Cooperative Transmission Utilizing High Order Superposition Modulation with Iterative Detection

In this paper, we propose an improved decode-and-forward (DF) relaying mode utilizing high order superposition modulation (HOSM) and iterative detection techniques, in which each user takes turns to transmit signal that is the superposition of its own and its partner's information. As the designed HOSM scheme is not gray mapping, we introduce iterative detection to further improve system performance. Simulation results show that the new strategy with superposition 16-QAM modulation (16-QAM SM) outperforms the classical DF system by about 1.5 dB and system with superposition 64-QAM modulation (64-QAM SM) is about 1 dB better than the classical DF scheme. Furthermore, the proposed systems with iterative detection can achieve extra 0.2-0.5 dB gains in the signal-to-noise ratio (SNR) range of interest.