TAILIEUCHUNG - Báo cáo hóa học: "Research Article Dynamic Model of Signal Fading due to Swaying Vegetation"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành hóa học dành cho các bạn yêu hóa học tham khảo đề tài: Research Article Dynamic Model of Signal Fading due to Swaying Vegetation | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2009 Article ID 306876 11 pages doi 2009 306876 Research Article Dynamic Model of Signal Fading due to Swaying Vegetation Michael Cheffena1 and Torbjorn Ekman2 1 University Graduate Center UNIK . Box 70 2027Kjeller Norway 2 Department of Electronics and Telecommunications Norwegian University of Science and Technology 7491 Trondheim Norway Correspondence should be addressed to Michael Cheffena cheffena@ Received 31 July 2008 Revised 1 December 2008 Accepted 18 February 2009 Recommended by Michael A. Jensen In this contribution we use fading measurements at 29 and 60 GHz and wind speed data to study the dynamic effects of vegetation on propagating radiowaves. A new simulation model for generating signal fading due to a swaying tree has been developed by utilizing a multiple mass-spring system to represent a tree and a turbulent wind model. The model is validated in terms of the cumulative distribution function CDF autocorrelation function ACF level crossing rate LCR and average fade duration AFD using measurements. The agreements found between the measured and simulated first- and second-order statistics of the received signals through vegetation are satisfactory. In addition Ricean K -factors for different wind speeds are estimated from measurements. Generally the new model has similar dynamical and statistical characteristics as those observed in measurements and can thus be used for synthesizing signal fading due to a swaying tree. The synthesized fading can be used for simulating different capacity enhancing techniques such as adaptive coding and modulation and other fade mitigation techniques. Copyright 2009 M. Cheffena and T. Ekman. This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution and reproduction in any medium provided the original work is properly .

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