame synchronization based on soft values [2] [3]. In addition, we exploit here a-priori information on the prevalence of 1's or 0's in the video bitstream and in packet headers, by performing application-aware and channel-aware MAC layer frame synchronization. Results show that the proposed approach results in an evident gain, at the expense of a small additional complexity.