Design The Indoor Visible Light Communication System Receiver Based On OFDM

OFDM technology is introduced into visible light communication system as it can improve the performance of the system, especially reduce the multipath effects. And compared with single carrier system using equalizer, multi-carrier system using OFDM is easier for hardware design. However, OFDM technology puts forward stricter synchronization requirements resulting in the more difficulty in the demodulation of the light signal. Therefore, it’s necessary to achieve the receiving and demodulation of the light signal by designing the indoor visible light communication receiver system based on OFDM.Firstly, this thesis introduces the basic structure of an indoor visible light communication receiver system based on OFDM. The receiver system includes light signal reception, signal synchronization and signal demodulation. The signal reception part of the receiver converts the light signal into the electrical signal. After amplifying and filtering processing, the analogy electrical signal is sampled and quantized into digital signal in ADC circuit.Secondly, signal reception part of the receiver is designed. By considering linearity, bandwidth, phase and time delay factors of the each circuit, we design the photoelectric conversion circuit, the pre-amplifier circuit, the filter circuit and the main amplifier circuit. Then the circuit simulation software is utilized to simulate the circuit so as to testify the requirements of linearity, bandwidth, phase and time delay factors of each circuit.Thirdly, this thesis designs signal synchronization and demodulation module based on Xilinx ISE development environment. We focus on the design of synchronization module, including frame synchronization, carrier synchronization and sysmbol synchronization. Demodulation module is divided into five parts including CP remove, FFT, inverse mapping, de-interleaving, channel decoding, which is corresponding with the modulation section in transmitter.Finally, the schematics drawing of all parts of the receiver and actual circuits based on the schematics are completed. Then light signal which is transmitted with special waveform is received and processed according to our receiver design. Meanwhile, the comparison of source and received waveform is to verify the final design so as to satisfy the original requirements.