Achievable Rate Analysis for Cooperative Relay Assisted Opportunistic-NOMA over Rician Fading Channels with Channel State Information

The average achievable rate of an opportunistic non-orthogonal multiple access (O-NOMA) based cooperative relaying system (CRS) with channel state information (CSI) known at the transmitter end is analyzed under Rician fading channels. For opportunistic transmission of signals, CSI is used for the source-to-relay and source-to-destination links. For opportunistic transmission, with the help of CSI, the transmitter instantaneously selects between the cooperative NOMA transmission and the direct transmission of signals. The average achievable rate of the O-NOMA and conventional NOMA (C-NOMA) based CRSs is considered for performance comparison and an asymptotic expression is also provided which shows that O-NOMA-based CRS achieves better average rate performance than C-NOMA-based CRS. Asymptotic results are verified through Monte Carlo simulations for various channel powers and power allocation coefficients. Numerical results verifiy that the derived analytical results are matched well with the Monte Carlo simulations.