[show abstract][hide abstract] ABSTRACT: We investigate transmission protocols for relay-assisted free-space optical
(FSO) systems, when multiple parallel relays are employed and there is no
direct link between the source and the destination. As alternatives to
all-active FSO relaying, where all the available relays transmit concurrently,
we propose schemes that select only a single relay to participate in the
communication between the source and the destination in each transmission slot.
This selection is based on the channel state information (CSI) obtained either
from all or from some of the FSO links. Thus, the need for synchronizing the
relays' transmissions is avoided and the slowly varying nature of the
atmospheric channel is exploited. For both relay selection and all-active
relaying, novel closed-form expressions for their outage performance are
derived, assuming the versatile Gamma-Gamma channel model. Furthermore, based
on the derived analytical results, the problem of allocating the optical power
resources to the FSO links is addressed, and optimum and suboptimum solutions
are proposed. Numerical results are provided for equal and non-equal length FSO
links, which illustrate the outage behavior of the considered relaying
protocols and demonstrate the significant performance gains offered by the
proposed power allocation schemes.
[show abstract][hide abstract] ABSTRACT: Free Space Optical (FSO) communication is a low cost and license free high bandwidth access technique, is a primary research area from last few years. Atmospheric turbulence plays a vital role in degrading the link performance. This paper presents the model study on the effects of atmospheric turbulence in FSO links. The study is based on the most popular gamma-gamma model distribution. The theoretical model is simulated by varying the height of link and the results are plotted in Mathworks® MATLAB®. The research demonstrates that the effects of turbulence depend primarily on wind speed and height of established FSO link. After varying the height of link, the effects of atmospheric turbulence on link performance can be clearly seen. The result also plotted for the attenuation of signal with varying visibility range conditions.
Proceedings of the Fourth IEEE International Conference on Computing, Communication and Networking Technologies, Tiruchingode, TN; 07/2013
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