BRDF Models for the Impulse Response Estimation in Indoor Optical Wireless Channels

Abstract

Indoor wireless optical communications (IWOCs) are highly conditioned by the communication channel, which depends on factors, such as the endpoints’ positions and the reflective surfaces inside the room. Reflections have an important impact on the channel properties, since both channel gain and multipath interference are directly affected by reflections. Therefore, the selection of the reflection model used in the channel characterization is a critical decision in order to achieve realistic and accurate channel estimation. Simulation software, for the IWOC channel impulse response estimation, usually simplifies reflections surfaces using basic models, such as the ideal diffuse reflector (Lambertian model) or Phong’s reflection scheme. However, these models do not provide accurate results when are used with some surfaces, like those with a high-level of specular reflection components. In this letter, the integration of new reflection models into the impulse response estimation of the IWOC channels is proposed. These models are based on bidirectional reflectance distribution function theories, such as Blinn’s or Lafortune’s models, which are frequently used in 3D image rendering.