Coordinated Scheduling for Non-Orthogonal Multiple Access (NOMA) in a Cloud-RAN System

In this paper coordinated scheduling technique is developed to enhance the performance of non-orthogonal multiple access (NOMA) in a cloud radio access network (C-RAN). As the density of users and base stations increases inter-cell interference (ICI) becomes the major obstacle in multi-cell networks. To mitigate the effects of ICI, scheduling-level coordination is performed where cloud is responsible for the scheduling policy. The concept of coordinated silencing is exploited to mitigate the effects of ICI on cell-edge users' performance.The problem of coordinated scheduling (CS) with silencing is formulated. A greedy heuristic algorithm is proposed in order to schedule the multiplexed users in a coordinated manner whilst satisfying the criterion of maximizing the sum proportional fairness (PF) metric. Simulation results demonstrates significant performance improvement in spectral efficiency of the cell-edge users' and system fairness with the proposed CS-NOMA scheme.