时变性负载电力线载波通信抗干扰技术研究

发布时间：2018-03-30 23:06

本文选题：时变性负载　切入点：电力线载波通信　出处：《华北电力大学(北京)》2016年硕士论文

【摘要】：本文针对时变性负载电力线信道面临噪声环境恶劣而且复杂多变的难题,在实际应用中未能充分考虑恶劣复杂的噪声环境对PLC通信的影响,重点研究了基于OFDM的自适应电力线载波通信的抗干扰问题。首先使用电力线载波信道测试仪对华北油田抽油机电机典型时变性负载运行环境下的电力线信道的时域和频域特性进行了现场测试,通过测试可以清楚地看到抽油机电动机变工况运行时除了产生背景噪声外,也会产生脉冲干扰。在一段时间内噪声幅度相对较小,而在另一段时间内干扰相对增大,但不能判断噪声的时频特性。在此基础上基于魏格纳时频分析法从不同时段和不同频段联合认知电力线信道噪声状况,通过仿真验证了该方法在子载波选取时不仅考虑了频率特性,还能清楚看出噪声的时变性大小,为OFDM系统子载波动态优化组合提供了依据。其次,结合频谱感知技术,根据接收端反馈和贝叶斯定理设计一种动态子载波选择算法,以概率预测的方式进行可用子载波的选择,仿真结果表明该算法可以实时根据信道特性变化动态地选取通信质量较好的子载波,有效降低了系统误码率,提高电力线通信OFDM系统的通信可靠性。最后,在对时变性负载电力线载波信道噪声特点研究基础上,本文重点研究了电力线信道噪声抑制算法,改进了原有的限幅消波算法,将发送端降低峰均功率比的技术与现有限幅/削波去噪算法结合起来,通过仿真验证该算法可以有效抑制电力线脉冲噪声,有效地改善了电力线通信OFDM系统噪声干扰严重导致通信可靠性不高的问题。
[Abstract]:This paper aims at the problem that the time-varying load power line channel is faced with a bad and complex noise environment. In practical application, the influence of the bad and complex noise environment on PLC communication is not fully considered. The anti-jamming problem of adaptive power line carrier communication based on OFDM is studied emphatically. Firstly, the time of power line channel under typical time-varying load operating environment of pumping unit motor in Huabei Oilfield is studied by using power line carrier channel tester. Field testing of domain and frequency domain characteristics was carried out. It can be clearly seen from the test that the pumping unit motor will produce pulse interference in addition to the background noise in the off-condition operation. The amplitude of noise is relatively small in one period of time, but the interference is relatively large in another period of time. But the time-frequency characteristic of noise can not be judged. Based on Wigner time-frequency analysis method, the noise status of power line channel is recognized from different time periods and different frequency bands. The simulation results show that the method not only takes frequency characteristics into account, but also clearly shows the time-varying size of noise, which provides a basis for the dynamic combination of subcarriers in OFDM system. Secondly, it combines with spectrum sensing technology. According to the feedback of receiver and Bayesian theorem, a dynamic subcarrier selection algorithm is designed, in which the available subcarriers are selected by probabilistic prediction. The simulation results show that the proposed algorithm can dynamically select subcarriers with good communication quality according to the variation of channel characteristics in real time, effectively reduce the bit error rate of the system and improve the communication reliability of the power line communication OFDM system. Based on the study of the characteristics of time-varying load power line carrier channel noise, this paper focuses on the power line channel noise suppression algorithm, and improves the original amplitude suppression algorithm. Combining the technology of reducing PAPR at the transmitter with the existing amplitude limiting / clipping de-noising algorithm, the simulation results show that the proposed algorithm can effectively suppress the power line impulse noise. It can effectively improve the problem of low communication reliability caused by noise interference in power line communication OFDM system.
【学位授予单位】：华北电力大学(北京)
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN913.6

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