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Title: Enhancing location estimation accuracy in WiMAX networks
Author: Isa, Azmi Awang Md
Awarding Body: Lancaster University
Current Institution: Lancaster University
Date of Award: 2011
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Due to the ever increasing demand for new services and applications, wireless broadband communications is becoming even more popular since users have been provided with an "anywhere any time" type of service. Mobile worldwide interoperability for microwave access (WiMAX) provides mobile broadband connectivity and some essential applications, including location and positioning (L&P) for mobile users. In this thesis, we have utilised some of the features offered by WiMAX, including multiple input multiple output (MIMO) and beamforming, to improve the location estimation accuracy of location services. In a MIMO system, the number of links is increased, not only for the spatial multiplexing of data to be transmitted or received, but also for simultaneous distance measurement between a base station (BS) and a mobile station (MS). Utilising MIMO will both significantly improve the capacity and throughput of a wireless link and facilitate improvement of the location accuracy of a MS. We have proposed a geometrical approach using a multiple linear lines of position (MLLOP) technique for MIMO antenna mode configurations in WiMAX networks with range measurements from only three BSs in non-line of sight (NLOS) environments. Going beyond MIMO systems, an innovative location estimation algorithm, involving virtual BSs in MIMO systems (called VirBSs), is proposed and investigated, offering the reduction in NLOS error effects. We also explored existing beamforming features for improving accuracy of location estimation. A hybrid positioning method is proposed that utilises the time of arrival (TOA) and direction of arrival (DOA)-based beamforming in MIMO systems. More specifically, two hybrid L&P techniques are presented. The first of these hybrid techniques expands the fundamental principle of using an MLLOP scheme by utilizing multiple LOP instead of circular LOP to determine new lower and upper bounds of DOA The second proposed technique utilises only one MIMO SS, with range and angle measurements from two or more multi-paths, thus extending the virtual BS concept to enhance estimation accuracy with no extra network infrastructure required. We have shown that all the developed techniques provide L&P accuracy improvement with lower implementation complexity and are compatible with the existing WiMAX specifications.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available