Research On Cooperation Scheme Of Small Base Stations In Ultra-dense Network

In recent years,with the rapid development of communication technology,a variety of new multimedia devices and user services are continually emerging.To improve the user data rate and increase the network capacity,the density of small base stations(SBSs)deployed in the network continues to increase,which leads to the formation of ultra-dense network(UDN).At the same time,the inter-cell interference(ICI)caused by the densely deployed same-frequency SBSs will seriously deteriorate the network performance,and coordinated multi-point(Co MP)transmission is regarded as an effective solution to this challenge.To alleviate the serious ICI,we propose a user-centric multi-point cooperation scheme,i.e.,Voronoi Co MP,in the control/data plane separation architecture(CDSA).This Co MP structure ensures that each user served by the base stations which are the closest ones of all SBSs to it.By utilizing the efficient cooperation between randomly deployed SBSs in the network,this scheme can maximize the useful power of each user and in the meantime minimize the interference.The simulation results show that,compared with the other two non-cooperative user association schemes,the Voronoi Co MP can effectively reduce the user outage probability and the network average outage probability,in addition,it will make a significant increase of the users' data rate and improve the average network throughput.The non-coordinated multi-point scheme based on Voronoi polygon inherits the significant characteristics of the Voronoi Co MP and it also has some advantages in improving network performance when compared with the other non-Co MP scheme.Then,we extend single-user multi-point cooperation to the situation of multi-user.Because of the poor performance improvement of the network-centric Co MP scheme and the higher complexity of the user-centric Co MP,to achieve the tradeoff between computational complexity and throughput gain,a hybrid SBS cooperation scheme is proposed.By combining Voronoi Co MP with the Delaunay triangulation-based Co MP,this hybrid Co MP scheme improves the efficiency of the base station for providing services to users,and achieve the balances between the performance gain and network overhead.In addition,we present two kinds of wireless resource allocation strategy,the simulation results show that with the reasonable allocation of the physical resource block considering the distance between SBS and user can improve the user data rate which meet the minimum requirement.This makes full use of network resources and verifies the effectiveness of the strategy.