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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: Joint MIMO-OFDM and MAC Design for Broadband Multihop Ad Hoc Networks | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2006 Article ID 60585 Pages 1-9 DOI 10.1155 WCN 2006 60585 Joint MIMO-OFDM and MAC Design for Broadband Multihop Ad Hoc Networks Dandan Wang and Uf Tureli Electrical and Computer Engineering Department Stevens Institute of Technology Hoboken NJ 07030 USA Received 1 November 2005 Revised 4 June 2006 Accepted 13 June 2006 Multiple-input multiple-output MIMO and orthogonal frequency division multiplexing OFDM are very promising techniques to exploit spatial diversity and frequency diversity in the physical layer of broadband wireless communications. However the application of these techniques to broadband multihop ad hoc networks is subject to inefficiencies since existing medium access control MAC schemes are designed to allow only one node to transmit in a neighborhood. Therefore adding more relays to increase the transmission range decreases the throughput. With MIMO-OFDM multiple transmissions can coexist in the same neighborhood. A new transceiver architecture with MIMO-OFDM and MAC scheme is proposed in this paper. The new MAC scheme multiple-antennas receiver-initiated busy-tone medium access MARI-BTMA is based on receiver-initiated busy-tone medium access RI-BTMA and uses multiple out of band busy tones to avoid the collision of nodes on the same channel. With the proposed MAC scheme multiple users can transmit simultaneously in the same neighborhood. Although basic MARI-BTMA shows good performance at high traffic load to improve the performance at low traffic loads 1-persistent MARI-BTMA is proposed so that users can choose different MAC scheme according to the statistical traffic load in the system. In this paper both theoretical and numerical analysis of the throughput and delay are presented. Analysis and simulation results show the improved performance of MARI-BTMA compared with RI-BTMA and carrier sensing medium access collision avoidance CSMA CA . Copyright .