tailieunhanh - Báo cáo hóa học: " Research Article A Linear Mixed-Effects Model of Wireless Spectrum Occupancy"

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 A Linear Mixed-Effects Model of Wireless Spectrum Occupancy | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2010 Article ID 203178 7 pages doi 2010 203178 Research Article A Linear Mixed-Effects Model of Wireless Spectrum Occupancy Srikanth Pagadarai and Alexander M. Wyglinski Department of Electrical and Computer Engineering Worcester Polytechnic Institute Worcester MA 01609 USA Correspondence should be addressed to Alexander M. Wyglinski alexw@ Received 6 January 2010 Revised 4 July 2010 Accepted 24 August 2010 Academic Editor R. C. De Lamare Copyright 2010 S. Pagadarai and A. M. Wyglinski. 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 cited. We provide regression analysis-based statistical models to explain the usage of wireless spectrum across four mid-size US cities in four frequency bands. Specifically the variations in spectrum occupancy across space time and frequency are investigated and compared between different sites within the city as well as with other cities. By applying the mixed-effects models several conclusions are drawn that give the occupancy percentage and the ON time duration of the licensed signal transmission as a function of several predictor variables. 1. Introduction Spectrum measurement studies conducted by wireless communications researchers have shown that the utilization of licensed wireless spectrum is relatively low 1 . This is a result of the fact that frequency bands are exclusively licensed to specific services and entities on a command-and-control basis by regulatory agencies for example . Federal Communications Commission FCC Industry Canada and . Office of Communications OfCom . Although such a scheme is effective in protecting the rights of the incumbent license holders a completely new strategy of spectrum allocation is needed in order to accommodate the .