Graph Method Based Clustering Strategy for Femtocell Interference Management and Spectrum Efficiency Improvement

In order to control the interference, and improve the spectral efficiency in the Femtocell and Macrocell Overlaid System (FMOS), the FMOS model is built and Combination of Frequency bandwidth dynamic division and Clustering Algorithm (CFCA) is proposed for Orthogonal Frequency Division Multiple Access (OFDMA) FMOS. In CFCA, the optimal clustering problem in terms of interference mitigation is constructed. A heuristic algorithm based on the graph method is proposed to solve the optimal problem, through which frequency reuse based on clusters is realized. Simulation results show that high spectrum efficiency is achieved and probability of cross-tier spectrum reuse is higher than 97.4%, which means the problem of the Macro MS Dead Zone around femtocells is effectively solved. Furthermore, statistical results of the user capacity provide guidelines for the actual FMOS planning.