Contributions to TOA-based location with wlan
- Autores: Marc Ciurana Adell
- Directores de la Tesis: Francisco Barceló Arroyo (dir. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2010
- Idioma: inglés
- Tribunal Calificador de la Tesis: Miquel Oliver Riera (presid.), Maria Carmen Domingo Aladrén (secret.), Luisa De Nardis (voc.), Christiane Höhne (voc.), María de los Ángeles Vázquez Castro (voc.)
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Location techniques that satisfy the requirements of advanced Location-Based Services (LBS) in environments where GPS fails are needed, therefore accurate indoor positioning is becoming increasingly important. This PhD Thesis is devoted to the research on location of mobile devices employing WLAN (IEEE 802.11). The use of this kind of wireless networks infrastructures for positioning enables a powerful synergy between communications and location and allows solutions with good performances at moderated costs. However the adopted WLAN location methods suffer from important limitations that prevents from applying them to some fields that need more flexible and robust solutions. The main objective of this PhD is exploring precise WLAN location methods that allow overcoming these limitations. The researched methods here are based on measuring the Time Of Arrival (TOA), which is the time that takes the signal propagating from the transmitter to the receiver. TOA-based location works in two stages: ranging and positioning. The ranging consists of estimating the distances between the targeted terminal and several WLAN access points, each distance obtained measuring the TOA and then multiplying it by the speed of the WLAN signal. After that, the positioning takes as inputs the estimated distances and the known coordinates of the involved access points and calculates the position of the terminal by means of a trilateration or tracking algorithm. The key problem is that the characteristics of the IEEE 802.11 protocols difficult to perform accurate TOA measurements. The main challenge that faces the research work reported here is demonstrating the feasibility of achieving this while keeping the modifications over standard WLAN consumer equipment at minimum. The objective of this work can be understood as exploring the current limits of TOA-based methods over WLAN, making contributions that form a complete TOA-based location method that goes a step forward with respect to the other existing proposals. First, research on TOA-based ranging -the key component of TOA-based location methods- is reported. The general adopted approach consists of performing Round Trip Time (RTT) measurements employing IEEE 802.11 MAC frames, taking the maximum advantage of the combination of IEEE 802.11 protocol and WLAN consumer devices mechanisms. After that, the performed research on trilateration/tracking -the second stage of TOA-based location methods- is explained. Finally some performed studies about the achieved location method are presented. Lloc i data Signatura
