Optical MIMO Communication Systems
An optical multiple-input multiple-output (MIMO) communication system uses multiple LED-based transmitters and multiple receivers to transfer parallel streams of data. As compared to a single-transmitter single-receiver system using the same amount of signal power, a MIMO system can provide higher data rates with fewer transmission errors and better reliability.
There are three different types of optical MIMO systems:
1. λ-MIMO: This system is implemented using a single luminaire composed of LEDs that emit different colors of light. Each LED acts as a different transmitter. Thus the parallel data streams can be transmitted over different colors of light. The receiver for this system implements optical filters to recover the signals transmitted over each color.
2. s-MIMO: This system is implemented using multiple luminaires that are placed at different locations on the ceiling. Each luminaire is composed of the same type of LED and thus emits the same color of light. In this case, the data streams are separated spatially because they each originate at a different spatial location. A ‘camera-like’ receiver can then separate the different signal streams and recover data.
3. h-MIMO: This system is a hybrid of the above two systems. It uses multiple luminaires, each composed of different colored LEDs to transmit signals that are separated in color and space. A ‘camera-like’ receiver that can distinguish different colors can then separate the different signal streams and recover data.
Our research in optical MIMO systems focusses on its design, analysis and optimization to achieve high data rates while providing good quality illumination. The framework generated by this work will enable the design of optimal dual-purpose communication and lighting systems.