Asymptotic Analysis of TWR Assisted FSO Links With Partial Dual-Relay Selection

In this letter, a partial-dual relay selection (P-DRS) scheme is proposed for amplify-and-forward protocol based two-way relay (TWR) assisted free space optical (FSO) communication systems. Closed form asymptotic expression is developed for the moment generating function (mgf) of the equivalent signal-to-noise ratio of the system, considering an optical channel that is modeled by the Gamma-Gamma distribution and affected by path losses and pointing errors. Expressions for the outage probability and average error probability are calculated based on the mgf. Finally, the mathematical analysis is accompanied with simulations to demonstrate the effectiveness of the proposed P-DRS scheme.