A Graph Coloring Based Resource Allocation In Hierarchical Networks

In order to meet the growing high data rate requirements of wireless communications system,deployment of home base stations in macrocell of heterogeneous networks(HetNets)has been widely used in mobile communications networks.As a complement and extend of macrocell,femtocells could enhance the indoor coverage of network,allowing users to achieve higher data rates and better quality of service.On the other hand,the popularity of HeNBs also brings the interference between macrocells and femtocells.This paper describes the basics of graph theory,associates graph theory vertex coloring algorithm with the allocation of resources,and make use of graph theory to solve the problems of wireless communication network resource allocation.Based on existing research and analysis of interference coordination algorithm,proposed the corresponding improvement for its shortcomings.The main contributions as following:First,for resource allocation problem in wireless communication system,the cost function improves the performance graph coloring algorithm and achieve a balanced spectrum reuse.Second,it’s able to analyze the spectral environment of the current communications services and allocate resources by providing the cognitive ability of the HeNBs to identify and estimate the interference sources.Because of small-scale coverage of femtocell,the estimate of user access spectrum environment according to spectrum sensing result could reduce overhead of feedback.Third,propose a resource allocation algorithm based on requirements in HetNets.The algorithm based on the interference graph construction methods to suit the diversity of the macrocells and femtocells in same spectrum allocates resources depending on balanced vertex coloring algorithm.In this paper,the threshold and the minimum number of coloring algorithm are used to ensure the link performance of users and to manage resource respectly.Then we based on the cost function to modify the coloring and balance the spectrum reuse.Finally,set priorities depend on the actual resource requirements,and allow some which satisfy certain conditions take more resource to meet the quality of its access to users of the service.The simulation results show that by following above steps,We could improve user data rates,while effectively enhance the fairness of the system.