On the performance of shot and Johnson noises in the LOS-optical wireless channel under sensible selection requirements of an Application-Specific Genetic Algorithm

The performance of Johnson and Thermal noises in the Line-Of-Sight (LOS) optical wireless channels has been monitored in a previously implemented application-specific genetic algorithm. The latter achieves sensible selection requirements of link parameters in different weather conditions and link characteristics, and the changes in thermal and Johnson noises are recorded correspondingly. The work is established based on OOK modulation, and a Johnson-noise limited channel is considered during darkness, where the ambient light effect is minimal, and a shot-noise limited channel during daylight. The paper shows that, in order to achieve an acceptable BER at the receiver photodiode, it is possible to maximize the channel link control margin by using an Application- Specific Genetic Algorithm (ASGA). The analysis shows that the transmitted power is not the only penalty, and minimum noise at the receiver photodiode does not always mean a better performance.