Coding-quantization exchange for constant-bit-rate image transmission overwireless channels

Recently, there has been an increased demand for the transmission of images over wireless channels due to Internet applications. However, wireless cha nnels are very noisy and subject to fading, which may cause drastic deterio ration to the quality of the received image. In this paper we investigate t he application of forward error correction (FEC) to combat the noisy enviro nment of wireless channels. FEC is applied to the most significant data of the image at the cost of increasing the quantization noise for the less sig nificant data in such a way that keeps the bit rate constant. This scheme i s applied on both AWGN and flat-fading channels. It is shown that the propo sed scheme, called Coding-Quantization Exchange (CQX), offers 2-3 dB enhanc ement in the SNR of the image for bad channels (low E-b/N-o).