Accurate Interference and Coverage Modelling in Finite OWC Networks

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.