| Indoor visible light wireless communication system is designed based on the white LED, which is the fourth environment-friendly and energy-saving lighting source. The system can not only meet the needs of ordinary indoor lighting, but also do a high-speed wireless optical communication. AS the white LED lighting technology being promoted, the system can supply a good solution for the future high-speed broadband wireless access. Because electric-power lines are widely distributed in our country, and the system can combine with the electric-power line communication in the future research, so the visible light communication system research has an important developing significance.On the basis of previous studies, this thesis does some relevant research on the application of QAM in the indoor visible light wireless communication. The system mainly consists of three modules: the signal transmission module, the signal receiving module and the QAM modulation and demodulation module. A deep research has been done on the high-power white LED driven technology, and the circuit simulation have been done for each sub-module of the transmission module, then the system simulation results have been given. In the signal receiving module, this paper does a circuit simulation on the frequency characteristics and linear characteristics of the photoelectric detection system, after that, the relevant functional tests had been done to the receiving system. QAM modulation module is a all-digital processing system based on FPGA, which takes full advantage of the various types of FPGA I/O channels, digital signal processing unit, built-in RAM modules, PLL modules and other resources for the real-time signal processing. Finally, the whole functional tests have been done for the indoor visible light communication system based on QAM, and the relevant testing results have been given in this thesis. |
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