Fractional frequency reuse in optical wireless cellular networks

Interference coordination in optical wireless cellular networks using different frequency reuse techniques are discussed and compared in this paper. On the one hand, full frequency reuse maximises the system throughput at the cost of poor cell-edge user performance. On the other hand, cluster-based static resource partitioning offers good cell-edge user performance at the cost of low system throughput. Fractional frequency reuse (FFR) is introduced as a compromise between cell-edge user performance and the system throughput with low system complexity. Simulation results show that a guaranteed user throughput of 5.6 Mbps and an average area spectral efficiency (ASE) of 0.3389 bps/Hz/m² are achieved by the FFR optical wireless system with appropriate power control factors. These results show considerable throughput improvement compared to both benchmark systems. It is also shown that by adjusting the LED transmission optical power of a system using visible light spectrum, the illumination requirement for an office room can be satisfied without extra lighting facilities.