Outage performance for parallel relay-assisted free-space optical communications in strong turbulence with pointing errors

This paper investigates the performance of parallel relay-assisted transmission for free-space optical (FSO) communication systems over strong turbulence channel. The analysis is carried out for systems employing decode-and-forward (DF) relays and for strong turbulence channel which can be modeled by the Gamma-Gamma distribution. Take atmospheric attenuation, atmospheric turbulence and pointing errors into account, a statistical model for the optical intensity fluctuation at the receiver is presented. For given weather and misalignment conditions, an exact analytical expression for the end-to-end outage probability of DF systems is obtained. The analytical and simulation results show that the closed-form expression can provide sufficient precision for evaluating outage performance of parallel relay-assisted FSO communications.