Over-Complete Mapping Aided, Soft-Bit Assisted Iterative Unequal Error Protection H.264 Joint Source and Channel Decoding

Abstract

In this paper we evaluate the performance of data-partitioned H.264 video transmission using Unequal Error Protection (UEP) Recursive Systematic Convolutional Codes (RSC). Sphere Packing modulation aided Differential Space Time Spreading is used to improve the overall BER performance and to enhance the objective quality of the transmitted video sequence expressed in terms of Peak Signal-to-Noise Ratio (PSNR). The effect of different error protection schemes on the attainable system performance is demonstrated, when using iterative Soft-Bit Source Decoding (SBSD) and channel decoding, while keeping the overall bit-rate budget constant. Additional system performance improvements are achieved by intentionally increasing the redundancy of the source coded bit-stream using Over-Complete Mapping (OCM). This is achieved by appropriately partitioning the total available bit rate budget between the source and channel codecs. EXIT Charts were used for analysing the attainable system performance. Explicitly, our experimental results show that the proposed UEP scheme outperforms its Equal Error Protection (EEP) counterpart by about 1 dB E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> at the PSNR degradation point of 1 dB. Additionally, an E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</sub> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> gain of 12 dB is attained using iterative soft-bit source and channel decoding with the aid of rate 3/4 OCM.