Seminars & Colloquia

Ming Li


"A Study on Deployment and Channel Assignment Problem for Access Points in Indoor Positioning Systems "

Wednesday July 10, 2013 09:30 AM
Location: 3211, EBII NCSU Centennial Campus
(Visitor parking instructions)



Deployment problem and channel assignment problem are crucial issues for improving the performance of Wireless Local Area Network (WLAN). They have been discussed for a period. However, we are the first, to the best of our knowledge, to consider the deployment problem and channel assignment problem including the aspect of positioning (especially, indoor positioning by WLAN.).

In conventional area of communication, deployment problem treats how to place base stations (access points) to achieve maximum coverage or use the least number of base stations to cover a target area. In our work, beside the issues above, the requirement of positioning accuracy is also considered. That is, our work treats how to use the least number of base stations to cover a target area so that every positioning point in the target area can satisfy a value of accuracy for positioning. Because deployment problem is NP hard, we propose rapid algorithms to solve our problem. In detail we firstly consider the relationship between AP (Access Point) Deployment Possible Points (APDPPs: the points can be deployed AP) and positioning points. Then, the relationship is simplified by Boolean algebra. On the basis of it, proposed methods are to find out the least number of AP-DPPs and deploy them. According to the results of simulation, our proposed methods shorten computational time compared with conventional methods. In future, approximate methods (greedy and genetic methods) will be considered. The computing time will be evaluated and approximate accuracy will be discussed.

Channel assignment problem is used to mitigate the interference among APs previously. In our work, after deploying base stations, we have to consider the channel assignment issue to improve the performance of WLAN. Two types of WLAN, that is Infrastructure Mode and Mesh Network Mode, for channel assignment methods are discussed. We propose static channel assignment methods for related stable WLAN environment such as office. Furthermore, a dynamic channel assignment method is proposed considering the changing WLAN environment such as airport. We confirm the effectiveness by simulations and our proposed methods are better than others. In future, we propose a mechanism to optimize wireless performance based on location information of terminals.

According to our work, deployment problem and channel assignment problem have been discussed and verified in the area of indoor positioning. Our work is important for both theory research and industry development in society.


Short Bio:

Dr. Ming Li was born in Shandong, China in 1982. He received a B.E in Computer Science from Shandong University of Science and Technology, China in 2005; a M.E and Ph.D. in Computer Science from Kyushu University, Japan in 2010 and 2013 respectively. He is a visiting scholar at NC State University in United States now. His current research interests is ubiquitous, location based service, wireless communication and mesh network.

Host: Rudra Dutta, Computer Science, NCSU

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