Wireless indoor positioning systems have become very popular in recent years. Location-based services (LBS) provide useful information to users based on the current user location or a given location. Therefore, one of the key techniques for LBS development is positioning, or identifying the coordinate of the spot where the user is currently located. For outdoor LBS, the GPS (Global Positioning System) provides a general solution for positioning. However, discovering a general solution for

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... positioning is still a hot research topic. These systems have been successfully used in many applications such as asset locating and tracking. This paper provides an overview about the RFID based indoor positioning technique. Also it reviews about the basic indoor location technologies and location estimation schemes.