Multispectral Optical camera communication links based on spectral signature multiplexing

Abstract

Optical camera communication is foreseen to have an essential role in future systems requiring wireless communication capability. In this regard, high-spectral-resolution cameras, such as multispectral (MS) cameras, present specific characteristics that can be exploited to provide new features to optical camera communication links. Using the MS cameras' features to take advantage of the light-emitting diode (LED) behaviour in a novel communication scheme is focussed. Notably, LED spectral response curves are different when their temperature changes. Therefore, these differences can be detected based on the MS cameras' spectral resolution. Thus, more than one communication channel can be attained using the same LED device since the camera can distinguish the different LED spectral signatures. This new approach is analysed in this work, including some equalisation techniques applied to the channel matrix in the receiver to improve the extraction of the transmitted signal reducing the inter-channel interference. For the specific MS camera employed in the experiments, up to two distinct channels could be obtained with the same transmitter at different temperatures, getting a bit error rate below the forward error correction limit. However, obtaining satisfactory results is highly dependent on the variation that temperature causes in the spectral signatures of the LEDs, so further experiments are recommended in future work with different devices.