An analytical framework for multilayer partial frequency reuse scheme design in mobile communication systems

Partial frequency reuse (PFR) is one of the key techniques to improve max-min fairness for cell-edge user equipments in the fourth generation of mobile communication systems. Recently, multi-layer PFR schemes have been proposed, which are considered to be a promising evolution of this technique. In this article, we propose an analytical framework for multi-layer PFR scheme design, which uses a triplet to completely describe a given PFR scheme. Then, closed-form expressions of the average spatial capacities of certain typical regions of a cell are derived. Based on a comprehensive analysis using this framework, a novel multi-layer PFR scheme is designed, which divides each cell into inner, middle, and outer layers, with two homolographic sublayers for the middle layer. Reuse factors for the three layers are 1, 3/2, and 3, respectively, and an orthogonal division of the spectrum among different layers is guaranteed. Based on our numerical results, this novel scheme outperforms the traditional 2-layer PFR scheme in max-min fairness without degrading the average spatial capacity. Compared with several representative multi-layer PFR schemes, it achieves a better tradeoff between these two metrics.