On the difficulty of bit-interleaved coded modulation for differentially encoded transmission over fading channels

Abstract

The application of bit-interleaved coded modulation (BICM) in combination w i t h differential encoding and non-coherent reception over flat fading channels is assessed. Since the labeling plays a cent r a l role for BICM w e propose a suitable definition of G r a y labeling for differentially encoded transmission. We show that for multiple symbol detection such a G r a y labeling d o e s n o t exist. Finally, w e illustrate the consequences on the capacity by comparing BICM and an optimum coded modulation scheme.