Unequally protected multi-stage vector quantization for time-varying channels
We present a source-channel coding system consisting of a multi-stage vector quantizer in conjunction with unequal protection against channel errors. The receiver estimates the channel conditions and decodes as many stages of the quantized signal as can be reliably decoded. The proposed overall system is optimized for robustness to time-varying noisy channels. Two versions of the system are designed and evaluated, which involve: (i) hard, and (ii) weighted decoding of the stage indices. Simulation results are given for Gauss-Markov sources transmitted over broadcast and fading channels. Consistent and substantial improvement is achieved over the standard multi-stage vector quantizer with equal error protection, and the gains are in the range of 3 to 5 dB.