Segmentation is best path for lower 3 GHz band — Elaluf-Calderwood

Silvia Elaluf-Calderwood

There is an ongoing discussion about how best to use various bands of radio spectrum. In the case of spectrum in the lower 3 GHz band, the best use is more efficient use.

This critical band is globally harmonized for 5G wireless, but here it’s in the hands of the U.S. military. The military wants to keep this spectrum for legacy radar systems while the wireless industry needs more spectrum to meet record consumer demand.

The solution doesn’t have to be an and/or. To satisfy commercial wireless and military needs, the 3 GHz band should be segmented. Segmentation will allow the military to be compensated for retuning or decommissioning its obsolete equipment, and the U.S. will get critical mid-band spectrum in the pipeline for 5G. This is an all-around win – or at least it should be seen as one.

The U.S. government holds a whopping two-thirds of U.S. radio spectrum, with the military being the single largest holder. Today’s spectrum pipeline is empty, and the Department of Defense’s allies in Congress have adopted an obstructionist policy on spectrum assignments that led to the FCC’s auction authority expiring for the first time ever earlier this year. Yet for the U.S. to remain competitive, government held spectrum – such as a portion of the lower 3 GHz band – must be cleared for commercial licensed use.

Sharing vs. segmenting

Segmenting isn’t sharing. DoD is expected to release a preliminary proposal on “sharing” the spectrum. The details are yet unclear, but the key example to date of sharing involves the U.S. Navy and 150 MHz in the Citizens Broadband Radio Service (CBRS) 3.55-3.700 MHz band. The military low power requirements render this band unusable for 5G, and hence its value per unit is about half of that for the corresponding full power, exclusively licensed spectrum for 5G. Segmenting the band is the solution that can make this spectrum band work.

However, the enthusiasm for the lower 3 GHz handover is not embraced at the same pace by different departments of the DoD. Negotiations have taken place under the umbrella of the Partnering on Advanced and Holistic Spectrum Solution (PATHSS), a task group established by the National Spectrum Consortium to bring together DoD, interagency partners, industry and academia. DoD’s concern is the cost to decommission or retune radar military equipment. Historically, the lower 3 GHz spectrum was solely designated to DoD, but wireless advocates argue that access to this band is crucial to meet 5G demand. New technologies have emerged which could help DoD reconfigure its equipment and allow the spectrum transition with minimal disruption.

Additionally, new research shows that the large American military global footprint may demonstrate coexistence between 5G in this spectrum band with radar systems. Indeed, the U.S. military itself enjoys this very coexistence abroad with at least 10 key installations in the lower 3 GHz band including Station-Keeping Equipment (SKE), the Airborne Warning and Control System (AWACS), the shipborne AN/SPY-1/6 system, and ground-based radars like AN/TPQ-53.

National security

The debate on American spectrum policy is tense, but it does not need to be. The conflict is symptomatic of a spectrum management system where a spectrum user – such as the military – has elbowed the traditional spectrum regulators at the FCC and NTIA. It’s time for cooler heads to prevail and work toward freeing up spectrum for commercial use. This should be considered a national security interest with economic benefits, an imperative for the United States to maintain its edge against adversaries such as China, which is moving quickly toward 6G.

The real-world evidence shows incumbent U.S. military radar systems are successfully coexisting alongside full-power, lower 3 GHz 5G networks abroad without resorting to unproven dynamic sharing regimes. The U.S. should make the same accommodations domestically to benefit the nation’s economy.

Regardless of what happens in the lower 3 GHz, there is a shortage of available midband spectrum. While Congress and the FCC manage DoD’s concerns, policymakers should identify a healthy pipeline of additional spectrum for commercial use, including in the 4 GHz and 7/8 GHz bands. This will ensure that U.S. companies can maintain their global wireless innovation leadership and provide American consumers with the best mobile connectivity possible.

Silvia Elaluf-Calderwood, PhD is a telecommunications engineer, a lecturer at the Florida International University (FIU) and an associate fellow at the Jack D. Gordon Institute for Public Policy at FIU.

Industry Voices are opinion columns written by outside contributors—often industry experts or analysts—who are invited to the conversation by Fierce Wireless staff. They do not necessarily represent the opinions of Fierce Wireless.