TAMPA, Fla. — Plans to use a part of Ku-band for 5G networks in the United States could disrupt Starlink broadband services even more than SpaceX previously estimated, the company said Oct. 4 as it released interference analysis from a third party.

SpaceX said the analysis validates its in-house study in June, when it warned Starlink would be unusable for most Americans if a 5G high-power mobile service is allowed to operate with 12 GHz band frequencies across the United States.

The analysis from engineering consulting firm Savid also shows “SpaceX may have underestimated the likelihood of interference and potential harm to Starlink services,” SpaceX senior director of satellite policy David Goldman wrote to the Federal Communications Commission.

Starlink uses 12 GHz spectrum to connect its satellites in non-geostationary orbit (NGSO) to user terminals. 

Satellite broadcaster Dish Network uses frequencies in the band to provide linear TV programming, and is seeking permission from the FCC to upgrade its license to provide terrestrial 5G services.

According to Dish and RS Access, a spectrum holding company that also seeks to adjust a license it has in the band to run a terrestrial network, their plans can coexist with other users of the band. 

RS Access, backed by billionaire Michael Dell, has commissioned studies from engineering firm RKF Engineering Solutions to show how such a network would impact fewer than 1% of terminals connecting to satellites in non-geostationary orbit (NGSO). 

Dish and RS Access point to mitigation techniques they say are readily available for affected terminals, although it is unclear how quickly they could deploy their proposed networks following FCC approval.

“SpaceX’s latest submission follows the company’s familiar pattern: making exaggerated claims in service of trapping 500 MHz of 5G-ready spectrum,” Dish executive vice president for external and legislative affairs Jeff Blum said via email.

“It is no surprise that yesterday’s filing from SpaceX includes a flawed technical analysis that purports – unsuccessfully – to rebut the multiple studies submitted to the FCC from the best experts in the field that have concluded that co-existence is eminently possible.”

SpaceX says the interference studies Dish and RS Access draw from are inaccurate and based on incorrect assumptions about its network.

In the letter to the FCC, Goldman said its latest analysis also addresses a claim from RS Access that “only a third party could truly analyze” how the proposed network would interfere with NGSO satellites.

NGSO broadband operator OneWeb also uses the band to connect user terminals. OneWeb submitted its own study to the FCC in July to show how using the spectrum for terrestrial 5G would severely disrupt NGSO broadband across the United States.

DirecTV, a Dish satellite broadcaster rival majority owned by U.S. telecoms giant AT&T, has said its TV customers also face major disruption if the FCC approves the plan. A study DirecTV filed with the FCC in July that underpinned its warning was also conducted by Savid.

“The record is definitive that unavoidable interference caused by high-power transmitters in the 12 GHz band would be devastating for millions of American consumers who depend on the satellite services in the band,” Goldman wrote to the FCC.

“SAVID’s technical conclusions validate SpaceX’s study and expose how RKF severely underestimates interference to Starlink customers.”

Third-party findings

While Savid found SpaceX’s power assumption in its June study was conservative in favor of Dish by a factor of four, SpaceX’s outside analyst said the report commissioned by RS Access underestimated by a factor of 40

Dish had also criticized how SpaceX’s earlier study extrapolated data from the Las Vegas region to simulate a nationwide interference impact.

According to Savid, the Las Vegas market is representative of other major regions in the U.S. where Starlink services are deployed.

SpaceX’s Goldman said Dish had also argued that SpaceX should not have assumed Dish “would actually deploy sufficient base stations to meet its build out requirements.”

However, he said Savid found that even Dish’s own base station assumptions would result in “degraded service which indicates a minor difference in results,” and at “many multiples of the levels that would still render the band useless for existing satellite services.”

He said RKF’s assumptions that Dish’s network would only operate under low power levels were also found to be inconsistent with a status report Dish issued in July, showing its progress deploying 5G in other spectrum bands. 

In the inteference analysis SpaceX released Oct. 4, Savid said Dish’s 5G deployment practice to date “clearly indicates” that Dish’s terrestrial mobile systems “will tend to maximize” base station transmission power.  

Savid also observed that the use of statistical methods in any of the analyses submitted to the FCC “washes out the real interference that a Starlink user will see from high-power terrestrial mobile base stations operating nearby,” Goldman added.

He called on the FCC to swiftly reject the terrestrial 5G plans.

Jason Rainbow writes about satellite telecom, space finance and commercial markets for SpaceNews. He has spent more than a decade covering the global space industry as a business journalist. Previously, he was Group Editor-in-Chief for Finance Information...