Queue Performance of Energy Harvesting Cognitive Radio Sensor Networks With Cooperative Spectrum Sharing

In this paper, we study the queue performance for energy-harvesting cognitive radio sensor networks (EHCRSNs) where the cooperation between the primary user and the sensor is applied. In EHCRSNs, energy harvesting provides a continual energy source for the power-limited sensor, while cognitive radio enables the sensor access the licensed spectrum, which can mitigate the spectrum-scarcity problem of the wireless sensor network. First, with the help of queue theory, we study the queue performance of the EHCRSN and the primary user when the sensor does not assist the service of the primary user. Through analyzing the dynamic energy harvesting and consuming process, we obtain the effect of energy harvesting on the queue performance of the EHCRSN. Then, we further analyze the queue performance when the cooperation between the sensor and the primary user is adopted. Through comparing the result, we observe the effect of energy harvesting on both the performance of the sensor and the primary user and find out the condition under which the cooperation can improve the system performance. The numerical results in different situations further demonstrate the relation between the queue performance and the energy harvesting rate and verify the analysis and the conclusion that the cooperation can improve queue performance under certain conditions. These results are very meaningful for the quality-of-service guarantee in EHCRSNs.