Research On Radio Resource Management In Ultra-dense Networks

The rapid development of mobile Internet makes the traditional cellular network can no longer meet the user's demand for network speed.In order to provide users with ubiquitous network coverage,higher speed and stable communication quality,the fifth generation of mobile communication system(5G)came into being.As one of the key technologies of 5G communication system,ultra dense network can effectively meet the coverage requirement and system capacity of 5G network by deploying small base stations on a large scale in hot areas.Although the deployment of small base stations can divert a large number of user services in the hot spot area,greatly reducing the load of the macro base station and making up for the blind coverage of the macro base station,the intensive deployment of the UDN also poses a huge challenge for the radio resource management.Such as interference management,power control,spectrum resource allocation and other issues.In this thesis,we mainly study the problem of radio resource management in ultra-dense networks.Firstly,a scheme of resource allocation based on clustering is studied for the cell interference problem in the ultra-dense network.Secondly,aiming at the problem of spectrum resource optimization,a hybrid spectrum resource allocation scheme is studied.The main contents of this thesis are as follows:Firstly,aiming at the co-layer interference and cross-layer interference among Femtocell in ultra-dense network,an improved resource allocation scheme based on cell clustering is proposed.The scheme is divided into two parts: The first part considers the MUEs rate requirement,The channel is allocated to the MUEs by cyclic sub-channel allocation algorithm,and then the water distribution algorithm is used to allocate the power.In the second part,based on the guaranteed MUEs rate,the improved ant colony optimization(ACO)Cluster to avoid falling into the local optimal solution,followed by heuristic algorithm for intra-cluster users sub-channel allocation and power distribution,based on the clustering further channel and power distribution.The simulation results show that the proposed scheme effectively suppresses the interference in the ultra-dense network,meets the user's rate requirement,and improves user satisfaction and fairness.Secondly,aiming at the problem of spectrum efficiency optimization in ultra-dense networks,a hybrid resource allocation scheme based on spectrum sharing and spectrum separation is proposed.The scheme is divided into two steps.The first step is to cluster the FBS through the interference graph,The FBS clusters and MBS with a close distance to the MBS adopt a resource allocation scheme with separated spectrum,and the resource allocation schemes with shared spectrum for the FBS clusters and the MBS with far distance from the MBS;The second step is to allocate resources to intra-cluster FUEs using Lagrange's dual solution in FBS clusters,including sub-channel allocation and power allocation.The simulation result shows that the algorithm can ensure the fairness of users and effectively improve the spectrum efficiency and system capacity.