Upper C-Band Flexible Use (3.98–4.2 GHz)

Current understanding

The FCC is opening 160 MHz of Upper C-band spectrum (3.98–4.2 GHz) for terrestrial flexible wireless (5G) use via competitive auction targeted for July 2027, extending the framework previously applied to the Lower C-band (3.7–3.98 GHz). New licensees will be required to fund the migration of incumbent Fixed Satellite Service (FSS) operations and to provide rebates for aircraft radio-altimeter retrofits to preserve aviation coexistence. The action is a final rule implementing a statutory auction mandate, with tighter performance obligations than the Lower C-band proceeding.

Evidence log

• 2026-08-03 — Auction of Flexible-Use Licenses in the Upper C-Band for Next-Generation Wireless Services Scheduled for April 27, 2027; Comment Sought on Competitive Bidding Procedures for Auction 115: 2027 Auction 115 announced for April 27, 2027 covering 3,248 flexible-use licenses in the 3.98–4.14 GHz upper C-band; FCC seeks comment on competitive bidding procedures (proposed rule). (novelty: 2)
• 2026-07-31 — Upper C-Band (3.98-4.2 GHz); Expanding Flexible Use of the 3.7 to 4.2 GHz Band: cross-connection with 5g-c-band-aviation-interference: Upper C-band buildout moves 5G operations directly adjacent to the 4.2–4.4 GHz radio-altimeter band; the rulemaking incorporates altimeter retrofit rebates as the primary aviation mitigation. (novelty: 3)

Open questions

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