Investigation of suitability of RF signal transmission over FSO links

Abstract

Transmission of modulated RF signal using FSO communications links is receiving a lot of research interest recently. We are developing a new advanced DWDM RoFSO link system capable of transmitting multiple RF signals. In this paper, we present results from analytical modeling reflecting on the design parameters of the RoFSO system to evaluate and predict its performance. The parameters of interests include the atmospheric turbulence characterization parameter, C <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</inf> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , as well as another important parameter in evaluating RF signals, SFDR. Results show that for W-CDMA signal transmission using RoFSO in presence of relative strong atmospheric turbulence, the SFDR value might occasionally drop below the required threshold of 60 dB. A 10 dB improvement of SFDR can be achieved when an optical power amplifier is employed. The paper also shows preliminary experimental results of a RF-FSO link performance in terms of CNR and ACLR when transmitting W-CDMA signal. Combination of theoretical and preliminary experimental works will give a helpful insight to the performance of the new RoFSO system.