Multiple-input multiple-output visible light communication receivers for high data-rate mobile applications
Chau, Jimmy C.
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Visible light communication (VLC) is an emerging form of optical wireless communication that transmits data by modulating light in the visible spectrum. To meet the growing demand for wireless communication capacity from mobile devices, we investigate multiple-input multiple-output (MIMO) VLC to achieve multiplexing capacity gains and to allow multiple users to simultaneously transmit without disrupting each other. Previous approaches to receive VLC signals have either been unable to simultaneously receive multiple independent signals from multiple transmitters, unable to adapt to moving transmitters and receivers, or unable to sample the received signals fast enough for high-speed VLC. In this dissertation, we develop and evaluate two novel approaches to receive high-speed MIMO VLC signals from mobile transmitters that can be practically scaled to support additional transmitters. The first approach, Token-Based Pixel Selection (TBPS) exploits the redundancy and sparsity of high-resolution transmitter images in imaging VLC receivers to greatly increase the rate at which complementary metal-oxide semiconductor (CMOS) active pixel sensor (APS) image sensors can sample VLC signals though improved signal routing to enable such high-resolution image sensors to capture high-speed VLC signals. We further model the CMOS APS pixel as a linear shift-invariant system, investigate how it scales to support additional transmitters and higher resolutions, and investigate how noise can affect its performance. The second approach, a spatial light modulator (SLM)-based VLC receiver, uses an SLM to dynamically control the resulting wireless channel matrix to enable relatively few photodetectors to reliably receive from multiple transmitters despite their movements. As part of our analysis, we develop a MIMO VLC channel capacity model that accounts for the non-negativity and peak-power constraints of VLC systems to evaluate the performance of the SLM VLC receiver and to facilitate the optimization of the channel matrix through the SLM.