The FCC has updated the out-of-band emissions limits for T-Mobile and SpaceX’s satellite program that brings connectivity to dead zones using the latter’s Starlink satellites. The relaxed limit will allow the service to operate at a higher power than before.
Section 25.202(k)(1) has established a uniform out-of-band emissions (OOBE) limit of -120 dBW/m2 /MHz to minimize harmful interference to terrestrial services.
SpaceX had requested a relaxation of the power flux density (PFD) limit, assuring that it would protect adjacent networks from harmful interference while ensuring a robust set of features for T-Mobile customers and first responders.
Right now, the direct-to-cell program is in beta and customers can only send texts over satellite. A relaxation in the limit is going to allow SpaceX to offer more features, including 911 emergency calling connectivity in off-the-grid locations.
If it continues to comply with section 25.202(k)(1), it will have to take some compensatory measures that will make the network slower and voice service will be delayed by years.
This is a huge blow to T-Mobile’s rivals
T-Mobile and SpaceX’s rivals, including AT&T, Verizon, and EchoStar had urged the FCC to not grant the waiver request, insisting that the established limit provided an appropriate level of protection for terrestrial networks. They also said that SpaceX failed to prove that a higher PFD level wouldn’t disrupt operations. They feared that a relaxed limit would slow down their networks.
SpaceX responded by saying if a waiver wasn’t granted, it would cut off the only lifeline available to customers during an emergency. It asserted that a one-size-fits-all aggregate PFD limit was burdensome and no company could meet the established threshold without compromising the quality of the service, thereby undermining the FCC’s vision.
The company also countered Verizon‘s argument by saying that it supported rules that would give it an advantage over companies operating at higher frequencies.
T-Mobile chimed in by saying that the -110.6 dBW/m2/MHz PFD level that SpaceX requested would protect adjacent terrestrial frequency bands. It strengthened its argument by stating that it operated in adjacent terrestrial frequency bands and wouldn’t support a relaxed limit if it caused harmful interference.
FCC grants a conditional waiver
SpaceX has been granted a waiver for 25.202(k)(1), allowing aggregate OOBE at a PFD level up to -110.6 dBW/m2 /MHz.
However, if SpaceX’s satellites are found to be causing interference to adjacent band terrestrial wireless networks, it must address the issue and cease operations under the waiver.
To limit the number of stakeholders that could potentially be affected, the “scope of the waiver is limited to the 5 megahertz band segments immediately adjacent to the PCS G Block in which SpaceX is operating.” This means that the waiver only applies to 1985-1990 MHz and 1995-2000 MHz. In all other bands, section 25.202(k)(1) must be complied with.
The FCC grants waivers when they serve a good cause and better serve the public interest. It says that both SpaceX and T-Mobile both provided engineering analyses that supported their claims.
The commission says it finds “good cause to waive the rule, subject to conditions that will protect terrestrial wireless carrier operations.”
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