FPGA Implementation Of MIMO For Visible Light Communication

As the radio frequency(RF) spectrum gets more and more congested with our constant use of Wi-Fi and 3G/4G, newer systems are being designed to alleviate if not replace some older ones. Visible Light Communication(VLC), a system in which information uses visible light as the media to transmit information has been showing promising results for indoor use. Combined with the technologies that are used in RF, it can provide high performance for relatively low costs. Techniques such as the orthogonal frequency division multiplexing modulation and multiple input multiple output(MIMO) can be adapted to work with visible light, they might not necessarily work without adjustment as the characteristics of RF waves and visible light waves differ.As part of a project to implement a VLC system on a FPGA hardware platform, the MIMO aspect is studied from a VLC point of view, which differs slightly from its RF counterpart. As the SNR is expected to be sufficiently high, a zero-forcing decoder with ordered successive interference cancellation is implemented. To do so, the pseudoinverse of the channel matrix needs to be computed. This is a complex process and can be done via different methods. We opt for the method using the singular value decomposition of a matrix to determine its pseudoinverse. Since resources available on hardware are more restricted than with software, hardware-efficient algorithms are used to get the most of FPGAs.