Non-linear Pre-coding for Non-Orthogonal Multiple Access in MU-MIMO System with Modulo-based Interference Cancellation

摘要

Multi-User Multiple-Input-Multiple-Output (MU-MIMO) systems and Non-Orthogonal Multiple Access (NOMA) are promising multiple access techniques for 5G wireless communication systems. MU-MIMO systems scale up channel capacity by taking advantage of spatial diversities. NOMA, on the other hand, increases spectrum efficiency by simultaneous transmission of multiuser streams over the same carrier with proper power weighting. Although combining NOMA and MU-MIMO (NOMA-MIMO) is promising, the cross contamination between the Inter-Antenna-Interference (IAI) and the Inter-Cluster-Interference (ICI) results in a difficult dilemma of pre-coding. While state-of-the-art researches mainly adopt the computational-intensive successive interference cancellation (SIC) schemes for ICI cancellation and receiver-side IAI suppression, in this paper we propose a non-linear pre-coding technique for two-cluster NOMA-MIMO cases allowing simple receiver-side modulo-based ICI cancellation and transmitter-side IAI suppressing pre-coding. The ergodic sum capacity and whole system bit-error-rate (BER) performance are provided to show the validity of the proposed approach.