tailieunhanh - báo cáo hóa học: " A utility-based approach for secondary spectrum sharing"

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: A utility-based approach for secondary spectrum sharing | Dashouk and Alanyali EURASIP Journal on Wireless Communications and Networking 2011 2011 32 http content 2011 1 32 3 EURASIP Journal on Wireless Communications and Networking a SpringerOpen Journal RESEARCH Open Access A utility-based approach for secondary spectrum sharing Maxim Dashouk and Murat Alanyali Abstract This paper provides a social welfare framework for coexistence of secondary users of spectrum in the presence of static primary users. We consider a formulation that captures spatial differences in available spectrum while considering general system topologies and utility functions a collection of wireless sessions is considered under an arbitrary conflict graph that indicates the sessions which cannot transmit simultaneously on a common channel. It is assumed that each session has a utility associated with its spectrum utilization. A carrier sense multiple accessbased randomized channel selection technique is considered to maximize the resulting sum of utilities. A measurement-based gradient ascent method is used to improve the channel selection performance and to achieve local maxima of the social welfare. Distributed versions of the method are discussed and shown to outperform previously published work in a variety of simulation scenarios that study effects of primary user presence varying secondary user density varying total channel availability. 1 Introduction Recent regulatory proceedings in wireless telecommunications offer tremendous potential for efficient spectrum usage via novel operational models of spectrum access. An important legislative development in the US for an example is the FCC s recent release 1 of a part of VHF UHF band for fixed broadband access systems to address the problem of spectrum scarcity. This development introduces the concept of secondary spectrum users that are allowed to use the spectrum while avoiding conflicts with primary users which in this particular case are TV broadcast services. .