MB-OFDM信道估计算法的研究
摘要
超宽带无线通信以其传输速率高、性能好、功耗低、成本低等诸多优点,已成为短距离无线通信的主要技术之一。在超宽带无线通信系统中,为了保证通信的有效性和可靠性,接收机必须准确的了解信道传输特性。因此,信道估计是超宽带无线通信系统中的关键技术之一。本文的主要工作就是研究基于多带正交频分复用(MB-OFDM)超宽带的信道估计算法。
本论文首先介绍了MB-OFDM超宽带通信系统的概念、特点等：其次描述了一般无线信道和超宽带信道,重点研究了IEEE 802.15.3a工作组提出的超宽带标准信道模型,并对这个信道模型进行了分析和仿真比较；最后,本论文的重点讨论了MB-OFDM超宽带系统的信道估计算法。先归纳总结了各种估计方法,重点分析了基于导频的信道估计算法,包括导频的分配,导频位置信道信息的获取和由导频位置信道信息获得所有位置的信道信息。接着在超宽带标准信道模型条件下,基于Matlab平台对MB-OFDM系统常用的信道估计算法(LS、MMSE和基于DFT的变换域估计算法)以及它们的改进算法进行了重点分析和仿真比较。先对同一算法及其各自的改进算法从误码率、信道均方误差和复杂度等方面进行性能比较分析,研究表明：这些改进算法比传统方法能够更好地跟踪信道的变化,改善了整个系统的性能：再对不同算法进行横向比较,研究表明：LS算法最简单,但性能不是很好；MMSE算法性能最好,但计算复杂度太高,实际难以实现；基于DFT的变换域估计算法,通过对LS估计的结果进行时域滤波,可以有效的提高信道估计的性能。
Ultra-wideband wireless communications (UWB) has been considered as one of the main techniques in short-range wireless communications because of its merits such as high transmission rate, good performance, small power, low cost and so on. In ultra-wideband communication systems, to ensure the effectiveness and reliability of communications, the receiver must have an accurate understanding of channel transmission characteristics. Therefore, channel estimation is one of key questions in ultra-wideband communication systems. The main work in this paper is to study the MB-OFDM ultra-wideband system channel estimation algorithms.
First of all, this paper introduces the concept of the MB-OFDM ultra-wideband systems, characteristics and so on. Secondly, the paper describes the characteristics of the general wireless channel and the ultra-wideband channel, focusing on the study IEEE 802.15.3a Working Group has put the ultra broadband standard channel models for this channel, and model for the analysis and simulation comparison. Finally, on this basis, focused on the MB-OFDM UWB system channel estimation algorithm. First summarizes a variety of estimation methods, and chiefly analyses the pilot-aided channel estimation algorithm, including the distribution of the pilot, the acquisition of the pilot channel information and all channel information. Then, in ultra-wideband standard channel models, based on Matlab platform under the conditions of MB-OFDM system commonly used by algorithm (LS channel estimate, MMSE DFT and based on the Fourier Transform algorithm domain estimates), as well as their focus on the improvements of the algorithms for the analysis and simulation comparison. Improved to the same algorithms and their respective algorithms from the BER, channel mean square error and other aspects of performance and complexity comparison, the research indicated that the improved algorithms can better track the changes of the channel and improve the overall performance of the system. And then compare horizontally to different algorithms, the research indicated that LS algorithm is the most simple, but not a very good performance; MMSE algorithm for best performance, but the computational complexity is too high, real hard to achieve; based on the DFT transformation territory estimate algorithm, through carries on the time domain filter to the LS estimate result, may effective the performance which enhances the channel to estimate.
本论文首先介绍了MB-OFDM超宽带通信系统的概念、特点等：其次描述了一般无线信道和超宽带信道,重点研究了IEEE 802.15.3a工作组提出的超宽带标准信道模型,并对这个信道模型进行了分析和仿真比较；最后,本论文的重点讨论了MB-OFDM超宽带系统的信道估计算法。先归纳总结了各种估计方法,重点分析了基于导频的信道估计算法,包括导频的分配,导频位置信道信息的获取和由导频位置信道信息获得所有位置的信道信息。接着在超宽带标准信道模型条件下,基于Matlab平台对MB-OFDM系统常用的信道估计算法(LS、MMSE和基于DFT的变换域估计算法)以及它们的改进算法进行了重点分析和仿真比较。先对同一算法及其各自的改进算法从误码率、信道均方误差和复杂度等方面进行性能比较分析,研究表明：这些改进算法比传统方法能够更好地跟踪信道的变化,改善了整个系统的性能：再对不同算法进行横向比较,研究表明：LS算法最简单,但性能不是很好；MMSE算法性能最好,但计算复杂度太高,实际难以实现；基于DFT的变换域估计算法,通过对LS估计的结果进行时域滤波,可以有效的提高信道估计的性能。
Ultra-wideband wireless communications (UWB) has been considered as one of the main techniques in short-range wireless communications because of its merits such as high transmission rate, good performance, small power, low cost and so on. In ultra-wideband communication systems, to ensure the effectiveness and reliability of communications, the receiver must have an accurate understanding of channel transmission characteristics. Therefore, channel estimation is one of key questions in ultra-wideband communication systems. The main work in this paper is to study the MB-OFDM ultra-wideband system channel estimation algorithms.
First of all, this paper introduces the concept of the MB-OFDM ultra-wideband systems, characteristics and so on. Secondly, the paper describes the characteristics of the general wireless channel and the ultra-wideband channel, focusing on the study IEEE 802.15.3a Working Group has put the ultra broadband standard channel models for this channel, and model for the analysis and simulation comparison. Finally, on this basis, focused on the MB-OFDM UWB system channel estimation algorithm. First summarizes a variety of estimation methods, and chiefly analyses the pilot-aided channel estimation algorithm, including the distribution of the pilot, the acquisition of the pilot channel information and all channel information. Then, in ultra-wideband standard channel models, based on Matlab platform under the conditions of MB-OFDM system commonly used by algorithm (LS channel estimate, MMSE DFT and based on the Fourier Transform algorithm domain estimates), as well as their focus on the improvements of the algorithms for the analysis and simulation comparison. Improved to the same algorithms and their respective algorithms from the BER, channel mean square error and other aspects of performance and complexity comparison, the research indicated that the improved algorithms can better track the changes of the channel and improve the overall performance of the system. And then compare horizontally to different algorithms, the research indicated that LS algorithm is the most simple, but not a very good performance; MMSE algorithm for best performance, but the computational complexity is too high, real hard to achieve; based on the DFT transformation territory estimate algorithm, through carries on the time domain filter to the LS estimate result, may effective the performance which enhances the channel to estimate.
引文
[1]Faranak Nekoogar.超宽带通信原理及应用Ultra-Wideband Communications Fundamentals and Applications.任品毅,廖学文,梁中华译[M].西安：西安交通大学出版社,2007.
[2]R. Scholtz, R. Weaver, E. Homier, et al. UWB Radio Deployment Challenges[C]//The 11th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications. London, UK,2000,1:620-625
[3]L. yang, G. Giannakis. Ultra-wideband Communications:An Idea Whose Time Has Come[J]. IEEE Signal Processing Magazine,2004,21(6):26-54
[4]A. Tewfik, E. Saberinia. High Bit Rate Ultra-wideband OFDM[C]//IEEE Global Telecommunications Conference. Taipei,2002,3:2260-2264.
[5]F. C. Commission. Rule part15[M].2002. http://ftp.fcc.gov/oet/info/rules/part 15/part 15 12 8 03.pdf
[6]Fantasma Networks Inc Publication. High performance wireless home network:an ultra-wideband solution[R].2001.
[7]M.Z.Win, et al... Ultra-wide bandwidth signal propagation for outdoor wireless communications[C]. IEEE VTC,1997, Vol.1:251-255.
[8]A.Saleh, R.Valenzuela. A statistical model for indoor multipath propagation[J]. IEEE JSAC, 1987,Vol.SAC-5(2):128-137.
[9]H.Suzuki. A statistical model for urban radio propagation[C]. IEEE Trans. on Commun.,1977, Vol.25:673-680.
[10]IEEE P802.15. Wireless Personal Area Network.02490rOP802-15-SG3a-Channel-Model-Subcommittee-Report-Final[EB/OL]. Index of/group/802/15/pub/2002/Nov02,2002-12-02.
[11]J. J. Van der Beek, O. Edfors, M. Sandell, etc. On channel estimation in OFDM systems, Proc. Of IEEE VTC'95,815-819
[12]Y. Chen. Channel estimation for OFDM systems with transmitter diversity in mobile wireless channel [J]. IEEE JSAC,1999,17(3):461-471.
[13]Osvaldo Simeone, Pilot-based channel estimation for OFDM systems by tracking the delay-subspace, IEEE Trans. On Wireless Communications,2004,3(1),115-325
[14]Smber G L, Barry J R, Mclanghlin S W, Li Y, Ingrain M A and Pratt T G. Broadband MIMO. OFDM wireless Communications[J]. Proceedings of the IEEE,2004,92(2):271-294.
[15]John Terry, July Heiskala. OFDM wireless LANs; a theoretical and practical guide. Indianapolis-Indi. Sams-2002
[16]M.Michele, M.Umberto. A comparison of pilot-aided channel estimation methods for OFDM system[J]. IEEE Trans. on Signal Processing,2001, Vol.49(12):3065-3073.
[17]R.Nilson, et al... An analysis of two-dimensional pilot-symbol assisted modulation for OFDM[C].Proc. IEEE int'l Conf. on Acoustics Speech and Signal Processing,1997:1845-1848.
[18]O.Edfors, et al... Analysis of DFT-based channel estimators for OFDM[C]. Personal Wireless Commun.,2000, Vol.12(1):55-70.
[19]M.X.Chang, Y.T.Su. Model based channel estimation for OFDM signals in rayleigh fading[J]. IEEE Trans. on Commun.,2002, Vol.50(4):540-544.
[20]X.W.Wang, K.J.Liu. OFDM channel estimation based on time-frequency polynomial model of fading multipath channels[C]. IEEE Globecom'01,2001:212-216.
[21]黄爱平.胡荣.基于导频和多项式模型的信道估计[J].电子学报,2002,Vol.30(4)：584-586.
[22]J.K.Moon, S.I.Choi. Performance of channel estimation methods for OFDM systems in a multipath fading channels[J]. IEEE Trans. on Consumer Electron.,2000, Vol.46(1):161-170.
[23]O.Edfors, et al... OFDM channel estimation by singular value decomposition[J]. IEEE Trans. on Commun.,1998, Vol.46(7):931-939.
[24]M.K.Odemir, H.Arslan. Channel estimation for wireless OFDM systems[J]. IEEE Commun. Surveys & Tutorials,2007, Vol.9(2):18:48.
[25]Y.H.Huang, et al... USB channel estimation:design and performance evaluation[C]. IEEE VTC, 2006,Vol.4:1961-1968.
[26]S.Y.Shin, et al... Performance analysis of MB-OFDM system using SVD aimed LMMSE channel estimation[C]. IEEE ICUWB.2007:840-844.
[27]X.J.Li, H.B.Qiu. Study on channel estimation for UWB MB-OFDM[C]. ICCT'06,2006:1-4.
[28]M. Z. WN, R.A. SCHOLTZ and M.A. BARNES. Ultra—wide bandwidth signalpropagation for indoor wireless communications. IEEE Int. ConLon Commun, June 1997:56-60.
[29]Boers Y, Driessen J N. Interacting multiple model particle filter[J]. IEEE roc.-Radar SonarNavig,2003,150(5):344-349.
[30]Heng Yuanjin, A novel channel estimation and tracking method for wireless OFDM systems based on pilot and kalman filtering. Consumer Electronics, IEEE Transactions on Volume 49, Issue 2, May 2003:275-283.
[31]佟学俭,罗涛.OFDM移动通信技术原理与应用[M].北京：人民邮电出版社,2003.
[32]王金龙,王呈贵等.无线超宽带通信原理与应用[M].北京：人民邮电出版社,2005
[33]张中兆,沙学军等.超宽带通信系统[M].北京：电子工业出版社,2010
[34]Maria-Gabriella Di Benedetto Guerino Giancola超宽带无线电基础Understanding Ultra Wide Band Radio Fundamentals葛利嘉 朱林等译[M].北京：电子工业出版社,2005
[35]Kazimierz Siwiak Debra mckeown超宽带无线电技术Ultra -Wideband Technology张中兆,沙学军等译[M].北京：电子工业出版社,2005
[36]朱刚 超宽带原理与干扰[M].北京：清华大学出版社/北京交通大学出版社,2009
[37]周恩 张兴等,下一代宽带无线通信OFDM与MIMO技术[M].北京：人民邮电出版社,2008
[38]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年11月.
[39]姜俊,付炜,张盛.OFDM-UWB系统的自适应联合信道估计算法[J].无线电工程.2008,38(2)：32-37.
[2]R. Scholtz, R. Weaver, E. Homier, et al. UWB Radio Deployment Challenges[C]//The 11th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications. London, UK,2000,1:620-625
[3]L. yang, G. Giannakis. Ultra-wideband Communications:An Idea Whose Time Has Come[J]. IEEE Signal Processing Magazine,2004,21(6):26-54
[4]A. Tewfik, E. Saberinia. High Bit Rate Ultra-wideband OFDM[C]//IEEE Global Telecommunications Conference. Taipei,2002,3:2260-2264.
[5]F. C. Commission. Rule part15[M].2002. http://ftp.fcc.gov/oet/info/rules/part 15/part 15 12 8 03.pdf
[6]Fantasma Networks Inc Publication. High performance wireless home network:an ultra-wideband solution[R].2001.
[7]M.Z.Win, et al... Ultra-wide bandwidth signal propagation for outdoor wireless communications[C]. IEEE VTC,1997, Vol.1:251-255.
[8]A.Saleh, R.Valenzuela. A statistical model for indoor multipath propagation[J]. IEEE JSAC, 1987,Vol.SAC-5(2):128-137.
[9]H.Suzuki. A statistical model for urban radio propagation[C]. IEEE Trans. on Commun.,1977, Vol.25:673-680.
[10]IEEE P802.15. Wireless Personal Area Network.02490rOP802-15-SG3a-Channel-Model-Subcommittee-Report-Final[EB/OL]. Index of/group/802/15/pub/2002/Nov02,2002-12-02.
[11]J. J. Van der Beek, O. Edfors, M. Sandell, etc. On channel estimation in OFDM systems, Proc. Of IEEE VTC'95,815-819
[12]Y. Chen. Channel estimation for OFDM systems with transmitter diversity in mobile wireless channel [J]. IEEE JSAC,1999,17(3):461-471.
[13]Osvaldo Simeone, Pilot-based channel estimation for OFDM systems by tracking the delay-subspace, IEEE Trans. On Wireless Communications,2004,3(1),115-325
[14]Smber G L, Barry J R, Mclanghlin S W, Li Y, Ingrain M A and Pratt T G. Broadband MIMO. OFDM wireless Communications[J]. Proceedings of the IEEE,2004,92(2):271-294.
[15]John Terry, July Heiskala. OFDM wireless LANs; a theoretical and practical guide. Indianapolis-Indi. Sams-2002
[16]M.Michele, M.Umberto. A comparison of pilot-aided channel estimation methods for OFDM system[J]. IEEE Trans. on Signal Processing,2001, Vol.49(12):3065-3073.
[17]R.Nilson, et al... An analysis of two-dimensional pilot-symbol assisted modulation for OFDM[C].Proc. IEEE int'l Conf. on Acoustics Speech and Signal Processing,1997:1845-1848.
[18]O.Edfors, et al... Analysis of DFT-based channel estimators for OFDM[C]. Personal Wireless Commun.,2000, Vol.12(1):55-70.
[19]M.X.Chang, Y.T.Su. Model based channel estimation for OFDM signals in rayleigh fading[J]. IEEE Trans. on Commun.,2002, Vol.50(4):540-544.
[20]X.W.Wang, K.J.Liu. OFDM channel estimation based on time-frequency polynomial model of fading multipath channels[C]. IEEE Globecom'01,2001:212-216.
[21]黄爱平.胡荣.基于导频和多项式模型的信道估计[J].电子学报,2002,Vol.30(4)：584-586.
[22]J.K.Moon, S.I.Choi. Performance of channel estimation methods for OFDM systems in a multipath fading channels[J]. IEEE Trans. on Consumer Electron.,2000, Vol.46(1):161-170.
[23]O.Edfors, et al... OFDM channel estimation by singular value decomposition[J]. IEEE Trans. on Commun.,1998, Vol.46(7):931-939.
[24]M.K.Odemir, H.Arslan. Channel estimation for wireless OFDM systems[J]. IEEE Commun. Surveys & Tutorials,2007, Vol.9(2):18:48.
[25]Y.H.Huang, et al... USB channel estimation:design and performance evaluation[C]. IEEE VTC, 2006,Vol.4:1961-1968.
[26]S.Y.Shin, et al... Performance analysis of MB-OFDM system using SVD aimed LMMSE channel estimation[C]. IEEE ICUWB.2007:840-844.
[27]X.J.Li, H.B.Qiu. Study on channel estimation for UWB MB-OFDM[C]. ICCT'06,2006:1-4.
[28]M. Z. WN, R.A. SCHOLTZ and M.A. BARNES. Ultra—wide bandwidth signalpropagation for indoor wireless communications. IEEE Int. ConLon Commun, June 1997:56-60.
[29]Boers Y, Driessen J N. Interacting multiple model particle filter[J]. IEEE roc.-Radar SonarNavig,2003,150(5):344-349.
[30]Heng Yuanjin, A novel channel estimation and tracking method for wireless OFDM systems based on pilot and kalman filtering. Consumer Electronics, IEEE Transactions on Volume 49, Issue 2, May 2003:275-283.
[31]佟学俭,罗涛.OFDM移动通信技术原理与应用[M].北京：人民邮电出版社,2003.
[32]王金龙,王呈贵等.无线超宽带通信原理与应用[M].北京：人民邮电出版社,2005
[33]张中兆,沙学军等.超宽带通信系统[M].北京：电子工业出版社,2010
[34]Maria-Gabriella Di Benedetto Guerino Giancola超宽带无线电基础Understanding Ultra Wide Band Radio Fundamentals葛利嘉 朱林等译[M].北京：电子工业出版社,2005
[35]Kazimierz Siwiak Debra mckeown超宽带无线电技术Ultra -Wideband Technology张中兆,沙学军等译[M].北京：电子工业出版社,2005
[36]朱刚 超宽带原理与干扰[M].北京：清华大学出版社/北京交通大学出版社,2009
[37]周恩 张兴等,下一代宽带无线通信OFDM与MIMO技术[M].北京：人民邮电出版社,2008
[38]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年11月.
[39]姜俊,付炜,张盛.OFDM-UWB系统的自适应联合信道估计算法[J].无线电工程.2008,38(2)：32-37.