2 research outputs found
A study of RF-over-fibre based active RFID indoor location system
Location systems developed for indoor environments have attracted increasing
interest, as a result of the rapidly growing location and navigation services provided
by the Global Positioning System (GPS). Location information of people and objects
can be used to cooperate with existing communication or database systems to provide
abundant services to system operators and end users. For example, equipment tracking
in hospitals ensure that location of the appropriate equipment can be provided
simultaneously with necessary medical services; attendee tracking at conferences may
encourage more efficient communications and networking; location of valuable assets
in factories or warehouses aids logistics and protects these assets from theft. Since
established global and terrestrial navigation systems cannot provide reliable location
services in indoor environments, these demands are increasingly being met by
wireless indoor location systems.
A review of the existing systems reveals that the current systems are able to provide
either an accurate location service with sophisticated system design at higher cost or a
less accurate location service by means of integrated systems supplemented by
existing facilities.
This thesis presents a novel design of an indoor location system that is based on an
RF-over-fibre backbone network, which is able to provide high location accuracy
while the network infrastructure can be shared with multiple wireless systems. It is the
first such demonstrator in this area. This research has been conducted by the author
through a research project called The Intelligent Airport (TINA), which is the
motivation for this research.
The TINA project seeks to develop a new seamless wireless/wired ubiquitous
infrastructure with high levels of computational capability to meet the application
requirements of future airport environments. In the TINA system, multiple wireless
services are provided through an integrated system supported by an RF-over-Fibre
network, which transports RF signals through optical fibres. The active RFID indoor location unit is an essential part of the TINA system, which will facilitate the
infrastructure to provide location-based services.
The thesis describes the detailed design of the active RFID indoor location system
proposed for the TINA project, and a few key issues discovered during trials of the
demonstration system developed. The overall system design, including ranging
technique, TDOA location finding algorithm, and hardware implementation, is
presented in this thesis. Particular contributions also include a numerical algorithm for
solving target location from TDOA measurement and a technique to determine the
chirp linearity requirement. The field trial results of the system design demonstrate the
principals and their location performance. The system has the potential to be extended
to other scenarios where RF-over-fibre networks are employed and accurate location
ability is desired
Physical Layer Challenges and Solutions in Seamless Positioning via GNSS, Cellular and WLAN Systems
As different positioning applications have started to be a common part of our lives, positioning methods have to cope with increasing demands. Global Navigation Satellite System (GNSS) can offer accurate location estimate outdoors, but achieving seamless large-scale indoor localization remains still a challenging topic. The requirements for simple and cost-effective indoor positioning system have led to the utilization of wireless systems already available, such as cellular networks and Wireless Local Area Network (WLAN). One common approach with the advantage of a large-scale standard-independent implementation is based on the Received Signal Strength (RSS) measurements.This thesis addresses both GNSS and non-GNSS positioning algorithms and aims to offer a compact overview of the wireless localization issues, concentrating on some of the major challenges and solutions in GNSS and RSS-based positioning. The GNSS-related challenges addressed here refer to the channel modelling part for indoor GNSS and to the acquisition part in High Sensitivity (HS)-GNSS. The RSSrelated challenges addressed here refer to the data collection and calibration, channel effects such as path loss and shadowing, and three-dimensional indoor positioning estimation.This thesis presents a measurement-based analysis of indoor channel models for GNSS signals and of path loss and shadowing models for WLAN and cellular signals. Novel low-complexity acquisition algorithms are developed for HS-GNSS. In addition, a solution to transmitter topology evaluation and database reduction solutions for large-scale mobile-centric RSS-based positioning are proposed. This thesis also studies the effect of RSS offsets in the calibration phase and various floor estimators, and offers an extensive comparison of different RSS-based positioning algorithms