Analysis of optical wireless links employing a beam clustering method and diversity receivers

High-speed nondirected optical wireless (OW) transmission is greatly desired for freedom of user mobility. In a mobile infrared wireless environment, it is difficult to maintain a signal-to-noise ratio (SNR) sufficient to support low error probability using the conventional diffuse optical wireless systems. We propose a novel beam clustering method (BCM) based on a line strip multibeam transmitter system (LSMS) combined with a diversity receiver and examine its performance under adverse conditions such as multipath dispersion and background noise. The BCM consists of three sets of spots aimed at different directions. BCM design, multipath dispersion, ambient light interference, and diversity receiver design are discussed. We investigate and compare the impact of user mobility on the performance of OW links for both BCM and conventional diffuse system (CDS). Simulation results for the BCM link characteristics are presented and comparison is made with CDS. Our results indicate that at the worst conventional communication link, BCM can substantially reduce the signal delay spread by nearly a factor of six and increase the SNR by more than 30 dB over the CDS.