Chapter 12 - Joint Source-Channel Coding and Decoding

Abstract

This chapter provides an overview of joint source-channel coding and decoding. We first address joint decoding techniques, which exploit the residual redundancy left by source coders in the compressed data stream to correct transmission impairments. Combined with concealment, these techniques may reduce the need for packet retransmissions when they are allowed. Then, this chapter introduces joint source-channel coding. Several joint coding techniques are presented, ranging from redundant signal representations via frames, correlating transforms, or channel codes, through the design of robust entropy codes, to hierarchical modulations and high-density constellations. All these techniques have to account for the presence of a network, which introduces protocol overheads. Thus, an overview on joint protocol-channel decoding techniques is finally provided. These techniques, implemented at the receivers, do not require any modification of the transmitter and are very helpful to get the best out of noisy packets that would be rejected by standard receivers. They allow all joint source-channel coding and decoding techniques employed at higher layer of the protocol stack to be really put at work in actual systems.