Dynamic Spectrum Leasing (DSL): A New Paradigm for Spectrum Sharing in Cognitive Radio Networks

Recently [1] proposed a dynamic spectrum leasing (DSL) paradigm for dynamic spectrum access in cognitive radio networks. In this paper, we formalize this concept by developing a more general game theoretic framework for the dynamic spectrum leasing and by carefully identifying requirements for the coexistence of primary and secondary systems via spectrum leasing. In contrast to hierarchical spectrum access, spectrum owners in proposed dynamic spectrum leasing networks, denoted as primary users, dynamically adjust the amount of secondary interference they are willing to tolerate in response to the demand from secondary transmitters. The secondary transmitters in turn attempt to achieve maximum possible throughput, or other suitably defined reward, opportunistically while not violating the interference limit set by the primary users. The new game-theoretic model, however, allows the secondary users to encourage the spectrum owners to push the interference cap upward based on demand. We have proposed a general structure for utility functions of primary users and the secondary users that allows the primary users to control the price and demand for spectrum access based on their required Quality-ofService (QoS). We establish that with these utility functions the DSL game has a unique Nash equilibrium to which the bestresponse adaptation finally converges. Moreover, it is shown that the proposed coexistence and best-response adaptations can be achieved without having any significant interaction between the two systems. In fact, it is shown that the only requirement is that the primary system periodically broadcasts two parameter values. We use several examples to illustrate the system behavior at the equilibrium, and use the performance at the equilibrium to identify suitable system design parameters.