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 Efficient MAC Protocol for Subcarrier-Wise Rate Adaptation over WLAN | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2010 Article ID 264838 9 pages doi 2010 264838 Research Article Efficient MAC Protocol for Subcarrier-Wise Rate Adaptation over WLAN Sung Won Kim 1 Byung-Seo Kim 2 and Sung Back Hong3 1 Department of Information and Communication Engineering Yeungnam University Gyeongsangbuk-do 712-749 Republic of Korea 2 Department of Computer and Information Communication Engineering HongIk University Jochiwon Chungcheongnam-do 339-701 Republic of Korea 3Future Network Research Department Electronics and Telecommunications Research Institute ETRI Daejeon 305-700 Republic of Korea Correspondence should be addressed to Byung-Seo Kim jsnbs@ Received 1 October 2009 Revised 9 March 2010 Accepted 18 May 2010 Academic Editor Wolfgang H. Gerstacker Copyright 2010 Sung Won Kim et al. 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. While bit-loading algorithms over wireless systems have been extensively studied the development of a protocol which implements bit-loading-based rate adaptation over wireless systems has not been highlighted. The design of such a protocol is not a trivial problem due to the overhead associated with the feedback information. In this paper a novel protocol is proposed to provide an efficient way to implement subcarrier-wise rate adaptation in OFDM-based wireless systems. When receiving a Ready-To-Send RTS packet the receiver determines the number of bits to be allocated on each subcarrier through channel estimation. This decision is delivered to the sender using an additional OFDM symbol in the Clear-To-Send CTS packet. That is bit-allocation over subcarriers is achieved using only one additional OFDM symbol. The protocol enhances the channel efficiency in spite of the overhead of one .
