Fair Resource Allocation Using the MCS Map for Multi-user Superposition Transmission (MUST)

In this paper, we tackle the practical error propagation and MCS (modulation and coding scheme) selection problem for non-orthogonal multiple access (NOMA) based on multi-user superposition transmission (MUST). Our formulation involves proportional-fair allocation of resource blocks to a set of users with guaranteed bounds of error rates. Since a majority of MCSs used in existing communication systems do not have closed-form expressions to evaluate the bit error rates of co-allocated NOMA users, we propose a method to integrate link-level NOMA simulation for solving the network optimization problem. By constructing an "MCS map" as the output of the NOMA simulator, the resource allocation algorithm can perform system-level allocation without involving link-level simulation on a bit-by-bit basis. Through evaluation results, we show that the proposed method based on the MCS map can outperform baseline approaches based on estimation of post-processing SINR of NOMA users. We also find that NOMA can indeed achieve significant gain over OMA, but the gain does not increase proportionally to the number of users allowed to share each resource block. Such diminishing returns suggest further optimization for NOMA in this direction.