Layered transmission of signals over power-constrained wireless channels

Transmission of layered information over a power-constrained channel is considered. We address the question of the power allocation policy where the goal is to minimize the overall end-to-end distortion. A layer containing significant information is more heavily protected against channel error through allocating more power to that layer. We define an appropriate coding gain and show that the Karhunen-Loeve transform (KLT) is the best unitary transform in the sense of maximizing this gain. Furthermore, we look that the embedded transmission of information and compare this method to orthogonal methods such as multicarrier transmission. We also consider end-to-end distortion optimization for broadcast channels.