Fisheye-lens-based space division multiplexing system for visible light communications

This paper presents the high-diversity space division multiplexing (SDM) visible light communications (VLCs) utilizing a fisheye-lens-based imaging receiver. The receiver features ultra-wide field-of-view, good illumination uniformity, ultra-high imaging quality, and compact size; therefore, it can realize omnidirectional receiving and provide high spatial diversity for the SDM VLC system. In the presented system, four data streams are parallelly transmitted by commercial phosphorescent white light-emitting diodes, and discrete multitone signals based on quadrature amplitude modulation and bit loading are employed to achieve high spectral efficiency. The experiment verifies that the interchannel interference is effectively alleviated due to the high spatial diversity provided by the fisheye-lens-based receiver, and an aggregate data rate of 1.3 Gbit/s is achieved with the limited 3-dB bandwidth of 20 MHz. Besides, it is feasible to extend the system to more channels to achieve higher capacity. The experimental results indicate that the fisheye-lens-based imaging receiver is a potential candidate for high-speed VLC applications.