Energy-Efficient Spectrum Leasing in Cognitive Relay Networks

In this paper, we propose an energy-efficient resource allocation algorithm to minimize the total average transmission power of secondary users (SUs) in cognitive relay networks. Each SU in cognitive relay networks can choose direct transmission or cooperative transmission with the help of relay nodes (RNs). The primary users (PUs) may lease the licensed spectrum for a fraction of time to SUs for some remuneration. So the SUs adopt time-division multiple-access (TDMA) to access the licensed spectrum. For energy efficiency, we jointly consider the time slot scheduling and transmission strategy selection (i.e. direct transmission or cooperative transmission) problem. Numerical results indicate that the transmission power consumption indeed decreases due to the cooperative diversity.