MIMO Visible Light Wireless Communication System Employed Camera-based Receiver

The white LED has the advantages of longer life, strong illumination, low power consumption, high electro-optical conversion efficiency, no harm to human eyes, good modulation and so on, and it is recognized as the new generation of green lighting source. Visible Light Communication(VLC) is the product combining white LED and communication technology. Its principle is modulating electrical signal onto white LEDs, and transferring the visible light data using the high speed twinkling signal which is not perceived by human eyes. In VLC system, the white LED has the dual function of communication and lighting, and it is a new wireless communication access.Currently, there are still many issues remain unresolved in the research of VLC technology. This artical makes the receiving end of the visible light communication as the breakthrough port, contraposing the problems of light source layout and multipath interference existed in the presented system based on photodiode receiver, replace photodiode with camera to conduct the signal reception. Meanwhile, it introduce Multiple-Input Multiple-Output(MIMO) technology into the system after its mechanism of signal receiving are altered. The main contents of this thesis are as follows:Firstly, fully investigate the research status quo of visible light wireless communication, explore the emitting principle and characteristics of white LEDs, analyze the composition of visible light communication’s channel link and the channel characteristics, understand the work principles of VLC system in depth, and find out the problems existed in the present research.After that, do researches of visible light parallel communication system and the receiving mechanism of VLC system. On the one hand, study the theory of traditional VLC parallel system deeply; On the other hand, explore the comosition and technical requirements of the optical signal receiver based on photodiode, analyze the receiving principle of image sensor in detail, and propose new receiving mechanism based on camera. Meanwhile, introduce MIMO into the new system, and put forward to the MIMO visible light wireless parallel communication system employed camera-based receiver.Finally, it works out the MIMO visible light wireless parallel communication system employed camera-based receiver. At the same time, the simulation experiments of this system are carried out, and a set of image processing algorithms are proposed in this paper to process the signal acquired in the receiving end. In the transmitting terminal, n lights are simulated by software and different signal sequences are sent respectively. In the receiver, camera is employed to receive the wireless signals. After that, the image processing algorithms are defined to recognize and restore the signal sequences.The result demonstrates that the minority error codes appeared in the experiments all can be rectified accurately, and the signal sequences sent in the transmitting end all can be restored in the receiving end exactly. The presented approach evades the layout problem of lighting, the synchronization problem, and the multipath interference problem existed in the presented system which based on the photodiode receiver by altering the mechanism of signal receiving. The way of transferring and receiving the signals based on multi-channels presented in the approach increases the use ratio of light source, and it possesses more practical value because of its operability.