Performance analysis of a 5 Gbps PAM-4 modulated visible light optical wireless communication link: impact of transmission power, receiver field-of-view, and concentrator design parameters

This paper presents a detailed performance study of a visible light communication (VLC) link using 4-level pulse amplitude modulation (PAM-4) at a 450 nm wavelength. Link performance is systematically evaluated as a function of transmission distance across varying transmission power (20, 18, 16 dBm), irradiance half-angle (60°, 40°, 20°), optical concentration factor (30°, 60°, 90°), index concentration factor (1.0, 1.5, 2.0), and detector surface area (1, 0.8, 0.6 cm 2 ). Eye diagrams at the maximum achievable distance for the forward error correction (FEC) threshold of log(BER) = −2.42 provide a qualitative view of signal degradation, complementing quantitative log(BER) and EVM results. Results show that increasing transmission power, detector area, index concentration factor, optical concentration factor, and irradiance half-angle each independently extend the maximum link distance while maintaining acceptable EVM. Under the optimum parameter combination (20 dBm, 1 cm 2 , index factor 2.0, optical concentration 30°, half-angle 60°), the link satisfies the FEC threshold up to 3 m, with an EVM of 18.83912 %, rising to 25.97188 % at 5 m. These findings offer practical design guidelines for maximizing transmission distance in high-speed PAM-4–based VLC links while meeting FEC-level error performance requirements.