Quantizer optimization in hybrid digital-analog transmission of analog source signals

Abstract

The paper proposes a system for combined source-channel coding for transmitting continuous amplitude source symbols on a discrete time, continuous amplitude channel. Two channel symbols are generated for each source symbol. The channel contains additive, white, Gaussian noise, and the measure of quality is the MSE of the reconstructed signal. The coder quantizes the symbols and transmits both the quantized symbol and the quantization error. The quantizer representation values and decision levels are optimized numerically. The results indicate that the use of a uniform quantizer is nearly optimal for a uniformly distributed source. Comparison to another combined source-channel coder designed for a binary channel reveals that the proposed system performs significantly better than the reference systems, more than 5 dB for every channel SNR above 15 dB.