Integer Linear Programming Formulations for Cognitive Radio Resource Allocation

Due to the significantly increased demand for wireless connectivity in recent years, the natural radio spectrum has become a very important and scarce resource. Since the utilization of the licensed spectrum may be very low, a major challenge in wireless communications is the efficient utilization of the resulting spectrum holes for secondary users (SUs). In this letter, we consider an offline resource allocation problem with user-specific parameters: find the best possible utilization of the given spectrum opportunities that can be achieved by satisfying the bandwidth demands of SUs. As a main contribution, we present two new modeling formulations—differing in terms of performance and complexity—that can cope with a particular additional constraint arising from hardware limitations. Based on numerical simulations, their computational behavior is investigated in more detail, and both approaches are shown to provide (much) better results than a state-of-the-art greedy strategy.