Abstract
Accuracy of iPhone Locations: Assisted GPS, WiFi and Cellular Positioning
Track: Education
Author(s): Paul Zandbergen
The 3G iPhone was the first consumer device to provide a seamless integration of three positioning technologies: Assisted GPS (A-GPS), WiFi positioning and cellular network positioning. This study presents an evaluation of the accuracy of locations obtained using these three positioning modes on the 3G iPhone. Results indicate that A-GPS locations obtained using the 3G iPhone are much less accurate than those from regular autonomous GPS units (average median error of 8 m for ten 20-minute field tests) but appear sufficient for most Location Based Services. WiFi locations using the 3G iPhone are much less accurate (median error of 74 m for 58 observations) and fail to meet the published accuracy specifications. Positional errors in WiFi also reveal erratic spatial patterns resulting from the calibration effort. Cellular positioning using the 3G iPhone is the least accurate positioning method (median error of 600 m for 64 observations), consistent with previous studies.
Paul Zandbergen
University of New Mexico - Geography
Bandelier West Room 111, MSC01 1110
1 University of New Mexico
Albuquerque , New Mexico 87131
United States
Phone: 505-277-3105
E-mail: zandberg@unm.edu