On the Random Coding Exponent for Differential Modulation and Detection

The random coding exponent for differential modulation with finite signal sets over block-fading channels and multiple-symbol differential detection with an observation window size of N symbols is considered. Different from and in extension to previous work, the channel coherence interval is independent of N and the case of spatial transmit diversity is included. In this context, we also devise bounds and approximations of the random coding exponent, which allow for efficient numerical evaluation. The presented numerical results provide useful information on the performance of coded differential transmission with short to moderate code lengths