中文摘要：

基于Xilinx现场可编程门阵列（FPGA）实时产生正交频分复用（OFDM）信号，其中包括伪随机二进制序列发生器（PRBS）实现、完全并行运算反傅里叶变换（IFFT）技术的应用以及数模转换（DAC）接口电路的设计等，OFDM电信号解调后的星座图具有较好的收敛性，相应的误差矢量幅度（EVM）为4．42％。当发射机与接收端存在采样频率偏差时，各子载数据产生不同的相位旋转，系统误比特率（BER）显著升高，采样频率同步后系统性能得到明显改善。通过搭建强度调制直接检测光OFDM（O—OFDM）实验系统，传输200km标准单模光纤（SSMF）后，在接收端对O—OFDM信号进行了离线处理，与背靠背（BTB）传输相比，光功率代价小于0．6dB，实验结果表明，所设计的O-OFDM发射机具有较好的性能。

英文摘要：

The real-time orthogonal frequency division multiplexing （OFDM） signal is generated based on Xilinx field programmable gate array （FPGA）,which includes pseudo-random binary sequence （PRBS） generator,inverse fast Fourier transform （IFFT） with completely parallel computing technology, and the design of digital-to-analog conversion （DAC） interface circuit. The constellation of demodulated OFDM signal has a good convergence, and the corresponding error vector magnitude （EVM） is 4.42 %. Bit error rate is significantly increased due to the different rotation phases for sub-carriers, when the sampling frequency offset exists between transmitter and receiver, and we get improved system performance after sampling frequency synchronization. The direct-detection optical OFDM experimental system is established, and then the off-line digital signal processing after 200 km standard single mode fiber transmission is taken. An optical power penalty of less than 0.6 dB is shown, compared with back-to-back （BTB） operation. The experimental results show that the designed real-time optical OFDM transmitter has good performance.