Dynamic resource allocation in OFDMA-based two-hop networks with fractional frequency reuse

Orthogonal frequency division multiple access (OFDMA)-based two-hop cellular networks have better network coverage via relay stations (RSs), and more degree of freedom in resource allocation. In this paper, a dynamic fractional frequency reuse (FFR) cell architecture with multi-cell consideration and resource allocation algorithm are proposed in such OFDMA-based two-hop cellular networks. The architecture dynamically divides the subcarriers into two virtual groups which are called super and regular groups corresponding to two geographical cell regions. An efficient hierarchical solution consisting of two main dynamic resource allocation (DRA) algorithms is also proposed to realize the proposed architecture. The solution first computes the sets of super and regular groups without rigid boundaries to maximize long term performance. Unlike the traditional two-hop scheme, where each RS is assigned fixed subcarriers to serve mobile stations (MSs), the proposed optimization algorithm assigns optimal subcarriers in regular group to RS to maximize instantaneous data rates with fairness consideration. Numerical results show that our proposed architecture and algorithm can achieve superior SINR performance and higher throughput compared with traditional two-hop architecture with static FFR.