Guard Band and Interference Issues Raised in 900 MHz Comments

A proposal that the FCC launch a rulemaking authorizing 5/5 MHz broadband deployments in the 900 MHz band received support in comments, which were due Thursday in docket 24-99. But commenters stressed that the relocation process must be voluntary, and that the rules must protect incumbents from harmful interference. The filings offer a snapshot of how 900 MHz is used today.

Anterix, the Enterprise Wireless Alliance and electric utilities sought the rulemaking (see 2402290064), which they see as the band's next evolution. In 2020, near the start of the COVID-19 pandemic, the FCC authorized 3/3 MHz deployments (see 2005130057).

Anterix told the FCC electric utilities are already using 900 MHz to build broadband networks in 15 states and standards are in the works for LTE in the spectrum. “Access to broadband technology is becoming as fundamental to a productive life in American society as access to clean water,” Anterix said. It also reported on virtual meetings last week with Wireless Bureau staff and aides to FCC Chairwoman Jessica Rosenworcel and Commissioner Brendan Carr.

“The FCC’s 2020 decision laid the groundwork for this growing telecommunications success story,” Anterix said. “It is now time to take the next step and provide for optional, expanded 5/5 megahertz broadband networks at 896-901/935-940 MHz … under an entirely voluntary relocation process,” which protects narrowband incumbents and operations in adjacent bands, the company said.

The proposed expanded 900 MHz segment would support “high-bandwidth utility use cases, such as video capability, and expand utility field worker applications,” said the Edison Electric Institute, which represents investor-owned utilities. “The proposed expanded 900 MHz segment will also allow electric companies higher capacity for the continually increasing sensor device deployments and potentially high-density meter deployments,” EEI said. In addition, EEI stressed that the relocation process must be voluntary.

EWA said it supported the petition because of its largely positive experience implementing the 2020 order. That order “offered a path for private enterprise users to secure spectrum for their own broadband networks,” EWA said. “That experience is the primary basis for EWA’s support for the expanded broadband segment proposed in the Petition, with the very important condition that all relocations from the current narrowband segments would be entirely voluntary,” the group said: “No incumbent would be required to relinquish channels in those segments except pursuant to a voluntarily negotiated agreement to do so.” EWA noted that the proposal would retain current interference protection rules, which have proven effective.

San Diego Gas & Electric (SDG&E) explained it’s using 900 MHz to build a private LTE network. “The energy sector's transition towards more dynamic and distributed systems requires substantial data throughput and low latency communications,” the utility said: “An expanded 5/5 MHz broadband segment in the 900 MHz Band” would support SDG&E’s “real-time monitoring and control capabilities over distributed energy resources, advanced metering infrastructure, and other IoT-driven applications critical for smart grid functionality.”

Other commenters also discussed the importance of protecting narrowband incumbents and of a voluntary relocation process.

The American Petroleum Institute said some of its members are among the largest narrowband users of the band and need protection. These members “heavily rely upon very large 900 MHz narrowband systems, particularly in the well-known areas of the Texas Gulf Coast and Southern Louisiana, but also at facilities in California and elsewhere throughout the United States,” API said: Their systems “support hundreds, sometimes thousands, of workers engaged in day-to-day operations, new facility construction, major facility expansions, and emergency response communications.”

“Given that the current 900 MHz band transition is ongoing,” the Association of American Railroads “was surprised by the new Petition and has no plans to voluntarily vacate its current and planned future use of this critical spectrum band.” The rules must protect railroads’ nationwide ribbon license from interference, “as acknowledged in the Petition, at no additional cost to AAR’s members and with no impediment to their future growth and expansion within the band,” railroads said.

Gogo Business Aviation raised concerns that the petition proposes no guard band between its air-to-ground uplinks and broadband operators using the 896-901 MHz band. A “cornerstone” of Gogo’s inflight service “is maintaining consistent and reliable service links between ground stations and aircraft by efficiently using a limited amount of spectrum, which is heavily utilized,” Gogo said. The company's ground stations receive transmissions from aircraft on the 894-896 MHz band and transmit to aircraft using 849-851, the filing said.

Space Data, which holds licenses in the adjacent narrowband personal communications service band, also stressed the importance of guard bands. “It is not clear from the information provided in the Petition whether the existing rules would be sufficient to protect operations in adjacent spectrum bands from interference created by the 5/5 MHz broadband networks,” Space Data warned.

Ericsson supported the petition. Utilities and businesses are “evaluating the automation and modernization of their communications systems,” Ericsson said. “Digitally driven automation is replacing labor-intensive manual work with systems that are more accurate and cost-effective,” the company said: “Increasing the amount of available spectrum can facilitate wireless connectivity, allowing [companies] the ability to reliably support, monitor, control, and optimize every aspect of their organization, both indoors and outdoors.”