Efficient integration of HAPs and mobile satellites via free-space optical links
Computer Networks: The International Journal of Computer and Telecommunications Networking
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The use of optical wavelengths for intersatellite link can lead the whole system at high data rates performing, low interference, low power requirement and small antenna size. Systems based on Wavelength Division Multiplexing (WDM) technology preserve data signal from interchannel interference. Proposed system is composed of one fixed node, a HAP, High Altitude Platform, in a quasi-stationary position at an altitude of 30 km from the Earth surface, and a mobile node on a LEO orbit which communicates by an optical link with HAP and other LEO microsatellites. The choice of microsatellites number guarantees a good area target coverage and a continuous data transfer from slave nodes to master, with the consequent increase in communication capacity. The HAP motion makes it possible to configure an ad-hoc network for the monitoring of natural and man-made disasters, or every emergency application on rural environment. The main constraint affecting the system performance is concerned with signal degradation, due to antenna misalignment as well as the Doppler effect suffered by the signal because of relative motion between satellite. The subsystem configuration is based on semiconductor laser, transmitting at ITU grid frequencies, and an EDFA preamplifier at receiver end. Copyright © 2008 John Wiley & Sons, Ltd.