Design Tradeoffs of Non-Imaging Angle Diversity Receivers for 6G Optical Wireless Access Networks

To achieve multi-Gb/s data rates in 6G optical wireless networks based on narrow infrared (IR) laser beams, a high-speed receiver with two key specifications is needed: a sufficiently large aperture to collect the required optical power and a wide field of view (FOV). This paper investigates the design tradeoffs for a non-imaging angle diversity receiver (ADR) coupled with photodiode (PD) arrays for laser-based optical wireless communication (OWC) with the aim to achieve data rates higher than 10 Gb/s and a half-angle FOV of 30 degrees. The design tradeoffs include the gain-FOV tradeoff for each element of the receiver and the area-bandwidth tradeoff for each PD array. Taking both tradeoffs into account, the rate maximisation is formulated as a non-convex optimisation problem to find the optimal configuration of the receiver bandwidth and FOV under the minimum FOV constraint. A low-complexity optimal solution is proposed and the ADR performance is studied using computer simulations.