Positioning Technique of Wireless LAN Terminals Using RSSI between Terminals

The IEEE 802.11 wireless LAN spreads very widely. The wireless VoIP technologies will accelerate spreading. In the environment in which almost all people take along their own wireless terminal, location information of terminals can be used as them of persons, and can support human collaborative work. We focus on the positioning technology of IEEE 802.11 devices. There are many researches of the technology already. Our target is providing precise relative location of IEEE 802.11 terminals with short site calibration process and no additional hardware. RSSI requires no additional hardware. However RSSI is affected by obstacles, multipath fading, etc. In this paper, we describe the design and implementation of a prototype of proposed positioning system called WiPS. To improve the accuracy of relative location, WiPS uses RSSI between terminals. WiPS can be work well, if LOS path between terminals are available and distance between terminals are less than several meters. WiPS does not need LOS path between access point and each terminal. We show the result of empirical study using a prototype. The order of terminals can be obtained precisely, when terminals are in line.