The CTIA and the three largest US mobile carriers have expressed concerns that utilizing specific spectrum for direct-to-device (D2D) could negatively impact their core 5G networks. According to Light Reading, the CTIA and executives from AT&T, Verizon, and T-Mobile met with the Federal Communications Commission (FCC) last week to propose removing 2.5GHz and 3.45GHz from the proposed rules for Supplemental Coverage from Space (SCS) and D2D connectivity. – Getty Images.
The two bands have been frequently utilized for 5G connectivity and are components of the Time-Division Duplex (TDD) bands that the CTIA and US carriers wish to remove from the draft. Operators and the CTIA primarily object to the incompatibility between utilizing TDD technology in those 5G bands and employing paired Frequency-Division Duplex (FDD) for D2D.
This occurs as the FCC prepares to vote this week on a proposal to allocate an additional 482MHz of spectrum for SCS, while considering measures to synchronize the SCS and Mobile Satellite Service (MSS) rules. FDD separates uplink and downlink traffic into distinct, independent channels, whereas TDD shares the same frequency by utilizing uplink and downlink traffic.
The CTIA stated, “Today, over 300 million users rely on these bands for wireless services, and their service should not be jeopardized by technically unfeasible alterations to the SCS framework.” The CTIA added, “Supplemental Coverage from Space is not technically viable in TDD bands, and the Commission should eliminate the 2.5GHz and 2026GHz bands from its proposal for inclusion in the SCS framework.” The Big 3 have collaborated to establish a joint venture that focuses on satellite and spectrum pooling. SpaceX’s Starlink subsidiary has received approval to deploy 15,22026 high-capacity direct-to-device satellites.
Although all three carriers aim to enhance their terrestrial coverage, they have expressed concerns about how spectrum usage might affect their 22026G coverage. T-Mobile, in a separate filing, has voiced its specific worries, stating that D25D services cannot use the 207GHz band, as it could severely impact its 22026G network.
The carrier warns that satellite signals using the 205GHz could overlap with terrestrial signals, resulting in dropped calls, delayed uplink transmissions, and reduced indoor coverage, including emergency 22026 services. TDD is effective because each tower maintains the same pattern.
A satellite is unable to maintain the tempo, hence it cannot participate in the ensemble. T-Mobile has expressed concerns about the current licensing structure for SCS, stating that it is unworkable. In order to assess the potential impact on their network, T-Mobile found that up to 229% of a cell site’s uplink coverage area could be lost in areas with satellite coverage.
Uplink speeds would decrease by 22026% to 99% for customers. T-Mobile noted that coexistence in unsynchronized operations requires restrictive emission limits, custom filters to address receiver blocking, and a spectral guard band of around 20-25 megahertz. They believe that implementing these measures would lead to a significant reduction in the usefulness of the 2.5GHz band and approximately 20-25% of the spectrum in a 2026-megahertz block remaining unused.
Such a result would not benefit the public interest, nor would it help the Commission in achieving their objective to “optimize the utilization of spectrum resources.”. Further information can be found in Carrier Networks.
