Combination of NOMA and MIMO: Concept and Experimental Trials

Non-orthogonal multiple access (NOMA) is a novel multi-user multiplexing scheme that improves spectral efficiency for LTE enhancements and 5G. By overlapping radio resources (e.g., time/frequency/code), but assigning different powers to the multiplexed users, NOMA is able to improve the system performance and fairness. In this paper, we review the concept of combining downlink NOMA with MIMO. Then, we introduce our experiment trials conducted to assess the performance of downlink NOMA combined with MIMO under realistic conditions. The sets of experimental trials are conducted in outdoor environments, one using NOMA combined with open-loop 2×2 MIMO and another using NOMA combined with closed-loop 4×2 MIMO.