Power Allocation for Downlink Multi-user SC-FDMA Visible Light Communication Systems

Visible light communication (VLC) is a wireless communication technology in which data is transferred over the huge and unused visible light spectrum. Light emitting diodes (LEDs) are used in data transmission and hence their nonlinearities including limited dynamic range lead to a considerable impact on the performance of VLC systems. Single-carrier frequency division multiple access (SC-FDMA) is commonly used to decrease the peak to average power ratio and hence has been introduced for single user VLC systems to mitigate the effect of nonlinearities. In this paper, we investigate the performance of a SC-FDMA VLC system for the scenario of dowlink multiuser data transmission. We consider optimizing the total transmission power and the subcarriers power allocation for a VLC access point to maximize the minimum achievable data rate of the VLC users under transmit power constraint. While calculating the achievable rate, we consider the effect of signal clipping due to the LED nonlinearities.