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Historically, the Federal Communication Commission (FCC) has focused on the Command and Control regime for regulating spectrum in which the FCC allocates frequencies for specific use with power limitations, service restrictions and build-out requirements. This regulatory regime has led to an dichotomy where on one hand spectrum is a scarce resource with the same frequency being allocated multiple times, while on the other hand actual measurements show sub 1% utilization.
One of the main reasons for the disconnect between allocation and use is that the spatial and time scales of regulation do not match the spatial and time scale of actual use. The spatial scale of the current regulation regime is countries or continents. Similarly, the time scale of regulation is years or decades. The FCC's method for enforcing this regime is to certify individual radios. Use on the other hand occurs spatially on the scale of coffee houses and cities and temporally on the scale of seconds/milli seconds.
One of the ways to bridge this gap is Opportunistic Spectrum sharing. Under such a regime, secondary users are allowed to operate in frequency bands without the consent of the Primary users (users that have been allocated the spectrum by the FCC) of these bands, as long as they do not interfere with the Primary user. The FCC has already legalized this type of sharing in the 5.4GHz band (5.470GHz to 5.725GHz). Devices in this spectrum range have to periodically sense for the presence of military radars.
The onus for sensing the Primary and backing off if the Primary reappears is on the secondary radio. A single radio cannot perform this job in a reliable manner without added costs. However in this case, 'strength in numbers' can play a vital role with multiple radios contributing towards a robust decision. The need for many radios raises multiple issues which form the main theme of my research. Moving to multiple radios also has implications on the current regulatory regimes. We need to move towards a regulatory regime where we regulate provable collective behavior rather than individual radios.
A comprehensive description of this research effect can be found here.
Protocol Implementation Design Flow