Long-Span Quasi-Millimeter-Wave-Band Fixed Wireless Access System Employing Link Adaptation by Symbol Rate

Mitsutoshi MATSUDA

IEICE TRANSACTIONS on Communications   Vol.E87-B    No.1    pp.117-123
Publication Date: 2004/01/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: PAPER
Category: Terrestrial Radio Communications
quasi-millimeter-wave-band,  FWA,  rain attenuation,  symbol rate,  link adaptation,  

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Quasi-millimeter-wave-band Fixed Wireless Access (FWA) systems have higher transmission rates than 2.4-GHz or 5-GHz systems, because the available frequency bandwidth for quasi-millimeter-wave-bands is broader than the 2.4-GHz and 5-GHz bands. However, quasi-millimeter-wave-band systems are unsuitable for long-span transmission because the attenuation caused by rain is large. We propose that the symbol rate be lowered for rainfall; i.e., when it rains, a low symbol rate is used. This means narrowing the equivalent noise bandwidth so that a margin for rain attenuation is obtained. We compared a method in which the symbol rate is either high or low with one in which the symbol rate is selectable over a range of values. We verified the beneficial effect of the two-rate method through calculations and simulations. A case study in the Tokyo metropolitan area showed that the service zone radius of this method is double that of conventional systems. Changing to a low symbol rate decreases the transmission rate, but periods of heavy rainfall comprise only about 1% of the amount of time in a year, and so the average decrease in the transmission rate is approximately zero.