Research On Cooperation Technology Of Visible Light Communication System

In recent years,with the rapid development of mobile communication technologies,the traditional radio communication has encountered some problems,such as the harm caused by electromagnetic radiation and the shortage of frequency spectrum resources.So,the visible light communication emerges as the times require,with advantages like environmental protection,rich spectrum resources,safety to human bodies and high security.This paper focused on the cooperation technology of the VLC system,and did the research on the collaborative scheduling algorithm,design and implementation of MAC layer protocol.Firstly,the paper gives an overview of the VLC systems.The paper briefly introduces the basic principles of visible light communication,including the system model,the channel characteristics and the noise model.Then the paper introduces the research progress of the cooperation technology of the VLC system.In addition,the paper also introduces the VLC MAC layer protocol,and analyzes the differences between the MAC layer protocols of two standards.Additionally,the layout optimization problem of LED lights of VLC systems under the shadow scene has been studied.The paper constructs the indoor block model,according to several typical scenario.By the way,the he distribution of SNR is under consideration.Apart from the shadow factor,the uniformity of coverage is also concerned.Then the paper establishes a multi-objective optimization model with these two targets.And the multi-objective optimization model can be converted to a single-objective optimization model.By controlling the change of weighted factor,the simulations find the optimization LED layout scheme,and the light intensity distribution as well as the distribution of SNR in these scheme has also been given.Furthermore,the paper studied scheduling problem of VLC system with the interference between Multi-users.The paper proposed a scheduling scheme which can achieve the high system capacity as well as fairness in the static scene using the classic marriage match scheme in game theory.In the mean times,the appraisal model of fairness is constructed.Simulation results show that the proposed scheme has better performance and fairness than the other two scheduling schemes.What's more,in order to adapt to the move scenarios,a partial performance optimization scheme called "cu scheduling" is proposed.The multiplex method and active methods is also been studied.Then,a scheduling scheme called "hybrid scheduling" is proposed which integrate the advantages of "cu scheduling" and global scheduling.Simulation results show that the proposed "hybrid scheduling" scheme achieves the high system capacity as well as low scheduling time,and it has the similar performance in different scenarios of motion,which shows a certain universality.Finally,the paper introduces the collaboration part of VLC MAC layer protocol design.The paper summarizes the overall framework and base modules of the existing improved MAC layer protocol.Then a cooperation scheme which helps to schedule the time slots during the process of data transmission is proposed.The feasibility of the algorithm is verified in the three scenarios.Besides,the paper completes the design of the switching module in MAC layer protocol.The program design process is described in the form of block.In the simulation,we run the coordinator side program in PC and run the device side program on the Raspberry,and the effectiveness of each function module was verified.