On the energy efficiency of fractional frequency reuse techniques

Fractional frequency reuse (FFR) and soft frequency reuse (SFR) are efficient interference avoidance techniques for emerging OFDMA cellular networks in improving system performance by regularly reusing the frequencies. In this paper, we evaluate the energy efficiency (EE) in bits/J and EE per channel per cell in bits/J/Hz/cell for both the static FFR and SFR systems, in Nakagami-m fading and path-loss. In addition, we analyze the effect of fixed and variable cell-edge power amplification factor, α, on the FFR and SFR systems EE, the area spectral efficiency and the capacity. Our simulation and analytical results show that the SFR EE is higher than the FFR EE at low and medium α, whereas at very high α, the opposite is true. The observation is valid in fully-loaded cells, however, in partially-loaded cells, even at high α, SFR EE outperforms FFR EE.