Radio Resource Optimization Of Lte In Unlicensed Frequency Bands Based On Service Classification

The vigorous development of the mobile Internet has brought about a sharp increase in the number of mobile smart devices,and the shortage of spectrum resources has become a major problem that needs to be solved urgently.Faced with such a huge amount of equipment access and traffic,how to use limited spectrum resources and emerging technologies to provide more reliable services for mobile users is an important research direction in the field of mobile communications.With the official commercial use of 5G(5th Generation)and the continuous in-depth research of 6G,the academic community has proposed two technologies to solve the shortage of spectrum resources:LTE-U technology and D2D(Device-to-Device)technology.LTE-U is a technology that uses the LTE protocol standard to communicate on the Wi Fi frequency band.After LTE is introduced into the free public Wi Fi frequency band,cellular users can use the resources of the unlicensed frequency band to realize data interaction,thereby improving the system spectrum utilization purposes.However,the services of LTE are different from services of Wi Fi networks.In LTE,there are real-time services that are sensitive to delay,such as voice and video services,and the delay must be guaranteed for such services.D2D was introduced in LTE Release 12.The core is to improve the spectrum utilization of LTE system through direct communication between devices and reduce the load of base stations.At the same time,due to the continuous maturity of autonomous driving technology,D2D technology has begun to be widely used in the field of car networking A V2V(Vehicle-to-Vehicle)technology that can realize direct communication between vehicles is formed.Compared with D2D technology,V2V communication technology also faces the problem of inter-user interference caused by vehicle users reusing the spectrum resources of cellular users.This problem can be solved by means of power control.Although the introduction of emerging technologies can improve system performance,it poses new challenges to issues such as delay assurance and interference management.This paper mainly studies how to realize the optimization scheme of LTE system delay in unlicensed frequency band,and the power control problem of V2V communication.Aiming at the problem of LTE system delay optimization in unlicensed frequency bands,this paper first calculates the transmission probability and collision probability of Wi Fi and LTE-U respectively,and then analyzes the MAC delay probability distribution of real-time services in LTEU.At the same time,a scheme that can guarantee the real-time service MAC delay in unlicensed band LTE is proposed,and the relationship between the delay and the contention window size is given.The solution is to divide the service types in LTE-U into ordinary services and real-time services in the coexistence system of LTE-U and Wi Fi.Common services have lower requirements for network transmission rates,such as browsing web pages,and this type of services is performing a back-off process,the contention window is generated by the classical binary exponential backoff algorithm to ensure coexistence with Wi Fi.For real-time services,services have higher rate requirements,and transmission delay has a greater impact on users,such as voice and video services.When performing the backoff process for such services,we dynamically generate competition based on the sensitivity of services to delay.The specific method is to introduce a delay influence factor into the binary exponential backoff algorithm,so that the size of the contention window changes dynamically with the sensitivity of the business to the delay.The simulation results show that the delay optimization scheme based on LTE service division can improve the performance of LTE-U system and provide users with more reliable services.Aiming at the power control problem of V2V communication,this paper proposes a QoE-oriented power control algorithm.The algorithm divides the V2V communication services in the cellular vehicle networking system into secure services and non-secure services based on the service types during vehicle communication.At the same time,different QoE evaluation models are used for secure and non-secure services.Then,taking the QoE of all users in the system as the objective function,the QoE of the LTE system is optimized by assigning appropriate transmit power to each V2V user.Compared with the traditional power control scheme,the QoE-based power control algorithm can achieve higher user satisfaction.