Reserch Of Carrierless Amplitide/Phase Modulatiom Based On Visible Lighe Communication

Visible light communication(VLC) has become a popular way of wireless communication because of its high bandwdth,excellent security and low power consumption.However due to the bandwidth of LED,traditional OOK modulationm can't meet the needs of high speed visible light system.Carrierless amplitude phase modulatiom has attracted increasingly attention in visible light communication because of its high spectrum utilization and low complexity.As it is known that CAP signal contains two cross channel information which are added in the time domain,so there exist not only intersymbol interference(ISI) but also cross channel interference when the timing information is not correct.Thus,the disgn of shaping filter and symbol sychronization are the two important question of CAP system espacially in real-time VLC system,The main content and innovations are listed as below:1. This paper studied history, current situation of high order mosulatiom, as well as theory of CAP. We duduced the nencessary and sufficient condition of non-ISI and non-CCI for CAP signal.Besides we the paper has successfully desagned correct shaping filter and researched the influence of rolling pressure coefficient,timing error to the CAP system.2. This paper designed complete model of CAP modulation and demodulation.Futhermore the paper completed the off-line experiment using MATLAB and analog circut at the speed of 500Mbit/s and the distance of 30-80cm.3. For the important technology of symbol sychronization,we creatively introduce the structure of interpolation filter loop which is often used in quadrate amplitude modulation(QAM) for wireless communication and successfully demonstrated the correction of this mothod in CAP system based on visible light communicatiom.Finally this paper has designed the important modules of CAP real-system with FPGA.