Accurate Interference and Coverage Modelling in Finite OWC Networks

Abstract

Abstract: Accurate modelling of interference and coverage in optical wireless communication (OWC) systems remains challenging due to the limitations of conventional approaches, which typically rely on infinite-network assumptions or simplified disc-shaped cell models. In practical deployments, OWC networks are finite and regularly structured, resulting in spatially varying interference patterns that are not captured by existing models. This paper proposes a comprehensive analytical framework for evaluating interference and coverage probability in finite OWC networks with regularly deployed grid-based nodes. The framework is developed for a baseline line-of-sight (LOS)-dominant scenario with regularly spaced nodes, ideal transmitter–receiver alignment, and unobstructed propagation conditions (i.e., without blockage or misalignment effects). It explicitly accounts for three-dimensional distances, inter-node spacing, system dimensions, and transmitter–receiver height differences, while incorporating boundary effects. To capture spatial variability, the network is partitioned into core, mid, and boundary zones. Semi-analytical expressions for the interference distribution are derived for each zone, revealing distinct behaviours and pronounced performance degradation in cell-edge regions. Analytical and simulation results demonstrate that commonly adopted disc-assumption models significantly overestimate system performance by neglecting edge effects. For example, at a signal-to-interference-plus-noise ratio (SINR) threshold of −3 dB, disc-based models predict approximately 95% coverage, whereas the proposed framework and simulations show that only about 75% of the core and mid zones satisfy this threshold. The results further show that increasing inter-node distance and adopting higher reuse factors substantially improve coverage, while larger height differences degrade performance by increasing the number of visible interferers. Overall, the proposed framework provides a realistic and generalisable tool for analysing finite OWC networks, enabling more accurate performance evaluation and more reliable network design and deployment.