Transmission of analog signals using multicarrier modulation: a combined source-channel coding approach

We have proposed and analyzed a combined source-channel coding scheme using multicarrier modulation. By changing the power and modulation of subchannels carrying different bits of the quantized signal, the channel-induced distortion can be minimized. We derive an algorithm for the allocation of power among subchannels. Analog sources quantized by scalar and vector quantizers are considered. For a Gaussian source scalar-quantized to 8 bit, multicarrier transmission yields a 13 dB improvement of signal-to-distortion ratio over a single-carrier system. Quantizers having a smaller number of bits yield smaller improvements. We consider both full-search and binary tree-search vector quantizers using a natural binary coding scheme. For a vector quantizer using 2 b/sample, multicarrier transmission yields an improvement in signal-to-distortion ratio that lies between 0.3 and 0.8 dB, depending on the quantizer design.