Tucson stands up CBRS network with help from Insight, JMA, Geoverse and Tilson

Tuscon's relatively flat topography helps the city make the most of the mid-band CBRS spectrum. (JMA Wireless)

Tucson CIO Collin Boyce realized about a year ago that his city was not ready for the online lifestyle that was coming with COVID. “32% of Tucsonians did not have high-speed internet connectivity,” Boyce said. “I approached the assistant city manager, and we had this conversation about doing wireless.”

Boyce wanted to invest in wireless because he knew the city couldn’t afford to connect everyone with fiber. But Wi-Fi also seemed too costly. Boyce figured he would need 7,000 access points for the 20-square-mile area he needed to cover. A friend encouraged him to look at LTE, and Boyce started researching providers online. One of the companies he emailed was JMA Wireless. 

“It was a two-sentence email from our website,” remembers JMA VP Melissa Ashurst, who focuses on the healthcare and education markets. Ashurst was already investigating ways to use CBRS for remote learning after seeing students in her own family end the school year prematurely due to a lack of community connectivity. Ashurst and Boyce were on the same page from the beginning, and it wasn’t long until JMA was planning a CBRS proof-of-concept for Tucson.

Today, JMA radios and software are part of a CBRS network that is expected to serve 1,000 active users by the end of March, and eventually scale to serve 5,000 households. Paid for with CARES Act funding, the network is owned by the city and has already attracted the attention of companies that want to test and deploy IoT technologies.

The CBRS network, which uses General Authorized Access spectrum, consists of 40 radio nodes connected to off-the-shelf servers that run JMA’s XRAN baseband software. A typical node has one JMA 5-watt CellHub radio, connected by jumpers to one or more antennas. Fiber connects the radios to the server locations. “Many of these are run back via the city’s fiber to a central server location,” said Ashurst. “Some server locations are standalone because of fiber availability.” Fiber also connects the baseband servers to the core network, supplied by Geoverse. The core connects to Google's Spectrum Access System, which negotiates the availability of the shared CBRS spectrum. 

Radios are mounted on towers that the city was already using for public safety applications, as well as on city-owned rooftops. In addition, 13 poles were installed specifically for the CBRS radios. Tilson is handling site construction and deployment, and the entire network rollout is overseen by integrator Insight Enterprises.

Tucson uses software to determine which residents are eligible to receive gateways and CBRS SIM cards to enable them to access the network. City residents can log in to a website to see if they qualify. Insight provides support to qualified users who have problems connecting, bringing in Tilson and Geoverse to help as needed. According to Boyce, the network is delivering 50 Mbps downstream at his house, which isn’t even in the prescribed coverage area, and people who live closer to the towers are getting faster speeds. Boyce added that network policies block Netflix, Hulu, and content that is not considered appropriate for minors.

RELATED: 25 Utah schools to deploy private LTE using CBRS

Now that the network is taking shape, JMA has started conversations with one of Tucson’s priority access license (PALs) holders for CBRS spectrum. Ashurst said a licensee could eventually connect its core to JMA’s baseband servers. “We could broadcast those PAL licenses over the same network infrastructure,” she said. “Because JMA is able to broadcast all 150 megahertz we can support … multiple cores.” 

Smart city initiatives

Tucson’s CBRS network was built to help bridge the digital divide, but Boyce wants to also leverage it for smart city initiatives. Two possible projects are connected traffic signals and onboard Wi-Fi for city buses. Boyce said he has been approached by Intel and by the utility that handles Tucson’s water service. Ashurst said the CBRS network has catapulted Tucson from a digital laggard to a smart city leader.

“For a city like Tucson to go from one of the worst connectivity cities in the country to the best, and be leading as a smart city, is amazing,” she said. “It’s an incredible story and I want to believe that over the next two to five years you’re going to see economic development that comes from these cities making these investments.”

Ashurst thinks that JMA’s software-defined radios are one reason companies are considering the CBRS network as a way to showcase their technologies. The network will be able to transition to 5G through software upgrades, she said, so companies looking at 5G-dependent IoT see a clear path forward in Tucson.