Hierarchical Modulation (HM) is widely employed across the telecommunication industry. The potential application of the coded HM scheme in cooperative communications has drawn a lot of interests. In this paper, a twin-relay aided triplelayer cooperative communication system is proposed. The system amalgamates rate-1/2 TTCM, triple-layer HM-64QAM and twinlayer SPM-16QAM schemes in the context of cooperative communications. We have optimized the entire system based on the HM ratio pair (R1;R2), the Superposition Modulation (SPM) weighting pair (; ) and the positions of the two relays. The simulation results show that our optimized system is capable of reliably transmitting a triple-layer HM-64QAM signal with the aid of two time slots at an average Signal-to-Noise-Ratio of 6:94 dB per time slot.
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