Compensating rain induced impairments in terrestrial FSO links using aperture averaging and receiver diversity

摘要

In this paper, we investigate the performance of a free space optical link considering the deteriorations caused by heavy rain. The applicability of receiver diversity and aperture averaging techniques to compensate the rain-induced impairments is analyzed on the basis of outage probability and signal to noise ratio at varying rain intensities. A 10-Mbps on-off keying modulated optical signal is taken as the test signal for which rain specific attenuation is calculated using a laboratory testbed having controlled rainfall conditions up to 250 mm/h. A 15-m single input multi output) optical link with selection combining technique at the receiver is used to observe diversity gain. Significant diversity improvement by a factor of 1.35 is observed by comparing the results with the conventional single input single output link. Experimental observations with and without aperture averaging shows average SNR gain of 1.58 and outage probability reduction of 12.3%.