Joint Channel-Diversity Coding for the Three-Way Free-Space Optical Systems through Atmospheric-Turbulence Channels

In this paper, we study the communications over the free-space optical (FSO) links in the presence of atmospheric turbulence that induces strong fading on the FSO channel. We consider the three-way systems where a wireless transceiver (or relay) that is present in the neighborhood of the source and destination shares its resources for assisting the source in delivering its message to the destination. In particular, we derive the error performance of the three-way FSO systems that are implemented with a convenient combination of channel and diversity coding. This joint channel-diversity coding that is associated with adapted decoding at the relay and the destination results in a better immunity against noise and fading and results in high performance levels over a very wide range of the signal-to-noise ratio. Another appealing feature of the considered system resides in the fact that the error protection is not associated with any reduction in the data rate.