Error-resilient image coding and transmission over wireless channels
This paper introduces and implements a point-to-point error-resilient image coding and transmission scheme over a CDPD (cellular digital packet data) wireless channel, combining a low-delay UDP (user datagram protocol) transport protocol in conjunction with a channel-optimized wavelet-based image coder. The image coder uses a robust channel-optimized trellis-coded quantization (COTCQ) stage that is designed to optimize the image coding based on the channel characteristics. Packets are formed with the property that image information is spread over different frequency bands. The channel characterization is conducted in such a way so as to minimize the packet loss rate and maximize the net data throughput. Furthermore, a receiver-based rate control mechanism is presented at the application level to reduce significantly the image distortions and packet loss rate. Results are presented to illustrate the performance of the proposed system.