Layout And Performance Analysis Of Visible Light Communication System In Spacecraft

In recent years,visible light communication(VLC)has become a popular and important research area in the field of optical communication.Compared with traditional radio frequency communication,the main reason of its popularity is that it has significant advantages in the environment without electromagnetic radiation and the availability of broader bandwidth.As for the shape of scene,mostly of which are regular and ideal in the traditional indoor VLC researches.In order to enrich the application scene of VLC and meeting the practical needs,this thesis establishes experiment in a more practical application scene and system of spacecraft,where taking into account the changeable length to meet different research needs.Different from top-layout style of visible light source placement in traditional indoor VLC research,this thesis studies the communication performance in space vehicle under different style of VLC system’s layouts and the influences under such different testing conditions.And then we also experiment and attain practical data for comparison between traditional genetic algorithm method and our new-approached researches.The simulation results of the experiment indicates that the method approached by this thesis could provide a capable reduction of energy cost and avoids the energy-wasting efficiently and meanwhile,satisfy the meet of lights and communication performance requirements.In this thesis,probable methods have been sought for reducing energy-cost by adjusting the layout of the light source and analyzing the correlation among the number,power of the light source and the length of the aircraft dynamically.In the traditional scheme,longer spacecraft length requires more light sources,which would result in unnecessary energy waste.As to improve the drawbacks mentioned above,we approached an efficient method by adopting genetic algorithms to determine the appropriate number of the light source and power of lights,which satisfies the requirements of the valid area ratio,meets the signal-to-noise ratio(SNR)factors,up to 90%.The simulation results indicate that the total power saving can reach up to 12% when the length varies from 5 to 12 meters.And it also occurs that when the length meets up to 6 meters,each increase of2 meters in the length it would need add 2 light sources to make sure we achieve the same performance.Considering the particularity of the spacecraft scene,this thesis studies a new layout style of light source instead of the traditional layout of placing the lights in the upper space.In this new layout method,we additionally put a pillar across the middle of the spacecraft horizontally,under which condition we analyze the power values and related communication quality data to determine whether the whole VLC performance of the spacecraft is better or not.With experiment simulation conducted and complex data we attained from above improved method got cleaned,we finally found that the new layout method could save up to 20% energy more than the traditional method does.