MIMO-OFDM系统信道估计技术研究
摘要
正交频分复用(OFDM)技术和多入多出(MIMO)技术作为提高数据传输速率的重要手段受到人们越来越多的关注。对于MIMO-OFDM系统,准确的信道状态信息(CSI)是保证信息可靠接收的保证。信道估计技术对同步、子载波分配等都有不同程度的影响。因此,准确的估计信道状态信息,是MIMO-OFDM系统的关键问题之一。
信道估计算法分为导频辅助信道估计算法和盲信道估计算法两种。本文主要针对MIMO-OFDM系统的导频辅助信道估计技术进行研究。
论文第一部分主要讨论了基于导频符号辅助调制(PSAM)方法的SISO-OFDM信道估计技术。通过分析块状导频及梳状导频两种导频分布图案,论文针对块状导频,仿真讨论了LS、MMSE两种估计算法,最后针对梳状导频,比较了线性内插、高斯内插和cubic-spline三种内插算法,并在matlab平台上给出了基于块状导频和基于梳状导频的SISO-OFDM信道估计算法的仿真分析结果。研究表明,当信噪比增大后,cubic-spline内插法性能明显优于线性内插和高斯内插。
论文的第二部分围绕基于梳状导频符号的MIMO-OFDM信道估计算法展开。首先对基于导频位置处的信道估计算法进行研究,并针对LMMSE计算量大复杂度高的缺点,将基于奇异值SVD分解的算法应用于此以降低运算复杂度。基于导频位置处信道估计算法,论文分析了基于插值的数据位置处信道估计算法,讨论了线性内插、高斯内插、cubic-spline内插和基于DFT的信道估计算法。在此基础上,论文对于基于DFT的传统信道估计算法进行了改进,通过在时域忽略次要采样来消除噪声干扰,从而提高了信道估计精度。最后,论文基于matlab仿真环境对基于导频符号的MIMO-OFDM信道估计算法进行了仿真实现。
Orthogonal Frequency Division Multiplex (OFDM) and Multiple Input Multiple Output (MIMO) are widely recognized as a revolutionary technology for providing higher data rate in the future broadband wireless communication system. Obviously, accurate channel state information is essential to reliable information recovery. Channel estimation technique has different levels of impact to synchronization and sub-carrier allocation. Therefore, the accurate estimation of the channel state information is one of the key issues for MIMO-OFDM system. There are mainly two channel estimation methods: pilot-aided channel estimation and blind channel estimation. This thesis mainly concerns only with the pilot-aided channel estimation techniques for MIMO-OFDM system.
First, pilot symbol assisted modulation (PSAM) channel estimation is investigated for SISO-OFDM systems, mainly focusing on the block-type and comb-type channel estimation. A comparative analysis on popular pilot assisted estimation algorithms is provided, including LS, LMMSE pilot estimation algorithms, followed by three interpolation algorithms, i.e. linear interpolation, Gaussion interpolation and cubic-spline interpolation. It is shown by Matlab simulation and analysis that, with the increase of signal-to-noise ratio, the cubic-spline interpolation algorithm outperforms other two interpolation algorithms.
Next, comb pilot symbol assisted modulation (PSAM) channel estimation for MIMO-OFDM system is investigated. For the channel estimation algorithm of pilot location, in order to reduce the high complexity of LMMSE algorithm, a simplified method based on the singular value decomposition is given. Then the channel estimation algorithm based on the interpolation of the data location, including linear interpolation, Gaussion interpolation, cubic-spline interpolation algorithms and DFT channel estimation method, is discussed. On this basis, by neglecting secondary sampling in the time-domain to eliminate noise interference, the traditional DFT channel estimation method is improved, followed by Matlab-based computer simulation and discussion.
信道估计算法分为导频辅助信道估计算法和盲信道估计算法两种。本文主要针对MIMO-OFDM系统的导频辅助信道估计技术进行研究。
论文第一部分主要讨论了基于导频符号辅助调制(PSAM)方法的SISO-OFDM信道估计技术。通过分析块状导频及梳状导频两种导频分布图案,论文针对块状导频,仿真讨论了LS、MMSE两种估计算法,最后针对梳状导频,比较了线性内插、高斯内插和cubic-spline三种内插算法,并在matlab平台上给出了基于块状导频和基于梳状导频的SISO-OFDM信道估计算法的仿真分析结果。研究表明,当信噪比增大后,cubic-spline内插法性能明显优于线性内插和高斯内插。
论文的第二部分围绕基于梳状导频符号的MIMO-OFDM信道估计算法展开。首先对基于导频位置处的信道估计算法进行研究,并针对LMMSE计算量大复杂度高的缺点,将基于奇异值SVD分解的算法应用于此以降低运算复杂度。基于导频位置处信道估计算法,论文分析了基于插值的数据位置处信道估计算法,讨论了线性内插、高斯内插、cubic-spline内插和基于DFT的信道估计算法。在此基础上,论文对于基于DFT的传统信道估计算法进行了改进,通过在时域忽略次要采样来消除噪声干扰,从而提高了信道估计精度。最后,论文基于matlab仿真环境对基于导频符号的MIMO-OFDM信道估计算法进行了仿真实现。
Orthogonal Frequency Division Multiplex (OFDM) and Multiple Input Multiple Output (MIMO) are widely recognized as a revolutionary technology for providing higher data rate in the future broadband wireless communication system. Obviously, accurate channel state information is essential to reliable information recovery. Channel estimation technique has different levels of impact to synchronization and sub-carrier allocation. Therefore, the accurate estimation of the channel state information is one of the key issues for MIMO-OFDM system. There are mainly two channel estimation methods: pilot-aided channel estimation and blind channel estimation. This thesis mainly concerns only with the pilot-aided channel estimation techniques for MIMO-OFDM system.
First, pilot symbol assisted modulation (PSAM) channel estimation is investigated for SISO-OFDM systems, mainly focusing on the block-type and comb-type channel estimation. A comparative analysis on popular pilot assisted estimation algorithms is provided, including LS, LMMSE pilot estimation algorithms, followed by three interpolation algorithms, i.e. linear interpolation, Gaussion interpolation and cubic-spline interpolation. It is shown by Matlab simulation and analysis that, with the increase of signal-to-noise ratio, the cubic-spline interpolation algorithm outperforms other two interpolation algorithms.
Next, comb pilot symbol assisted modulation (PSAM) channel estimation for MIMO-OFDM system is investigated. For the channel estimation algorithm of pilot location, in order to reduce the high complexity of LMMSE algorithm, a simplified method based on the singular value decomposition is given. Then the channel estimation algorithm based on the interpolation of the data location, including linear interpolation, Gaussion interpolation, cubic-spline interpolation algorithms and DFT channel estimation method, is discussed. On this basis, by neglecting secondary sampling in the time-domain to eliminate noise interference, the traditional DFT channel estimation method is improved, followed by Matlab-based computer simulation and discussion.
引文
[1]Recommendation ITU-RM.1645:Vision frame work and over all objectives of the future development of IMT-2000 and of systems beyond IMT-2000.
[2]Zahariadis T.Trends in the Path to 4G.Communications Engineer,2003,Vol.1(1),PP.12-15.
[3]Chuang J.and Sollenberger N.Beyond 3G:wideband wireless data access based on OFDM and dynamic Packet assignment.IEEE Communications Magazine,2000,Vol.38(7),PP.78-87.
[4]Sampath H,Tellado J,A fourth-generation MIMO-OFDM broad wireless Systems design,performance,and field trial results.IEEE Communications Magazine,2002,vol.40(9),PP.143-149.
[5]Doufexi A.,Armour S,Butler M.,etc.A comparison of the HIPERLAN/2 and IEEES02.11a wireless LAN standards.lEEE Commun.Magazine,vol.40,no.5,PP·172-180,May2002.
[6]A.van Zelst,TC.W.Schenk.Implementation of a MIMO OFDM- based wireless LAN system.IEEE Transactions on Signal processing,2004,vol.52(2),PP.483-494.
[7]S.Alamouti.a simple transmit diversity technique for wireless communications.IEEE J.Sel.Areas Commun,Vol.16,No.8,pp:1451-1458,Oct 1998
[8]Tarokh.V,Jafarkhani.H,Calderbank.A.R.Space-time block codes from orthogonal designs.Information Theory,IEEE Transactions,vol.45,issue 5,pp.1256-1267,July 1999
[9]Siavash M.Alamouti.A simple transmit diversity technique for wireless communications.IEEE J.Select.Areas Commun.vol.16,pp.1451-1458,Aug.1998.
[10]刘刚、郭漪、葛建华,MIMO-OFDM系统中的信道估计,华中科技大学学报,2005.9,26-29
[11]王颖、孟嗣仪,MIMO-OFDM系统中的信道估计方法分析,中国数据通信,2005.6,122-125.
[12]杨大成,移动传播环境,机械工业出版社,2003,178-262.
[13]Hiroshi Harada,Ramjee Prasad,Simulation and software radio for mobile communications
[14]佟学俭、罗涛,OFDM移动通信技术原理与应用,人民邮电出版社,2003.
[15]张海滨.正交频分复用的基本原理与关键技术.国防工业出版社.2006
[16]况少平、郭庆平、李黎,OFDM时域信道估计的MMSE简化算法,武汉理工大学学报,2005.8,120-122.
[17]胡蝶、杨绿溪,OFDM系统中基于导频的时变信道估计,电子与信息学报,2004.9,1376-1382.
[18]Xiaowen Wang,K.J.Ray Liu,OFDM Channel Estimation Based on Time Frequency Polynomial Model of Fading Multipath Channel,IEEE,2001,460-464.
[19]张海霞、袁东风、江铭炎、吴大雷,正交频分复用系统在不同信道下的性能分析,山东大学学报,2004.2,85-88.
[20]Aleksandar Jeremic,Timothy A.Thomas,OFDM Channel Estimation in the Presence of Interference,IEEE,3429-3439.
[21]韩旭东、张春业、曹建海,MIMO-OFDM无线局域网的研究及其关键技术,中国数据通信,2004.2,17-22.
[22]贺莉娟,MIMO-OFDM系统信道估计分析,中国新通信,2005,70-72.
[23]周鹏,赵春明,盛彬,MIMO-OFDM系统中基于导频辅助的信道估计,电子与信息学报,2007.01,vol29,133-137.
[24]Suh C,Hwang C S,and Choi H.Comparative study of time-domain and frequency-domain channel estimation in MIMO-OFDM systems[A].IEEE 14th Proceedings on PIMRC'2003,Beijing,2003,2:1095-1099.
[25]Barhumi I,Leus G,and Moonen M.Optimal training design MIMO OFDM systems in mobile wireless channels[J].IEEE for Trans.on Signal Processing,2003,51(6):1615-1624.OFDM systems,"in Proc.IEEE 54th Vehicular Technology Conf.,
[26]Yi Gong and K.B.Letaief,Low rank channel estimation for space-time coded wideband pp.772-776,Fall 2001.
[27]Ya Jing,Dongming Wang,Ming Chen,Reduced Complexity MIMO-OFDM Channel Estimation based on Parametric Channel Model,IEEE,2004,1372-1376.
[28]Edfors,M.Sandell,J-J.vande Beek,S.K.Wislon,and P.O.Bojesson.Analysis of DFT-based channel estimation for OFDM.Personal Wireless Communieation,Kuwer AcademiePublishers,vol.12,no.1,Jan.2000.
[29]Zhao Y,Li W,WU W.An efficient channel estimation method for OFDM systems with multiple transmit antennas.IEEE International Conference onInfo-tech&Info-net,Beijing,2001,PP.335-339.
[30]杨志刚,何丰.基于导频符号的OFDM信道估计技术研究.寒山师范学院学报.2006年03期
[31]吴伟陵、牛凯,移动通信原理,电子工业出版社,2005,252-262、290-322
[32]Enrique Ulffe Whu,Stanford University,MIMO-OFDM Systems for High Data Rate Wireless Networks,Advanced Wireless Networks,MIMO-OFDM WirelessNetworks,1-7.
[33]Changho Suh,Chan-Soo Hwang,Hokyu Choi.comparative study of time-domain and frequency-domain channel estimation in MIMO-OFDM systems.The 14th IEEE 2003
[34]张继东,郑宝玉,基于导频的OFDM信道估计及其研究进展,通信学报,2003.11,vol24 No.11
[35]孙翠珍,曾召华,韩晓冰,无线通信中基于导频的OFDM信道估计算法仿真研究。西安理工大学学报,2006,22(2):195-198.
[36]张恩伟,姜媛儿,孙松林.OFDM系统中插值技术的研究与实现.中国无线电,2006(5):62-66.
[37]王阶,汪利辉,龚耀寰.宽带快衰落信道中高斯插值算法研究.实验科学与技术,2006(2):8-11.
[38]沈若聘,李健,基于梳状导频的OFDM信道估计算法,电力系统通信,200805,vol29,pp38-42.
[39]Wang Yi,Tao Xiaofeng,Zhang Ping.Scheme of pilot design and channel estimation in M IMO2OFDM system[J].Journal of Beijing University of Posts and Telecommunications,2007,30(3):45249.
[40]Kang G,Hasselbach P,Yu Yang,et al.Pilot design for inter2cell interference mitigation in M IMO OFDM systems[J].IEEE Commun Letters,2007,11(3):2732239.
[41]王德胜,朱光喜,林宏志.MIMO-OFDM最优导频设置与优化的信道估计方法.通信学报,2005,26(1):34239
[42]王东明,高西奇,尤肖虎等.宽带MIMO-OFDM系统信道估计算法研究.电子学报,2005,33(7):125421257
[43]唐云,王玲,MIMO-OFDM信道估计算法研究,通信技术,200705,pp80-83.
[44]Beek J,Sandell M,OFDM channel estimation by singular value decomposition.IEEE VTC'96,May 1996,923-927
[45]Li Y.Winters J H,Sollenberger N R.MIMO-OFDM for wireless communications:Signal detection with enhanced channel estimation.IEEE Trans.Vol.50,pp:1471-1477.Sept 2002
[46]Xiaoyun Hou,,Baoyu Zheng,Channel estimation for MIMO-OFDM-based wireless networks,.1883-1887,Sept 2004
[47]胡蝶,杨绿溪,一种改进的MIMO-OFDM系统信道估计算法,电路与系统学报,2006年8月
[48]董亮,毕光国,基于空时分组训练序列的低复杂度MIMO-OFDM信道估计通信学报2006年第06期
[49]王宝文,吴国荣,刘文远,MIMO-OFDM系统中一种有效的信道估计方法,计算机应用,Journal of Computer Applications,2006年06期
[50]王萍;朱琦;阎海亮;基于IEEE802.16e的MIMO-OFDM系统的信道估计.南京邮电大学学报(自然科学版),2006年04期
[2]Zahariadis T.Trends in the Path to 4G.Communications Engineer,2003,Vol.1(1),PP.12-15.
[3]Chuang J.and Sollenberger N.Beyond 3G:wideband wireless data access based on OFDM and dynamic Packet assignment.IEEE Communications Magazine,2000,Vol.38(7),PP.78-87.
[4]Sampath H,Tellado J,A fourth-generation MIMO-OFDM broad wireless Systems design,performance,and field trial results.IEEE Communications Magazine,2002,vol.40(9),PP.143-149.
[5]Doufexi A.,Armour S,Butler M.,etc.A comparison of the HIPERLAN/2 and IEEES02.11a wireless LAN standards.lEEE Commun.Magazine,vol.40,no.5,PP·172-180,May2002.
[6]A.van Zelst,TC.W.Schenk.Implementation of a MIMO OFDM- based wireless LAN system.IEEE Transactions on Signal processing,2004,vol.52(2),PP.483-494.
[7]S.Alamouti.a simple transmit diversity technique for wireless communications.IEEE J.Sel.Areas Commun,Vol.16,No.8,pp:1451-1458,Oct 1998
[8]Tarokh.V,Jafarkhani.H,Calderbank.A.R.Space-time block codes from orthogonal designs.Information Theory,IEEE Transactions,vol.45,issue 5,pp.1256-1267,July 1999
[9]Siavash M.Alamouti.A simple transmit diversity technique for wireless communications.IEEE J.Select.Areas Commun.vol.16,pp.1451-1458,Aug.1998.
[10]刘刚、郭漪、葛建华,MIMO-OFDM系统中的信道估计,华中科技大学学报,2005.9,26-29
[11]王颖、孟嗣仪,MIMO-OFDM系统中的信道估计方法分析,中国数据通信,2005.6,122-125.
[12]杨大成,移动传播环境,机械工业出版社,2003,178-262.
[13]Hiroshi Harada,Ramjee Prasad,Simulation and software radio for mobile communications
[14]佟学俭、罗涛,OFDM移动通信技术原理与应用,人民邮电出版社,2003.
[15]张海滨.正交频分复用的基本原理与关键技术.国防工业出版社.2006
[16]况少平、郭庆平、李黎,OFDM时域信道估计的MMSE简化算法,武汉理工大学学报,2005.8,120-122.
[17]胡蝶、杨绿溪,OFDM系统中基于导频的时变信道估计,电子与信息学报,2004.9,1376-1382.
[18]Xiaowen Wang,K.J.Ray Liu,OFDM Channel Estimation Based on Time Frequency Polynomial Model of Fading Multipath Channel,IEEE,2001,460-464.
[19]张海霞、袁东风、江铭炎、吴大雷,正交频分复用系统在不同信道下的性能分析,山东大学学报,2004.2,85-88.
[20]Aleksandar Jeremic,Timothy A.Thomas,OFDM Channel Estimation in the Presence of Interference,IEEE,3429-3439.
[21]韩旭东、张春业、曹建海,MIMO-OFDM无线局域网的研究及其关键技术,中国数据通信,2004.2,17-22.
[22]贺莉娟,MIMO-OFDM系统信道估计分析,中国新通信,2005,70-72.
[23]周鹏,赵春明,盛彬,MIMO-OFDM系统中基于导频辅助的信道估计,电子与信息学报,2007.01,vol29,133-137.
[24]Suh C,Hwang C S,and Choi H.Comparative study of time-domain and frequency-domain channel estimation in MIMO-OFDM systems[A].IEEE 14th Proceedings on PIMRC'2003,Beijing,2003,2:1095-1099.
[25]Barhumi I,Leus G,and Moonen M.Optimal training design MIMO OFDM systems in mobile wireless channels[J].IEEE for Trans.on Signal Processing,2003,51(6):1615-1624.OFDM systems,"in Proc.IEEE 54th Vehicular Technology Conf.,
[26]Yi Gong and K.B.Letaief,Low rank channel estimation for space-time coded wideband pp.772-776,Fall 2001.
[27]Ya Jing,Dongming Wang,Ming Chen,Reduced Complexity MIMO-OFDM Channel Estimation based on Parametric Channel Model,IEEE,2004,1372-1376.
[28]Edfors,M.Sandell,J-J.vande Beek,S.K.Wislon,and P.O.Bojesson.Analysis of DFT-based channel estimation for OFDM.Personal Wireless Communieation,Kuwer AcademiePublishers,vol.12,no.1,Jan.2000.
[29]Zhao Y,Li W,WU W.An efficient channel estimation method for OFDM systems with multiple transmit antennas.IEEE International Conference onInfo-tech&Info-net,Beijing,2001,PP.335-339.
[30]杨志刚,何丰.基于导频符号的OFDM信道估计技术研究.寒山师范学院学报.2006年03期
[31]吴伟陵、牛凯,移动通信原理,电子工业出版社,2005,252-262、290-322
[32]Enrique Ulffe Whu,Stanford University,MIMO-OFDM Systems for High Data Rate Wireless Networks,Advanced Wireless Networks,MIMO-OFDM WirelessNetworks,1-7.
[33]Changho Suh,Chan-Soo Hwang,Hokyu Choi.comparative study of time-domain and frequency-domain channel estimation in MIMO-OFDM systems.The 14th IEEE 2003
[34]张继东,郑宝玉,基于导频的OFDM信道估计及其研究进展,通信学报,2003.11,vol24 No.11
[35]孙翠珍,曾召华,韩晓冰,无线通信中基于导频的OFDM信道估计算法仿真研究。西安理工大学学报,2006,22(2):195-198.
[36]张恩伟,姜媛儿,孙松林.OFDM系统中插值技术的研究与实现.中国无线电,2006(5):62-66.
[37]王阶,汪利辉,龚耀寰.宽带快衰落信道中高斯插值算法研究.实验科学与技术,2006(2):8-11.
[38]沈若聘,李健,基于梳状导频的OFDM信道估计算法,电力系统通信,200805,vol29,pp38-42.
[39]Wang Yi,Tao Xiaofeng,Zhang Ping.Scheme of pilot design and channel estimation in M IMO2OFDM system[J].Journal of Beijing University of Posts and Telecommunications,2007,30(3):45249.
[40]Kang G,Hasselbach P,Yu Yang,et al.Pilot design for inter2cell interference mitigation in M IMO OFDM systems[J].IEEE Commun Letters,2007,11(3):2732239.
[41]王德胜,朱光喜,林宏志.MIMO-OFDM最优导频设置与优化的信道估计方法.通信学报,2005,26(1):34239
[42]王东明,高西奇,尤肖虎等.宽带MIMO-OFDM系统信道估计算法研究.电子学报,2005,33(7):125421257
[43]唐云,王玲,MIMO-OFDM信道估计算法研究,通信技术,200705,pp80-83.
[44]Beek J,Sandell M,OFDM channel estimation by singular value decomposition.IEEE VTC'96,May 1996,923-927
[45]Li Y.Winters J H,Sollenberger N R.MIMO-OFDM for wireless communications:Signal detection with enhanced channel estimation.IEEE Trans.Vol.50,pp:1471-1477.Sept 2002
[46]Xiaoyun Hou,,Baoyu Zheng,Channel estimation for MIMO-OFDM-based wireless networks,.1883-1887,Sept 2004
[47]胡蝶,杨绿溪,一种改进的MIMO-OFDM系统信道估计算法,电路与系统学报,2006年8月
[48]董亮,毕光国,基于空时分组训练序列的低复杂度MIMO-OFDM信道估计通信学报2006年第06期
[49]王宝文,吴国荣,刘文远,MIMO-OFDM系统中一种有效的信道估计方法,计算机应用,Journal of Computer Applications,2006年06期
[50]王萍;朱琦;阎海亮;基于IEEE802.16e的MIMO-OFDM系统的信道估计.南京邮电大学学报(自然科学版),2006年04期