A Cross Layer Scheme for H.264/AVC Video Transmission over Wireless Network

In this paper, we propose a cross-layer design which combines Packet Forward Error Correction (P-FEC) at the application layer with a Symbol unequal FEC in the MAC layer (S-FEC). The aim is to minimize the Packet Loss Rate (PLR) and maximize the visual quality of video transmitted over a wireless network (WN). The proposed scheme is based on a FEC compatible with the semantics of the H.264/AVC video encoding. This mechanism relies on a rate distortion algorithm controlling the channel rates under global rate constraints given by the WN. Based on a data partitioning tool (DP), the proposed optimization mechanism takes into consideration both the packet type and packet length which leads to an unequal error protection (UEP). A Reed-Solomon S-FEC is adapted to unequal protected data. Indeed the unrecoverable S-FEC blocks can be balanced by a P-FEC in the application layer. Simulation experiments over random generated noise show that UEP scheme has a Bit Error Rate (BER) greater than or equal to BER at the output of the Equal Error Protection scheme (EEP) and demonstrate various Packet Loss Rate (PLRs) in terms of packet type. Contrary, the UEP scheme has a greater computational complexity than EEP. In particular, our proposed cross-layer UEP improves the average video peak signal-to-noise ratio (PSNR) by up to 4dB, compared to an EEP scheme.