Adaptive Spectrum Sharing for Half-Duplex and Full-Duplex Cognitive Radios: From the Energy Efficiency Perspective
Dongming Li, Julian Cheng, Victor C. M. Leung · IEEE Transactions on Communications · 2018
In traditional cognitive radio networks (CRNs), the interweave, underlay, overlay, and hybrid spectrum sharing schemes are only spectrum-efficient in specific circumstances. In order to improve the robustness of spectrum sharing schemes in a dynamic traffic environment from the perspective of energy efficiency, adaptive spectrum sharing schemes are proposed in this paper for both half-duplex (HD) and full-duplex (FD) CRNs. The proposed schemes allow the secondary users to adaptively access the licensed spectrum, provided that PUs' traffic arrives at a low rate and energy efficiency gains exist. Based on the intermittent nature of the arrival and departure processes for PUs' traffic, closed-form expressions of energy efficiency for the traditional interweave, underlay, overlay, hybrid and the proposed schemes are investigated for both HD and FD modes. By defining energy efficiency loss, the impacts of the spectrum sensing error and channel estimation error are analyzed to evaluate the energy efficiency of the proposed schemes. Theoretical analysis shows that the proposed adaptive spectrum sharing schemes improve the minimum energy efficiency in HD mode and improve the overall energy efficiency in FD mode. The numerical results validate the energy efficiency improvements and the robustness of the proposed schemes.