Low-Complexity Spatial Modulation for IM/DD Optical Wireless Communications

A bipolar pulse amplitude modulation (PAM)-based optical spatial modulation transmission scheme is developed for intensity modulation/direct detection optical wireless communications. In the proposed scheme, multiple light emitting diodes (LEDs) and multiple photodiodes are employed at the transmitter and receiver, respectively. The transmit LEDs are divided into two groups. The first group of LEDs transmits the positive part of the PAM symbol, while the second group of LEDs transmits the absolute value of the negative part of the bipolar PAM symbol. Besides, spatial shift keying is employed in the active LED group to improve data rate. According to the transmit strategy, a novel low-complexity receiver algorithm is developed.