Block Markov Superposition Transmission of Short Codes for Indoor Visible Light Communications

This letter presents a coded modulation scheme for indoor visible light communication (VLC), which is based on the recently proposed coding scheme called block Markov superposition transmission (BMST). As the bandwidth of a single light-emitting-diode (LED) light is limited, we use parallel LED wicks to transmit simultaneously multiple coded bit-streams, resembling a multiple access system. At the transmitter, a single stream of data is first encoded by a properly designed BMST encoder and then partitioned equally into multiple streams, each of which, in the case of no precoding, is used to drive an LED wick in an on-off keying (OOK) manner. With a tailored power-allocation scheme, the noise-free received signals can form an equispaced pulse amplitude modulation (PAM) constellation. Also proposed is the use of precoding to achieve Gray mapping, which plays an important role in reducing complexity without degrading performance since no iterative processing is required between the detection and the decoding. Simulation results show that the proposed scheme achieves a significant coding gain.