Indoor localization systems have a variety of applications such as tracking
of assets, indoor robot navigation, and monitoring of people (e.g. patients) in
hospitals or at home. Global positioning system (GPS) offers location accuracy
of several meters and is mainly used for outdoor location-based applications as its
accuracy degrades significantly in indoor scenarios. Wireless local area networks
(WLAN) have also been used for indoor localization, but the accuracy is too low
and power consumption of WLAN terminals is too high for most applications.
Ultra-wideband (UWB) localization is superior in terms of accuracy and power
consumption compared with GPS and WLAN localization, and is thus more
suitable for most indoor location-based applications [1-4].
The accuracy and precision requirements of localization systems depend on
the specific characteristics of the applications. For example, centimeter or even
millimeter localization accuracy is required for dynamic part tracking, while
decimeter accuracy might be sufficient for tracking patients in hospitals or at
home. Note that accuracy is not the only aspect of the overall performance of the
system. Factors such as cost, range, and complexity should also be considered
in system design.
In the first part of this dissertation, a centimeter-accurate UWB localization
system is developed. The technical challenges to achieve centimeter localization
accuracy are investigated. Since all the receivers are synchronized through
wire connection in this system, a wireless localization system with centimeter
accuracy is introduced in order to make the system easier for deployment. A
two-step synchronization algorithm with picosecond accuracy is presented, and
the system is tested in a laboratory environment.
The second part of this dissertation focuses on reducing the complexity of
UWB localization systems when the localization accuracy requirement is relaxed.
An UWB three-dimensional localization scheme with a single cluster of
receivers is proposed. This scheme employs the time-of-arrival (TOA) technique
and requires no wireless synchronization among the receivers. A hardware and
software prototype that works in the 3.1-5.1 GHz range is constructed and tested
in a laboratory environment. An average position estimation error of less than
3 decimeter is achieved by the experimental system.
This TOA scheme with receivers in a single unit requires synchronization
between the transmitter and the receiver unit. In order to further reduce system
complexity, a new time-difference-of-arrival localization scheme is proposed.
This scheme requires multiple units, each operating on its own clock. It avoids
synchronization between the transmitter and receivers, and thus makes the development
of the transmitter extremely simple. The performance of this system
is simulated and analyzed analytically, and turns out to be satisfactory for most
indoor localization applications. / Graduation date: 2013
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/30349 |
| Date | 13 June 2012 |
| Creators | Ye, Ruiqing |
| Contributors | Liu, Huaping |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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