Optical spatial modulation for indoor wireless communications in presence of inter-symbol interference

In this paper, we analyze an indoor wireless communications system using optical spatial modulation (OSM) when is subject to inter-symbol interference (ISI). An array of light emitting diodes (LEDs) is used in transmitter and an array of photo diodes (PDs) is used in receiver. Each group of k information bits selects a unique transmitting LED from the 2^k total number of available LEDs. In the receiver, an optimal maximum likelihood (ML) detector is used to identify the transmitting LED. A channel model with ISI is introduced and the OSM system performances are tested in presence of additive white Gaussian noise (AWGN). The signal-to-interference-and-noise ratio (SINR) is estimated as function of channel path gains. The bit error rate (BER) is analyzed by simulation as function of SINR for different distances between transmitter and receiver. The simulation results reveal that for SINR values closer to the upper limit, SM receiver performs better than in the only presence of AWGN.