基于OFDM的电力线载波信道估计算法研究

发布时间：2018-01-23 10:50

本文关键词： 电力线通信 OFDM 电力线通信协议标准信道估计技术　出处：《重庆大学》2013年硕士论文　论文类型：学位论文

【摘要】：电力线网络覆盖广泛，接入方便，在宽带接入和智能家庭网络等应用方面越来越受到人们的关注。正交频分复用(OFDM)技术的抗噪声和多径能力强、频谱利用率高，加之容易实现高速传输，因此众多的通信协议标准都选择OFDM技术作为数字调制技术，，在电力线载波通信中亦具有广阔的应用前景。本文研究了基于OFDM的电力线载波通信信道估计算法。首先，介绍了基于OFDM的电力线载波通信相关标准，着重研究了G3协议标准和PRIME标准，给出了两个相关标准的系统框图和详细参数，并用Matlab仿真实现了两个标准的发射信号功率谱密度。其次，分析了基于OFDM的电力线载波通信系统的设计，介绍了OFDM技术的基本原理和关键技术，着重研究了基于OFDM的电力线载波系统组成的框图，主要参数等。再次，介绍了电力线信道下的信道估计算法：首先，详细介绍了电力线信道的信道特性，着重研究了电力线输入阻抗特性、噪声特性以及衰落特性。其次，针对导频的信道估计算法，指出了OFDM系统中非盲估计算法研究的三个要点：(1)发送端导频的选择与插入，讨论了块状导频、梳妆导频的插入方法；(2)接收端导频位置信道信息获取的方式，详细分析了LS(Least Squares)、MMSE(MinimumMean Square Error)、SVD(Singular Value Decomposition)这三种典型的信道估计算法的原理与特点。通过Matlab仿真表明：MMSE算法的性能最好，但是MMSE算法复杂度很高，难以在实际中得到应用；SVD算法复杂度相对MMSE算法要低，但是随着信噪比的增加，SVD算法的性能要差一些；相对来说LS算法的性能是最低的，但是LS算法简单且易于实现；(3)通过导频位置获取的信道信息恢复出所有时刻信道的信息，介绍和比较了三种典型的插值算法：线性内插、Cubic插值算法和高斯插值算法。最后，本文根据电力线信道的特性采用了一种基于LS算法的改进信道估计算法。通过Matlab仿真比较表明改进后的算法运算简单且大大提高了LS算法的信道估计性能，在恶劣的信道环境下保证了可靠性。本文的研究结果对电力线通信接收机的实际应用具有一定的价值，也为今后设计完全自主知识产权基于OFDM电力线通信芯片奠定了基础。
[Abstract]:Power line network has wide coverage and convenient access, and has attracted more and more attention in broadband access and intelligent home network applications. Orthogonal Frequency Division Multiplexing (OFDM) technology has strong anti-noise and multi-path capability. Because of the high spectrum efficiency and the high speed transmission, the OFDM technology is chosen as the digital modulation technology in many communication protocol standards, and it also has a broad application prospect in the power line carrier communication. A power line carrier channel estimation algorithm based on OFDM is studied in this paper. First of all, the paper introduces the power line carrier communication standards based on OFDM, focuses on the G3 protocol standard and PRIME standard, and gives the system block diagram and detailed parameters of the two related standards. Two standard transmit signal power spectral density are realized by Matlab simulation. Secondly, the design of power line carrier communication system based on OFDM is analyzed, and the basic principle and key technology of OFDM technology are introduced. The block diagram and main parameters of power line carrier system based on OFDM are studied. Thirdly, the channel estimation algorithm under the power line channel is introduced. Firstly, the channel characteristics of the power line channel are introduced in detail, focusing on the power line input impedance characteristics, noise characteristics and fading characteristics. Aiming at the channel estimation algorithm of pilot frequency, this paper points out three key points of the non-blind estimation algorithm of OFDM system: 1) the selection and insertion of pilot frequency at the transmitter end, and discusses the insertion method of block pilot and dressing pilot. (2) the method of obtaining the channel information of pilot position at the receiving end is analyzed in detail by LS(Least Squares). MMSE(MinimumMean Square error. SVD(Singular Value Decomposition). The principle and characteristics of these three typical channel estimation algorithms are discussed. The Matlab simulation shows that the performance of the Matlab algorithm is the best. However, the complexity of MMSE algorithm is very high, so it is difficult to be applied in practice. The complexity of SVD algorithm is lower than that of MMSE algorithm, but the performance of SVD algorithm is worse with the increase of SNR. The performance of LS algorithm is the lowest, but LS algorithm is simple and easy to implement. The channel information obtained from the pilot position is used to recover the channel information at all times. Three typical interpolation algorithms are introduced and compared: linear interpolation cubic interpolation algorithm and Gao Si interpolation algorithm. Finally. According to the characteristics of power line channel, an improved channel estimation algorithm based on LS algorithm is proposed in this paper. The results of Matlab simulation show that the improved algorithm is simple and greatly improves the channel of LS algorithm. Estimated performance. The reliability is guaranteed in the bad channel environment. The results of this paper have certain value for the practical application of power line communication receiver, and also lay a foundation for the design of independent intellectual property rights based on OFDM power line communication chip in the future.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TN913.6

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