Performance analysis of user association strategy based on power-domain non-orthogonal multiple access in visible light communication multi-cell networks

A multi-cell visible light communication (VLC) network with non-orthogonal multiple access (NOMA) introduces an inter-cell interference (ICI), which causes poor experience of overlap-area user association. In this study, we focus on the strategic analysis of user association in multi-cell NOMA-VLC networks and reveal the relationship between the performance of user association and visible-light cell deployment. First, we establish the model of power-domain NOMA in multiple cells of VLC. Second, when the principle of proximity access (PPA) considers channel attenuation, we present the violation of the principle of proximity access (VPPA) based on signal-to-interference-plus-noise ratio (SINR) and derive a closed-form sufficient condition for overlap-area users based on the visible light channels. Third, based on the sufficient condition, we perform the strategic analysis of user association in two cases, i.e., the scenario probability with different numbers of users and the probability of the ratio of channel gains with an edge user are deduced. In addition, we evaluate the performance of user association by the deployment of lighting angles and inter-cell distance. Finally, the simulation results indicate that the VPPA achieves better data rate performance than the PPA based on the sufficient condition. Furthermore, the probability distributions in numerical results show that the situations with the VPPA reach a certain scale of occurrence probability.