11,690 research outputs found
Average symbol error rate analysis of reconfigurable intelligent surfaces based free-space optical link over Weibull distribution channels
Optical wireless communication (OWC) enables wireless connectivity using ultraviolet bands, infrared or visible. With its advantages features as high bandwidth, low cost, and operation in an unregulated spectrum. Free-space optical (FSO) communication systems are near terrestrial as a communication link between transceivers, the link is line-of-sight and successfully transmitted optical signals. Nevertheless, the optical signals transmissions over the FSO channels bring challenges to the system. To overcome the challenges posed by the FSO channels, the most common technique is to use relay stations, the most recent is the reconfigurable intelligent surfaces (RISs) technique. This study introduces a Weibull distribution model for a free-space optical communication link with RISs assisted, the parameter used to evaluate the performance of the system is the average symbol error rate (ASER). The RISs effect is examined by considering the influence of the transmitter beam waist radius, shape parameter, aperture radius, scale parameter, and signal-to-noise ratio on the ASER
Evaluating pointing errors on ergodic capacity of DF relay-assisted FSO communication systems
Ergodic capacity of decode-and-forward (DF) relay-assisted free-space optical (FSO) communication systems when line of sight is available is analyzed over gamma-gamma fading channels with pointing errors. Novel closed-form approximate ergodic capacity expression is obtained in terms of the H-Fox function for a 3-way FSO communication system when the α-μ distribution to efficiently approximate the probability density
function (PDF) of the sum of gamma-gamma with pointing errors variates is considered. Moreover, we present a novel asymptotic expression at high signal-to-noise ratio (SNR) for the ergodic capacity of DF relay-assisted FSO systems. The main contribution
in this work lies in an in-depth analysis about the impact of pointing errors on the ergodic capacity for cooperative FSO systems. In order to maintain the same performance in terms of capacity, it is corroborated that the presence of pointing errors
requires an increase in SNR, which is related to the fraction of the collected power at the receive aperture, i.e. A 0 . Simulation results are further demonstrated to confirm the accuracy and usefulness of the derived results.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech. The authors wish to acknowledge the financial support given by Spanish MINECO Project TEC2012-32606
Relay-Assisted Free-Space Optical Communications
The atmospheric lightwave propagation is considerably influenced by
the random variations in the refractive index of air pockets due to
turbulence. This undesired effect significantly degrades the
performance of free-space optical (FSO) communication systems.
Interestingly, the severity of such random degradations is highly
related to the range of atmospheric propagation. In this thesis, we
introduce relay-assisted FSO communications as a very promising
technique to combat the degradation effects of atmospheric
turbulence. Considering different configurations of the relays, we
quantify the outage behavior of the relay-assisted system and
identify the optimum relaying scheme. We further optimize the
performance of the relay-assisted FSO system subject to some power
constraints and provide optimal power control strategies for
different scenarios under consideration. Moreover, an application of
FSO relaying technique in quantum communications is investigated.
The results demonstrate impressive performance improvements for the
proposed relay-assisted FSO systems with respect to the conventional
direct transmission whether applied in a classical or a quantum communication channel
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