ToA Path Estimation for Indoor Positioning Using MUSIC algorithm for Time Resolution Enhancement
Author
Laursen, Mathias Hjorth
Term
4. term
Education
Publication year
2017
Submitted on
2017-06-08
Pages
81
Abstract
Behovet for indendørs positionering og navigation vokser. Dette speciale undersøger, om et indendørs positioneringssystem kan forbedres ved at kombinere ToA og MUSIC for bedre tidsopløsning. ToA estimerer position ved at måle, hvor lang tid et trådløst signal er om at nå frem. Indendørs reflekteres signalet fra vægge og genstande, så flere kopier af signalet ankommer forskudt i tid (multipath), hvilket kan gøre ToA mindre præcis. MUSIC-algoritmen er en signalbehandlingsmetode, der kan adskille tætliggende ankomsttider og dermed forbedre ToA-estimater. I arbejdet undersøges trådløse kanalers egenskaber, da de er vigtige for at udvikle og evaluere et indendørs system. Der udvikles en model for et ToA-system, og simuleringer bruges til at vurdere effekten af forskellige kanalegenskaber, især forskelle i ankomsttid mellem reflekterede signalveje, samt hvor meget MUSIC forbedrer adskillelsen. Derudover gennemføres målinger for at vurdere MUSICs ydeevne i trådløse kanaler under både frilinje (LOS) og uden frilinje (NLOS) forhold. Testene viser en markant forbedring ved at kombinere ToA og MUSIC sammenlignet med et traditionelt ToA-baseret system.
The demand for indoor positioning and navigation is growing. This thesis explores whether an indoor positioning system can be improved by combining ToA and the MUSIC algorithm to achieve better time resolution. ToA estimates position by measuring how long a wireless signal takes to arrive. Indoors, signals reflect off walls and objects, so multiple copies arrive at slightly different times (multipath), which can reduce ToA accuracy. The MUSIC algorithm is a signal processing method that can separate closely spaced arrival times and thus refine ToA estimates. The work investigates wireless channel characteristics because they are key to designing and evaluating an indoor system. A model of a ToA system is developed, and simulations assess the impact of different channel properties, especially differences in time of arrival between reflected paths, as well as the improvements provided by MUSIC. In addition, measurements evaluate MUSIC’s performance on real wireless channels under both line-of-sight (LOS) and non-line-of-sight (NLOS) conditions. Test results show a significant improvement when combining ToA and MUSIC compared with a traditional ToA-based system.
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