Will rule the airwaves: A DARPA grand challenge seeks autonomous radios to manage the wireless spectrum

IN THE EARLY 2000S, BLUETOOTH ALMOST MET AN UNTIMELY END. The first Bluetooth devices struggled to avoid interfering with Wi-Fi routers, a higher-powered, more-established cohort on the radio spectrum, with which Bluetooth devices shared frequencies. Bluetooth engineers eventually modified their standard—and saved their wireless tech from early extinction—by developing frequency-hopping techniques for Bluetooth devices, which shifted operation to unoccupied bands upon detecting Wi-Fi signals. • Frequency hopping is just one way to avoid interference, a problem that has plagued radio since its beginning. Long ago, regulators learned to manage spectrum so that in the emerging wireless ecosystem, different radio users were allocated different frequencies for their exclusive use. While this practice avoids the challenges of detecting transmissions and shifting frequencies on the fly, it makes very inefficient use of spectrum, as portions lay fallow. • Today, demand is soaring for the finite resource of radio spectrum. Over the last several years, wireless data transmission has grown by roughly 50 percent per year, driven largely by people streaming videos and scrolling through social media on their smart-phones. To meet this demand, we must allocate spectrum as efficiently as possible. Increasingly, that means that wireless technologies cannot have exclusive frequencies, but rather must share available spectrum. Frequency hopping, which Bluetooth uses, will be part of the solution, but to cope with the surging demand we are going to have to go far beyond it.