Noncoherent coded modulation for 32QAM

A new non-coherent coded 32QAM (NCC-32QAM) scheme is presented. A particular trellis-coded modulation without parallel branches was chosen and a special mapping rule developed for the channel signal assignment so that differential coherently equivalent sequences were eliminated. On the receiver side, neither pilot signal nor training sequence is needed for synchronisation purposes. The detection process involves two steps. The first one consists of seeking for the initial carrier phase using a particular noncoherent detection metric. The second one uses the conventional Viterbi decoding algorithm in conjunction with an iterative phase updating. Simulation results show that the performance of this new NCC-32QAM is very close to that of the coherent 32QAM even for low signal-to-noise ratio. Indeed, only 0.3 dB is lost compared with the coherent trellis-coded 32QAM for a bit error rate of 10^-6.