Multi-beam optical wireless access point design for 6G LiFi networks: eye safety-coverage tradeoff

We propose a multi-beam optical wireless access point (AP) design comprising a vertical-cavity surface-emitting laser (VCSEL) array followed by a plano-convex lens as a cost-effective and scalable solution for 6G LiFi broadband access networks. The proposed AP design presents a fairly simple angle diversity transmitter (ADT) solution to provide seamless coverage by means of narrow infrared (IR) laser beams without the need for beam steering. We have developed a propitiatory algorithm to compute the maximum permissible transmit power (MPTP) for VCSELs as a function of the array-to-lens distance within the focal length of the lens under the eye-safety constraint. For a given data rate requirement, the outage probability is evaluated over the AP coverage area by assuming a non-imaging angle diversity receiver (ADR), and a tradeoff is identified between the MPTP value and the coverage performance. Simulation results demonstrate that the minimum of the outage probability varies with the array-to-lens distance depending on the target data rate.