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Gray-Space Spectrum Sharing with Cellular Systems and Radars, and Policy Implications

Abstract This dissertation considers gray-space primary-secondary spectrum sharing, in which secondary devices are allowed to transmit when primary transmissions are strong enough that additional interference is tolerable. Various novel sharing mechanisms are proposed for two different types of primary system: cellular systems, and rotating radars. Both cases when primary and secondary systems cooperate (cooperative sharing), and when they do not (coexistent sharing) are considered. Even in the scenario where radars are densely packed, a secondary transmitter can get almost 1.2 bps/Hz on average, when 5% of the transmitters are competing for the shared spectrum. One also shows the potential of sharing models in which a secondary system has information about a primary system, but does not cooperate in real time. It is found that even with fluctuations and interruptions in secondary transmissions while radars rotate, the shared spectrum could be used efficiently for applications that generate much of the traffic on mobile Internet, but not for real-time. For sharing with cellular systems, the efficiency of cooperative and coexistent sharing is compared. When both achievable secondary transmissions and primary power consumption are of concern, coexistent sharing is found to be as effective as cooperative sharing.