Specialists are expecting the knowledge of location will trigger yet another revolution in mobile services. Location-base services (LBS) have attracted many researchers and enterprises and one of the key aspects of LBS is positioning technology. Considering a wider and more complex field - ubiquitous computing, location is the fundamental element. This work focuses on some aspects of the new techniques of terrestrial positioning systems. Wireless LAN is one of the most popular systems used for positioning for indoor environments and public places. We have investigated the trilateration and fingerprinting approaches and the results showed the advantages of fingerprinting. A novel method to generate the fingerprints database based on Universal Kriging (UK) was developed, which can not only significantly decrease the training time, but also increase the accuracy of estimates. In mobile phone positioning systems, most techniques suffer from the non-line-of-sight (NLOS) propagation. We investigated the specifics of NLOS error, and proposed a method to mitigate the errors. Furthermore, a new algorithm named WSMM (wireless signal map matching) was discussed. Simulations and experiments verified the idea, and the accuracy of positioning can be improved greatly. Since fingerprinting technique can utilize rather than suffer from the NLOS propagation, it was also applied in mobile phone positioning system. Experiments showed both the deterministic approach and probabilistic approach can provide better results comparing with other techniques in suburban area. To achieve a robust positioning system and provide more useful information of the user, multisensor combination and data fusion are necessary. As the first step of future research, a mulitsensor synchronization system was developed. This system can promisingly achieve synchronization with error less than 0.4 ms, which is suitable for most land applications. Hence the main findings of this thesis are: (1) a novel method of yielding fingerprint database for both wireless LAN (WLAN) and mobile phone systems when using the fingerprinting technique for positioning; (2) a database method to mitigate NLOS error for mobile phone positioning systems; (3) a low cost synchronization system for integration of multiple sensors.
| Identifer | oai:union.ndltd.org:ADTP/187119 |
| Date | January 2006 |
| Creators | Li, Binghao, Surveying & Spatial Information Systems, Faculty of Engineering, UNSW |
| Publisher | Awarded by:University of New South Wales. School of Surveying and Spatial Information Systems |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Copyright Binghao Li, http://unsworks.unsw.edu.au/copyright |
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