Effect of the incident angle of a transmitting laser light on the coverage of a NLOS-FSO network

In this paper, we propose a model of the coverage and achievable data rates in No Line-of-Sight Free-Space Optical Communications (NLOS-FSOC) as a function of the angle of incidence. NLOS-FSOC uses diffuse reflected light to establish communication between two or more stations that are with or without line-of-sight to each other. Different from free-space optical communications (FSOC), NLOS-FSOC uses a diffuse reflector (DR) between a transmitter and a receiver so that LOS is not required between them but between the station and the DR. Unlike a mirror, the DR reflects the incident light to all directions but to itself and that reflection broadcast the optical channel to all receivers within LOS. The optical broadcast channel establishes a true optical local area network (OLAN). However, the reflected power and the coverage of an OLAN largely depend on the angle of incidence of transmitted laser beam. Therefore, the planning and building of an OLAN with NLOS-FSOC must consider this angle to optimize coverage, to set range, or to estimate the achievable communication data rates.