Abstract
Fog and dust are used to be considered as major performance degrading factors for free space optic (FSO) communication links. Despite the number of field measurements, performed in foggy environments during the last decades, most of the proposed channel attenuation models are deterministic, i.e., assumed the channel attenuation constant over time. Stochastic behavior of the channel is still understudied. In this paper, we investigate the probabilistic behavior of the FSO channel in fog and develop a new statistical model for the signal attenuation. Moreover, we derive a probability distribution function (PDF) for the channel state. Using this PDF, we study the FSO system performance considering various metrics including average signal-to-noise ratio, average bit error rate, channel capacity, and probability. of outage Closed form expressions are derived for the average SNR and outage probability. We found acceptable performance with moderate and light fog. However, under thick and dense fog, the system performance poorly deteriorates. Finally, we derived closed form expressions for the average attenuation-distance product and the link availability that will potentially be very helpful for network design and planning.
Highlights
IN contrast to radio frequency (RF), free space optics (FSO) has access to a huge bandwidth which can be a promising solution to the RF spectrum scarcity problem [1]
In [8], we developed Johnson SB based probability density function (PDF) as a model for the random FSO channel and studied numerically the system performance in terms of average bit error rate (BER) and channel capacity
In this paper we introduce and derive closed-form expressions for the average attenuation-distance product (ADP) and link availability, as useful and practical tools for network operators to properly design and plan FSO links operating in foggy environments
Summary
IN contrast to radio frequency (RF), free space optics (FSO) has access to a huge bandwidth which can be a promising solution to the RF spectrum scarcity problem [1]. The interest in FSO channel modelling and performance study has increased rapidly during the last decade This is due to the improvement in laser technology industry and the exponential growth in bandwidth demand [2,3]. Fog in literature is considered as a limiting factor for FSO links that decreases the visibility to few meters, due to very high attenuation, that may exceed hundreds of dBs/km under heavy fog [3,4,5]. Fathallah are with the Electrical Engineering Department, King Saud University, Riyadh 11421, Saudi Arabia They are with the KACST Technology Innovation Center in Radio Frequency and Photonics (RFTONICs) center, Riyadh 11421, Saudi Arabia. They are with the KACST Technology Innovation Center in Radio Frequency and Photonics (RFTONICs) center, Riyadh 11421, Saudi Arabia. (E-mail: mesmail@ ksu.edu.sa)
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