Performance Evaluation of Non-Orthogonal Multiple Access in Visible Light Communication
IEEE Transactions on Communications
In this paper, the performance of non-orthogonal multiple access (NOMA) is characterized in a downlink visible light communication (VLC) system for two separate scenarios. For the case of guaranteed quality of service (QoS) provisioning, we derive analytical expressions of the system coverage probability and show the existence of optimal power allocation coefficients on two-user paired NOMA. For the case of opportunistic besteffort service provisioning, we formulate a closed-form expression of
... form expression of the ergodic sum rate, which is applicable for arbitrary power allocation strategies. The probability that NOMA achieves higher individual rates than orthogonal multiple access (OMA) is derived. Also, we give an upper bound of the sum rate gain of NOMA over OMA in high signal-to-noise ratio (SNR) regimes. Both simulation and analytical results prove that the performance gain of NOMA over OMA can be further enlarged by pairing users with distinctive channel conditions. We also find out that the choice of light emitting diodes (LEDs) has a significant impact on the system performance. For the case of guaranteed QoS provisioning, LEDs with larger semi-angles have better performance; while for the case of opportunistic besteffort service provisioning, LEDs with 35 • semi-angle give nearly optimal performance. Index Terms-Non-orthogonal multiple access (NOMA), visible light communication (VLC), coverage probability, ergodic sum rate, order statistics.