Experimental Results on the Performance of Optical Spatial Modulation Systems

Spatial Modulation (SM) is a relatively new technique to include information bits in the spatial domain, combining multiple-input multiple-output (MIMO) and digital modulation techniques. The increase on the overall data rate is achieved by activating only one transmitter at any time, whereas the index of the active emitter represents data bits. At the receiver side the active transmitter index is estimated based on the channel gain for the different paths. In this work we show the behaviour of an optical SM wireless communications system. A fully operative test system consisting of four transmitters and one receiver has been implemented and tests have been conducted to obtain the symbol error rate (SER) for different link distances. Results show the strong relation between the error rate achieved and the relative channel gain differences between all channels rather than the individual signal-to-noise ratio (SNR).