Optimization of fractional frequency reuse in long term evolution networks

In cellular systems, Fractional Frequency Reuse (FFR) partitions each cell into two regions; inner region and outer region and allocates different frequency band to each region. Since the users at the inner region are less exposed to inter-cell interference, the frequency resources in each inner region can be universally used. Based on this frequency band allocation, FFR may reduce channel interference and offer large system capacity. This paper proposes a mechanism that selects the optimal FFR scheme based on the user throughput and user satisfaction. In detail, the mechanism selects the optimal size of the inner and outer region for each cell as well as the optimal frequency allocation between these regions that either maximizes the mean user throughput or the user satisfaction. The mechanism is evaluated through several simulation scenarios.

I. Introduction

Orthogonal Frequency Division Multiple Access (OFDMA) has become an attractive technology in recent years and it is part of various system standards for mobile communications. This happens because each terminal occupies a subset of subcarriers (called OFDMA traffic channel) and each traffic channel is assigned exclusively to one user at any time [1].