tailieunhanh - Báo cáo hóa học: "Research Article Resource Distribution Approaches in Spectrum Sharing Systems"

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 Resource Distribution Approaches in Spectrum Sharing Systems | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2008 Article ID 598080 15 pages doi 2008 598080 Research Article Resource Distribution Approaches in Spectrum Sharing Systems Takefumi Yamada 1 Dennis Burgkhardt 2 Ivan Cosovic 3 and Friedrich K. Jondral2 1 NTT DoCoMo Inc. 3-5 Hikari-no-oka Yokosuka-shi Kanagawa 239-8536 Japan 2 Institut fur Nachrichtentechnik Universitat Karlsruhe TH 76128 Karlsruhe Germany 3 DoCoMo Communications Laboratories Europe GmbH Landsberger Strasse 312 80687 Munich Germany Correspondence should be addressed to Takefumi Yamada yamadatak@ Received 29 June 2007 Revised 14 December 2007 Accepted 3 March 2008 Recommended by Milind Buddhikot It is increasingly difficult to satisfy growing demands for spectrum with the conventional policy of fixed spectrum allocation. To overcome this problem flexible dynamic spectrum sharing methods that can significantly improve spectrum utilization of the spectrum have gained increasing interest recently. This paper presents two dynamic spectrum sharing approaches a centralized and a decentralized one. The centralized approach is based on hierarchical trading. Each level of hierarchy is composed of markets that are associated with a certain spatial area and trading occurrence frequency whereas area size and trading occurrence frequency depend on the hierarchy level. The decentralized approach is based on game-theory. There it is assumed that the operators are averse to unequal payoffs and act unselfishly enabling a stable and sustainable community. Numerical results show that in the observed scenario both proposals outperform the reference case of fixed resource allocation significantly in terms of utilized bandwidth. Whereas negotiation costs for spectrum brokerage appear in the centralized approach nonnegligible amounts of spectrum are lost in the decentralized approach due to collisions. Thus a hybrid of centralized and decentralized .