Design and Performance Research of Adaptive Direct Current Biased Offset Optical-OFDM System for Visible Light Communication
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摘要: 传统的直流偏置光正交频分复用(DCO-OFDM)系统通过添加直流偏置(DC)和限幅获得单极性信号，由于傅里叶逆变换(IDFT)输出时域信号的随机性，固定的直流偏置会产生较大的非线性限幅失真。该文提出设计自适应直流偏置光正交频分复用(ADCO-OFDM)系统，以双边限幅前、后符号之间的均方误差(MSE) 最小化为优化目标，求解使非线性限幅失真最小的DC。介绍了ADCO-OFDM系统原理、推导了子载波比特信噪比(SNR)，建立了均方误差最小化优化模型，并给出了最优直流偏置的求解过程。采用蒙特卡罗(Monte Carlo)仿真方法分析了误码率(BER)和光功率消耗，验证了系统设计和性能分析的正确性。Abstract: The traditional Direct Current (DC) biased offset Optical Orthogonal Frequency Division Multiplexing (DCO-OFDM) system obtains a unipolar signal by adding a DC offset and limiting amplitude. Due to the randomness of the Inverse Discrete Fourier Transform (IDFT) output time domain signal, a fixed DC offset will produce larger non-linear limiting distortion. It is proposed to design an Adaptive DC offset Optical OFDM (ADCO-OFDM) system to minimize the Mean Square Error (MSE) between the symbols before and after bilateral clipping as the optimization objective, and to solve the DC that minimizes nonlinear clipping distortion. The principle of the ADCO-OFDM system is introduced, the Signal-to-Noise Ratio (SNR) of sub-carrier bits is deduced, an optimization model for minimizing the mean square error is established, and the process of solving the optimal DC offset is given. The Monte Carlo simulation method is used to analyze the Bit Error Rate (BER) and optical power consumption, which verifies the correctness of the system design and performance analysis.
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