  Signal fading due to atmospheric channel impairments and pointing error is a
major bottleneck for the performance of optical wireless communication (OWC).
In this paper, we consider an amplify-and-forward (AF) optical relaying to
enhance the performance of the OWC system with a negligible line-of-sight (LOS)
link under the combined effect of fog and pointing error. We analyze the
end-to-end performance of the relay-assisted system, which consists of
complicated probability distribution functions. We derive analytical
expressions of the outage probability, average signal-to-noise ratio (SNR), and
ergodic rate in terms of OWC system parameters. We also develop an exact
integral-form expression of these performance metrics using the half-harmonic
mean of individual SNRs to validate the tightness of the derived analytical
expressions. The numerical and simulation analysis shows that the proposed
dual-hop relaying has significant performance improvement when comparing to the
direct transmission over considered channel impairments. Compared to the direct
transmission, the relay-assisted system requires almost $30$ times less
transmission power to achieve the same outage probability. The considered
system also provides a significant gain in the average SNR and ergodic rate for
practical scenarios of OWC deployment.

Signal Processing