Research On Coexistence Mechanism Of LTE-U And WiFi In Unlicensed Bands

The explosion of mobile wireless communications equipments leds to increasingly scarce spectrum resource,and high requirement of cellular mobile communication technologies.LTE-U technology has arised much attention in both academia and industry area as one of the key technologies for next-generation cellular mobile communication systems.LTE-U technology,which could explore large potential capacities from the unlicensed spectrum for mobile communication systems,can increase the spectrum utilization of unlicensed bands.However,radio access technologies of WiFi which using the unlicensed band is different from that of LTE-U.If behaviors of LTE-U system are not limited,the transmission performance of WiFi will be seriously affected.Therefore,the problem of harmonious coexistence between LTE-U and WiFi system needs to be solved.This article focuses on the resource allocation issues of LTE-U and WiFi system under single operator and multi-operators' scenarios.Through in-depth research on efficient resource allocation,it will achieve harmonious coexistence with WiFi system and result in performance improvement.In single-operator scenario,in order to protect WiFi from serious interference by LTE-U,and guarantee the service quality of LTE-U for delay sensitive services in the unlicensed spectrum,a LTE-U and WiFi coexistence scheme based on reinforcement learning algorithm is proposed.Firstly,the proposed scheme puts forward a dynamic LTE-U frame structure based on the blank subframe scheme.The frame structure can be dynamically adjusted,thus the proportion of blank subframes and transmission time intervals in a LTE-U frame is changing.Secondly,a reinforcement learning algorithm is introduced to adjust LTE-U frames according to the throughput requirements of LTE-U and WiFi to maximize LTE-U throughput satisfaction degree,delay satisfaction degree and WiFi spectrum utilization.Finally,the spectrum utilization of LTE-U and WiFi can be maximized.In multi-operators scenario,in order to ensure the fairness of resource allocation among multiple operators,while guaranteeing the transmission performance of WiFi users and the transmission quality of delay-sensitive LTE-U users,a resource scheduling algorithm based on delay priority is proposed.Firstly,the proposed algorithm provides a subchannel allocation scheme based on user delay priority.Secondly,the proposed algorithm considers the transmission rate of users,the cost of interference and delay impact on the network performance,and maximizes the spectrum utility of the network under the delay requirements of delay sensitive LTE-U users.