A Cross-Layer Unequal Error Protection Scheme for Prioritized H.264 Video using RCPC Codes and Hierarchical QAM

We investigate the rate-compatible punctured convolutional (RCPC) codes concatenated with hierarchical QAM for designing a cross-layer unequal error protection scheme for H.264 coded sequences. We first divide the H.264 encoded video slices into three priority classes based on their relative importance. We investigate the system constraints and propose an optimization formulation to compute the optimal parameters of the proposed system for the given source significance information. An upper bound to the significance-weighted bit error rate in the proposed system is derived as a function of system parameters, including the code rate and geometry of the constellation. An example is given with design rules for H.264 video communications and 3.5-4 dB PSNR improvement over existing RCPC based techniques for AWGN wireless channels is shown through simulations. Keywords—Wireless Transmission, Unequal Error Protection (UEP), Rate-Compatible Punctured Convolutional (RCPC) Code, Hierarchical Modulation, H.264/AVC Video Coding