Multiple user pair scheduling in TWR-FSO systems in presence of building sway

This paper investigates a two-way relay (TWR) assisted free space optical (FSO) communication system with multiple user pairs sharing a single relay via scheduling. A two-way, half-duplex, network-coded relay is considered which serves multiple user pairs over an optical channel characterized by path loss, atmospheric turbulence, and pointing errors (building sway). In addition, the relay employs a scheduler based on absolute signal-to-noise ratio (SNR) and normalized SNR based scheduling schemes. Novel closed form expressions for outage probability for both the scheduling schemes are derived and numerically analyzed for the considered system and channel models.