LED Half-Power Angle Optimization for Ultra-Dense Indoor Visible Light Communication Network Deployment

Due to limited interference range, the advantage of visible light communication (VLC) over wireless fidelity (WiFi) lies more in the unit-area transmission rate rather than the single-link transmission rate. To characterize the achievable transmission rate per unit area, we consider an indoor downlink VLC network with dense attocell configuration for the transmitters with single-color light-emitting diode (LED) and multi-color LEDs, assuming binomial distributed users. We divide each attocell into central region and boundary region, and propose the transmission protocols based on such attocell division. We optimize the LED half-power angle to maximize the mean achievable transmission rate per unit area. More specifically, we investigate the rates of cell-center and cell-boundary users under fairness consideration for the single LED transmitter system. We characterize the mean achievable transmission rate per unit area under the white light constraints in the multiple LEDs transmitter system. The performance of the proposed transmission protocols is evaluated by numerical results.