Mobile phone positioning helps navigate in the concrete jungle

A man gets lost when hiking. He is unable to tell the rescue service his exact position even though his mobile is working. Meanwhile, a pedigree dog, the apple of the owner’s eye, runs off. What to do these people do?

Mobile phone positioning helps locate lost people quickly and reliably. In the future, the volume of positioning services is expected to grow and their quality improve when the US GPS service is complemented by the European Galileo satellite positioning system.

However, a number of open issues remain in the utilisation of the new satellite positioning technology. Professor Markku Renfors, Head of the Institute of Communications Engineering at the University of Tampere, has led a research project exploring ways of combining various positioning technologies as economically and reliably as possible.

One of the things studied was how to use different positioning technologies side by side. The project was launched to ensure that the six companies involved possessed the capabilities to make use of the Galileo satellite positioning system, the upgraded GPS and the positioning potential offered by the communications networks in their products.

According to Renfors, it was possible to combine the positioning technologies evaluated in the project extensively, which will facilitate commercialisation.
For example, the efficiency of signal processing within the units can be improved to reduce power consumption and lower the price.

Signals reach indoors

One of the main challenges was to ensure that positioning works indoors and in the “concrete jungle” where high-rise buildings interfere with signal reception.

“For one thing, the acceleration sensors included in the units can be used as positioning aids. They can be used to calculate the distance and direction of movement from the starting point, which makes it possible to determine their position exactly even if the satellite signal is temporarily lost. Also, pseudolites, or fake satellites, can be installed indoors to transmit a GPS-type signal”, Markku Renfors says.

The pseudolites were developed by the corporate partner in the project, Space Systems Finland in Espoo. For instance, pseudolites are used to control mining vehicles underground where conventional satellite signals do not reach.

The project, which is part of the AVALI Technology Programme of Tekes, the Finnish Funding Agency for Technology and Innovation, was coordinated by the Digital Media Institute of the Tampere University of Technology.

The project was launched in 2003 and ended in February 2006. The companies involved in the project were the Elisa Corporation, European Communications Engineering Oy, Fastrax Oy, Nemo Technologies, Space Systems Finland Oy and u-Nav Microelectronics Finland Oy.