Performance analysis of free-space optical wireless channels using finite-SNR DMT

摘要

An outdoor free-space optical (FSO) point-to-point communication system is considered which is operating under weak turbulence. The presence of a weak turbulence is common in the case of FSO systems working with high beam lasers and such an FSO channel is modeled with a log-normal probability distribution function. For this system the outage probability and the finite-SNR diversity gain are analyzed for fixed variance of light intensity. We observe that the finite-SNR diversity gain decreases exponentially as the multiplexing gain increases, whereas in case of radio frequency (RF) channels the decrease in diversity gain is linear. Apart from this, we also observe that the diversity gain peaks up with increase in average signal-to-noise ratio (SNR) at the receiver and further reduces as SNR is increased. Furthermore, at a fixed SNR, the reduction in variance of light intensity increases the diversity gain.