DIGITAL-ANALOG SUPERPOSITION CODING FOR OFDM CHANNELS WITH APPLICATION TO VIDEO TRANSMISSION

A new approach to hybrid digital-analog (HDA) video transmission over orthogonal frequency division multiplexing (OFDM) channels is presented. The goal is to achieve the best video quality by optimal power allocation, when the OFDM sub-channels have unequal and time-varying signal-to-noise ratios (SNR). In this method, the quantization error of a video encoder is superimposed on digital quadrature amplitude modulation (QAM) symbols. A solution to the power allocation problem is presented. Experimental comparisons with layered video coding and adaptive modulation shows that the proposed HDA approach is able to achieve a better video quality most of the time, particularly whenever there is a high motion content.