Research For Interference Management In Dense Small Cell Networks

With the rapid expansion of mobile communication users and the rapid growth of business volume,the data traffic in mobile communication networks keeps the rapidly growing trend,which has become a serious challenge to future mobile communication systems.The gain of current available bandwidth is limited,so that the 3GPP standard proposes a solution of deploying low-power small base stations to solve the growing data traffic;and it is necessary to deploy small base stations intensively for hotspots with larger flow.However,if considering the same frequency deployment model,intensive deployment of small base stations would inevitably lead to more serious co-layer interference and cross-layer interference.Therefore,the 3GPP standard proposes an enhanced inter-cell interference coordination(eICIC)and Coordinated Multi Point-Joint Transmission(CoMP-JT)technology to solve the interference problem.In addition,taking into account the feature that the number of user terminals and traffic keep changing in the mobile communication network,for small base stations without user access or with only a few number of users access during some time,keeping active all the time would result in unnecessary energy consumption.Moreover,with the rapid growth of energy consumption of communication industry,providing green solutions that can improve the energy efficient has become an important research,the 3GPP standard has proposed a small cell fast On/Off technology.In this thesis,an interference management scheme in small cell networks which combines eICIC and CoMP-JT and the small cell On / Off interference avoidance mechanism are discussed.The main contents of this paper are as follows:First of all,in the case of dense small cell networks,considering the co-frequency networking model,a dense small cell interference management scheme is proposed for the joint eICIC and CoMP-JT for the cross-layer and co-layer interference.The proposed interference management scheme takes into account the influence of CoMP-JT on the user association,the almost blank subframe configuration and the resource allocation,and maximizes the system throughput by using the Lagrange dual method while ensuring the lowest user rate.Our simulation results show that the proposed interference management can improve the network throughput and spectrum efficiency as compared with the interference management method based on enhanced inter-cell interference coordination.Then,from the point of energy efficiency,especially for the situation that small number of users or less traffic in cells,we propose small cell fast On/Off technology combining eICIC with COMP-JT in TR 36.872 Small Cell Scenario 1.That is,we consider the same frequency deployment.This paper studies the proposed interference management algorithm from four aspects: user density,the number of small base stations,the transmission power of small base stations and the moving speed of user equipment.The simulation results show that the introduction of small cell fast On/Off technology can effectively improve the energy efficiency in Small cell Scenario 1,while improving the spectrum utilization.