Full-Duplex Assisted LTE-U/Wifi Coexisting Networks in Unlicensed Spectrum

With the boosting of mobile services, licensed spectrum for wireless networks becomes more and more crowded. To explore new spectrum for cellular users, more and more mobile operators are interested in deploying the long-term evolution in unlicensed spectrum (LTE-U), which utilizes the unlicensed spectrum occupied by Wi-Fi. Because the medium access control (MAC) protocols of LTE-U and Wi-Fi are different, the synchronization between the LTE-U users and Wi-Fi users cannot be guaranteed for LTE-U/Wi-Fi coexisting networks, thus resulting in the throughput deterioration of LTE-U and Wi-Fi users. In this paper, we propose the full-duplex two-threshold spectrum sensing (FDTT-SS) algorithm for LTE-U/Wi-Fi coexisting networks, where both LTE-U and Wi-Fi users adopt the listen-before-talk mechanism, with adaptive priority for LTE-U. Using our proposed FDTT-SS scheme, the LTE-U/Wi-Fi average transmission time can be guaranteed by avoiding the collisions among LTE-U/Wi-Fi users. We further develop the FDTT-MAC protocol that can significantly increase the sum throughput while guaranteeing the fairness for LTE-U/Wi-Fi coexisting networks. Numerical results show that our proposed fair FDTT-MAC protocol can improve the channel utilization in unlicensed spectrum and can increase the throughput of Wi-Fi without greatly degrading the throughput of LTE-U for coexisting wireless networks as compared with existing schemes.