QoS constrained secondary spectrum sharing

Spectrum is one of the most precious radio resource. With the increasing demand for wireless communication, efficiently using the spectrum resource has become an essential issue. With the Federal Communications Commission´s (FCC) spectrum policy reform, secondary spectrum sharing has become a viable option. One of the policy reforms introduces the concept of an interference temperature-the total allowable interference in a spectral band. This means that secondary users can use different transmit powers as long as the sum of these power is less than the interference threshold. In this paper, we study the quality of service (QoS) issue in secondary spectrum sharing subject to an interference temperature constraint. A non-linear optimization problem with the objective to maximize the total transmitting rate of the secondary users is formulated. The non-linear optimization is solved efficiently using geometric programming techniques. We also propose a joint coordination and power control (JCPC) algorithm with the objective to maximize the secondary system capacity. JCPC is a distributed algorithm and requires only local feedback information. This algorithm is proved to converge to the Nash equilibrium solution