Research On Virtualization Technology Of 5G Wireless Network

The three major scenarios of 5G networks(such as enhanced mobile broadband,ultrareliable low-latency communications,and large-scale machine-type communications)have proposed multi-dimensional key performance indicators for network design,such as spectrum efficiency and energy efficiency(EE),Delay,reliability,etc.However,traditional vertically closed networks are difficult to flexibly deploy network functions and resources.5G network function virtualization(NFV)technology overcomes the shortcomings of the existing network facilities and application software and hardware tight coupling,long development cycle,etc.,and through the virtualization of physical resources,it can achieve flexible,efficient and controllable network design,to better adapt to the needs of new applications,which has received extensive attention from academia and industry.At this stage,NFV research still has some technical challenges that need to be solved urgently,e.g.the realization of cross-layer allocation of virtual resources between the physical layer and the network layer,virtual network orchestration methods,the joint optimization of communication,storage and computing three-dimensional resources,and the vehicular network realization of reliable and low-latency communication,etc.In response to the above challenges,this dissertation focuses on virtual resource allocation(RA)and launches research on key technologies of NFV.The main contribu tions are as follows:(1)Aiming at the problem of energy-efficient virtual resource allocation method of orthogonal frequency division multiple access(OFDMA)system,this dissertation focuses on the resource virtualization method of multiple virtual network operators sharing physical infrastructure,and considers users Fairness issues.Firstly,this dissertation proposes a virtual resource allocation architecture for the downlink of OFDMA system.Secondly,this dissertation models the virtual resource allocation as a mixed integer nonlinear programming problem,which is to maximize the network energy efficiency of the link with the worst channel condition,and meet the constraints of user rate,power,and sub-carrier.In order to convert the non-convex problem,we reconstruct the problem of optimization and propose an iterative algorithm for energy efficiency optimization.Thirdly,through the smooth curve and conditional relaxation,the fractional non-convex problem is transformed into a solvable subtractive equivalent optimization problem,and then the optimal solution is approached.Synthetically considering the Lagrangian dual method and Dinkelbach method,the subcarrier allocation and power allocation are jointly optimized,we propose an energy efficiency optimization algorithm based on sub-gradient.The simulation results show that the virtual network energy efficiency optimization algorithm proposed in this dissertation(ie,the energy efficiency optimization algorithm based on sub-gradient)has better energy efficiency performance than traditional solutions.The virtual network energy efficiency optimization algorithm can achieve better energy efficiency performance in the three scenarios of the best link,average link and worst link in channel conditions.(2)Aiming at the energy efficiency and time delay optimization of the virtual slicing of the fog radio access network(F-RAN),firstly,this dissertation introduces virtual slices,uses random models to model virtual resources,time-varying channel conditions,and random data arrival and analyzes them,and embeds virtual slices that integrate virtual wireless,cache,and computing resources into the physical layer.In traditional mobile networks,data enters the actual queue,while in a customized virtual slice,data enters several collaborative virtual queues according to user requirements.Secondly,this dissertation models the optimization problem as maximizing the energy efficiency of F-RAN,and guarantees the delay constraint,queue stability constraint(that is,the queue length is below the delay requirement threshold?),the rate requirement of the specified virtual slice,and the subcarrier constraint and power constraints,etc.Thirdly,the above optimization problem is a non-convex problem.By transforming constraints and using the Lyapunov method to minimize the upper bound of the offset plus penalty function,the optimal virtual resource allocation at time slot t is obtained,so that the optimization problem is transformed into convex problem,an iterative algorithm for energy efficiency optimization based on virtual resource allocation is proposed.This algorithm does not require any prior knowledge about traffic arrival rate or channel statistics.Through time slot iteration,the algorithm result can approach the theoretical optimal energy efficiency.In addition,in order to reduce the complexity of the algorithm,this dissertation separates the allocation of buffering and computing resources from the subcarrier and power allocation and decouples each other,and decomposes the original problem into two sub-problems of optimal energy efficiency and optimal delay,and further proposes low complexity Virtual resource allocation energy efficiency optimization algorithm,compared with existing algorithms,this algorithm has the advantage of low complexity.Finally,the simulation results prove that the iterative algorithm for energy efficiency optimization based on virtual resource allocation and the energy efficiency optimization algorithm for low-complexity virtual resource allocation proposed in this dissertation are superior to the existing fog access network resource allocation methods,and the energy efficiency of low-complexity virtual resource allocation is better.Compared with the traditional virtualization algorithm,the optimized algorithm improves the network energy efficiency under the condition of guaranteed delay.(3)Aiming at the problem of open-loop ultra-reliable low-latency uplink car networking communication resource allocation,this dissertation first designs a virtual cell-based ultrareliable low-latency communication(URLLC)network architecture,taking open-loop physical communication as the third generation partnership project(3GPP)vehicle to everything(V2X)network alternative,considering time-varying network slicing conditions,random road conditions and user mobility,through network slicing and resource prediction Allocation guarantees reliability and achieves ultra-low latency on the uplink.Focus on open-loop communication of uplink edge network with limited backhaul and feedback control,the edge network of the virtual cell,wireless network slicing technology,resource pre-allocation and multi-point cooperative uplink access are proposed to maximize the uplink reliability.Secondly,this dissertation analyzes the feasibility of the uplink by using a random geometric model to simulate the physical layer access interference and collision.Through the queuing model of serving virtual cells in network slicing and the queuing model of data queues in virtual cells,we analyze the stability of the network,and give the steadystate analysis,effective bandwidth,and effective capacity proof of the virtual cell.Thirdly,this dissertation jointly considers URLLC,takes the ultra-reliability of the network as the optimization goal and models it,maximizes the probability of successful connection and the non-collision probability of multiple access,while meeting the network stability constraints.In addition,using Lyapunov optimization technology,using a distributed method to obtain the best resource allocation strategy,and through virtual resource slicing,to solve the challenge of high computational and system complexity in resource pre-allocation and the compromise between stability and reliability.The minimum throughput in the virtual cell is maximized,and the virtual resource slice optimization resource pre-allocation algorithm is proposed.Compared with existing algorithms,this algorithm has the advantages of low complexity,system stability and high reliability.At last,through network reliability,stability simulation and parameter impact simulation on system performance,the correctness of the theoretical analysis and the uplink vehicular network performance of open-loop URLLC are verified.