PERFORMANCE ANALYSIS OF ADAPTIVE MIMO TECHNIQUES FOR ANGULAR DIVERSITY RECEIVER-BASED VISIBLE LIGHT COMMUNICATION

Correlation between the channels is the primary factor that restricts data rates in multiple-input multiple-output visible light communications (MIMO-VLC). Different receiver designs have been proposed to reduce this correlation value, while adaptive modulations that perform better under the correlated channel effect have been studied on the transmitter side. In this study, we conducted a performance analysis of MIMO-VLC systems by utilizing adaptive MIMO modulations at the transmitter side and angular diversity receiver (ADR) structures at the receiver side. As adaptive modulations, created using spatial diversity (SD) and spatial multiplexing (SMP) modulations, SD/SMP switching, adaptive SMP (aSMP), and SD-assisted adaptive SMP (SD-aSMP) are considered. Analytical and simulation results were obtained for achievable data rates in an indoor environment. Cumulative distribution function (CDF) graphs were used to assess the overall performance based on these data rates. GADR has an advantage over ADR in low SNR regions but performs similarly in high SNR regions. The SD-aSMP scheme demonstrated the best performance across all SNR regions as a hybrid modulation, taking advantage of diversity gain in low SNR and multiplexing gain in high SNR regions. The adaptive SMP schemes benefit from increasing the number of LEDs and increasing the elevation angle up to 60 degrees.