Impact of the Direct Link on the Performance of Single-Relay Buffer-Aided FSO Communications.

This work targets the performance analysis of buffer-aided (BA) Free-Space Optical (FSO) relaying with a single decode-and-forward (DF) relay. In particular, we study the impact of activating the direct source-destination link on the system performance. Based on a Markov chain analysis, we derive closed-form expressions for the system outage probability (OP) and average packet delay (APD). Moreover, we carry out an asymptotic analysis and evaluate the achievable diversity order. Results show that while activating the direct link reduces the APD in all scenarios, this activation might either increase or decrease the diversity order depending on the relay position.