On the performance of coded optical spatial modulation

The performance of hard and soft convolutional channel coding techniques for optical spatial modulation (OSM) are analyzed in this paper. OSM is a recently proposed multiple-input multiple-output (MIMO) technique for indoor optical wireless (OW) communication. In OSM only one transmitter is active at a time and the others are turned off. The spatially separated transmit units are considered as spatial constellation points, i.e. the incoming bit sequence activates one of the transmit units. The active transmitter radiates a certain intensity level at a particular time instance. At the receiver side, optimal detection techniques are used to estimate the active transmitter index and retrieve the original information bits. In this paper, channel coding is applied to OSM and the performance of hard and soft detections are analyzed analytically and validated through Monte Carlo simulations. It is shown that the performance can be significantly enhanced by applying channel coding techniques and a gain in signal-to-noise-ratio (SNR) of about 5 dB and 7 dB at a bit-error-ratio (BER) of 10^-4 are achieved for hard and soft decisions, respectively.