An Effcient Joint Beamforming and SIC Optimization Method for MIMO-NOMA

Achieving higher spectrum efficiency has been a critical performance target for the forthcoming 6G era. Non-orthogonal multiple access (NOMA) is regarded as an effective technique to improve the spectrum efficiency a nd t he cluster-free NOMA is a novel generalized downlink NOMA transmission framework. However, there still lacks an efficient joint beamforming and SIC optimization algorithm for cluster-free NOMA. In this paper, we propose a novel channel correlation based two-loop greedy (CC-TLG) algorithm to obtain a near-optimal solution with dramatically reduced complexity. CC-TLG maximizes the WSR of users based on the user channel correlation coefficients, where the outer loop add users one by one based on the WSR in a greedy manner, and the inner loop generates a near-optimal SIC operation based on both the channel correlation coefficients and WSR in a greedy way. Finally, simulations demonstrates the effectiveness of the proposed CC-TLG algorithm.