Unified cooperative location system

• Author(s): Navalho, David Precatado
• Date: 2009
• Persistent ID: http://hdl.handle.net/10362/2420
• Origin: Repositório Institucional da UNL
• Subject(s): Location system; Fingerprinting; Information sharing; GPS; GSM; Wi-Fi; Bluetooth; Mobile devices
• Document Type: Master thesis
• Language: English
• Advisor(s): Preguiça, Nuno
• Contributor(s): RUN

Description

Dissertação apresentada na Faculdade de Ciências e Tecnologia da Universidade Nova de Lisboa para a obtenção do Grau de Mestre em Engenharia Informática.

The widespread use of smaller, less expensive, and more capable mobile devices, has opened the door for more complex and varied mobile computing applications. Additionally, manufacturers are increasingly equipping these handheld devices with every type of wireless connectivity and sensors that can be explored for providing more complex services. In recent years, several techniques for location estimation have been developed, providing different degrees of accuracy. Some of these solutions require the installation of specific hardware in the environment, while others explore the existing infrastructure. In particular, it is possible to explore the existing communication infrastructure to build a location system relying on signal strength measures. However, while several systems already exist to locate users based on different approaches, there is no single one that is good for every situation while providing high accuracy, low cost and ubiquitous coverage. Not only that, but very few research has been made regarding on how a group of users can cooperate to improve accuracy or reduce energy consumption while using the location system. This work presents the Unified Cooperative Location System, a modular and extensible location system. Its modular design can use every available technology on each device and different algorithms for location estimation. This approach allows to provide location services with high availability by relying on different technologies. It also allows to reduce the energy consumption on devices by sharing the responsibility of executing energy-heavy operations. The system also includes an information exchange mechanism, allowing devices to gather location information from nearby users, like GPS or Wi-Fi, which would otherwise be unavailable for some. The results of our experiences show that the possibility of exchanging GSM information provides a practical solution for location estimation based on multiple GSM signals, thus significantly increasing location accuracy with this technology.