Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Wireless networks: Mobile devices keep track

A more sensitive technique for determining user position could lead to improved location-based mobile services

Many mobile-phone applications (apps) use spatial positioning technology to present their user with location-specific information such as directions to nearby amenities.

By simultaneously predicting the location of the mobile-user and the data access points, or hotspots, improved accuracy of positioning is now available, thanks to an international research team including Sinno Jialin Pan from the A*STAR Institute for Infocomm Research1. Software developers expect that such improvements will enable a whole new class of apps that can react to small changes in position.

Traditionally, device position was determined by the Global Positioning System (GPS) that uses satellites to triangulate approximate location, but its accuracy falters when the mobile device is indoors. An alternative approach is to use the ‘received signal strength’ (RSS) from local transmitters. Attenuation of radio waves by walls can limit accuracy; and, it is difficult to predict signals in complex, obstacle-filled environments.

Software developers have tried to circumvent these problems by using so-called ‘learning-based techniques’ that identify correlations between RSS values and access-point placement. Such systems do not necessarily require prior knowledge of the hotspot locations; rather they ‘learn’ from data collected on a mobile device. This also has drawbacks: the amount of data can be large, making calibration time consuming. Changes in the environment can also outdate the calibration.

Pan and his co-workers reduced this calibration effort in an experimental demonstration of a protocol that calculates both the positions of the device and the access points simultaneously — a process they call colocalization. “Integrating the two location-estimation tasks into a unified mathematical model means that we can fully exploit the correlations between mobile-device and hotspot position,” explains Pan.

First, the researchers trained a learning-based system with the signal-strength values received from access points at selected places in the area of interest. They used this information to calibrate a probabilistic ‘location-estimation’ system. Then, they approximated the location from the learned model using signal strength samples received in real-time from the access points.

Experimental trials showed that this approach not only required less calibration, but it was more accurate than other state-of-the-art systems. “We next want to apply the method to a larger-scale environment,” says Pan. “We also want to find ways to make use of the estimated locations to provide more useful information, such as location-based advertising.” As this technique could help robots navigate by themselves, it may also have important implications for the burgeoning field of robotics.

The A*STAR-affiliated researchers contributing to this research are from the Institute for Infocomm Research

Journal information

Pan, J. J., Pan, S. J., Yin, J., Ni, L. M. & Yang, Q. Tracking mobile users in wireless networks via semi-supervised colocalization. IEEE Transactions on Pattern Analysis and Machine Intelligence 34, 587–600 (2012).

A*STAR Research | Research asia research news
Further information:

More articles from Information Technology:

nachricht Worldwide glacier information system to go
30.11.2015 | Universität Zürich

nachricht Laser process simulation available as app for first time
23.11.2015 | Fraunhofer-Institut für Lasertechnik ILT

All articles from Information Technology >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: How Cells in the Developing Ear ‘Practice’ Hearing

Before the fluid of the middle ear drains and sound waves penetrate for the first time, the inner ear cells of newborn rodents practice for their big debut. Researchers at Johns Hopkins report they have figured out the molecular chain of events that enables the cells to make “sounds” on their own, essentially “practicing” their ability to process sounds in the world around them.

The researchers, who describe their experiments in the Dec. 3 edition of the journal Cell, show how hair cells in the inner ear can be activated in the absence...

Im Focus: Climate study finds evidence of global shift in the 1980s

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...

Im Focus: Innovative Photovoltaics – from the Lab to the Façade

Fraunhofer ISE Demonstrates New Cell and Module Technologies on its Outer Building Façade

The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...

Im Focus: Lactate for Brain Energy

Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.

In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...

Im Focus: Laser process simulation available as app for first time

In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.

Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...

All Focus news of the innovation-report >>>



Event News

Urbanisation and migration from rural areas challenging agriculture in Eastern Europe

30.11.2015 | Event News

Fraunhofer’s Urban Futures Conference: 2 days in the city of the future

25.11.2015 | Event News

Gluten oder nicht Gluten? Überempfindlichkeit auf Weizen kann unterschiedliche Ursachen haben

17.11.2015 | Event News

Latest News

Teamplay IT solution enables more efficient use of protocols

30.11.2015 | Trade Fair News

Greater efficiency and potentially reduced costs with new MRI applications

30.11.2015 | Trade Fair News

Modular syngo.plaza as a comprehensive solution – even for enterprise radiology

30.11.2015 | Trade Fair News

More VideoLinks >>>