In a recent filing with the Federal Communications Commission (FCC) T-Mobile questioned the viability of Lockheed Martin’s shared use of its 3.45 GHz mid-band spectrum. Lockheed Martin had previously filed comments to the FCC outlining its efforts to find a solution with the carrier, and indicated that T-Mobile has been uncooperative in the process.

In December 2022 the Commission issued a special temporary authority (STA) asking T-Mobile to negotiate with Lockheed Martin for the latter’s continued use of the spectrum, “under an experimental authorization,” for testing of Department of Defense (DoD) systems.

T-Mobile wrote to the FCC that it has since conducted analyses and field tests to determine the impact of Lockheed Martin’s operations on T-Mobile’s use of its 3.45 GHz mid-band spectrum, which the carrier invested nearly $3 billion to secure in the commission’s Auction 110 in 2022.

From its analyses, T-Mobile found that the “anticipated levels of interference would prevent any meaningful use of the 3.45 GHz band by T-Mobile within the affected partial economic area (PEA),” according to the FCC filing.

“Indeed, some levels of interference would destroy our networking equipment,” the company wrote.

T-Mobile claimed that its usual network management techniques that involve shifting traffic to one base station when others are unavailable would no longer be possible with Lockheed Martin continuing operations, because the level of interference would be “so high that no base stations could effectively use the 3.45 GHz band.”

“Consequently, T-Mobile can currently identify no mitigation techniques that would permit Lockheed Martin to operate in a manner that would not create catastrophic inference to its network and customers,” the filing added.  

T-Mobile also pointed out the radars used for Lockheed Martin tests operate both inside and outside the 3.45-3.55 GHz band. With the amount of interference being caused by high power land, sea and airborne radars into commercial systems, the carrier said it “remains skeptical about the potential for commercial shared use of spectrum with these government systems.”

“That is why T-Mobile has continued to advocate for a bifurcated approach to band sharing in cases where coexistence has proven to be impractical in a co-channel environment,” the carrier wrote.

Lockheed Martin, in an earlier FCC filing, said that it had provided T-Mobile with a list of potential mitigation techniques for proposed real-world testing in the PEAs. According to the Lockheed Martin filing, T-Mobile responded that the proposed techniques would cause “constraints to T-Mobile’s network and are thus unacceptable.”

The entire list of mitigations proposed for testing by Lockheed Martin was rejected as “draconian measures” by T-Mobile shortly before the carrier made its own filing.

“Lockheed Martin continues to try to understand T-Mobile’s approach for solutioning the situation, particularly when one of the ‘draconian’ mitigation testing techniques Lockheed Martin proposed progressing was previously identified by T-Mobile itself as a potential candidate for real-world mitigation testing in the PEAs,” Lockheed Martin added.

Lockheed Martin in its filing emphasized that the intention of the commission’s STA order was explicitly for the two parties to reach an agreement “to permit continued spectrum access for design and testing of important radar systems while minimizing impacts on flexible-use wireless networks.”

The company noted that it first suggested to adhere to a self-imposed high-power operating window, a time when T-Mobile would be least likely to be using the 3.45-3.525 GHz segment of the 3.45 GHz band. However, Lockheed Martin claimed that T-Mobile still reported that Lockheed Martin was seeking to conduct operations in some “busy hour timeframes.”

“Lockheed Martin has not otherwise been informed by T-Mobile of any changes to its previously communicated expected ‘busy hours’,” the company’s filing added.

Lockheed Martin noted in their communications T-Mobile has been in favor of “only measures for which the sole burden of implementation falls on Lockheed Martin. Except for the initial proposed, but since abandoned mitigation technique, Lockheed Martin has not been offered any mitigation techniques by T-Mobile for either party to consider for implementation.”

T-Mobile maintained to the FCC that it will continue to negotiate in good faith with Lockheed Martin to explore how the corporation can modify its operations to permit its use of systems through “experimental authorization on a secondary basis.”

Meanwhile, Lockheed Martin had more favorable reviews for the other carriers it is working with under the commission’s STA.

The company in its filing expressed appreciation for AT&T’s “continued willingness to collaborate on real-world testing opportunities,” and commended Dish Networks as well for its support for the real-world testing of mitigation techniques and being “engaged in the cooperative process.”

Both Lockheed Martin and T-Mobile declined Fierce’s request for comment on their respective FCC filings.

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