可见光通信中融合VOOK和分层OFDM的高效频谱混合调制方法

为了满足可见光通信(VLC)的照明和高速率数据传输的双重需求，该文提出一种融合可变开关键控(VOOK)和分层正交频分复用(OFDM)的高效频谱混合调制。首先针对分层OFDM调制方法设计了相应的VOOK信号，避免了VOOK对分层OFDM信息传输的干扰。然后，为了保证混合调制信号工作在发光二极管(LED)的线性区间，提出一种全新的重构分层光OFDM(RLO-OFDM)，并构建VOOK-RLO-OFDM混合调制方法，实现了调光控制和高效频谱数据传输的双重功能。混合调制能够并行地进行VOOK和RLO-OFDM的信号检测，同时，RLO-OFDM的信号检测可以采用标准的OFDM接收机，无须依赖串行干扰消除方式，显著地降低了接收复杂度和处理时延。仿真结果表明，所提方法能够实现线性调光控制，且具有高效的频谱效率。

Spectrum-Efficient Hybrid Modulation Based on VOOK and Layered OFDM for Visible Light Communications

In order to satisfy the requirements of illumination and high-speed transmission in Visible Light Communications (VLC), a novel spectrum-efficient hybrid modulation based on Variable On-Off Keying (VOOK) and layered Orthogonal Frequency Division Multiplexing (OFDM) is proposed in this paper. First, the VOOK signal is designed to avoid the interference with the layered OFDM transmission. In order to ensure that the hybrid signal operates in the linear dynamic range of Light-Emitting Diode (LED), a novel Reconstructed Layered Optical OFDM (RLO-OFDM) is further conceived. Then, the RLO-OFDM and VOOK signals are combined for simultaneous transmission to realize the dual functionalities of dimming control and spectrum-efficient data transmission. At the receiver side, the VOOK and RLO-OFDM signals are detected in parallel. Moreover, a standard OFDM receiver can be directly employed to detect the RLO-OFDM signal without requiring successive interference cancellation, which reduces notably the receiver complexity and processing latency. Simulation results show that the proposed scheme is capable of supporting the linear dimming control, and achieving high spectrum efficiency.