How much C-band spectrum was reallocated for 5G in the US?

The FCC reallocated 280 MHz of the 3.7-4.2 GHz satellite downlink band for 5G terrestrial mobile use in its February 2020 C-Band Order. The 3.7-3.98 GHz segment was auctioned in Auction 107 (December 2020-January 2021) for $81.2 billion, making it the most expensive spectrum auction in history. Satellite services were transitioned to the upper 200 MHz (3.98-4.2 GHz), with a 20 MHz guard band at 3.98-4.0 GHz. Incumbent satellite operators received $9.7 billion in accelerated relocation payments for clearing the spectrum ahead of schedule.

Do all countries follow the same C-band allocation?

No. The ITU divides the world into three regions with different allocation tables. Region 1 (Europe, Africa, Middle East) and Region 3 (Asia-Pacific) maintain the full 3.4-4.2 GHz for satellite downlinks, though many countries within these regions are independently reallocating portions for 5G (notably 3.4-3.8 GHz in Europe under CEPT ECC Decision 11-06). Region 2 (Americas) has pursued the most aggressive terrestrial reallocation, with the US clearing 3.7-3.98 GHz and Brazil clearing 3.7-3.8 GHz. In tropical countries where C-band satellite is critical for reliable television and internet distribution, regulators have been slower to reallocate, preserving the full downlink band.

What interference protections exist between 5G and C-band satellite?

The FCC mandates several coexistence measures: earth station operators must install bandpass filters with minimum 40 dB rejection at the new 3.98 GHz band edge to block 5G out-of-band emissions, 5G base stations within a protection zone around registered earth stations must limit EIRP and use beamforming to steer nulls toward the satellite antennas, and a 20 MHz guard band separates the 5G allocation (3.7-3.98 GHz) from the remaining satellite downlink (4.0-4.2 GHz). The Satellite Industry Association estimates that approximately 3,400 earth stations in the US required filter upgrades at an average cost of $10,000-50,000 per site.

What is C-Band Satellite Allocation? | 3.7-4.2 GHz Spectrum Rules

Definition & Regulatory Context

C-band satellite allocation refers to the international and national regulatory frameworks that assign the 3.7-4.2 GHz (downlink) and 5.925-6.425 GHz (uplink) frequency bands to the Fixed Satellite Service (FSS) under the ITU Radio Regulations. These allocations, established at the 1971 World Administrative Radio Conference (WARC-71), have governed the deployment of thousands of geostationary satellite transponders and tens of thousands of earth station antennas worldwide.

The allocation landscape changed dramatically in 2020 when the FCC reallocated the lower 280 MHz (3.7-3.98 GHz) of the US C-band downlink to terrestrial 5G NR mobile broadband, raising $81.2 billion in Auction 107. This reallocation forced satellite operators to compress their services into the remaining 200 MHz (3.98-4.2 GHz with a 20 MHz guard band) and triggered a global debate about balancing the economic value of 5G mobile spectrum against the critical role of C-band satellite communications in tropical regions where rain fade makes higher-frequency bands unreliable.

Key Specifications

ITU FSS Allocation (worldwide):

Downlink: 3.7-4.2 GHz (500 MHz) | Uplink: 5.925-6.425 GHz (500 MHz)

FCC Post-Auction (US only):

5G Mobile: 3.7-3.98 GHz (280 MHz) | Guard: 3.98-4.0 GHz (20 MHz) | Satellite: 4.0-4.2 GHz (200 MHz)

Filter Rejection Requirement:

Earth station filter: ≥ 40 dB rejection at 3.98 GHz band edge

Roll-off rate: ≥ 30 dB/MHz in transition band

Regional Allocation Comparison

Region/Country	5G Allocation	Remaining Satellite	Status
United States	3.7-3.98 GHz	4.0-4.2 GHz	Deployed (2022+)
Europe (CEPT)	3.4-3.8 GHz	3.8-4.2 GHz	Partially deployed
Japan	3.6-4.1 GHz	4.1-4.2 GHz	Active
Brazil	3.7-3.8 GHz	3.8-4.2 GHz	Deployed (2022)
India	3.3-3.67 GHz	3.7-4.2 GHz (full)	Satellite preserved
Africa (most)	None	3.7-4.2 GHz (full)	Satellite preserved

Practical Application

A US cable television headend receiving 20 C-band satellite channels on a 4.5 m antenna must install interference mitigation after the 5G deployment on 3.7-3.98 GHz. The operator installs a waveguide bandpass filter centered at 4.1 GHz with 200 MHz passband (4.0-4.2 GHz) providing 55 dB rejection at 3.98 GHz and 70 dB at 3.9 GHz. The filter insertion loss of 0.3 dB marginally reduces the system G/T from 24.5 to 24.2 dB/K. The operator also retunes the LNB local oscillator and reprograms the integrated receiver/decoders to lock onto the transponders that were migrated from the lower 280 MHz to the upper portion of the band. Total cost: $35,000 for the filter, LNB replacement, and repointing, partially offset by FCC relocation payments.

Frequently Asked Questions

How much C-band was reallocated for 5G in the US?

280 MHz (3.7-3.98 GHz) auctioned for $81.2 billion. Satellite compressed to 200 MHz (4.0-4.2 GHz) with a 20 MHz guard band. Operators received $9.7 billion in accelerated clearing payments.

Do all countries follow the same allocation?

No. ITU Regions differ: US cleared 280 MHz, Europe 400 MHz (3.4-3.8 GHz), India preserved the full 3.7-4.2 GHz for satellite. Tropical countries tend to preserve C-band satellite for rain-fade reliability.

What protects satellite from 5G interference?

Earth station filters with 40+ dB rejection at 3.98 GHz, a 20 MHz guard band, 5G base station EIRP limits near earth stations, and beamforming null-steering. ~3,400 US earth stations required filter upgrades at $10K-50K each.

C-Band Satellite Allocation