Developing Spectrum Sharing Technique and Demonstrating its Application

Existing radio communications systems rely on the formal maintenance of a separation of their signals in the frequency domain (RF spectrum). Currently these systems rely on administrative measures to assign frequencies to users based on maintain therequired separation in frequency and in distance. Because the results of potential interference are likely to result in a significant disruption of communications for affected users, the administrators of the frequency allocation systems tend tooverprotect users by conservatively allocating users to frequencies. This results in wasted RF spectrum, especially in cases where the users are itinerant. Even in dense RF environments, much of the spectrum is unused most of the time. This system willallow users to share spectrum in time and frequency. The system will listen for quiet portions of the spectrum and assign a user to that frequency which has the least probability of being used during the course of a transmission. This spectrum sharingsystem will mine the ambient RF spectrum for unused bandwidth and dynamically assign it for communications. This is a revolutionary development in the use of the limited natural resource, which is only possible through the use of advanced computing anddigital signal processing technology.Currently Army units must carefully coordinate RF frequencies to minute detail when an operation is planned for an area. This coordination must include not only Army and US Military users, but all other users, militaryand civilian, enemy and allied within an area. Not all of these entities are cooperative, so much work must be done on the basis of assumptions and conservative planning. Even with this attention to detail, units may still run into interference problemsonce they are deployed, and this can reduce the operational effectiveness of their communications. This proposed system will allow units to deploy into the field with minimal prior frequency coordination and automatically identify and select unusedfrequencies for use by their communications systems. Ultimately this technology is expected to transition to the civilian sector to improve the management and utilization of the RF spectrum for commercial users, which is currently a tremendous economicand technical problem not only in the United States, but also worldwide. The potential applications of this technology are enormous and the effect on society and our military and economic security will be substantial.