An energy efficiency scheduling scheme for cognitive radio networks

In this paper, we focus on operation-modes scheduling in cognitive radio networks (CRNs), in which a cognitive base-station assigns available frequencies to secondary users (SUs). This is formally stated as the problem of maximizing the energy efficiency (defined as the ratio of the total rate of SUs to total energy consumption), which is a nonlinear integer programming, and then present a polynomial time heuristic algorithm to address it. In contrast to existing schemes, in our proposed scheme, the SUs, who do not have any data to transmit or no frequency is assigned to them, transit into the sleep-mode. This would significantly reduce the energy consumption. Furthermore, since SUs consume significant energy during the channel switching, depending on the difference between frequencies of current and new assigned frequencies (i.e, channel switching bandwidth), in our proposed scheme, a new frequency is assigned to SUs if it is at the vicinity of the current frequency. This results in decreased channel switching bandwidth for SUs (which in turn results in decreased energy consumption) and lowered computational overhead. Our simulation results indicate that our algorithm outperforms existing scheduling algorithms for CRNs in terms of energy consumption and the channel switching bandwidth for SUs, without reducing the throughput.