In this article, a new modulation scheme named Direct Current biased Optical Generalised Frequency Division Multiplexing (DCO-GFDM) for Visible Light Communications (VLC) is explored. The DCO-GFDM enhances spectral efficiency by slicing both grids on the time-frequency plane and uses a circularly rotating filter for pulse shaping. In the Circular Pulse shaped DCO-GFDM (CP-DCO-GFDM), Root Raised Cosine (RRC) pulse is widely employed. This destroys the orthogonality among sub-carriers and degrades the Bit Error Rate (BER) performance. Therefore, in this work, a Linearly Pulse shaped DCO-GFDM (LP-DCO-GFDM) is proposed to retain the orthogonality among the sub-carriers and simultaneously improve BER and Peak-to-Average Power Ratio (PAPR) performance. The performance of CP/LP-DCO-GFDM is studied under double sided clipping distortion that occurs at the Light Emitting Diode (LED). Presented simulation results agree well with the theoretical results. Additionally, we present an experimental validation of the LP-DCO-GFDM on a Universal Software Radio Peripherals (USRP) based VLC test bed. The experimental results, in terms of Error Vector Magnitudes (EVM)s, the received constellations, and the received spectrum in comparison with DCO-OFDM shows improved performance.

中文翻译：

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可见光通信系统中线性脉冲形广义频分复用的实现

在本文中，探索了一种新的调制方案，称为可见光通信（VLC）的直流偏置光广义频分复用（DCO-GFDM）。DCO-GFDM通过在时频平面上切片两个栅格来提高频谱效率，并使用圆形旋转滤波器进行脉冲整形。在圆脉冲形DCO-GFDM（CP-DCO-GFDM）中，广泛使用了根升余弦（RRC）脉冲。这破坏了子载波之间的正交性并且降低了误码率（BER）性能。因此，在这项工作中，提出了一种线性脉冲形DCO-GFDM（LP-DCO-GFDM），以保留子载波之间的正交性，并同时提高BER和峰均功率比（PAPR）性能。CP / LP-DCO-GFDM的性能是在发光二极管（LED）发生的双面削波失真下进行研究的。给出的仿真结果与理论结果吻合良好。此外，我们在基于通用软件无线电外围设备（USRP）的VLC测试床上展示了LP-DCO-GFDM的实验验证。与DCO-OFDM相比，在误差矢量幅度（EVM），接收的星座图和接收的频谱方面的实验结果显示出改进的性能。