A subcarrier nulling technique based on Reed–Solomon (RS) encoding and nonlinear distortion measurement in orthogonal frequency-division multiplexing (OFDM)-based visible-light communication (VLC) is proposed. The effect of nonlinear clipping imposed by the low dynamic range in an OFMD-VLC leads to a non-uniform distortion on the data-bearing OFDM subcarriers. This distortion combined with the low bandwidth modulation of the light-emitting diode could limit the throughput of the VLC system. The proposed technique employs the clipping distortion to adaptively select and null the group of subcarriers that are responsible for the peak values in the OFDM symbol. Using the frequency domain RS block code, the OFDM transmitter is provided with the flexibility to find and remove the accumulated in-band distortion anywhere within the OFDM frame without the need for prior subcarrier reservation. With the help of log-likelihood ratio detection, nulled subcarriers are estimated at the receiver, and the RS codewords with erasure are recovered and decoded without using side information. This technique mitigates the error vector magnitude and reduces the peak to average power ratio in an OFDM-VLC under severe clipping conditions with reduced complexity. The proposed technique bit error rate performance is studied and compared with traditional techniques in a VLC system with clipping constraint.

中文翻译：

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在块编码 OFDM-VLC 中用于误差矢量幅度和峰均功率比降低的自适应副载波归零

在基于正交频分复用(OFDM) 的可见光通信(VLC) 中，提出了一种基于Reed-Solomon (RS) 编码和非线性失真测量的副载波归零技术。OFMD-VLC 中的低动态范围所施加的非线性限幅效应会导致承载数据的 OFDM 子载波出现非均匀失真。这种失真与发光二极管的低带宽调制相结合，可能会限制 VLC 系统的吞吐量。所提出的技术采用限幅失真来自适应地选择和归零负责 OFDM 符号中峰值的副载波组。使用频域RS块码，OFDM 发射机可以灵活地查找和消除 OFDM 帧内任何地方的累积带内失真，而无需事先预留子载波。在对数似然比检测的帮助下，在接收器估计空子载波，并且在不使用辅助信息的情况下恢复和解码具有擦除的 RS 码字。该技术减轻了误差矢量幅度，并降低了 OFDM-VLC 在严重限幅条件下的峰均功率比，同时降低了复杂度。在具有限幅约束的 VLC 系统中研究了所提出的技术误码率性能并与传统技术进行了比较。并且在不使用边信息的情况下恢复和解码具有擦除的RS码字。该技术减轻了误差矢量幅度，并降低了 OFDM-VLC 在严重限幅条件下的峰均功率比，同时降低了复杂度。在具有限幅约束的 VLC 系统中研究了所提出的技术误码率性能并与传统技术进行了比较。并且在不使用边信息的情况下恢复和解码具有擦除的RS码字。该技术减轻了误差矢量幅度，并降低了 OFDM-VLC 在严重限幅条件下的峰均功率比，同时降低了复杂度。在具有限幅约束的 VLC 系统中研究了所提出的技术误码率性能并与传统技术进行了比较。