Rysavy: CBRS Is a Subpar Way to Share Spectrum
The citizens broadband radio service (CBRS) band uses technology that's “simplistic” and “at this point …obsolete,” so it shouldn’t be considered the best model for sharing, Rysavy Research President Peter Rysavy said. Rysavy spoke as part of an American Enterprise Institute series on spectrum, posted Monday. He also argued that 7/8 GHz spectrum should be allocated for full-power licensed use. CBRS hasn't been very widely used because “it involves coordination between incumbents and secondary users,” and “there’s a very complicated environmental sensing capability that secondary users must rely on to detect” DOD operations.
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CBRS was also “specified to operate at very low power levels, which means that anyone wanting to provide coverage over a wide area has to deploy five to seven times as many cell sites as a cellular network running at full power,” Rysavy said: “It’s very simplistic because it’s either on or off, meaning that if the government needs to use those frequencies for a radar system, the network has to stop using those frequencies entirely.”
One proposal is an approach called active radio access network technology, Rysavy said. It “relies on the intelligence in today’s networks with beamforming and rapidly adapting to the environment,” he said: “With active RAN, the network doesn’t have to stop using those frequencies entirely; it can reconfigure itself to not direct radio energy in a way that would interfere with the military systems.” He called for flexible policies that accommodate various power levels.
Rysavy noted that while Wi-Fi and licensed spectrum are important to carriers, the 6 GHz band is fully allocated in the U.S. for Wi-Fi, making 7/8 GHz more important for them. The U.S. “has a real imbalance between unlicensed and licensed spectrum in mid-band frequencies,” he said: “There’s more than three times as much spectrum right now available for Wi-Fi as there is for mobile networks. I think that ratio just does not make sense.”