The Channel Capacity Increases with Power

Abstract

It is proved that for memoryless vector channels, maximizing the mutual information over all source distributions with a certain average power or over the larger set of source distributions with upperbounded average power yields the same channel capacity in both cases. Hence, the channel capacity cannot decrease with increasing average transmitted power, not even for channels with severe nonlinear distortion.

This is the third and last version of "The channel capacity increases with power." Future improvements, including results for multiuser channels, will be presented under the title "On monotonic capacity-cost functions," http://arxiv.org/abs/1209.2820