Research On Energy Saving And Deployment Optimization In Dense Heterogeneous Small Cell Networks

In recent years,with the rapid development of mobile Internet,mobile users,mobile communication equipments and mobile communication data are growing sharply at an alarming rate.The traditional macro cellular network has been unable to cope with this situation.In recent years,the industry proposes that a number of small base stations can be deployed within the traditional macrocell to form heterogeneous network architectures as a solution.The academia calls these small base stations as small cells,and describes this new type of cellular networks as heterogeneous small cell networks which have been proven with the expansion of system capacity,the enhancement of data rate,the improvement of indoor coverage and many other advantages.However,the existence of small cell in the heterogeneous small cell network makes the network structure become more complicated than ever,which poses serious challenges to system energy saving,nodes deployment planning,resource allocation and other issues.Firstly,this paper describes the heterogeneous small cell network in detail,including its emergence background,concept,advantages and research status.Then the energy consumption problem and the related research on energy saving for the heterogeneous small cell network are emphatically expounded.Various energy-saving schemes proposed by the current academia to solve the energy consumption problem of heterogeneous small cell network are combed.Secondly,our research works focuse on two aspects:the design and optimization of energy-saving strategies for heterogeneous small cell networks and the optimization of nodes deployment in two-tier heterogeneous small cell networks,respectively.In the first research work,considering the different small cell energy saving scenarios under the premise of ensuring the users' quality of service,two different small cell energy-saving strategies are designed successively to reduce the energy consumed by heterogeneous small cell networks.The theoretical expressions of success probability and energy consumption are both analyzed and deduced by taking advantage of the stochastic geometric theory tools to evaluate the effectiveness of the small cell energy-saving strategies,and then the system energy consumption under the small cell energy-saving strategies are both modeled as the mathematical optimization problems,and the optimal solution of each mathematical optimization problem is analyzed.The simulation results show that both these two different small cell energy-saving strategies can provide a very effective energy saving and energy efficiency improvement for heterogeneous small cell networks.In the second research work,aimed at a two-tier heterogeneous small cell network,the approximate theoretical expressions of each small cell tier's coverage performance and the system energy efficiency with the small cell deployment density as a parameter are derived respectively by making full use of the stochastic geometric theory tools,thus the relationships between the small cell tier's coverage performance,the system energy efficiency and the small cell deployment density are established respectively,and then according to these relationships,it can improve the coverage performance of each tier and the system energy efficiency for tiered heterogeneous small cell networks by optimizing the nodes deployment density,which gives a reference to promote the performance of the whole system by adjusting the nodes deployment density in heterogeneous small cell networks.