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 MACD-Based Motion Detection Approach in Heterogeneous Networks | Hindawi Publishing Corporation EURASIP Journal on Wireless Communications and Networking Volume 2008 Article ID 540873 14 pages doi 2008 540873 Research Article MACD-Based Motion Detection Approach in Heterogeneous Networks Yung-Mu Chen Tein-Yaw Chung Ming-Yen Lai and Chih-Hung Hsu Department of Computer Science and Engineering Yuan Ze University 135 Yuan-Tung Road Chung-Li Taiwan 32003 Taiwan Correspondence should be addressed to Tein-Yaw Chung csdchung@ Received 2 January 2008 Revised 19 May 2008 Accepted 22 July 2008 Recommended by Athanasios Vasilakos Optimizing the balance between handoff quality and power consumption is a great challenge for seamless mobile communications in wireless networks. Traditional proactive schemes continuously monitor available access networks and exercise handoff. Although such schemes achieve good handoff quality they consume much power because all interfaces must remain on all the time. To save power the reactive schemes use fixed RSS thresholds to determine when to search for a new available access network. However since they do not consider user motion these approaches require that all interfaces be turned on even when a user is stationary and they tend initiate excessive unnecessary handoffs. To address this problem this research presents a novel motion-aware scheme called network discovery with motion detection NDMD to improve handoff quality and minimize power consumption. The NDMD first applies a moving average convergence divergence MACD scheme to analyze received signal strength RSS samples of the current active interface. These results are then used to estimate user s motion. The proposed NDMD scheme adds very little computing overhead to a mobile terminal MT and can be easily incorporated into existing schemes. The simulation results in this study showed that NDMD can quickly track user motion state without a positioning system and perform network discovery rapidly enough to achieve a much lower
