Optimal relay placement and diversity analysis of relay-assisted free-space optical communication systems

Relay-assisted free-space optical (FSO) transmission exploits the fact that atmospheric turbulence fading variance is distance dependent and yields significant performance gains by taking advantage of the resulting shorter hops. In this paper, we investigate how to determine optimal relay locations in serial and parallel FSO relaying so as to minimize the outage probability and quantify performance improvements obtained through optimal relay placement. We further present a diversity gain analysis for serial and parallel FSO relaying schemes and quantify their diversity advantages in terms of the number of relays and channel parameters.