Power Allocation Algorithm of Optical MIMO NOMA Visible Light Communications

Visible light communication (VLC) is a promising technique in future networks due to its advantages of high data rate and licensed-free spectrum. In this paper, we apply the non-orthogonal multiple access (NOMA) technique to improve the achievable sum rate of multipleinput multiple-output (MIMO)-based multi-user visible light communication (VLC) systems. To ensure efficient and low complexity power allocation in indoor MIMO-NOMA-based VLC systems, a normalized gain difference power allocation (NGDPA) method is first proposed by exploiting users' channel conditions. We investigate the performance of an indoor 2x2 MIMO-NOMA based multi-user VLC system through numerical simulations. The obtained results show that the achievable sum rate of the 2x2 MIMO-VLC system can be significantly improved by employing NOMA with the proposed NGDPA method. It is demonstrated that NOMA with NGDPA achieves a sum rate improvement of up to 29.1% compared with NOMA with the gain ratio power allocation method in the 2 x 2 MIMO-VLC system with three users.