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 On Wireless Ad Hoc Networks with Directional Antennas: Efficient Collision and Deafness Avoidance Mechanisms | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2008 Article ID 867465 14 pages doi 2008 867465 Research Article On Wireless Ad Hoc Networks with Directional Antennas Efficient Collision and Deafness Avoidance Mechanisms Yihu Li and Ahmed Safwat Laboratory for Advanced Wireless Networks Department of Electrical and Computer Engineering Queen s University Kingston Ontario Canada K7L 3N6 Correspondence should be addressed to Ahmed Safwat Received 26 September 2007 Accepted 29 May 2008 Recommended by Athanasios Vasilakos Wireless ad hoc networks allow anywhere anytime network connectivity with complete lack of central control ownership and regulatory influence. Medium access control MAC in such networks poses extremely timely as well as important research and development challenges. Utilizing directional antennas in wireless ad hoc networks is anticipated to significantly improve the network performance due to the increased spatial reuse and the extended transmission range. Nevertheless using directional antennas in wireless ad hoc networks introduces some serious challenges the most critical of which are the deafness and hidden terminal problems. This paper thoroughly explores these problems one of which is discovered and reported for the first time in this paper. This paper also proposes a new MAC scheme namely directional MAC with deafness avoidance and collision avoidance DMAC-DACA to address both problems. To study the performance of the proposed scheme a complete directional communication extension to layers 1 2 and 3 is incorporated in the ns2 simulator. The simulation results show that DMAC-DACA significantly enhances the performance and increases the network throughput. This paper also reveals that deafness has a greater impact on network performance than the hidden terminal problem. Copyright 2008 Y. Li and A. Safwat. This is an open access article distributed under the Creative
