基于电力线信道的小波去噪及OFDM同步技术研究
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摘要
目前对电力线通信的研究已相当广泛,但离产品的大规模商用化还有一定的距离,电力线信道的噪声去除技术成为其制约因素之一,且还在不断的探究之中。本文重点对电力线信道中噪声如何更加有效去除的问题进行了分析和研究,鉴于同步技术在电力线通信中的重要作用,还提出了一种适合于电力线信道的OFDM盲同步算法。文中通过模拟低压电力线信道噪声环境,在改进阈值平移不变量去噪法中首次采用一种新的阈值函数,使阈值的变化与噪声的小波变换随尺度的变化特性相一致。二者仿真实验表明,改进的盲同步算法具有良好的定时估计和频率偏移估计性能;而改进的平移不变量去噪算法能够有效改善信号的信噪比,减小原始信号和估计信号之间的均方根误差,去噪效果更好。
Power line communication has been widely researched up to now, but there is a stretch to go on to adopt on a large scale, the de-noising methods in the power line channel become one of the restriction factor and is probed deeply into constantly. The de-noising in the power line channel is analyzed and researched in this paper. Considering the importance of synchronization, a modified blind OFDM synchronization algorithm is proposed. Through simulating the noise condition, the improved threshold function is firstly adopted, which makes the threshold’s changes be consistent with the noise’s property according to the decomposing scale. The computer simulation results show that the perfect blind OFDM synchronization algorithm performs well in the estimation of the timing, and the method based on the amended translation invariant wavelet can effectively improve the signal-noise ratio, reduce the root mean square error between the original signal and the estimated signal, and has a better de-noising effect.
Power line communication has been widely researched up to now, but there is a stretch to go on to adopt on a large scale, the de-noising methods in the power line channel become one of the restriction factor and is probed deeply into constantly. The de-noising in the power line channel is analyzed and researched in this paper. Considering the importance of synchronization, a modified blind OFDM synchronization algorithm is proposed. Through simulating the noise condition, the improved threshold function is firstly adopted, which makes the threshold’s changes be consistent with the noise’s property according to the decomposing scale. The computer simulation results show that the perfect blind OFDM synchronization algorithm performs well in the estimation of the timing, and the method based on the amended translation invariant wavelet can effectively improve the signal-noise ratio, reduce the root mean square error between the original signal and the estimated signal, and has a better de-noising effect.
引文
[1] Markus Sebeck, Gerd Bumiller. A Network Management SyStem for Power-line Communication and its Verification by Simulation[C]. ISPL’2000, Limerick, Ireland. April 2000, 225-232.
[2]赵丙镇.电力线高速通信技术的现状与发展[J].电力系统通信. 2003, 24(1): 12-16.
[3]李平,赵志辉,张振仁.低压电力线信道中脉冲噪声的建模及仿真[J].继电器. 2007, 35(5).
[4]孟逢逢.电力线通信及其在家电信息化中的应用[J].电子技术. 2006,33(8): 22-24.
[5] KELLER PIAZZO L, MANDARINI P,et al. Orthogonal frequency division multiplex synchronization techniques for frequency-selective fading channels[J]. IEEE J Select Areas Commun. 2001,19(6): 999-1008.
[6] TURELI U, LlU H, ZOLTOWSKI. M D. OFDM blind carrier offset estimation: ESPRIT[J]. IEEE Trans Commun. 2000, 48(9): 1459-1461.
[7]张继东,郑宝玉.基于导频的OFDM信道估计及其研究进展[J].通信学报. 2003,24(11):116-124.
[8]周一青,胡爱群.利用训练帧进行OFDM系统同步的新算法[J].通信学报. 2001,22(4):13-18.
[9] K. Izumi, D. Umehara, S. Denno. Performance Evaluation of Wavelet OFDM Using ASCET[C]. IEEE ISPLC 2007, Pisa, Italy. 2007.
[10] Hao Zhou, Malipatil A, and Yih-Fang Huang. OFDM Carrier Synchronization Based on Time-Domain Channel Estimates[J]. IEEE Trans. on Wireless Communications. 2008,7(8):2988-2999.
[11] Juha Heiskala,John Terry. OFDM Wireless LANS:A Theoretical and Practical Guide[M].北京:电子工业出版社,2003年.
[12] Hoshyar R, Jamali H, Bahai A R S. Turbo Coding Performance in OFDM Packet Transmission[C].IEEE Vehicular Technology Conference. 2000:805-810.
[13] Torabi M,Soleymani M R. Turbo Coded OFDM for Wireless Local Area Networks[J]. Proceedings of the 2002 IEEE Canadian Conference on Electrical and Computer Engineering. 2002:1363-1367.
[14]徐佰勋,白旭滨,傅孝毅.信号处理中的数字变换和估计方法[M].北京:清华大学出版社,2004年.
[15]郑宝玉,张继东.基于小波去噪的OFDM信道估计新方法[J].电子与信息学报. 2006,28(3):415-418.
[16] Haibo He, Shijie Cheng, Youbing Zhang, and J. Nguimbis. Home Network Power-Line Communication Signal Processing Based on Wavelet Packet Analysis[J]. IEEE TRANSACTIONS ON POWER DELIVERY. 2005,20(3).
[17]吴正国,夏立,尹为民.现代信号处理技术——高阶谱、时频分析与小波变换[M].武汉:武汉大学出版社,2003年.
[18]郎锐.数字图像处理学Visual C++实现[M].北京:北京希望电子出版社,2002年.
[19]张士文,殳国华,韩正之.低压电力线通信技术综述[J].华北电力技术. 2001(1):27-29.
[20] Zhai.M. Estimation of Impulse Noise Parameters in Power Line Communications Channel Based on Artificial Neural Networks[C]. The 8th International Conference on Signal Processing. 2006,3.
[21]房曙光.低压电力线通信信道特性[J].继电器. 2007,35(22):53-56.
[22] Morgan H.L. Chan, Robert W. Donaldson. Amplitude, Width, and Interarrival Distributions for Noise Impulses on Intrabuilding Power Line Communication Networks[J]. IEEE Trans on Electromagnetic Compatibility. 1989,31 (3):320-323.
[23]关维国,吕娓,戴永彬.基于小波的多载波调制技术的电力线通信仿真[J].电力系统及其自动化学报. 2006:18(67-70).
[24] Zimmermann M, Dostert K. The Low Voltage Power Distribution Network as Last Mile Access Network-Signal Propagation and Noise Scenario in the HF-Range[J]. AEU International Journal on Electronics and Communications. 2000,54(1):131-138.
[25]王乔晨,郭静波,王赞基.低压配电网电力线高频噪声的测量与分析[J].电力系统自动化. 2000,26(1):18-21.
[26] Shaw A,and Srivastava S. A Novel preamble structure for robust timing synchronization in OFDM system [C]. IEEE Region 10-Conference, Taipei,Taiwan,Oct.30,Nov.2. 2007:1-4.
[27] Akbari M H, Ahmadian M, and Salari S. Joint Frame and Frequency Synchronization for MIMO OFDM Systems with ZCZ Sequence[C]. 3rd IEEE/IFIP International Conference in Central Asia, Tashkent, Uzbekistan,Sept 26-28. 2007:1-5.
[28] van de Beek J J, Sandell M, and Borjesson P O. ML estimation of time and frequency offset in OFDM system [J]. IEEE Trans.on Signal Processing. 1997,45(7):1800-1805.
[29] Tiejun Lv, and Jie Chen. ML Estimation of Timing and Frequency offset Using Multiple OFDM symbols in OFDM symbols[C]. Global Telecommunications Conference, San Francisco,USA,Dec 1-5. 2003: 2280-2284.
[30] Sharma N and Papadias C B. Reduced-complexity ML decoding of rate 6/8 and rate 1 linear complex space-time codes for up to eight transmit antennas with phase feedback[J]. IEEE Signal Processing Letters. 2005,12(8):565-568.
[31] M.Okada, S.Hara,S. Komaki and N. Morinaga. Optimum synchronization of orthogonal multi-carrier modulatied signal[J]. In Proc. IEEE PIMRC, Taiwan. 1996,10:863-867.
[32] W.D. Warner,C. Leung. OFDM / FM frame synchronization far mobile radio data communications[J]. IEEE Trans. Veh. Technol. 1993,42:302-313.
[33] Park Byungoon, Cheon Hyunsoo, Kang Changeon, etal. A novel timing estimation method for OFDM systems[J]. IEEE Communications Letters. 2003,7(8):239-241.
[34]崔小准,陈豪,胡光锐等.一种新的突发OFDM传输系统定时和载波频率捕获联合算法[J].计算机学报. 2004,27(12):1712-1718.
[35] Minn H, Bhargava V K, Letaief K B. A Robust timing and frequency synchronization for OFDM systems[J]. IEEE Transactions on Wireless Communications. 2003,2(4):822-839.
[36]任光亮,常义林.无线OFDM系统时频同步方法研究[J].西安电子科技大学学报. 2005,32(5):758-761.
[37] Kenkichi Takahashi and Takahiko Saba. A Novel Symbol Synchronization Algorithm with Reduced Influence of ISI for OFDM Systems[C]. IEEE Global Telecommunication Conference, San Antonio, TX, USA, Nov 25-29. 2001,1:524-528.
[38] Granado J, and Torralba A. Method for frequency offset estimation in OFDM with application to OFDM with application to power line communication[J]. IEEE Electronics Letters. 2003,39(5):468-450.
[39] Donoho D L. De-noising by soft-thresholding[J]. IEEE Trans on Information Theory. 1995,41(3):613-627.
[40]张兆宁,董肖红,潘云峰.基于小波变换模极大值去噪方法的改进[J].电力系统及其自动化学报. 2005,17(2):9-12.
[41]苏丽,赵国良,张仁彦.基于改进小波阈值法的平移不变心电信号去噪[J].哈尔滨工程大学学报. 2006,27 (6).
[42]罗志增,张清菊,蒋静坪.表面肌电信号的小波消噪改进算法[J].浙江大学学报(工学版). 2007,41(2):213-216.
[43] Wang Ju, Fan Shaosheng. Power Communication Denoising Based on Fast Algorithm of Tranlation Invariant Wavelet [C]. Chinese Control Conference. 2007:306-309.
[44] Mallat S, Hwang W L. Singularity detection and processing with wavelets [J]. IEEE Trans on Information Theory. 1992,38 (2):617-643.
[45]潘金凤.基于小波变换模极大值的脉冲噪声去除方法[J].山东理工大学学报(自然科学版). 2007,21(5):69-72.
[2]赵丙镇.电力线高速通信技术的现状与发展[J].电力系统通信. 2003, 24(1): 12-16.
[3]李平,赵志辉,张振仁.低压电力线信道中脉冲噪声的建模及仿真[J].继电器. 2007, 35(5).
[4]孟逢逢.电力线通信及其在家电信息化中的应用[J].电子技术. 2006,33(8): 22-24.
[5] KELLER PIAZZO L, MANDARINI P,et al. Orthogonal frequency division multiplex synchronization techniques for frequency-selective fading channels[J]. IEEE J Select Areas Commun. 2001,19(6): 999-1008.
[6] TURELI U, LlU H, ZOLTOWSKI. M D. OFDM blind carrier offset estimation: ESPRIT[J]. IEEE Trans Commun. 2000, 48(9): 1459-1461.
[7]张继东,郑宝玉.基于导频的OFDM信道估计及其研究进展[J].通信学报. 2003,24(11):116-124.
[8]周一青,胡爱群.利用训练帧进行OFDM系统同步的新算法[J].通信学报. 2001,22(4):13-18.
[9] K. Izumi, D. Umehara, S. Denno. Performance Evaluation of Wavelet OFDM Using ASCET[C]. IEEE ISPLC 2007, Pisa, Italy. 2007.
[10] Hao Zhou, Malipatil A, and Yih-Fang Huang. OFDM Carrier Synchronization Based on Time-Domain Channel Estimates[J]. IEEE Trans. on Wireless Communications. 2008,7(8):2988-2999.
[11] Juha Heiskala,John Terry. OFDM Wireless LANS:A Theoretical and Practical Guide[M].北京:电子工业出版社,2003年.
[12] Hoshyar R, Jamali H, Bahai A R S. Turbo Coding Performance in OFDM Packet Transmission[C].IEEE Vehicular Technology Conference. 2000:805-810.
[13] Torabi M,Soleymani M R. Turbo Coded OFDM for Wireless Local Area Networks[J]. Proceedings of the 2002 IEEE Canadian Conference on Electrical and Computer Engineering. 2002:1363-1367.
[14]徐佰勋,白旭滨,傅孝毅.信号处理中的数字变换和估计方法[M].北京:清华大学出版社,2004年.
[15]郑宝玉,张继东.基于小波去噪的OFDM信道估计新方法[J].电子与信息学报. 2006,28(3):415-418.
[16] Haibo He, Shijie Cheng, Youbing Zhang, and J. Nguimbis. Home Network Power-Line Communication Signal Processing Based on Wavelet Packet Analysis[J]. IEEE TRANSACTIONS ON POWER DELIVERY. 2005,20(3).
[17]吴正国,夏立,尹为民.现代信号处理技术——高阶谱、时频分析与小波变换[M].武汉:武汉大学出版社,2003年.
[18]郎锐.数字图像处理学Visual C++实现[M].北京:北京希望电子出版社,2002年.
[19]张士文,殳国华,韩正之.低压电力线通信技术综述[J].华北电力技术. 2001(1):27-29.
[20] Zhai.M. Estimation of Impulse Noise Parameters in Power Line Communications Channel Based on Artificial Neural Networks[C]. The 8th International Conference on Signal Processing. 2006,3.
[21]房曙光.低压电力线通信信道特性[J].继电器. 2007,35(22):53-56.
[22] Morgan H.L. Chan, Robert W. Donaldson. Amplitude, Width, and Interarrival Distributions for Noise Impulses on Intrabuilding Power Line Communication Networks[J]. IEEE Trans on Electromagnetic Compatibility. 1989,31 (3):320-323.
[23]关维国,吕娓,戴永彬.基于小波的多载波调制技术的电力线通信仿真[J].电力系统及其自动化学报. 2006:18(67-70).
[24] Zimmermann M, Dostert K. The Low Voltage Power Distribution Network as Last Mile Access Network-Signal Propagation and Noise Scenario in the HF-Range[J]. AEU International Journal on Electronics and Communications. 2000,54(1):131-138.
[25]王乔晨,郭静波,王赞基.低压配电网电力线高频噪声的测量与分析[J].电力系统自动化. 2000,26(1):18-21.
[26] Shaw A,and Srivastava S. A Novel preamble structure for robust timing synchronization in OFDM system [C]. IEEE Region 10-Conference, Taipei,Taiwan,Oct.30,Nov.2. 2007:1-4.
[27] Akbari M H, Ahmadian M, and Salari S. Joint Frame and Frequency Synchronization for MIMO OFDM Systems with ZCZ Sequence[C]. 3rd IEEE/IFIP International Conference in Central Asia, Tashkent, Uzbekistan,Sept 26-28. 2007:1-5.
[28] van de Beek J J, Sandell M, and Borjesson P O. ML estimation of time and frequency offset in OFDM system [J]. IEEE Trans.on Signal Processing. 1997,45(7):1800-1805.
[29] Tiejun Lv, and Jie Chen. ML Estimation of Timing and Frequency offset Using Multiple OFDM symbols in OFDM symbols[C]. Global Telecommunications Conference, San Francisco,USA,Dec 1-5. 2003: 2280-2284.
[30] Sharma N and Papadias C B. Reduced-complexity ML decoding of rate 6/8 and rate 1 linear complex space-time codes for up to eight transmit antennas with phase feedback[J]. IEEE Signal Processing Letters. 2005,12(8):565-568.
[31] M.Okada, S.Hara,S. Komaki and N. Morinaga. Optimum synchronization of orthogonal multi-carrier modulatied signal[J]. In Proc. IEEE PIMRC, Taiwan. 1996,10:863-867.
[32] W.D. Warner,C. Leung. OFDM / FM frame synchronization far mobile radio data communications[J]. IEEE Trans. Veh. Technol. 1993,42:302-313.
[33] Park Byungoon, Cheon Hyunsoo, Kang Changeon, etal. A novel timing estimation method for OFDM systems[J]. IEEE Communications Letters. 2003,7(8):239-241.
[34]崔小准,陈豪,胡光锐等.一种新的突发OFDM传输系统定时和载波频率捕获联合算法[J].计算机学报. 2004,27(12):1712-1718.
[35] Minn H, Bhargava V K, Letaief K B. A Robust timing and frequency synchronization for OFDM systems[J]. IEEE Transactions on Wireless Communications. 2003,2(4):822-839.
[36]任光亮,常义林.无线OFDM系统时频同步方法研究[J].西安电子科技大学学报. 2005,32(5):758-761.
[37] Kenkichi Takahashi and Takahiko Saba. A Novel Symbol Synchronization Algorithm with Reduced Influence of ISI for OFDM Systems[C]. IEEE Global Telecommunication Conference, San Antonio, TX, USA, Nov 25-29. 2001,1:524-528.
[38] Granado J, and Torralba A. Method for frequency offset estimation in OFDM with application to OFDM with application to power line communication[J]. IEEE Electronics Letters. 2003,39(5):468-450.
[39] Donoho D L. De-noising by soft-thresholding[J]. IEEE Trans on Information Theory. 1995,41(3):613-627.
[40]张兆宁,董肖红,潘云峰.基于小波变换模极大值去噪方法的改进[J].电力系统及其自动化学报. 2005,17(2):9-12.
[41]苏丽,赵国良,张仁彦.基于改进小波阈值法的平移不变心电信号去噪[J].哈尔滨工程大学学报. 2006,27 (6).
[42]罗志增,张清菊,蒋静坪.表面肌电信号的小波消噪改进算法[J].浙江大学学报(工学版). 2007,41(2):213-216.
[43] Wang Ju, Fan Shaosheng. Power Communication Denoising Based on Fast Algorithm of Tranlation Invariant Wavelet [C]. Chinese Control Conference. 2007:306-309.
[44] Mallat S, Hwang W L. Singularity detection and processing with wavelets [J]. IEEE Trans on Information Theory. 1992,38 (2):617-643.
[45]潘金凤.基于小波变换模极大值的脉冲噪声去除方法[J].山东理工大学学报(自然科学版). 2007,21(5):69-72.