Energy efficiency in cooperative cognitive wireless networks

In this work, we analyze the energy efficiency of a wireless link, while considering spectrum sharing, and cooperation. Insightful results are obtained using a simple network model, with two source-destination pairs. We assume that one source-destination pair has higher priority to use the spectrum, while the other pair is allowed to access the channel under power constraints. The proposed cooperative scheme, named Cooperative Underlay, allows simultaneous transmissions of both high- and low-priority users, and the low-priority user may be requested to act as a relay. We investigate the trade-off between energy efficiency and throughput for the high-priority user, with and without cooperation, and demonstrate the improvement in energy efficiency due to the use of cooperation. Additionally, we study the case that the relay node can transmit and receive simultaneously, and discuss the effect of self-interference in the energy efficiency, for different degrees of accuracy in interference cancellation.