Design And Optimization Of User Association Strategies For Green Networks

With hundreds of thousands times of data traffic growth and the access of users,the network has a serious traffic congestion problem.In order to ensure the demand of user throughput and service quality,the traditional isomorphic network has been unable to cope with the increasing number of users,so it is necessary to use hybrid network,that is,introduce some small base stations with low-power nodes,so as to improve system capacity and reduce system energy consumption.In the hybrid networks,network energy efficiency has become a more and more important issue,It has become a very important research focus to improve network energy efficiency by optimizing user association and power control..Based on a thorough understanding of the current domestic and foreign research on the optimization of energy efficiency of user association in hybrid networks,this paper deeply studies the optimization of energy efficiency of user association in different access modes,establishes models in different systems,achieves energy efficiency optimization through joint optimization of user association and power control,and finally compares them.A better energy efficiency optimization system is developed.The main research works of this paper are as follows:(1)A user association strategy for energy efficiency optimization based on TDMA system is proposed.An energy efficiency optimization scheme for joint optimization of user association and power control based on TDMA system in 5G hybrid network is proposed.In order to maximize the energy efficiency of the system,a user association algorithm is designed to limit the maximum number of users associated with the base station.Then,according to the known user association,the power control is optimized by using Dinkelbach algorithm and convex optimization toolbox.The maximum energy efficiency of the system is obtained by alternatingiteration optimization of user correlation and power control.The proposed alternating optimization algorithm is verified by MATLAB simulation.(2)A user association strategy for energy efficiency optimization based on OFDMA system is proposed.Considering the same-layer interference and cross-layer interference,a system model is proposed to maximize the energy efficiency of hybrid networks by optimizing power control and subcarrier correlation.To limit the maximum number of associated users in small base stations,the base station user association optimization is carried out first,and then the subcarrier user association optimization is carried out.That is to say,it is divided into two parts: first,the macro base station user subcarrier correlation is carried out to maximize the energy efficiency of the macro base station user,and then the small base station user is combined to optimize the subcarrier correlation and power control to maximize the energy efficiency of the network,considering the cross-layer interference.Dinkelbach algorithm and Lagrange multiplier method will be used to solve the problem,and MATLAB is used to simulate and verify it.(3)An energy efficiency oriented user association strategy based on NOMA system is proposed.On the basis of 2),however,a subcarrier is no longer allocated to only one user,but shared by multiple users.The non-orthogonal transmission between different users on the same subcarrier will cause the problem of inter-user interference.That is to say,on the basis of 2),we should consider not only the interference between macro base station users and small base station users using the same subcarrier,but also the interference between macro base station users using the same subcarrier and small base station users using the same subcarrier.Then,Dinkelbach algorithm and Lagrange multiplier method are applied to solve the problem,and the simulation is carried out with MATLAB.