Indoor Optical Wireless Channel Characteristics With Distinct Source Radiation Patterns

In conventional indoor optical wireless communication, the transmitter is usually empirically viewed as a source with a Lambertian radiation pattern. This paper comprehensively studies the impact of practical source radiation patterns on channel characteristics, including light-emitting diodes (LEDs) from Nichia and Lumileds Philips. Compared with the Lambertian pattern, differences in impulse and frequency responses, spatial distributions of optical path loss (OPL), and root mean square (RMS) delay spread based on different patterns are clearly observed from simulation. The standard deviation reduction of OPL and RMS delay spread can be up to more than 3.1 dB and 0.138 ns for two practical sources, whereas the respective dynamic ranges of the conventional Lambertian pattern are just 5.1 dB and 0.67 ns. Meanwhile, the radiation pattern from Lumileds Philips provides almost uniform transmission characteristics that are independent of the receiver position.