Performance Analysis of Non-Orthogonal Multiple Access in Free Space Optical Communication System

In this paper, a multipoint-to-point system consisting K users and a central node with non-orthogonal multiple access (NOMA) technique over free space optical (FSO) channel is characterized for two cases. In the case of guaranteed user's quality of service (QoS), the outage probability is derived. Another case is that user's QoS is determined by their own channel conditions. The developed analytical results of ergodic sum data rate show that NOMA outperforms orthogonal multiple access (OMA). Besides, the power control scheme is proposed, and results show that the power control scheme has great influence to the user's QoS. Monto Carlo simulation has been done, and it matches quite well with the theoretical analysis.