Random-blockage model and adaptive feedback strategy of CSI for an indoor VLC network

This paper investigates the feedback period of channel state information (CSI) considering random blockage for an indoor visible light communication (VLC) network. First, a random-blockage model (RBM) for the indoor VLC network was built. Through the RBM, a closed expression for the dynamic blockage and self-blockage probability were obtained. Based on the statistical method and RBM, a coherence distance model (CDM) under random blockage was established. Through the CDM, the weighted coherence distance of channel gain for user equipment at any position can be obtained under a specific distribution density of blockers. Based on the CDM, an adaptive feedback strategy for CSI was proposed, thus realizing the timely feedback of CSI under random blockage. Finally, the effectiveness of the above RBM and CDM was verified via simulation. The value obtained by Monte Carlo simulation is consistent with the theoretical value obtained by the RBM. Compared with the fixed-period feedback strategy, the adaptive feedback strategy was able to achieve compromise between improving channel reliability and reducing feedback overhead. The average interrupted time ratio and the average mean square error between the recovered channel gain and the actual channel gain were significantly reduced.