BER Analysis of Multi-User NOMA Networks in the Presence of Interference

This letter considers a multi-user non-orthogonal multiple access (NOMA) system in the presence of arbitrary co-channel interference (CCI) signals. Taking into account the precise statistics of the self-interference signals of NOMA users, it derives a new unified expression for the bit error rate (BER) of an arbitrary number of users. The users may employ various modulation schemes and orders, including M-ary pulse amplitude modulation with arbitrary orders, M-ary quadrature amplitude modulation with arbitrary orders, or a combination of both with arbitrary orders. The newly derived expression is then applied to a multi-user NOMA in two different interference scenarios: (i) fixed located CCI, and (ii) Poisson point process-based randomly located CCI. The preciseness of the BER expression for different number of users and modulation schemes/orders is verified via numerical and simulation results.