What is it about?
Airborne optical networks can use several UAVs as alternative relays and select the relay offering the strongest channel. In practice, however, the channel must first be estimated and that information fed back to the transmitting node. Because UAVs move, the channel may have already changed by the time the relay decision is made. We therefore develop a statistical model for outdated log-normal airborne optical channels and analyze relay selection under this more realistic condition. We then determine how transmit power should be adjusted through a carefully selected pre-amplification factor so that the received power remains above a required threshold with a specified reliability.
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Why is it important?
Relay-selection methods often assume perfect, up-to-date channel information, an assumption that may not hold in airborne networks. Our results demonstrate the practical consequence: with no additional power margin—that is, a unity amplification factor—the received power needed to meet the BER target falls below its required threshold approximately 50% of the time. By properly choosing the pre-amplification factor according to the outdated-channel statistics, the designer can instead control the probability of this failure and satisfy a desired reliability level.
Perspectives
This work shows that outdated channel information should not simply be treated as an unavoidable implementation error. Its effect can be statistically characterized and explicitly incorporated into power control. This creates a practical link between channel aging, relay selection, and reliability requirements: the system can choose the required power margin according to how strongly the current channel remains correlated with its earlier estimate. Such an approach can support more dependable relay-assisted UAV networks without relying on the unrealistic assumption of perfectly current channel knowledge.
Assist. Prof. Mohammed Elamassie
Ozyegin Universitesi
Read the Original
This page is a summary of: Multi-Hop Airborne FSO Systems With Relay Selection Over Outdated Log-Normal Turbulence Channels, IEEE Transactions on Vehicular Technology, March 2024, Institute of Electrical & Electronics Engineers (IEEE),
DOI: 10.1109/tvt.2023.3328557.
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