Outage Performance and DMT Analysis of DF Parallel Relaying in FSO IM/DD Communications

In this paper, we investigate the performance of cooperative diversity transmission in free-space optical (FSO) communications. We consider an FSO cooperative diversity system with a single decode-and-forward relay and a line-of sight link between the source and the destination. Focusing on high signal-to-noise ratio (SNR) regime, we develop performance characterizations in terms of outage probability, outage diversity and coding gains, and diversity-multiplexing tradeoff (DMT). Our results demonstrate that cooperative diversity improves the performance of FSO communications by bringing diversity advantages.