DESIGN OF MUTIPLE DESCRIPTIONS WITH SYMBOL-BASED TURBO CODES OVER NOISY CHANNELS WITH PACKET LOSS
Mehrdad Valipour, Farshad Lahouti · 2007
Multiple descriptions (MD) with symbol-based turbo (SBT) codes are proposed, where the decoder exploits both nonuniformity of descriptions and their dependencies. A distortion-power adaptive system is obtained by setting an entropy constraint for quantizer design, which together with the MD index assignment (IA), control the level of redundancy at the MD source coder output. This is in turn exploited by the source and channel decoders for robust transmission in presence of noise and packet loss (PL). At the source coder, the IA is designed for an M-description vector quantizer using an efficient simulated annealing algorithm. Through sensitivity analysis, it is shown that in contrast to noisy channels without PL, it is better that MD is designed for the operating channel SNR in the presence of PL. Numerical results indicate improved performance in comparison to the prior art.