当前矿井下通信信号调制识别方法忽略了获取信号包络剩余概率分布和信号噪声的抑制,无法获取通信信号正确序列,导致识别效率低、误差大且通信信号白噪声较高,因此提出基于混合正交频分复用技术(Orthogonal Frequency Division Multiplex...当前矿井下通信信号调制识别方法忽略了获取信号包络剩余概率分布和信号噪声的抑制,无法获取通信信号正确序列,导致识别效率低、误差大且通信信号白噪声较高,因此提出基于混合正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)的矿井下通信信号调制识别方法。以井下宽阔地带、井下构造复杂地区以及井下狭窄地区为主要通信环境,分别获取几种情况下的多径信号包络对应的密度函数,分析其分布特征,得到接收信号包络的剩余概率分布,由此证明矿井通信信号为OFDM信号序列。在子载波组的基础上获得接收信号的序列,并消除其循环前缀,并基于此调制码元序列获取信号合并器中的输出信号,提取高阶累积量,消除信道衰落噪声。通过欧式距离分类方法,根据获取的信号特征向量进行分类,利用建立矿井下通信信号调制方式的判决准则,完成基于混合OFDM的矿井下通信信号调制识别。为验证所提方法的有效性,设计了仿真实验。实验结果表明,与传统方法对比,所提方法的通信信号调制识别耗时更短、正确率更高,并能够有效抑制通信信号噪声,可为相关领域研究提供有力支撑。展开更多
A full-duplex optical passive access scheme is proposed and verified by simulation, in which hybrid 64/16/4-quadrature amplitude modulation(64/16/4QAM) orthogonal frequency division multiplexing(OFDM) optical signal i...A full-duplex optical passive access scheme is proposed and verified by simulation, in which hybrid 64/16/4-quadrature amplitude modulation(64/16/4QAM) orthogonal frequency division multiplexing(OFDM) optical signal is for downstream transmission and non-return-to-zero(NRZ) optical signal is for upstream transmission. In view of the transmitting and receiving process for downlink optical signal, in-phase/quadrature-phase(I/Q) modulation based on Mach-Zehnder modulator(MZM) and homodyne coherent detection technology are employed, respectively. The simulation results show that the bit error ratio(BER) less than hardware decision forward error correction(HD-FEC) threshold is successfully obtained over transmission path with 20-km-long standard single mode fiber(SSMF) for hybrid downlink modulation OFDM optical signal. In addition, by dividing the system bandwidth into several subchannels consisting of some continuous subcarriers, it is convenient for users to select different channels depending on requirements of communication.展开更多
文摘当前矿井下通信信号调制识别方法忽略了获取信号包络剩余概率分布和信号噪声的抑制,无法获取通信信号正确序列,导致识别效率低、误差大且通信信号白噪声较高,因此提出基于混合正交频分复用技术(Orthogonal Frequency Division Multiplexing,OFDM)的矿井下通信信号调制识别方法。以井下宽阔地带、井下构造复杂地区以及井下狭窄地区为主要通信环境,分别获取几种情况下的多径信号包络对应的密度函数,分析其分布特征,得到接收信号包络的剩余概率分布,由此证明矿井通信信号为OFDM信号序列。在子载波组的基础上获得接收信号的序列,并消除其循环前缀,并基于此调制码元序列获取信号合并器中的输出信号,提取高阶累积量,消除信道衰落噪声。通过欧式距离分类方法,根据获取的信号特征向量进行分类,利用建立矿井下通信信号调制方式的判决准则,完成基于混合OFDM的矿井下通信信号调制识别。为验证所提方法的有效性,设计了仿真实验。实验结果表明,与传统方法对比,所提方法的通信信号调制识别耗时更短、正确率更高,并能够有效抑制通信信号噪声,可为相关领域研究提供有力支撑。
基金supported by the National Natural Science Foundation of China(No.61107064)the Chongqing University Innovation Team Founding(No.KJTD201320)the Chongqing Science and Technology Commission Foundation(No.cstc2016jcyjA 1233)
文摘A full-duplex optical passive access scheme is proposed and verified by simulation, in which hybrid 64/16/4-quadrature amplitude modulation(64/16/4QAM) orthogonal frequency division multiplexing(OFDM) optical signal is for downstream transmission and non-return-to-zero(NRZ) optical signal is for upstream transmission. In view of the transmitting and receiving process for downlink optical signal, in-phase/quadrature-phase(I/Q) modulation based on Mach-Zehnder modulator(MZM) and homodyne coherent detection technology are employed, respectively. The simulation results show that the bit error ratio(BER) less than hardware decision forward error correction(HD-FEC) threshold is successfully obtained over transmission path with 20-km-long standard single mode fiber(SSMF) for hybrid downlink modulation OFDM optical signal. In addition, by dividing the system bandwidth into several subchannels consisting of some continuous subcarriers, it is convenient for users to select different channels depending on requirements of communication.
