Coordinated resource allocation with fractional frequency reuse for downlink OFDMA networks

This paper investigates coordinated resource allocation for cell-center and cell-edge users in multicell orthogonal frequency division multiple-access (OFDMA) wireless networks. Here, we assume the data symbols of each user is only known by one base station (BS). Referring to the fractional frequency reuse (FFR) scheme, the resources for cell-center and cell-edge users are partitioned. Based on such resource planning, the objective of our resource allocation scheme is to maximize both of cell-edge and cell-center users´ throughput, subject to per base-station power constraints. Moreover, the proposed resource allocation scheme also considers the cell-center users´ performance requirement. Note that the ratio of transmit powers for cell-center users to cell-edge users can be adjusted in FFR scheme, which is introduced in the so-called soft frequency reuse (SFR) scheme. We propose a modified dual decomposition method (MDDM) to solve the above-mentioned resource allocation problem, where the joint subcarrier assignment and power allocation are performed. To simplify the computation complexity, a suboptimal algorithm (SOA) is presented to decouple the optimization problem into three sub-problems. Simulation results demonstrate the efficacy of MDDM and SOA.