Improving SINR in Indoor Cellular Visible Light Communication Networks

In this paper, we first investigate the negative impact of light reflections and then introduce an angle diversity receiver (ADR) to mitigate the interference effect resulting from light reflections in an indoor cellular optical wireless communications (OWC) network. As the ADR consists of multiple photodiodes (PDs), a proper signal combining scheme is essential to optimize the system performance. Therefore, four different combining schemes, the select best combining (SBC), the equal gain combining (EGC), the maximum ratio combining (MRC) and the optimum combining (OPC), are investigated. The results indicate that the OPC scheme achieves the best performance among these combination schemes. In particular, when we use a seven-PD ADR as the optical detector, the OPC scheme can significantly suppress the interference signal resulting from light reflections and can achieve a signal to interference plus noise ratio (SINR) performance that is close to the SINR performance of the same configuration that is free of light reflections.