Two U.S. Army Research Laboratory (ARL) researchers have come up with an algorithm that enables localization of humans and robots in areas where GPS is unavailable. Their technique uses the direction of the signal instead of the time taken to determine the location.

The technique is announced from ARL official web site. According to ARL researchers Gunjan Verma and Dr. Fikadu Dagefu, the Army needs to be able to localize agents operating in physically complex, unknown and infrastructure-poor environments.

In most civilian applications, solutions such as GPS work well for this task, and help us, for example, navigate to a destination via our car. However, such solutions are not suitable for the military environment.

The team of ARL developed a novel technique for determining the direction of arrival, (DoA), of a radio frequency signal source, which is a fundamental enabler of localization.

“The proposed technique is robust to multiple scattering effects, unlike existing methods such as those that rely on the phase or time of arrival of the signal to estimate the DoA,” Verma said. “This means even in the presence of occludes that scatter the signal in different directions before it is received by the receiver, the proposed approach can accurately estimate the direction of the source.”

Importantly, when the signal is extremely noisy, the estimator correctly outputs that no DoA is present, rather than incorrectly estimating an arbitrary direction.

The researchers have validated the approach with several publically available as well as in-house collected measurement datasets at 40MHz and 2.4GHz bands, as well as data from high fidelity simulations.

A journal paper documenting the research has been accepted for publication in the Institute of Electrical and Electronics Engineers Transactions on Vehicular Technology.