Research On Optimal Coexistence Of IEEE 802.11 And 5G In Unlicensed Band

With the continuous development and application of Internet of Things technology,the massive growth of different types of wireless network terminals lead to that the existing spectrum resources of licensed band cannot support the outbreak of mobile data traffic.Therefore,it is necessary to use the unlicensed band for alleviating the current contradiction from spectrum resource scarcity.In the unlicensed band,multiple wireless networks coexist in the same space.How to integrate different access mechanisms and effectively avoid interference is a challenging problem.Through optimal contention access mechanisms,IEEE 802.11 and 5G NR can coexist in the unlicensed band.However,most of the current researches on the coexistence only focus on the overall performance improvement while they ignore the fairness between IEEE 802.11 and 5G NR.Therefore,this thesis considers the fairness coexistence between Wi-Fi and Wi Gig in IEEE 802.11 and 5G NR,respectively.The main research contents are as follows:(1)The optimal coexistence between Wi-Fi and 5G NR networks is achieved by contention access mechanism with frame structure adjustment and bandwidth part switching technique.Firstly,the throughput models of Wi-Fi system,5G NR system and coexisting system in unlicensed band are analyzed,respectively.Thereinto,through adjusting the frame structure of NR in the unlicensed band,the throughput of users can be improved.Then,the bandwidth part technique is used to flexibly switch spectrum resources,and the length of the spectrum switch timer is dynamically adjusted due to the collision probability of users,which can effectively decrease the delay.Finally,the joint optimal throughput and delay of 5G NR users in coexistence network is formulated.This nonlinear optimization problem is linearized through analyzing,and then solved for its optimal solution.Simulation results show that the proposed scheme can effectively improve the throughput of 5G NR users and decrease the delay while it guarantees the minimum throughput limit of Wi-Fi users.(2)The optimal coexistence between Wi Gig and 5G NR networks is achieved by omni-directional listen-before-talk and directional listen-before-talk access techniques.Firstly,the throughput models of Wi Gig system with omni-directional listen-before-talk,5G NR system with omni-directional listen-before-talk and 5G NR system with directional listen-before-talk in millimeter-wave band are analyzed.Then,the optimal problem is formulated to achieve the fairness between total throughput with omni-directional listen-before-talk and total throughput with directional listen-before-talk in the coexistence network.Then,the nonlinear terms in the problem are transformed into the linear ones by reformulation-linearization technique and piecewise linearization.Finally,the Long Short-Term Memory network can be used to predict the total throughput of coexistence network for more users.Simulation results show that the proposed scheme achieves the fairness between Wi Gig and 5G NR networks,and can effectively predict the total throughput of more users.