Multi-input multi-output (MIMO) indoor optical wireless communications

Indoor optical wireless systems often use arrays of transmitters and receivers to achieve high data rates. MIMO offers the potential to use these components to transmit data in parallel between multiple sources and detectors. The slowly varying incoherent communications channel can be measured using straightforward techniques, and resulting channel matrix used to recover data that is transmitted in parallel from a number of sources. In this paper we report results from several preliminary indoor communications experiments. A four channel MIMO system that uses white light LEDs for communication (and associated illumination) is described, as well as experiments in a diffuse environment, using infra-red sources. Design issues, as well as future opportunities and challenges are also discussed.