Frequency Reuse with Higher-Order Sectorisation and Directional Terminals for Improved Capacity in Realistic Terrain

We evaluate the performance of a low-power narrowband system utilising higher-order sectorisation (HOS) at the base stations (BS) and directional antennas (DA) at fixed user equipment (UE). We use a specific rotational frequency reuse scheme (RFR) for directional UEs and extend it for HOS (3, 6 and 12 sectors) by considering antenna orientations for interference avoidance. We propose two novel schemes for directional UEs with a cluster size less than one, named double frequency reuse (DFR) and triple frequency reuse (TFR). These schemes are tested and compared to conventional frequency reuse (CFR) through simulations in a realistic geographic terrain. The simulation results indicates that the proposed schemes are helpful to achieve higher capacity while using different BS and UE antenna beamwidths. It is shown that scheme RFR provides a performance enhancement compared to CFR only with wider UE antenna beamwidths. The implementation of DFR achieves reduced outage probability and offers a large increase in average spectral efficiency per cell (ASE) of up to 84.8-81.6% in 6 and 12 sectored system. The scheme TFR provides a maximum ASE of up to 149-153% in 6 and 12 sectored system. However, in a six-sectored system, TFR only meets the coverage criteria with a narrow beamwidth antenna of 20 degrees.