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
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).
More articles from Information Technology:
15 years virtual reality innovations for oil and gas visualization
19.12.2013 | Fraunhofer-Institut für Intelligente Analyse- und Informationssysteme IAIS
Programming smart molecules
13.12.2013 | Harvard University
Swimming microengines made from platinum and iron are highly efficient in removing organic pollutants from water using hydrogen peroxide.
Researchers from the Max Planck Institute for Intelligent Systems in Stuttgart have developed a new method for the active degradation of organic pollutants in solution by using swimming microengines.
The mobile microcleaners consist of an outer iron and an inner platinum layer, thereby combining two functionalities. Hydrogen peroxide, which must be ...
A 12-year study of massive stars has reaffirmed that our Galaxy has four spiral arms, following years of debate sparked by images taken by NASA's Spitzer Space Telescope that only showed two arms.
The new research, which is published online today [17 December] in the Monthly Notices of the Royal Astronomical Society, is part of the RMS Survey, which was launched by academics at the University of Leeds.
Astronomers cannot see what our Galaxy, which is called the Milky Way, looks like because we ...
In collaboration with the University of Basel, an international team of researchers has observed a strong energy loss caused by frictional effects in the vicinity of charge density waves.
This may have practical significance in the control of nanoscale friction. The results have been published in the scientific journal Nature Materials.
Friction is often seen as an adverse phenomenon that leads to wear and causes energy loss. Conversely, however, too little friction can be a disadvantage as well – ...
A new type of transistor that could make possible fast and low-power computing devices for energy-constrained applications such as smart sensor networks, implantable medical electronics and ultra-mobile computing is feasible, according to Penn State researchers.
Called a near broken-gap tunnel field effect transistor (TFET), the new device uses the quantum mechanical tunneling of electrons through an ultrathin energy barrier to provide high current at low voltage.
Penn State, the National Institute of Standards and Technology and IQE, a specialty wafer manufacturer, jointly presented their findings at ...
The team of Johannes Zuber at the IMP in Vienna, Austria, managed to overcome remaining key limitations of RNA interference (RNAi) - a unique method to specifically shut off genes.
By using an optimized design, the scientists were able to inhibit genes with greatly enhanced efficiency and accuracy. The new method facilitates the search for drug targets and improves the interpretation of experimental results.
The IMP will make this „RNAi toolkit“ available to researchers. Results of the study are published in ...
20.12.2013 | Materials Sciences
20.12.2013 | Life Sciences
20.12.2013 | Life Sciences
19.12.2013 | Event News
11.12.2013 | Event News
10.12.2013 | Event News