Dynamic sharing of radio spectrum: a brief history

This article reviews the various approaches to dynamic sharing of spectrum that have been employed over time, identifies the costs and benefits of these approaches, and offers conclusions on the characteristics of radio services that benefit most from the use of dynamic sharing. Dynamic sharing is a powerful tool for spectrum management. It offers the opportunity for substantial efficiency gains. Modern technology, especially embedded computer controllers, makes this spectrum management technique much more viable than it was in the past. Dynamic spectrum sharing will be a valuable tool in the era of low-cost radios. It works best when the time scale of fluctuations in the use of the radio channel are small relative to license terms-that is it works better with telephone calls than with broadcast signals