Optical spatial modulation based visible light communications with an arbitrary number of transmitters

Abstract

Recently, the optical spatial modulation (OSM) technique has been proposed for visible light communication (VLC). However, its design flexibility is limited by the fact that the number of transmitters has to be a power of two, given that the number of bits mapped by the transmit antenna index at each time slot is required to be an integer. In the paper, to break the limitation on the required number of transmitters, a new bit mapping scheme for OSM based VLC with an arbitrary number of transmitters is proposed. When the number of transmitters is not a power of two, the symbols at the transmitters are mapped by different numbers of bits. By employing the pulse amplitude modulation, constellations with different modulation orders are exploited for radiated symbols so as to guarantee that the total number of bits transmitted at each timeslot remains the same. Moreover, the channel state information at the transmitters is taken into consideration in order to obtain better performance. Furthermore, a new channel adaptive bit mapping scheme is proposed. Numerical results on bit error rate performance are provided and substantiate that the proposed scheme can achieve better performance.