Multi-resolution modulation: an optimization criterion based on information theory

Although the degree of protection for transmitted bits offered by multi-resolution modulation (MRM) depends on the bits\´ perceptual importance, the channel capacity concept introduced by Shannon intentionally excludes the notion of information importance. In response to this exclusion, the authors introduce an alternate information theory-based quantity, called "weighted channel capacity", which explicitly integrates the notion of information importance and which can be used as an MRM optimization criterion. To accomplish this, the chain rule of mutual information was used to weight the influence of each bit according to its perceptual importance. Numerical results for the "weighted channel capacity" quantity are provided for the hierarchical pulse amplitude modulation (H-PAM) class on the AWGN channel.