Operational rate-distortion design for joint source-channel coding over noisy channels
An optimal joint source-channel coding (OJSCC) scheme is developed for memoryless generalized Gaussian distribution (GGD) sources encoding and transmission over noisy channels. Two channel models are studied, binary symmetric channels (BSC) for memoryless channels and Gilbert-Elliott channels (GEC) for bursty channels. The operational rate-distortion (R-D) function we adopted represents an end-to-end error measurement that includes errors due to both quantization and channel noise. In particular, we are able to incorporate both the channel transition probability and channel bit error rate in the case of bursty channels. With the operational R-D function, we can achieve an optimum tradeoff between source coding accuracy and channel error protection under a fixed transmission rate. Experiments show that for BSC, OJSCC outperforms the best channel optimized scalar quantization (COSQ) system at high bit rate constraint; while for GEC, we show that the optimal design achieves better performance than the popular designs based on either the average BER or the worst BER. Moreover, based on the results of OJSCC, we propose a robust joint source-channel coding (RJSCC) scheme based on a combination of OJSCC with allpass filtering, RJSCC can be applied to a broad class of GGD sources with shape factor /spl nu/<2.0 to achieve an improved transmission performance.