Has DOD hit its limit on sharing spectrum?

The Defense Advanced Research Projects Agency unveiled a $2 million dynamic spectrum sharing competition on March 23 aimed at helping military and commercial users share increasingly cramped wireless communications bandwidth on the fly.

The news might eventually give Defense Department CIO Terry Halvorsen a degree of relief, but in the meantime, the military is being increasingly pinched in the effort to move potentially lucrative government-owned spectrum to commercial providers.

During a March 22 hearing held by the House Armed Services Committee's Emerging Threats and Capabilities Subcommittee, Halvorsen told lawmakers he was concerned that commercial providers' appetite for spectrum could outstrip the military's efforts to share -- and in some cases vacate -- its bandwidth.

"What I worry about is that the private-sector demand will exceed our ability to keep pace and that we could, if we're not careful, put some national systems at risk," he said. "In this business, I get that time is valuable, but there is a physical limitation to how fast we can move DOD systems...to share spectrum or get out of some spectrum."

Halvorsen said that although spectrum sharing and other efforts to open more spectrum have gone well to date, "I hear from industry that we have to go faster. I don't know if we can go much faster today on how we look at spectrum and make the decision on where we can get out and how we would share."

DARPA's Spectrum Collaboration Challenge (SC2), unveiled at a commercial wireless convention in Las Vegas, will explore how the military and commercial providers might more effectively and efficiently share spectrum.

SC2 is a three-year test beginning in 2017 in which teams will compete to see which one can most effectively use radio technology to collaborate with other kinds of radios and optimize spectrum on the fly. The goal is to infuse radios with machine-learning capabilities so they can collectively develop strategies to optimize spectrum in ways static allocation methods can’t.

"DARPA challenges have traditionally rewarded teams that dominate their competitors, but when it comes to making the most of the electromagnetic spectrum, the team that shares most intelligently is going to win," SC2 Program Manager Paul Tilghman said in a statement released on March 23. "We want to radically accelerate the development of machine-learning technologies and strategies that will allow on-the-fly sharing of spectrum at machine timescales."

To support the competition, DARPA plans to build the largest-of-its-kind wireless test bed. Afterward, the facility will become a center for evaluating spectrum-sharing strategies, tactics and algorithms for next-generation radio systems. Researchers will be able to remotely conduct large-scale experiments in user-defined, high-density radio frequency environments that can replicate busy city neighborhoods or battlefield environments.