Optimizing direct-modulated laser LiFi systems for hospital environments through simulation-driven analysis of BER, SNR, and Q-factor performance

<ns3:p> <ns3:bold>Background</ns3:bold> Modern hospital environments require wireless communication systems that ensure electromagnetic interference (EMI) compliance, privacy, and high throughput for mission-critical applications, such as telemetry, medical imaging, and Electronic Health Record (EHR) synchronization. Traditional RF-based wireless systems are susceptible to EMI, limited spectrum availability, and security issues. Direct-Modulated Laser (DML)-based Light Fidelity (LiFi) offers a promising alternative by leveraging the visible spectrum for high-speed, interference-free communication in terms of intended optical emissions. <ns3:bold>Methods</ns3:bold> The optimized configuration achieves BER &lt; 10⁻⁹, SNR ≈ 74.94 dB, and Q ≈ 18.84 at 25 m, surpassing hospital reliability thresholds (BER &lt; 10 <ns3:sup>-9</ns3:sup> ; Q &gt; 6). Launch powers ≥ +5 dBm are required beyond ~15 m, modulation indices of 0.8–1.0 yield higher Q across distances, narrow beam divergences (1–2 mrad) maintain stronger SNR, and receiver apertures of 4–6 mm provide a balance between light collection and noise. <ns3:bold>Results</ns3:bold> The optimized configuration achieves BER well below commonly cited hospital-grade analytical reliability thresholds (BER &lt; 10⁻⁹), SNR ˜ 74.94 dB, and Q ˜ 18.84 at 25 m, surpassing hospital reliability thresholds (BER &lt; 0 <ns3:sup>-9</ns3:sup> Q &gt; 6). Launch powers = +5 dBm are required beyond ~15 m, modulation indices of 0.8–1.0 yield higher Q across distances, narrow beam divergences (1–2 mrad) maintain stronger SNR, and receiver apertures of 4–6 mm provide a balance between light collection and noise in a best-case, well-aligned configuration. <ns3:bold>Conclusions</ns3:bold> This paper introduces a four-parameter DML-LiFi optimization framework unique to a given hospital, which offers a theoretical explanation of link-budget feasibility and parameter sensitivity to idealized indoor environment. These results indicate an upper-bound performance study, and not a demonstration of deployment-ready reliability, and are meant to be used in future experimental and system-level studies that focus on mobility, line-of-sight blockage, ambient-light-induced shot noise, electromagnetic interference pickup, and eye-safety constraints in hospital settings. </ns3:p>