Performance Analysis for Relay-Aided Multihop BPPM FSO Communication System Over Exponentiated Weibull Fading Channels With Pointing Error Impairments

The performances of the decode-and-forward (DF) multihop free-space optical communication system with exponentiated Weibull distribution considering the fading induced by pointing error have been studied. With Meijer´s G-function, the probability density function (PDF) of the aggregated channel model and the closed-form expression for the average bit error rate (ABER) of binary pulse position modulation are derived. The average bit-error-rate performance is then investigated with different hop numbers H, turbulence strength values, receiver aperture sizes, beamwidths, and jitter variances. Compared with the case without pointing error, the mitigation effect of aperture averaging for fading is more significant over the aggregated channel, regardless of the selected H, and it is less effective for the degradation induced by the increase in H, which can be restrained by larger beamwidth and lower jitter. The outage probability is also investigated, and the results show that aperture averaging has less of an effect on the outage probability under moderate turbulence than that under the weak turbulence condition at a given value of H, which is different from the scenario without pointing error. After this, the end-to-end average capacity is analyzed. Monte Carlo simulation is provided to confirm the validity of the proposed ABER expression.