User-oriented graph based frequency allocation algorithm for densely deployed femtocell network

Femtocell is a promising technology for improving indoor coverage and offloading the macrocell. Femtocells tend to be densely deployed in populated areas such as the dormitories. However, the inter-tier interference seriously exists in the co-channel Densely Deployed Femtocell Network (DDFN). Since the Femtocell Access Points (FAPs) are randomly deployed by their customers, the interference cannot be predicted in advance. Meanwhile, new characteristics such as the short radius of femtocell and the small number of users lead to the inefficiency of the traditional frequency reuse algorithms such as Fractional Frequency Reuse (FFR). Aiming for the downlink interference coordination in the DDFN, in this paper, we propose a User-oriented Graph based Frequency Allocation (UGFA) algorithm. Firstly, we construct the interference graph for users in the network. Secondly, we study the conventional graph based resources allocation algorithm. Then an improved two steps graph based frequency allocation mechanism is proposed. Simulation results show that UGFA has a high frequency reuse ratio mean while guarantees a better throughput.