Social-aware D2D cooperative communication to mitigate blind spots in VLC networks

Visible light communication (VLC) technology has abundant spectrum resources and can effectively relieve the shortage of the wireless spectrum resource, but its line of sight is easily blocked and the communication distance is short, resulting in limited network coverage and the existence of communication blind spots. In this paper, we investigate a device-to-device (D2D) technology-assisted VLC-D2D hybrid downlink system. Then, we propose a social-aware D2D cooperative communication to mitigate blind spots (SDMBS) algorithm to alleviate the blind spots in the VLC network and get seamless coverage for indoor communications. In SDMBS algorithm, we design a vertex coloring-based VLC device access (VCVDA) algorithm to reduce the inter-cell interference between multiple VLC access points. Moreover, in order to enable blind devices that cannot access the VLC network to communicate successfully, we introduce the social trust relationships into the VLC networks. By analyzing the three social attribute factors of device’s centrality, stability and similarity, we put forward a social-aware based D2D device access (SADDA) algorithm. Finally, to improve device online time, we adopt a power control algorithm based on the Lambert W function to maximize the energy efficiency of the D2D link. Simulation results show that SDMBS can enhance the energy efficiency of the D2D link while improve the system access performance compared to comparative algorithms.