Dynamic Orthogonal Frequency Division Multiple Access resource management for downlink interference avoidance in two-tier networks

作者：Kao Shang Juh; Wang Hsiu Lang^*

来源：International Journal of Communication Systems, 2015, 28(2): 281-295.

DOI：10.1002/dac.2668

• OFDMA
• two-tier network
• interference management
• frequency resource management
• fractional knapsack problem
• graph coloring

In two-tier networks, which consist of macrocells and femtocells, femtocells can offload the traffic from macrocells thereby improving indoor signal coverage. However, the dynamic deployment feature of femtocells may result in signal interference due to limited frequency spectrum. The tradeoff between broad signal coverage and increased signal interference deserves further exploration for practical network operation. In this paper, dynamic frequency resource management is proposed to avoid both co-tier and cross-tier Orthogonal Frequency Division Multiple Access downlink interference and increase frequency channel utilization under co-channel deployment. A graph-based non-conflict group discovery algorithm is proposed to discover the disjoint interference-free groups among femtocells in order to avoid the co-tier interference. A macrocell uses the femtocell gateway for frequency resource allocation among femtocells to avoid cross-tier interference. We formulate the optimized frequency resource assignment as a fractional knapsack problem and solve the problem by using a greedy method. The simulation results show that the average data transfer rate can be increased from 21% to 60%, whereas idle rate and blocking rate are decreased in the range of 15% ?22% and 60% ?82%, respectively, as compared with conventional graph coloring and graph-based dynamic frequency reuse schemes.

• 出版日期2015-1-25