Wireless Resource Optimization For OFDMA Femtocell Network

With the rapid development of multimedia technology,the number of users in the macro cellular network is increasing.However,the communication performance of users within the coverage can not be guaranteed well.In another word,the increase of the number of users brings us challenges.The pico cell technology with low energy consumption and small area coverage emerges to satisfy the user's high quality communication requirements.However,it takes new interference in the network,the one is the interference between adjacent Femtocell(co-tier interference),and the other one is the interference between Femtocell and Macrocell(cross-tier interference).Suppressing and eliminating these interferences is a key component of Femtocell network optimization.In this paper,we use convex optimization and simulated annealing algorithm to optimize the different Femtocell network scenarios.Specific work includes as follows:First,in order to effectively solve the interference problem for Femtocell network in a closed access mode,a cluster-based resource allocation mechanism for Femtocell networks is proposed.The mechanism mainly includes three aspects in order to reduce the complexity of channel assignment.Firstly,we use the graph theory and convex optimization theory to cluster the femtocell base station;And then a subchannel allocation algorithm based on data rate fairness is used to allocate channel to Femtocell users(FUE)and Macrocell users(MUE);Finally,the distributed power allocation algorithm is used to allocate the power of the Femtocell network in which the channel assignment has been completed.In order to verify the effectiveness of the proposed mechanism,a Femtocell network model in a closed access mode is built.Simulation results show that the proposed mechanism can effectively inhibit the co-tier and cross-tier interference of r of Femtocell networks,and guarantee the fairness of users while meeting the data rate requirement of users.Second,in order to control the serious co-tier and cross-tier interference for Femtocell network in the hybrid access mode,a resource allocation mechanism based on simulated annealing algorithm is proposed.The mechanism mainly includes: First,according to the interference between the FBS,the FBS can be assigned to different clusters so as to resist the interference between them,at the same time reduce the complexity of resource allocation;Then,the channel allocation algorithm based on the minimum SINR maximization is used to complete the clustering of Femtocell network;Finally,the distributed power allocation algorithm is used to allocate the power.In order to verify the effectiveness of the mechanism,a Femtocell network model in the hybrid access mode is built.Simulation results show that the proposed scheme can effectively suppress the co-tier and cross-tier interference of Femtocell network in the hybrid access mode,and ensure users transmission rate and fairness.