Dimming control scheme based on hybrid LACO-SCFDM for visible light communications

This paper proposes a hybrid layered asymmetrically clipped optical(HLACO) single-carrier frequency-division multiplexing(SCFDM) scheme for dimmable visible light communication. It designs a signal structure that combines layered asymmetrically clipped optical(LACO)-SCFDM and negative LACO-SCFDM in proportion for improving the inherent weaknesses of orthogonal frequency-division multiplexing(OFDM)-based dimmable schemes and further enhancing the system performance. Compared to the HLACO-OFDM-based dimming scheme, it obtains a lower bit error ratio and enables efficient communication over broader dimming range. Its spectral efficiency realizes 2.875 bit·s^(-1)·Hz^(-1) within the dimming range of 30%–70%, and the attainable average spectral efficiency gains exceed at least 19.21% compared to other traditional dimmable schemes.

融合VOOK的混合ACO-OFDM可见光通信技术研究

调光控制可以实现发光二极管(LED)亮度的变化,满足用户的各种照明需求。可见光通信(VLC)是基于LED照明基础上发展而来的一种通信技术,兼备照明和通信的双重功能,因此,调光控制在VLC领域值得深入研究。本文提出一种全新的兼容调光控制的VLC系统,该系统将可变单载波开关键控(VOOK)和多载波混合非对称剪裁正交频分复用(HACO-OFDM)融合传输,实现LED调光和高效数据传输的双重功能。同时,针对混合信号引入时间选择性偏置,保证混合信号工作在LED的线性区间,消除非线性失真的影响。更为重要的,引入的时间选择性偏置不会干扰VOOK和HACO-OFDM信号的传输,在接收端,两种信号可以独立地完成检测,不会影响彼此的传输性能,系统误码率不会变差。并且整个系统添加的部分模块未对系统复杂度带来较大的影响。仿真结果验证了提出方案的有效性。