Experimental implementation of digital equalizer for multilevel signal in visible light communication
Experimental implementation of digital equalizer for multilevel signal in visible light communication
复制标题
可见光通信多电平信号数字均衡器的实验实现
DOI：
10.1117/1.oe.59.1.016110
复制
发表时间：
2020-01-01
影响因子：
1.3
通讯作者：
Lu, Huimin
中科院分区：
文献类型：
--
作者：
Jin, Jianli;Wang, Jianping;Lu, Huimin
抽象的。提出了一种由两个平方根升余弦滤波器和一个有限脉冲响应（FIR）滤波器组成的均衡方案，以补偿可见光通信（VLC）中发光二极管（LED）引起的高频信道衰落。利用基于该方案的数字均衡器，对VLC系统在不同多级基带信号下的性能进行了实验分析。结果表明，当在 VLC 系统中引入所提出的数字均衡器时，传输速率在前向纠错阈值下增加了一倍。因此，当 LED 的 3dB 带宽仅为 13 MHz 时，即可实现 120 Mb/s 的传输速率。考虑到传输性能和计算复杂度，还对FIR抽头系数的数量进行了优化，在采用的数字均衡器中将FIR抽头系数的数量设置为32。进一步研究了系统性能改进与每个符号相同比特的信号欧氏距离之间的关系。结果表明，较长的欧氏距离有利于采用所提出的均衡器的 VLC 系统传输性能的提高。
Abstract. An equalization scheme consisting of two square-root-raised-cosine filters and a finite impulse response (FIR) filter is proposed to compensate the channel fading at high frequency induced by light-emitting diodes (LEDs) in visible light communication (VLC). Using the digital equalizer based on this scheme, the performance of the VLC system with different multilevel baseband signals is analyzed experimentally. It is demonstrated that, when the proposed digital equalizer is introduced in the VLC system, the transmission rate is shown to double under forward error correction threshold. As a result, a transmission rate of 120 Mb/s is realized when the LED’s 3-dB bandwidth is only 13 MHz. The number of the FIR tap coefficients was also optimized by considering the transmission performances and computational complexity, which is set to 32 in the adopted digital equalizer. The relation between the system performance improvement and signal Euclidean distance with the same bit per symbol is further investigated. The results reveal that the longer Euclidean distance is beneficial to the improvement of transmission performance for the VLC system with the proposed equalizer.