低压电力线通信中的OFDM核心算法研究

发布时间：2018-05-12 20:33

本文选题：低压电力线载波通信 + 正交频分复用　；参考：《福州大学》2014年硕士论文

【摘要】：电力线载波(Power Line Carrier, PLC)通信是一种以中、低压配电网作为传输媒介实现数据传输的通信方式。它以现有的配电网为基础设施,不需任何布线,建设成本低,而且具有其它任何一种有线网络无法相比拟的覆盖范围,在远程抄表自动化、配电网自动化、智能家居等应用场合具有特有的优势。但是低压电力线作为通信信道时有其固有的不利特性,具体表现为负载多、衰减大、时变以及噪声干扰复杂等方面,因此有必要选择一个适合此环境的调制解调方式来保证电力线载波通信的可靠性。正交频分复用(OFDM)技术具有抗干扰能力强、频谱利用率高、可以用IFFT/FFT实现调制解调等优点,因此在电力线载波通信领域得到了越来越广泛的应用。然而,OFDM技术也存在缺点：对接收端同步系统性能要求较为苛刻、较高的峰值平均功率比(PAPR)等。本文正是研究基于OFDM的低压电力线载波通信技术,重点分析了同步技术,设计一个适合在低压电力线噪声环境下传输数据的通信系统。本文首先针对国内的电力线噪声环境,对低压电力线信道的噪声特性进行分析,从系统实际应用、测试的环境出发,建立能满足电力线信道噪声环境的噪声数学模型,并分析了电力线信道的传输特性,为研究电力线信道对通信系统性能的影响提供了理论基础。接着,本文研究了OFDM通信系统,包括信道估计方法、基本参数选择原则等。然后,重点研究了OFDM的核心技术同步技术,包括以下几部分：①分析同步对系统的影响；②研究三种经典的基于训练序列的同步算法,分析这三种算法的优缺点；③提出一种计算量小,对系统硬件要求低的同步算法；④通过定时检测概率和同步均方误差分析,验证本文提出的算法性能良好；⑤对提出算法进行进一步优化。之后,研究了OFDM系统中降低峰均比的技术,对比了几种常见的降低OFDM系统峰均比的方法,研究了一种改进的Nyquist脉冲整形的方法来降低系统的峰均比。最后,本文设计了一个适合在低压电力线上通信的完整的OFDM系统方案,其中同步模块采用本文提出的同步算法。介绍了系统的发送端和接收端各个模块的设计过程,使用MATLAB软件对各个模块进行了仿真分析,对整个系统的误码率性能进行了仿真,验证了系统的可用性,对本项目后续采用DSP和FPGA实现基于OFDM的低压电力线通信系统奠定了理论基础。
[Abstract]:Power Line Carrier, PLC) communication with power line carrier is a kind of communication mode which uses medium and low voltage distribution network as transmission medium to realize data transmission. It takes the existing distribution network as the infrastructure, does not need any wiring, has low construction cost, and has a range of coverage that can not be compared with any other kind of wired network, in remote meter reading automation, distribution network automation, Smart home and other applications have unique advantages. However, the low-voltage power line as a communication channel has its inherent disadvantages, such as more loads, large attenuation, time-varying and complex noise interference, etc. Therefore, it is necessary to select a modulation and demodulation method suitable for this environment to ensure the reliability of power line carrier communication. Orthogonal Frequency Division Multiplexing (OFDM) has been widely used in power line carrier communication field because of its strong anti-jamming ability, high spectral efficiency and the ability to realize modulation and demodulation with IFFT/FFT. However, OFDM technology also has some disadvantages, such as demanding performance of receiver synchronization system, high peak-to-average power ratio (PAPR) and so on. This paper studies the low voltage power line carrier communication technology based on OFDM, analyzes the synchronization technology, and designs a communication system suitable for transmitting data under the low voltage power line noise environment. In this paper, the noise characteristics of the low voltage power line channel are analyzed in the light of the domestic power line noise environment, and a mathematical model of noise which can satisfy the noise environment of the power line channel is established from the practical application of the system and the testing environment. The transmission characteristics of power line channel are analyzed, which provides a theoretical basis for studying the influence of power line channel on the performance of communication system. Then, this paper studies the OFDM communication system, including channel estimation methods, basic parameter selection principles and so on. Then, the key technology of OFDM synchronization is studied, including the following parts: 1, analyzing the influence of synchronization on the system. Secondly, three classical synchronization algorithms based on training sequence are studied, and the advantages and disadvantages of these three algorithms are analyzed. (3) A synchronization algorithm with low hardware requirement and low computational complexity is proposed. By analyzing the timing detection probability and the synchronous mean square error, it is verified that the proposed algorithm has good performance and further optimizes the proposed algorithm. After that, the techniques of reducing PAPR in OFDM system are studied, several common methods of PAPR reduction in OFDM system are compared, and an improved Nyquist pulse shaping method is studied to reduce the PAPR of the system. Finally, this paper designs a complete OFDM system scheme suitable for communication on low voltage power line, in which the synchronization module adopts the synchronization algorithm proposed in this paper. This paper introduces the design process of each module in the transmitter and receiver of the system, simulates and analyzes each module with MATLAB software, simulates the BER performance of the whole system, and verifies the usability of the system. It lays a theoretical foundation for the implementation of low voltage power line communication system based on OFDM by DSP and FPGA.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN913.6

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