On ASER Performance of M-ary QAM Schemes Over DF Coordinated-NOMA

In this work, we investigate the performance of a power domain based downlink decode and forward coordinated-non-orthogonal multiple access (NOMA) system with two users and one relay node. The system is considered to operate in half-duplex mode over a Rayleigh faded channel, where the weak user is heavily shadowed with no direct link. Framework for average symbol rate error (ASER) and asymptotic ASER of generalized M-ary QAM for both weak and strong user is developed. Further, the impact of various power levels over different QAM schemes for the users is analyzed. Furthermore, the impact of symmetric and asymmetric constellations for the users is also considered and their impact over the system is detailed and useful insights drawn. The derived analytical expressions are verified through Monte-Carlo simulations, and compared with non-coordinated NOMA.