Research On Multi-Carrier And Visible Light Communication System

With the deepening of information technology, human demand on the network increases, communication business showing explosive growth. The increasing number of devices, more Internet users, faster broadband speeds, more video sources, results a surge of more IP traffic, thereby increasing the transmission capacity of the backbone network and transmission rate requirements.In order to improve the efficiency and capacity of transmission, transmission system at the transmitting port they use a series of lasers. However, since the respective laser indicators do not completely identical, so that the stability of the experimental system is affected. What’s more, because of a large number of lasers used, the transmission system is not convenient to a commercial technology. Therefore, the use of stable multi-carrier light source as transmitter has become a hotspot for research. Among multi-carrier light source generation scheme, the generation way which is based on the Re-circulating frequency shifter structure program has produced stable, high flatness multi-carrier. Moreover, the number of subcarriers generated is much more than the other schemes. So that it is very suitable for terabit transmission system and become a major research program. But because of its Re-circulating structure characteristics, results in accumulation of noise, reduces the generated multi-carrier signal to noise ratio, meanwhile affecting the quality of the multi-carrier light source. Therefore, how to further improve the signal to noise ratio for high-speed transmission system has become a focus of research.Due to the surge in global Internet users and users with pervasive wireless access technologies, existing wireless access technology will face serious challenges in speed, capacity, security, reusability, and many other areas. Visible light communication technology as a new wireless access technology, due to its multiplexing features which is combine communication and energy, has broad application prospects. What is more, both bands free, convenient security features, makes it getting more and more attention.Current visible light communication system uses mainly LED as a transmitter, which combines communication and energy at the same time. But use photodetector at receiving end to receive the optical signal. This way only completes communication function. This is a function of the asymmetry of the system architecture. So it will cause energy waste while difficult practical, limiting the development of visible light communication systems research. To solve the above problems, design the new visible light communication system architecture that can easy to be commercialization, becoming an important research direction.According to the above problems, this paper will study both part of the multi-carrier and visible light communication system. The main work is divided into the following aspects:1. Expound the development status and research significance from both wired and wireless.2. Analyze the principle and system architecture of generating multi-carrier lighting based on RFS. Study impact of multi-carrier on linewidth of light source and the accumulation of ASE noise.3. Analysis of the basic principle of DI. Improved scheme is proposed to generate the better multi-carrier light source. Order from the theoretical analysis, simulation, experiment verification to achieve the improved structure be able to fit for the expectation.4. Research the basic theory of visible light communications, as well as Ethernet and serial communication protocols. Simulate the MAC controller development and serial communication based on FPGA. Apply serial communication protocol to the visible light communication system.5. Research the solar cell work theory. Design a symmetrical function visible light communication system. Make the experimental platform to verify the system feasible.In summary, this paper will study separately the multi-carrier light source and visible light communication system. The aspect of the multi-carrier is research on the principle of generating multi-carrier. Study the influence of accumulated noise generated by the RFS structure and the main reason for noise accumulating. Based on analysis and research of Delay Interferometer, we propose a modified multi-carrier generation scheme, which improve multi-carrier light quality obviously. Visible light communication system part study basic system theory and related communication protocols. Complete the visible light communication system. Further do some research on the solar cell and apply it to the visible light communication system. Achieve multiplexing communication function and energy at send and receive parts. Do experimental verification for the proposed visible light communication system.