Analysis of subcarrier intensity modulation-based optical wireless DF relaying over turbulence channels with path loss and pointing error impairments

The authors consider a subcarrier intensity-modulated relayed optical wireless communication system under the combined influence of path loss, atmospheric turbulence and pointing error impairments. The turbulence-induced fading is modelled by independent but not necessarily identically distributed (i.n.i.d.) Gamma-Gamma fading statistics where the relaying protocol followed by the system is decode and forward (DF). First, the statistics of instantaneous signal-to-noise ratio at the destination is derived, followed by the novel and exact closed-form expression for outage probability of the system. Then using the moment generating function-based approach, the authors evaluate error performance of the system in terms of average symbol error rate (SER) for M-ary phase shift keying modulation schemes. Further, as a special case for M = 2, that is, binary phase shift keying modulation scheme, the exact closed-form expression of average SER is derived in terms of mathematically tractable Meijer´s G-function and extended generalised bivariate Meijer´s G-function. Finally, at the end of the paper, various numerical examples are included to demonstrate the effect of different system parameters on the performance of the system and are verified by Monte-Carlo simulations.