Cross-Layer Optimization with Power Control in DS-CDMA Visual Sensor Networks

In this paper, we propose an approach for cross-layer optimization with power control for a direct sequence-code division multiple access (DS-CDMA) visual sensor network where nodes monitor scenes with varying levels of motion. Our technique simultaneously assigns a source coding rate, a channel coding rate, and a power level to all nodes in the network based on two criteria that maximize the quality of video of the entire network as a whole, subject to a constraint on the total chip rate. One method minimizes the average end-to-end distortion amongst all nodes, while the other method minimizes the maximum distortion of the network. To reduce the computational complexity of the solution, universal rate-distortion characteristics (URDCs) are obtained experimentally to relate bit errors probabilities to the distortion of corrupted video. The URDCs are used in conjunction with channel characteristic plots obtained by using rate-compatible punctured convolutional (RCPC) codes for channel coding.