A novel scan priority based WLAN position estimation.

摘要

Global Positioning System (GPS) products help to navigate while driving, hiking, boating, and flying. GPS uses a combination of orbiting satellites to determine position coordinates. This works great in most outdoor areas, but the satellite signals are not strong enough to penetrate inside most indoor environments. As a result, a new strain of indoor positioning technologies that make use of 802.11 wireless LANs is beginning to appear on the market. In WLAN positioning the system either monitors propagation delays among the wireless nodes (access points and users) to triangulate and calculate relative position or it maintains the database of location fingerprints which is used to identify the most likely match of incoming signal data with those preliminary surveyed and saved in the database. An issue with these systems, however, is that there are no standards. All solutions are vendor-specific. For example, Ekahau offers the Ekahau Positioning Engine (EPE) that locates laptops or PDA devices within 1 meter (3.5 feet) in less than a second. EPE is a software-only solution based on Java that runs on Windows NT/2000/XP, WinCE 3.0 and Pocket PC 2002.;In this thesis we investigate the issue of deploying WLAN positioning software on mobile platforms. We suggest a novel scan order (of access points) based location estimation system that helps avoid complex computations and in-turn avoid the need for high processing capability among mobile devices. We further discuss the performance of such a system in comparison to Simple Comparison based approach (a variant of novel scan order based approach) and Probabilistic approach with Integrity Monitoring.