Research On Energy Saving And Energy Harvesting In Multi-Tier Heterogeneous Small Cell Networks

In recent years,with the development of mobile Internet and the popularization of mobile smart devices,wireless communication data have exploded,and the traditional macro-cellular networks has not provided low-latency and high rate for so many mobile users.Therefore,a large number of small base stations,called small cell,are deployed in the macro-cellular network in order to expand the system capacity,increase the data rates and improve the mobile user experience,which has gradually become a research hotspot in the field of wireless communication.However,different small cells randomly deployed in the heterogeneous networks,which is a significant challenges to the energy saving,interference management and mobile switching.Besides,the heterogeneous small cell networks will tend to the more concentrated and result in more serious energy consump tion in the future.Therefore,how to design a valid mechanism to save energy has become one of the major research issues in the heterogeneous small cell networks.This article focuses on energy saving and energy harvesting technologies in the multi-tier heterogeneous small cell networks.The main achievements of the research are as follows:1.The paper proposes an adaptive cell zooming mechanism to solve the problem of energy saving in multi-tier heterogeneous small cell networks composed of macrocell,picocell and femtocell base stations.In the mechanism,the macrocell base stations reduce their coverage areas by adjusting their transmitting power while the small cell base stations provide the service for mobile users by using adaptive scaling scheme,and the greedy mechanism is used to solve the scaling problem of the small cell.The mechanism proposed in this paper is compared with the two traditional methods and investigate that the radius of macrocell and the density of small cells affect on the system performance.Simulation results show that the proposed mechanism can improve by nearly 15 percent of energy efficiency and reduce the probability of outage by more than 60 percent.When there are a large number of mobile users,the proposed mechanism is more prominent.2.An algorithm combined wireless energy harvesting and cell zooming is presented to solve the problem of energy harvesting in the multi-tier heterogeneous small cell networks,consisting of macrocell,small cell and wireless energy harvesting sensor nodes.In the algorithm,the wireless energy harvesting sensors cooperate with the small cell to provide services for mobile users with the poor quality of service.And when mobile users have a better received signal from the small cell,small cell only provide service for mobile users and the wireless energy harvesting sensor nodes enter sleeping and energy harvesting mode.Besides,the influence of spatiotemporal volatility of mobile users on system performance is taken into consideration.Compared with the cell zooming without the wireless energy harvesting,the relation between the system performance,such as energy consumption,probability of outage and system capacity,and the spatiotemporal volatility of mobile users is investigated.The experimental simulation results reveal that the proposed mechanism can reduce energy loss by nearly 20%,increase the system capacity by approximately 25%,and reduce the probability of outage effectively.In particular,the proposed mechanism is better when the mobile users frequently move.