Private LTE cellular enables remote learning for a Utah school district

The Murray School District in suburban Salt Lake City is using private LTE to keep 6,000 students connected to their classrooms, as mandated remote schooling continues through the COVID pandemic’s late stages.

The district had been looking for a private LTE system to provide reliable connectivity for homework and remote classes since 2016, having identified a real digital divide in its student body. Home Wi-Fi or public cellular data connections didn’t always provide enough bandwidth to handle live and recorded video, particularly in households where several students and their parents might be trying to connect at the same time.

The private LTE network didn’t pan out until recently, however, after the formerly restricted citizens broadband radio service (CBRS) became more widely available in January 2020. Before that, licensing sufficient broadband spectrum was far too expensive for a suburban school district, according to Jason Eyre, CTO of the Murray schools.

With CBRS, the Utah Education Network, a state-level non-profit, provides the needed spectrum to Murray and other school districts as well as technical expertise that a school district might not have in-house.

The system works as follows. Baicell Nova 436q LTE radios are placed on rooftops of each of the district’s 10 schools. They’re held in place by cinderblocks, making them relatively easy to install and adjust to provide better coverage to specific areas. Students are issued Cradlepoint IBR900 routers that receive the LTE signal and provide Wi-Fi for them to use with school-provided Chromebooks.

There are still occasional issues getting LTE signals to reach students who live near high-voltage lines or river bottoms, but the district is working with county authorities to place additional transmitters for fuller coverage. Download speeds range between 28 and 193Mbps.

Traffic received by a rooftop radio travels via ethernet to a virtual media gateway in the school that separates control-plane traffic from user-plane traffic. The control traffic travels via VLAN over the schools’ fiber-optic internet connections to UEN servers running a virtual EPC core that can handle routing, manage session states, and enforce policies, among other functions. User traffic is routed to the schools’ networks or through those networks to the internet.

Eyre says that makes the system comparatively simple to manage from the district’s perspective since almost all of the heavy lifting for routing, security and content filtering (a state law requirement) is done by the UEN.

The school also provided teachers with iPhone SE 2s that connect to the LTE network, enabling some new possibilities for remote lessons. For example, an auto shop teacher might point the camera at a car engine and demonstrate basic maintenance and functionality, Eyre said.

The system isn’t exactly cheap, according to Eyre, who said that the EPC core cost “hundreds of thousands of dollars,” but relief funding for state educational agencies made available in the wake of the pandemic via the federal CARES Act helped defray much of the cost, and he cites “a few dollars a month per radio” as the eventual cost of the network.