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发光二极管(LED)是可见光通信系统(VLC)中最主要的非线性器件,同时由于通带内非平坦的频率响应还伴随着记忆效应。LED的记忆非线性主要恶化了VLC系统的误差矢量幅度(EVM)和比特误码率(BER)。预失真技术通常被用来补偿LED的非线性,从而提高可见光通信系统的性能。现有的预失真技术都不具备自适应性并且没有考虑到LED的记忆效应。提出了一种新的预失真架构,即在发射端增加一路反馈链路来获得LED的输出信号,同时使用记忆多项式模型来自适应地训练并补偿LED的记忆非线性。仿真结果显示提出的预失真技术的BER性能优于现有的方法。
Light Emitting Diodes (LEDs) are the most important non-linear devices in the visible light communication system (VLC), with a memory effect due to the non-flat frequency response in the passband. The memory non-linearity of the LED mainly deteriorates the error vector magnitude (EVM) and bit error rate (BER) of the VLC system. Predistortion techniques are often used to compensate for the non-linearity of LEDs, thereby improving the performance of visible light communication systems. Existing pre-distortion techniques are not adaptive and do not take into account the memory effect of the LED. A new predistortion architecture is proposed, in which one feedback loop is added at the transmitting end to obtain the LED output signal, and a memory polynomial model is used to adaptively train and compensate the memory nonlinearity of the LED. The simulation results show that the BER performance of the proposed predistortion technology is superior to the existing methods.