Research On The Physical Cell Identity Self Configuration And Spectrum Allocation Algorithm Of Heterogeneous Network Based On Graph Theory

The rapid development of mobile Internet and the rapid rise of multimedia services, the user demand data traffic is growing. In order to alleviate the contradiction between the user’s demand and the limited capacity and the low indoor signal coverage of the traditional cellular network, the different kinds of low power base station nodes are introduced in the macro cellular network. This method can effectively solve the problem of coverage in the macro cellular network, and improve the network capacity and spectrum efficiency. However, in a variety of cell types of heterogeneous network scenario, the terminal user’s cell selection and handover is very important. The physical cell identity is an important parameter for cell selection and handover, and the spectrum allocation of heterogeneous networks has an important influence on the performance of the whole network, so it is very important to study the physical cell identity self-configuration and spectrum allocation algorithm in heterogeneous networks.In this paper, we mainly study the PCI self configuration algorithm of Pico cell and the spectrum allocation algorithm of femtocell in heterogeneous networks. The main work is as follows:Firstly, this paper studies the PCI self-configuration algorithm of Pico cell in Macro-Pico two layer heterogeneous networks. Consider to the current algorithm is only meet PCI do not conflict and not to be confused with the basic principles, and not the pursuit of PCI multiplexing to minimize interference and the number of PCI use minimized optimization objectives. Therefore, this paper proposes a greedy algorithm based on PCI multiplexing frequency. First, according to the network using a PCI frequency decision PCI order of use, followed by the use of Floyd algorithm to obtain the number of hops between the cells and calculate the weight of each cell, and then reuse each PCI greedy, so that the number of the PCI minimizes. On this basis, the paper also proposes a PCI-based minimum interference greedy algorithm. In the of conflict free and confusion free phase, the algorithm gives priority to the minimum distance between the cell and the two cells configurations with different PCI, and in the interference minimization phase, with the aid of UE measurement method, the algorithm gives the cell configured the PCI of the minimal reuse interference. Therefore, this algorithm minimizes the interference of PCI. Simulation results show that compared with the existing PCI self configuration, the proposed algorithm has lower conflict and confusion probability, and better signal and interference plus noise ratio.Secondly, the spectrum allocation algorithm in Macro-Femto two layer heterogeneous networks is studied. Considering the characteristics of division of the frequency spectrum of the status and family base station, using cognitive radio technology, a dynamic spectrum allocation algorithm based on user SINR and distributed greedy algorithm is proposed to optimize the spectrum efficiency. Simulation results show that the proposed algorithm has better system throughput. Then, according to the actual rate demand of home users, this dynamic spectrum allocation algorithm is proposed based on the user’s rate requirement. The simulation shows that the algorithm has better user satisfaction rate.