Design And Implementation Of Network Scheme Of Visible Light Communication Technology And Media Access Control Layer

In recent years, with the rapid development of mobile terminals,Internet has gradually become our part of life. Also, the way to access wireless network technology has developed rapidly. Faced with the user's increasingly high demand for network speed, the new technology and solutions have also come up. Visible light communication, as a way of wireless access, has also gained much progress in all aspects. Traditional methods of wireless communication such as MIMO, QAM, and other methods were adopted in visible light communication to increase the number of access terminals and communication speed. In latest research,off-line communication speed has reached lOGbit/s and analog bandwidth has attained 400MHz through equalization technology.Though criteria have improved, application and Realization of the visible light communication system are rare, especially in visible light communication network area. As for this problem, in this dissertation, we present some of our study results on visible light communication system network and media access control. The main content of this paper is as follows:1. This paper is mainly focused on the second layer of OSI network protocol. First, we made some research about the characteristics of Visible Light Communication System. Then, compared with the proposed system's solution in other papers, we got the final scheme that uses the CSMA/CA protocol as our Media Access Control method.2. Based on the research results above, a suitable plan for the media access control of visible light communication system is presented. In this scheme, the architecture of the system and some key parameters of the Media Access Control method are presented. Finally, through simulation,the feasibility and effectiveness of the design are verified. Using CSMA/CA with RTS/CTS protocol is useful to increase the throughput rate of Visible Light Communication system.3. In the visible light communication system, due to the attenuation caused by the semi-angle at half power of LED, we need more AP to increase coverage area. But this will also cause the overlapping area problem that one packet dual submit. In order to solve this problem, we come up with a simple method in PHY layer to avoid extra invalid transmission. Diagram of the corresponding collision detection scheme at AP is presented.4. Based on the work above, in this thesis, the realization and control of CSMA/CA protocol are given. Block diagram of the MAC layer and state diagram of each module in FPGA and Microblaze are depicted. The whole project is programmed by Verilog HDL and C programming language. Through RS232 serial communication mode between PC an MAC layer, the thesis implemented the CSMA/CA access control method in terminal and AP. This paper also tested the M? interface between MAC layer and Ethernet chip. Finally, authentication method was tested in PHY layer.