NDWI’s RadioHound sensing platform could play role in CBRS

RadioHound (NDWI)
The RadioHound sensor was developed at Notre Dame Wireless Institute. (NDWI)

RadioHound, a project hatched at the University of Notre Dame Wireless Institute (NDWI) for dynamic spectrum monitoring, couldn’t come at a better time.

The RadioHound system is a customized sensing network capable of tuning from 25 MHz to 6 GHz, covering nearly all widely deployed wireless devices. As described in a paper published last year, knowledge about RF users can enable better use of spectrum, such as having a secondary user accessing spectrum when the licensed primary user is not active in the band.

It comes at the same time a lot of stakeholders in the U.S. are setting up shop for the Citizens Broadband Radio Services (CBRS) 3.5 GHz band—one in which spectrum sensing and management will be crucial in order to make it all happen.

RadioHound has been in the works for a few years. “This is fairly mature, and there’s a lot of interest in the marketplace for CBRS sensing,” said Harish Punjabi, managing director of the Wireless Institute at the University of Notre Dame.

He isn’t naming names, but it’s a good bet the NDWI is talking to some of the major players in the CBRS ecosystem, which includes dozens of companies in the growing CBRS Alliance.

The NDWI is part of the NSF Industry/University Cooperative Research Center (I/UCRC) called Broadband Wireless Access and Applications Center (BWAC), which interacts with industry and federal agency members to identify, execute and demonstrate projects in collaborative, precompetitive wireless research and development. Recent industry partners of the institute include Nokia, Sprint, National Instruments and InterDigital.

The vision for RadioHound is to put a sensor in every device, becoming sort of like a Waze for spectrum usage. The idea is to create a repository of sorts for seeing when and where spectrum is being occupied.

In the paper published by IEEE last year, the students described the RadioHound system as containing three major components: a set of client sensors, a centralized database/server/controller and a user interface. The custom printed circuit board extension is hosted by Raspberry Pi.

The big key is to get the sensors down to a cost level that makes it all affordable on a mass scale. With current sensors ranging from $200 to $300, they laid out a near-term target of less than $40, but with a long-term goal of less than $10.

Initially positioned as the “innovation band,” the type of sharing and sensing envisioned for the 3.5 GHz band is something that hasn't been done before in the U.S. The FCC decided to create three tiers of spectrum usage: a tier for incumbents, a Priority Access tier for licensed uses and a General Authorized Access tier for unlicensed uses. The three tiers are to be coordinated through dynamic Spectrum Access System (SAS) administrators.

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The FCC is considering some controversial rule changes to the 3.5 GHz band, in part to make it more in tune with 5G in other parts of the world, and elements of the entire CBRS ecosystem are yet to be established and certified. But already a lot of work has transpired through the Wireless Innovation Forum (WinnForum) and the CBRS Alliance, led by Google and other stakeholders, including Federated Wireless.

RadioHound doesn’t have FCC certification because it’s a research platform and not yet commercial. Considering it is not a transmitting device, it will apply for the "unintentional radiator" certification, which is considered by NDWI faculty to be a minor hurdle, according to Punjabi.