Visible Light Communications: Simplified Co-Equalisation of Fast OFDM in a Multiple-Input Multiple-Output Configuration

In this paper we experimentally demonstrate, for the first time, a simplified co-equalisation for imaging multiple-input multiple-output based visible light communication systems. We show that in such systems, where all channels have similar magnitude responses, an equaliser trained on a single channel produces coefficients that may be used in the form of a look-up table to equalise the remaining channels without the need for explicit or bespoke training. The system demonstrated is based on the fast-orthogonal frequency division multiplexing based on pulse amplitude modulation scheme to improve the spectral efficiency, where a data rate of 80 Mb/s is achieved using four light-emitting diodes, each of a 4 MHz raw bandwidth. We show that the reported system performance closely matches that of the traditional and more computationally complex system in terms of bit-error rate.