User-Oriented Graph Based Frequency Allocation Algorithm for Densely Deployed Femtocell Network

Femtocell is a promising technol- ogy for improving indoor coverage and offloa- ding the macrocell. Femtocells tend to be den- sely deployed in populated areas such as the dormitories. However, the inter-tier interfer- ence seriously exists in the co-channel Den- sely 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 sh- ort radius of femtocell and the small number of users lead to the inefficiency of the tradi- tional frequency reuse algorithms such as Fra- ctional Frequency Reuse （FFR）. Aiming for the downlink interference coordination in the DDFN, in this paper, we propose a User-orie- nted Graph based Frequency Allocation （UGFA） algorithm. Firstly, we construct the interfer- ence graph for users in the network. Secondly, we study the conventional graph based resou- rces allocation algorithm. Then an improved two steps graph based frequency allocation mec- hanism is proposed. Simulation results show that UGFA has a high frequency reuse ratio mean while guarantees a better throughput.