Application of Angle Diversity Technique to Optical Wireless Communication Systems for Smartphones

Abstract

Much attention has been paid to optical wireless communication (OWC) systems since the systems have a possibility to offer wideband communication channel, e.g., inside building environment. In this context, the application of the OWC technology to smartphone communication is of great interest.  It is possible to construct the angle diversity receiving systems using multiple receivers on the surfaces of a smartphone device to achieve stable communication when a smartphone moves around two-dimensionally and rotates three-dimensionally.  An angle diversity configuration with multiple receivers facing different directions have been reported, but the literature is only focused on the condition when the receivers are supposed to move around two-dimensionally, but three-dimensional rotation of the device has not been well considered.  In this paper, we consider the OWC systems for a smartphone that is supposed to move around two-dimensionally and rotate three-dimensionally.  Computer simulation has been performed for the maximal-ratio combining of the output of four receivers placed on the top, front, right, and left surfaces of a smartphone device.  It has been made clear that the diversity receiving systems using four receivers give stable signal-to-noise ratio performance under realistic usage condition of a smartphone.  It has also been found that a semi-angle field-of-view of a receiver should be at least 60 degrees to achieve stable performance.  

Keywords

• optical wireless communication; visible light communication; angle diversity; maximal-ratio combining ; equal-gain combining

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