OFDM系统中一种基于子空间盲信道估计的改进算法
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摘要
OFDM是一种无线环境下的高速传输技术,该技术的基本原理是将高速的串行数据分解成多路低速率的并行数据,并针对不同的载波分别进行调制。因此通过各个子载波的联合编码,OFDM系统可以具有良好的抗多径衰落和时延弥散的能力,并且保持较高的传输速率。
本文主要研究了OFDM通信系统中的信道估计参数问题。首先讨论了OFDM系统信道估计发展现状,然后在分析了其基本原理的前提下,提出了一种改进的OFDM盲信道估计模型,此改进算法的优点在于在循环前缀大于或小于信道阶数两种情况下该算法不用任何变形都可以直接适用。而仿真结果也表明,在循环前缀大于信道阶数的情况下,改进后的算法比文献[32-34]提出的算法收敛速度更快。
最后本文在此基础上进一步研究,引入了虚拟子载波技术。这一方面使得算法的适用范围更加完善,在没有循环前缀的情况下依然成立,另一方面可以潜在的提高系统地频带利用率。最后,本文提出的算法没有采用传统的子空间分解方法,即不必求接收信号的二阶统计量,而是直接对接收信号进行分解。仿真结果表明,该算法的实用性比较强,且适用范围的扩大并没有以牺牲大量的系统性能为代价。
OFDM is a kind of high-speed wireless transmission technology, which bases on the principle that the high-speed serial data will be broken down into multiple low-speed parallel data, and the parallel data be modulated by exploiting the different carrier modulation. So through the joint coding to all subcarriers,OFDM system can get a good capacity of the anti-multipath fading and the delay diffusion, and maintain a higher transfer rate.
This paper have studied the channel estimation parameters of the OFDM systems.Firstly the article discussed the development status quo of channel estimation technology in OFDM systems,and then on the basis of the literature [32-34],a improved OFDM blind channel estimation model is proposed. This method has the advantage that the algorithm still works for OFDM systems when the cyclic prefix is greater than or less than the number of channel bands. The simulation results also show that in the situation that the cyclic prefix is greater than the number of channel bands,the improved algorithm convergence faster than the algorithm mentioned in the literature [32-34].
Finally, this article also introducd the virtual subcarrier technology on the base of the improved OFDM channel estimation algorithm. On the hand this connection make the application of the algorithm better in the absence of cyclic prefix, on the other hand it could potentially improve the bandwidth utilization. The algorithm that uses subspace decomposition method does not want the the second-order statistics of the receiving signals, But exploites the receiver signal decomposition directly. Simulation results show that the algorithm is very practical, and in all kinds of circumstances for CP, the performance is excellent.
本文主要研究了OFDM通信系统中的信道估计参数问题。首先讨论了OFDM系统信道估计发展现状,然后在分析了其基本原理的前提下,提出了一种改进的OFDM盲信道估计模型,此改进算法的优点在于在循环前缀大于或小于信道阶数两种情况下该算法不用任何变形都可以直接适用。而仿真结果也表明,在循环前缀大于信道阶数的情况下,改进后的算法比文献[32-34]提出的算法收敛速度更快。
最后本文在此基础上进一步研究,引入了虚拟子载波技术。这一方面使得算法的适用范围更加完善,在没有循环前缀的情况下依然成立,另一方面可以潜在的提高系统地频带利用率。最后,本文提出的算法没有采用传统的子空间分解方法,即不必求接收信号的二阶统计量,而是直接对接收信号进行分解。仿真结果表明,该算法的实用性比较强,且适用范围的扩大并没有以牺牲大量的系统性能为代价。
OFDM is a kind of high-speed wireless transmission technology, which bases on the principle that the high-speed serial data will be broken down into multiple low-speed parallel data, and the parallel data be modulated by exploiting the different carrier modulation. So through the joint coding to all subcarriers,OFDM system can get a good capacity of the anti-multipath fading and the delay diffusion, and maintain a higher transfer rate.
This paper have studied the channel estimation parameters of the OFDM systems.Firstly the article discussed the development status quo of channel estimation technology in OFDM systems,and then on the basis of the literature [32-34],a improved OFDM blind channel estimation model is proposed. This method has the advantage that the algorithm still works for OFDM systems when the cyclic prefix is greater than or less than the number of channel bands. The simulation results also show that in the situation that the cyclic prefix is greater than the number of channel bands,the improved algorithm convergence faster than the algorithm mentioned in the literature [32-34].
Finally, this article also introducd the virtual subcarrier technology on the base of the improved OFDM channel estimation algorithm. On the hand this connection make the application of the algorithm better in the absence of cyclic prefix, on the other hand it could potentially improve the bandwidth utilization. The algorithm that uses subspace decomposition method does not want the the second-order statistics of the receiving signals, But exploites the receiver signal decomposition directly. Simulation results show that the algorithm is very practical, and in all kinds of circumstances for CP, the performance is excellent.
引文
[1]Zysman,G.Y.Tarallo.J.A.Howard.R.E,et al."Techonology evolution for mobile and personal communications".BLTJ,2000 Jan-Mar:107-129
[2]罗涛,乐光新等多天线通信原理与应用 北京:北京邮电大学出版社,2005,1-5
[3]彭林 第三代移动通信技术 电子工业出版社 2003,2
[4]L.J.Cimini,JR,et al."Advanced Cellular Internet Service(ACIS)".IEEE Commun.Mag,1998,36(10):150-159
[5]J.Chuang,N.Souenberger."Beyond 3G:Wideband wireless date acess basedon OFDM and dynamic packet assignment".IEEE Commun.Mag,2000,38(7):78-87
[6]Y Kim,et al."Beyond 3G:Vision Requinements and Enabling Technologies".IEEE Comm.Magazine.Mar.2003,40(3):120-124
[7]吴伟陵.移动通信中的关键技术.北京:北京邮电大学出版社,2000.
[8]X.Cai end A.N.Akansu,"A subspace method for blind channel identification in OFDM systems" in Proc.ICC,New Orleans,LA,Jul.2000,pp.929-933.
[9]Blostein.S.D."Multiple antenna systems their role and impact in future wireless access".IEEE Comm.Mag.Jul.2003.41(70):94-101
[10]侯永民,戎蒙恬 一种有效的MIMO-OFDM系统盲信道估计算法 应用科学学报,第23卷第3期,2005年5月
[11]王颖,孟嗣仪MIMO—OFDM系统中信道估计方法分析(北京交通大学,电子信息工程学院)新技术与新业务
[12]姚维坚,曹雪虹MIMO-OFDM系统信道估计技术的分析 信息技术InformationTechnology第11期 2005年
[13]郭凌,邵世祥 多载波CDMA上行链路中的盲信道估计算法(南京邮电学院,江苏南京210003)重庆邮电学院学报第17卷第2期2005年4月
[14]隗炜,周雷,张贤达.异步CDMA系统中一种新颖的盲自适应多用户检测方法.清华大学学报(自然科学版),Vol.41 No.9:94-97,2001
[15]Shengli Zhou,Student Member,IEEE,Bertrand Muquet,and Georgios B.Giannakis,Fellow,IEEE "Subspace-Based(Semi-)Blind Channel Estimation for Block Precoded Space-Time OFDM" IEEE Trans.on Signal processing,VOL.50,NO.5,May 2002
[16]Zhiguo Ding and Darren B.Ward,Member,IEEE "Subspaee Approach to Blind and Semi-Blind Channel Estimation for Space-Time Block Codes ".IEEE Trans.on Wireless Commun.VOL.4,NO.2,March 2005
[17]Qi Bi,et al." Wireless mobile communication at the start of the 21st century".IEEE Commun.Mag,2001,39(1):110-116
[18]Necker,M.and Stuber,G L," Totally Blind Channel Estimation for OFDM over FAST Varying Mobile Channels".ICC 2002,no.1,April 2002 pp.421-425
[19]S.Zhou and G.B.Giannakis," Finite-Alphabet Baseed Channel Estimation for OFDM and Related Multicarrier System".IEEE Trans.on Signal Processing,VOL.49,NO.8,pp,1402-1414,Aug,2001
[20]许晓杰 MIMO-OFDM中信道估计的技术和译码算法研究 吉林大学硕士学位论文,2006,5
[21]Sumit Roy,Senior Member,IEEE and Chengyang Li "A Subspace Blind Channel Estimation Method for OFDM Systems Without Cyclic Prefix" IEEE Trans.on Wireless communications,VOL.1,NO.4,October 2002
[22]T.S.Rappaport." Wireless Communication:principles practice".北京:电子工业出版社1998
[23]J.H.Winters." Smart Antenna for Wireless Systems".IEEE personal communications,1998,1(2):23-27
[24]M.Sandell and O.Edfors,"A comparative study of pilot-based channel estimators for wireless OFDM" Research Report TULSA 1996:19,Div.of Signal Processing,Lulea University of Technology,Sept.1996.
[25]S.Coleri,M.Ergen,A.Bahai."Channel estimation 2004.techniques based on pilot arrangement in OFDM systems" IEEE Trans.Broadcast.,VOL.48,NO.3,pp.223-229,Sept 2002
[26]李子,蔡跃明,阚春荣,徐友云,OFDM信系统中的盲信道估计(1解放军理工大学通信工程学院,江苏南京210007 2移动通信国家重点实验室)SIGNAL PROCESSING,2005年10月 第21卷 第5期.
[27]B.Muquet and M.de Courville,"Blind and semi-blind channel identi-fication methods using second order Estimation for OFDM systems",in Proc.IEEE Int.Conf Acoust.,Speech,Signal Processing,VOL.3,pp.2745-2748 Phoenix,AZ,Mar.1999
[28]E.Moulines,P.Duhamel,J.—F,Cardoso,ands.Mayrargue,"Subspace method for the blind identification of multichannel FIR filters",IEEE Trans.Signal Processing,VOL.43,pp.516- 525,Jan.1995.
[29]Rui Lin and Athina P.Petropulu,Senior Member,IEEE " linear Precoding Assisted Blind Channel Estimation foe OFDM Systems",IEEE Tran VOL.54,NO.3,MAY 2005
[30]N.Chotikakamthorn and H.B.Suzuki,"On identifiablility of OFDM blind channel estimation",in Proc.VTC Amsterdam,Netherland,Sept,1999,pp.2358-2361.
[31]C.K.Ho,B.Farbang-Boroujeny and F.Chin,"Added Pilot Semi-Blind Channel Estimation Scheme for OFDM in Fading Channels",GLOBECOM 200,NO.1,Now 2001pp.3075-3079
[32]张瑞齐 OFDM通信系统盲信道估计算法研究,硕士学位论文,2005,
[33]张瑞齐,廖桂生.一种循环保护前缀不足的OFDM信道估计算法[J]电波科学学报,2005,20(5):632-636.
[34]黄学军,毕厚杰,余松煜 OFDM系统信道盲估计的子空间算法 上海交通大学学报 第38卷增刊 2004年10月
[35]张贤达 《现代信号处理》(第二版),清华大学出版社,2002:37-151
[36]杨炜伟,蔡跃明,李子ZP-OFDM系统中基于信号子空间迭代拟合的盲信道估计(解放军理工大学通信工程学院,江苏南京210007)解放军理工大学学报第6卷第4期.2005
[37]Wei Kang and Benoit Champagne,Member,IEEE "Subspace-Based Blind Channel Estimation:Generalization and Performance Analysis" IEEE Trans.on Signal Processing,VOL.53,NO.3,pp,1402-1414,March,2005
[38]Bertrand Muquet,Member,IEEE,Marc de Courville,Member,IEEE,and Pierre Duhamel,Fellow,IEEE " Subspace-Based Blind and Semi-Blind Channel Estimation for OFDM Systems",IEEE Trans.on Signal Processing,VOL.50,NO.7,July,2002
[39]张贤达 《信号处理中的线性代数》(第一版),科学出版社,1997
[40]Chengyang Li,Member,IEEE,and Sumit Roy,Senior Member,IEEE "Subspace-Based Blind Channel Estimation for OFDM by Exploiting Virtual Carriers"IEEE Trans.on Wireless communications,VOL.2,NO.1,January 2003
[41]朱晓,张海滨.基于虚拟子载波的盲信道估计改进算法信息技术2007年第7期1009-2552(2007)07-0001-03
[2]罗涛,乐光新等多天线通信原理与应用 北京:北京邮电大学出版社,2005,1-5
[3]彭林 第三代移动通信技术 电子工业出版社 2003,2
[4]L.J.Cimini,JR,et al."Advanced Cellular Internet Service(ACIS)".IEEE Commun.Mag,1998,36(10):150-159
[5]J.Chuang,N.Souenberger."Beyond 3G:Wideband wireless date acess basedon OFDM and dynamic packet assignment".IEEE Commun.Mag,2000,38(7):78-87
[6]Y Kim,et al."Beyond 3G:Vision Requinements and Enabling Technologies".IEEE Comm.Magazine.Mar.2003,40(3):120-124
[7]吴伟陵.移动通信中的关键技术.北京:北京邮电大学出版社,2000.
[8]X.Cai end A.N.Akansu,"A subspace method for blind channel identification in OFDM systems" in Proc.ICC,New Orleans,LA,Jul.2000,pp.929-933.
[9]Blostein.S.D."Multiple antenna systems their role and impact in future wireless access".IEEE Comm.Mag.Jul.2003.41(70):94-101
[10]侯永民,戎蒙恬 一种有效的MIMO-OFDM系统盲信道估计算法 应用科学学报,第23卷第3期,2005年5月
[11]王颖,孟嗣仪MIMO—OFDM系统中信道估计方法分析(北京交通大学,电子信息工程学院)新技术与新业务
[12]姚维坚,曹雪虹MIMO-OFDM系统信道估计技术的分析 信息技术InformationTechnology第11期 2005年
[13]郭凌,邵世祥 多载波CDMA上行链路中的盲信道估计算法(南京邮电学院,江苏南京210003)重庆邮电学院学报第17卷第2期2005年4月
[14]隗炜,周雷,张贤达.异步CDMA系统中一种新颖的盲自适应多用户检测方法.清华大学学报(自然科学版),Vol.41 No.9:94-97,2001
[15]Shengli Zhou,Student Member,IEEE,Bertrand Muquet,and Georgios B.Giannakis,Fellow,IEEE "Subspace-Based(Semi-)Blind Channel Estimation for Block Precoded Space-Time OFDM" IEEE Trans.on Signal processing,VOL.50,NO.5,May 2002
[16]Zhiguo Ding and Darren B.Ward,Member,IEEE "Subspaee Approach to Blind and Semi-Blind Channel Estimation for Space-Time Block Codes ".IEEE Trans.on Wireless Commun.VOL.4,NO.2,March 2005
[17]Qi Bi,et al." Wireless mobile communication at the start of the 21st century".IEEE Commun.Mag,2001,39(1):110-116
[18]Necker,M.and Stuber,G L," Totally Blind Channel Estimation for OFDM over FAST Varying Mobile Channels".ICC 2002,no.1,April 2002 pp.421-425
[19]S.Zhou and G.B.Giannakis," Finite-Alphabet Baseed Channel Estimation for OFDM and Related Multicarrier System".IEEE Trans.on Signal Processing,VOL.49,NO.8,pp,1402-1414,Aug,2001
[20]许晓杰 MIMO-OFDM中信道估计的技术和译码算法研究 吉林大学硕士学位论文,2006,5
[21]Sumit Roy,Senior Member,IEEE and Chengyang Li "A Subspace Blind Channel Estimation Method for OFDM Systems Without Cyclic Prefix" IEEE Trans.on Wireless communications,VOL.1,NO.4,October 2002
[22]T.S.Rappaport." Wireless Communication:principles practice".北京:电子工业出版社1998
[23]J.H.Winters." Smart Antenna for Wireless Systems".IEEE personal communications,1998,1(2):23-27
[24]M.Sandell and O.Edfors,"A comparative study of pilot-based channel estimators for wireless OFDM" Research Report TULSA 1996:19,Div.of Signal Processing,Lulea University of Technology,Sept.1996.
[25]S.Coleri,M.Ergen,A.Bahai."Channel estimation 2004.techniques based on pilot arrangement in OFDM systems" IEEE Trans.Broadcast.,VOL.48,NO.3,pp.223-229,Sept 2002
[26]李子,蔡跃明,阚春荣,徐友云,OFDM信系统中的盲信道估计(1解放军理工大学通信工程学院,江苏南京210007 2移动通信国家重点实验室)SIGNAL PROCESSING,2005年10月 第21卷 第5期.
[27]B.Muquet and M.de Courville,"Blind and semi-blind channel identi-fication methods using second order Estimation for OFDM systems",in Proc.IEEE Int.Conf Acoust.,Speech,Signal Processing,VOL.3,pp.2745-2748 Phoenix,AZ,Mar.1999
[28]E.Moulines,P.Duhamel,J.—F,Cardoso,ands.Mayrargue,"Subspace method for the blind identification of multichannel FIR filters",IEEE Trans.Signal Processing,VOL.43,pp.516- 525,Jan.1995.
[29]Rui Lin and Athina P.Petropulu,Senior Member,IEEE " linear Precoding Assisted Blind Channel Estimation foe OFDM Systems",IEEE Tran VOL.54,NO.3,MAY 2005
[30]N.Chotikakamthorn and H.B.Suzuki,"On identifiablility of OFDM blind channel estimation",in Proc.VTC Amsterdam,Netherland,Sept,1999,pp.2358-2361.
[31]C.K.Ho,B.Farbang-Boroujeny and F.Chin,"Added Pilot Semi-Blind Channel Estimation Scheme for OFDM in Fading Channels",GLOBECOM 200,NO.1,Now 2001pp.3075-3079
[32]张瑞齐 OFDM通信系统盲信道估计算法研究,硕士学位论文,2005,
[33]张瑞齐,廖桂生.一种循环保护前缀不足的OFDM信道估计算法[J]电波科学学报,2005,20(5):632-636.
[34]黄学军,毕厚杰,余松煜 OFDM系统信道盲估计的子空间算法 上海交通大学学报 第38卷增刊 2004年10月
[35]张贤达 《现代信号处理》(第二版),清华大学出版社,2002:37-151
[36]杨炜伟,蔡跃明,李子ZP-OFDM系统中基于信号子空间迭代拟合的盲信道估计(解放军理工大学通信工程学院,江苏南京210007)解放军理工大学学报第6卷第4期.2005
[37]Wei Kang and Benoit Champagne,Member,IEEE "Subspace-Based Blind Channel Estimation:Generalization and Performance Analysis" IEEE Trans.on Signal Processing,VOL.53,NO.3,pp,1402-1414,March,2005
[38]Bertrand Muquet,Member,IEEE,Marc de Courville,Member,IEEE,and Pierre Duhamel,Fellow,IEEE " Subspace-Based Blind and Semi-Blind Channel Estimation for OFDM Systems",IEEE Trans.on Signal Processing,VOL.50,NO.7,July,2002
[39]张贤达 《信号处理中的线性代数》(第一版),科学出版社,1997
[40]Chengyang Li,Member,IEEE,and Sumit Roy,Senior Member,IEEE "Subspace-Based Blind Channel Estimation for OFDM by Exploiting Virtual Carriers"IEEE Trans.on Wireless communications,VOL.2,NO.1,January 2003
[41]朱晓,张海滨.基于虚拟子载波的盲信道估计改进算法信息技术2007年第7期1009-2552(2007)07-0001-03
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