An accurate model of worst case signal to interference ratio for frequency reuse cellular systems

In cellular networks, fractional frequency reuse (FFR) is an efficient inter-cell interference (ICI) mitigation scheme. Although many related research papers are published in this area. Formulas to handle this scheme in more accurate manner are still required. In this paper, closed-form formulas for worst case signal to interference ratio (SIR) in frequency reuse three, four, soft frequency reuse (SFR), and sectored FFR are derived. Also, an accurate closed-form formulas for inner radius for all these cases are driven based on worst SIR case taking into account the interference effect only and the impact of interference combined with path loss effect. Analytical models are validated using Long Term Evolution (LTE) simulator. Simulation results show that the proposed analytical models are in good agreement with those obtained through simulations and they are more accurate than previously published analytical treatments as they consider the practical scenarios.