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This paper discusses the time-of-arrival (TOA) based indoor visible light communication (VLC) positioning system in a non-line-of-sight environment. The propagation delay is assumed to be gamma distributed. The generalized Cramer-Rao lower bound for multipath propagation is derived as the theoretical accuracy limitation. The performance of the positioning system is affected by the shape parameter and the scale parameter of gamma distribution. The influences on positioning accuracy of multipath effects are analyzed through discussing the physical meaning of the gamma distribution parameters. It is concluded that the lower bound of positioning accuracy is attained when variance of the non-line-of-sight propagation-induced path lengths is zero. The simulation result proves that the theoretical positioning accuracy is in the order of centimeters with the given scenario.

In this paper, we demonstrate a high-definition 3-liquid-crystal-on-silicon (3-LCOS) home cinema projection system based on RGB laser source modules. Both red and blue laser modules are composed of an array of laser diodes, and the green laser is based on an optically pumped semiconductor laser. The illumination engine is designed to realize high energy efficiency, uniform illumination, and suppression of speckle noise. The presented laser projection system producing 1362 lm D65 light has a volume of about 450×360×160  mm3.