Two-Dimensional Superposition Modulation and Power Allocation for Cooperative Wireless Communication System
Superposition modulation provides an alternative approach to transmit a node's own data packets along with its neighbor's relay packets in the same time-slot and frequency, which can improve spectral efficiency of cooperative wireless communication system. The authors propose a design criterion for two-dimensional superposition modulation based cooperative transmission where two users cooperate to transmit their data to a Base Station. They investigate M-PSK superposition modulation based cooperative scenario for Rayleigh fading channels and thoroughly derive the average Symbol Error Rate (SER) of such system with decode-and-forward relaying. Furthermore, they introduce a design parameter called power allocation ratio, i.e., ratio of transmit power for relay data to total power, which can be adaptively changed within the derived limit.