Block-coded Modulation: Novel Design Techniques and Rotational Invariance

In this paper we describe a simple method to implement two block-coded modulation (BeM) families previously reported by the present authors. This method considerably simplifies the bit mapping procedure, and makes it possible to implement the two BeM families with long block lengths and large signal alphabets. Next, we address the problem of rotationally invariant code design that is necessary to cope with the phase ambiguity of the carrier recovered at the receiver to demodulate the received signal. For both BeM families, we describe for which block lengths and how rotationally invariant codes can be designed. Finally, we also introduce the concept of hybrid BeM in which only some of the transmitted symbols take their values from an expanded signal alphabet. At the expense of a slight performance loss with respect to the previous BeM implementation, hybrid BeM leads to a significant further reduction ofthe encoder-decoder complexity.