The More We Share, the More We Have: Spectrum Sharing as the New Frontier

n Richard Feynman’s famous essay, There’s Plenty of Room at the Bottom, he pointed out that innovation in physics had a great frontier to explore at smaller and smaller scales of matter. In communications, the frontier has been defined not by what has been getting smaller, but rather by what has been getting shorter; that is, not measurements of atoms, but rather of wavelengths. In the last century, the slice of the electromagnetic spectrum that went from 100 meters to 10 meters (or in terms of frequency, from 3 MHz to 30 MHz) was often referred to as “Shortwave” radio. Well, that “short” proved not to be short enough. Since then, the utilized wavelengths have continued to get shorter and shorter as the demand for more radio communications capacity has continued to grow. Today, the frontier of exploitation of the radio spectrum is in what is termed centimeter spectrum, that is, wavelengths in the band from 100 to 10 millimeters, and millimeter spectrum, in the band from 10 to 1 millimeter. Shorter than this is still possible, but then we get into the far infrared and our terminology shifts from talking about radio to talking about light.