Probabilistic Cooperative Location Estimation in

Probabilistic Cooperative Location Estimation in - This...

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Probabilistic Cooperative Location Estimation in Wireless Networks Yi Ouyang , Pang-Chang Lan , Tzu-Wei Lo , Yao-Cheng Tien , Sheng-Yi Ho , Ping-Cheng Yeh †‡ Graduate Institute of Communication Engineering Department of Electrical Engineering National Taiwan University Taipei, Taiwan Abstract —Applications of location estimation have drawn lots of interests in recent years. Many schemes have been developed to estimate the locations of the concerned users. Conventionally, the location of each user is estimated independently by its own observations from the local environment. In this paper, we propose a cooperative location estimation scheme. From the encounter history of a specific user meeting other users and the location estimation results of other users, the user is able to further improve the accuracy of its location estimation. Simulation results show that the cooperative algorithm provides a significant gain over the non-cooperative scheme and the location estimation accuracy increases with the number of users involved in cooperation. I. INTRODUCTION The location estimation of mobile terminals (MTs) has drawn lots of interests in recent years. The technology of location estimation can be applied to a variety of applications such as pet-tracking, patient-caring, victim-rescuing, etc. The location estimation schemes can be divided into two cate- gories: non-probabilistic schemes and probabilistic schemes. A typical example of the non-probabilistic schemes is Global Positioning System (GPS), which estimates the location of MT by geometric trilateration. However, GPS does not work well for indoor applications. To overcome the indoor limitation, several non-probabilistic schemes have been developed. Some of them operate on sensor networks while some of them on wireless local area network (WLAN). For location estimation using sensor networks, typically a large number of sensors are first deployed to receive or emit signals. For instance, the Active Badge location system [1] is a centralized system using infrared sensors. In this system, each user carries a tag called Badge that emits signals with an unique ID. The user signal is sensed by the pre-deployed infrared sensors to track the user location. Based on the Active Badge location system, the Bat system [2], [3] was proposed. In this system, bat-like ultrasound transmitters are attached to the user, so the ultrasound sensors can compute the user location by trilateration. On the other hand, several non- probabilistic location estimation schemes have been proposed for wireless LAN [4], [5], [6], [7]. These schemes mainly estimate the locations by collecting the signal information such as signal strength (SS), angle of arrival (AOA), and time difference of arrival (TDOA) between access points (AP).
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This note was uploaded on 10/01/2010 for the course ELEC 6111 taught by Professor Brown during the Spring '10 term at E. Illinois.

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Probabilistic Cooperative Location Estimation in - This...

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