Direction finding of Wi-Fi transmitters

Technology
We developed an apparatus for Direction Finding of Wi-Fi transmitters, i.e., estimating the Angle-of-Arrival (AoA) of a received Wi-Fi signal, while using standard off-the-shelf hardware and requiring no infrastructure deployment, no preliminary on-site calibration and no cooperation from the target Wi-Fi transmitter.
The key achievement in this work is the approach of employing for our needs inherent characteristics of Wi-Fi devices which are originally used for other purposes.

Need and Advantages
This technique can be used for locating Wi-Fi transmitters (both access-points and end-users), and can be the basis for an indoor-GPS system. As we take advantage of inherent characteristics of modern wireless standards, the proposed method is readily applicable for other standards such as LTE (4G).

Potential Applications
Wi-Fi indoor localization is an active field of R&D both academically and commercially. Our technology may provide any Wi-Fi device (smartphone, laptop, Wi-Fi router, etc.) with the ability of finding the relative direction to other Wi-Fi devices, without any need of cooperation, calibration, infrastructure deployment or user intervention.
At the moment, we see at least three groups of applications that are based on this technology:
1) Locating Malicious Wi-Fi Transmitters (Security Application) – using our technology, any Wi-Fi device, static or dynamic, will be able to locate malicious Wi-Fi devices (such as rogue access-points or malicious end-user). It might even be distributed as a smartphone app.
Existing commercial products (such as FLUKE AirCheck) require maneuvering the locator device with directional antenna and walking back and forth in the area of the target transmitter
2) Indoor Self-Localization (Indoor-GPS) – Indoor navigation (Indoor-GPS) is a hot area of R&D, which is ruled by giants (Apple, Google, Intel, etc.). Most Indoor-GPS systems are based on Wi-Fi localization, usually using the Received Signal Strength Indicator (RSSI). Several system architectures and designs, based on our technology, can be suggested for implementing an indoor-GPS system. Our technology will be able to provide a precise location with much smaller dependence on the Wi-Fi infrastructure and its changes.
3) Passive Indoor Localization of End-Users (Commercial Analytics) – The fact that our technology can locate any Wi-Fi device without any cooperation from its side brings the unique ability to collect precise location data of unfamiliar users. This can be used for commercial analyses like collecting statistics of consumers' behavior and thus provide useful insights for business decisions. Similar products (like Navizon) count the number of active Wi-Fi users in range for these statistics collection, and has no data regarding their accurate location.

Stage of Development
The developed technology has been proved using a working prototype based on a commercial off-the-shelf Wi-Fi card. The prototype provides AoA estimation with median error of ~10o.

Patents
US provisional application filed

Project manager

Oren Calfon
VP Business Development, ICT

Project researchers

Ofer Amrani
T.A.U Tel Aviv University, Engineering
School of Electrical Engineering

Avishai Wool
T.A.U Tel Aviv University, Engineering
Engineering - General Department