NAB Expresses Concern About T-Band Changes, NWCC Responds
Tuesday, May 17, 2022 | Comments

In a meeting with the FCC, the National Association of Broadcasters (NAB) urged caution with moving forward with any changes to the rules governing the T-band as requested by a petition of rulemaking from the National Wireless Communications Council (NWCC).

In a letter responding to the meeting, the NWCC argued against some of the NAB’s points and reiterated its stance that changes need to be made to the rules to protect LMR users from interference.

In June, the NWCC, formerly the Land Mobile Communications Council (LMCC), filed the petition asking the FCC to address issues involving TV station interference protections in the band. Specifically, the NWCC proposed changing the protection rules to reflect the migration of TV stations from analog to digital operations, as the previous rules were based on TV stations operating analog.

In comments throughout the proceeding, the NAB has said the FCC should use caution in moving forward with any changes and argued that updating the rules could lead to more interference to LMR stations. The NAB has urged the FCC to not change the rules. In a May 2 phone call with the FCC, officials from the NAB reiterated that stance.

In that call, the NAB noted that many propagation models “are probalistic, not deterministic” and argued that many interference issues arise from “outlier cases,” according to an NAB ex parte filing describing the call.

“Thus, even if a model correctly predicts that sharing can be successful 99 percent of time, the one percent use case may present substantial interference issues lasing many hours over many days that cannot be accurately forecast in advance and may require significant adjustments to operating parameters to resolve,” the ex parte filing said.

NAB again reiterated that if the FCC does take action on the petition, it should do so with caution.

“For these reasons, NAB respectfully suggests that adjusting the commission’s current rules risks creating additional instances of harmful interference between television stations and T-band operators, including public safety operations, making the existing problem worse instead of better,” the filing said. “To the extent the commission chooses to move forward with a notice of proposed rulemaking in this matter, it must bear in mind that it is land mobile operators, not broadcasters, seeking changes to rules that already result in interference. Accordingly, the commission must expressly make plain that broadcasters will not bear sole responsibility for mitigating interference issues that will inevitably arise.”

In an ex parte letter to the FCC, the NWCC agreed with the NAB that propagation models are probalistic and not deterministic but disagreed with its contention that most interference issues come from outlier cases.

“In fact, the FCC relies on these models and the related contour and mileage separation criteria to allow systems in many bands, providing a multitude of differing services, to co-exist compatibly in our increasingly congested spectrum,” the NWCC’s filing said. “The alternative would be to establish rules based on spectrally wasteful worst-case scenarios, an approach the FCC, rightfully, has rejected repeatedly.”

The NWCC argued that there have always been instances where the models don’t work, leading to interference, and that the FCC is equipped to deal with those instances as they arise.

“For the reasons detailed in the petition and in previous filings in this proceeding, the NWCC does not expect the changes proposed in the petition to result in additional cases of interference from television stations to land mobile operations,” the NWCC’s filing said. “It would not have filed the petition if that were the expected result. However, in the unlikely event that interference should occur, the NWCC is confident that the FCC will pursue its normal course of determining how to resolve the matter to serve the public interest, without prejudging where responsibility lies as demanded by NAB.”

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