A Distance-Aware Buffer-Aided Relaying Protocol for Cooperative FSO Communications

In this paper, we consider a parallel-relaying decode-and-forward (DF) Free-Space Optical (FSO) network with an arbitrary number of relays that are equipped with finite-size buffers. For such networks, we propose a novel relaying scheme that prioritizes the transmission and reception at the relays according to their distances from the terminal nodes. This strategy achieves load balancing among the relays’ buffers and thus avoids the congestion/starvation of these buffers without the need to acquire the exact buffer state information. A Markov chain framework is presented and an asymptotic analysis is carried out to evaluate the advantageous diversity gains that can be reaped from the proposed relaying scheme.