Optimal Fractional Frequency Reuse and Power Control in Wireless Heterogeneous Networks
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Heterogeneous wireless networks have emerged as a new paradigm to meet the fast increasing wireless capacity and coverage demands. Due to the co-deployment of high power and low power nodes in the same network using the same spectrum, more advanced interference coordination and radio resource management schemes are required than in the traditional cellular network in order to achieve high capacity and good user experience. In this paper, we propose an optimal fractional frequency reuse and power control scheme that can effectively coordinate the interference among high power and low power nodes. The parameters of scheme are optimized to maximize the sum of the long term log-scale throughput among all the user equipments (UEs). The Lagrange dual function is first derived for the proposed optimization problem. Gradient descent method is then used to search the optimal solution for the convex dual problem. Due to the strong duality condition, the optimal solution for the dual problem is also the optimal solution for the original problem. Simulation results showed that the proposed scheme can greatly improve the wireless heterogeneous network performance on system capacity and user experience.