Adaptive Hierarchical Modulation and Power Allocation of Cooperative Relay
Lindong Wu, Zesong Fei, Chen Luo, Jingming Kuang · 2011
In this paper, we consider a Demodulate-and-Forward (DMF) cooperation system, in which a new adaptive hierarchical modulation (HM) and power allocation scheme is proposed. In our new scheme, hierarchical 16-Quadrature Amplitude Modulation (16-QAM HM) is used to offer two different degrees of protection to the transmitted messages and we also employ power allocation between source and relay. A new optimization function based on maximizing the channel capacity, is given to obtain the optimal HM constellation and the best power allocation factor. We assume that all the channel state information (CSI) is available. Simulation results show that the proposed DMF system with our new strategy outperforms the reference system by about 2-2.5 dB.