Location Service for Mobile Device

1. Location Service for Mobile Device • New Ideas • Increasing proliferation of 802.11 base stations and PC card  use 802.11 wireless LAN infrastructure to determine mobile device location inside building • Signal strength can be measured and there is a correlation between signal strength and distance • Signal strengths from multiple base stations can triangulate the exact location • Key Design/Approach • Data collation: mapping the service area in advance for an accurate signal map • Algorithm 1: best matching: O(n2) • Algorithm 2: multidimensional search O(log(n)) • GUI (see above) • Limitation : Placement of Base stations limited to certain locations • Results/Lesson Learned • Implemented in Linux • Tested in ACES 6th floor • Beacon stations: 2 • Service granularity: 10 feet • Accuracy: 90% of the time: within 15 feet • Lesson learned: • 802.11 Linux driver does not support “promiscuous” mode to pick up beacons from multiple base stations • Resolved to ad-hoc mode Project team: Ravishankar Chamarajnagar, Jeff Napper URL: http://www.cs.utexas.edu/users/ravshank/mobile_project/project.html