Research On User Association And Resource Allocation Algorithm In Millimeter Wave Heterogeneous Network

The 21st century is the age of information.In recent years,with people's increasingly high demands on the speed,capacity and time delay of wireless communication,traditional wireless network has been unable to meet the communication demand with explosive growth.At present,a large number of studies have found that millimeter wave heterogeneous networks can meet the requirements of the fifth-generation mobile communication system(Fifth Generation Mobile System,5G)for high-speed and large-capacity.Compared with traditional cellular communication,it can greatly improve the system throughput and energy efficiency.In this thesis,the millimeter wave heterogeneous network is taken as the research goal to study the problem of user association and resource allocation in this network.The main work is as follows:First,the problem of user association in millimeter wave heterogeneous networks is studied.The problem of the association between the user and the base station is transformed into an integer programming problem with the goal of optimal system throughput by establishing a mathematical model.To solve this problem,this thesis first introduces a low-complexity heuristic association algorithm to obtain the suboptimal solution of system throughput.Based on the matching theory in graph theory,the user and the base station are constructed into a bipartite weighted graph,and the target problem is transformed into a solution to the optimal matching problem,and the KM(Kuhn Munkres,KM)algorithm is used to solve the global optimal matching.The simulation results show that the user association algorithm based on the KM algorithm can achieve the performance of the exhaustive matching algorithm while significantly reducing the computational complexity.After solving the user association problem,this thesis focuses on the problem of resource allocation in millimeter wave heterogeneous networks.Resource allocation is a very challenging non-convex problem.This thesis jointly model the sub-channel allocation and power allocation problem as a mixed integer nonlinear fractional programming problem.First,the sub-channel allocation variable is relaxed by the penalty function method,then use fractional planning and DC programming theory to solve.Unlike the step-by-step optimization algorithm that decouples the sub-channel allocation and power allocation problems into two sub-problems in the existing resource allocation research,the joint optimized resource allocation algorithm the thesis proposed is characterized by synchronous optimization of sub-channel allocation and power allocation problems The results show that the proposed algorithm can effectively solve this problem and obtain higher system energy efficiency.