NCTA and one of its biggest members, Charter, have asked the FCC to clarify that new wireless licensees in the C-Band (occupying 3.7 GHz-3.98) can't interfere with Citizens Broadband Radio Services (CBRS) service in the adjacent 3.5 GHz band. 

Related: Divided FCC Votes to Proceed with C-Band Auction

Charter petitioned the FCC for that "clarification," saying under the technical rules the FCC adopted for the C-Band, such harmful interference is "highly likely," and NCTA-the Internet & Television Association filed comments in support of that position. 

The CBRS license auction is scheduled to begin July 23. The C-Band auction is scheduled to begin in December.

NCTA and Charter concede the FCC took steps to try and ensure that the wireless carriers who will be getting the lower portion of the C-Band at auction can peacefully co-exist with CBRS, the commission " stopped short of explicitly stating that all CBRS operations are entitled to protection from harmful interference from adjacent operations in the 3.7-3.98 GHz band," NCTA said in its comments. 

"In particular," said NCTA, that is "because CBRS operations and new 3.7 GHz Service Licensees will use the same spectrum for both downlink and uplink operations...it is possible that downlink operations in one band will occur at the same time as uplink operations in the adjacent band. If a higher-powered C-Band base station using TDD is transmitting while a nearby CBRS base station is trying to receive, the CBRS base station will suffer blocking interference—that is, it will be overwhelmed, and will not be able to hear the user equipment across the entire CBRS band, leading to "coverage loss and throughput reduction” for licensees in the CBRS band. 

NCTA joined Charter in asking the FCC to make that clarification by making wireless carriers hwo get C-Band licenses to "work in good faith" with CBRS operators to resolve any harmful interference. 

The FCC voted 3-1 along party lines Oct. 23, 2018, to change the rules on licenses for the 3.5 GHz (CBRS) band to make it more attractive for providers of 5G, which includes cable ops looking to up their mobile broadband game. The change was billed as a way to spur investment in the band and promote more efficient use, including for 5G.

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