The real problem with using WiFi for location finding is that most schemes are based on doing an RF signal characteristic map of the area and using the RSSI levels to predict where a tag is located. You should check the Real Time Location Services (RTLS) or Precision Location Services (PLS). Ekahau and AeroScout use this technique for one level of location finding. However, accuracy of less than 3 meters requires very accurate timing information to calculate and triangulate time of flight to improve the location estimate. You encounter the same accuracy levels that HDOP (Horizontal Dilution of Precision) that GPS encounters. A lot of work has been done with both WiFi and 802.15.4 (WSN) at the academic and commercial levels. The problem with RF mapping is that the environment's RF characteristics can change based on large numbers of people and other objects that cause RF reflections and absorptions that result in inaccurate time of flight and there fore increase your error. Check out Harvard's MoteTrack WSN technology. Also Cricket using high frequency audio signals for location finding posted high degree of accuracy, however, ambient noise levels cause the same accuracy problems as RF. Cordially, Charles Bolton. -----Original Message----- From: Andrew Fortier [mailto:] Sent: Thursday, July 13, 2006 2:46 PM To:
Subject: [Wear-Hard] WiFi Positioning Hi, My research group is looking at using indoor positioning for a wearable we're designing. Has anyone had good luck using WiFi? If so can you recommend any software and/or techniques? We don't need it to be particularly accurate (10 meters or so would be fine), but ease of setup would be nice as we're thinking about covering a fairly large space (like a mall). Appreciate the input! Andrew Fortier Wearable Computing Lab University of Oregon _______________________________________________ Wear-Hard mailing list
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