Wireless communications continue to gain in popularity, but wireless communications are constrained due to a lack of available, interference free spectrum that may be used for reliable communications within a geographic area. A leading cause of the lack of available spectrum is the manner in which spectrum has been historically allocated. Since the early days of radio and telegraph transmission, the available radio spectrum in the United States and other jurisdictions has been carved up by regulatory agencies into discrete bands or channels. Use of spectrum bands has been restricted to certain types of users or certain licensees. Because many of these bands were allocated at a time when technology was very primitive and data rate requirements were very low, the bands were not allocated in an efficient manner for current demands.
The US President's Council of Advisors on Science and Technology (PCAST) has indicated that traditional practice of clearing federal spectrum by relocating federal users and subsequently auctioning the spectrum for commercial use is impractical and unsustainable. The costs and the timelines involved in relocating Federal users and equipment are daunting, and in some cases, simply impractical. At the same time, there are various Federal spectrum bands that are currently used in a sporadic and low duty-cycle manner, both geographically and in time. PCAST recognizes the need to implement a Spectrum Access System (SAS) that securely facilitates commercializing Federal spectrum without impeding Federal users, and also provide for temporary or permanent revocation of the commercial rights and pre-emption in favor of Federal Users.