正交频分复用系统中载频偏移估计算法的研究
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摘要
正交频分复用(OFDM)技术已经在无线通信领域有了广泛应用，它将是未来无线宽带接入系统的基本技术之一，并且已经被业界定为未来移动通信系统的核心技术。载频偏移问题是OFDM技术应用要解决的关键之一，它对系统的性能影响很大，近年来成为人们研究的热点。
本文简单介绍了OFDM系统的产生、发展，及其基本工作原理、特点和技术优势。在此基础上讨论了四类载波频率偏移估计算法的主要思想和各自的优缺点，并提出了一些改进方法。
作者研究了MLE、SCA及其改进方法和两种基于子空间的算法：类
MUSIC和类ESPRIT算法．分析了它们的主要思想、实现方法和各自的优缺点．并分别进行了仿真；改进了MLE结合SCA的方法，提出了在得到较准确的帧定时后使用SCA算法进行整个粗细频偏估计的方法，仿真结果表明它有更好的估计精度和较小的计算量；创造性地采用两种经典的ESPRIT方法(LS．ESPRIT和TLS—ESPRIT)估计载波频率偏移，也达到了与类ESPRIT算法相近甚至更好的估计性能；最后作者把频偏估计算法应用于一个设计的OFDM系统中，仿真表明应用频偏估计及校正方法很好地消除了载频偏移的影响，保证了良好的系统性能。
Orthogonal Frequency Division Multiplexing(OFDM)has been extensively used in the
areaofradio communication systems，itwillbethebasictechniqueofthefuturebroadband radio
access system，and also has been considered as the core technique of future mobile
communication system．Cartier frequency offset is the key problem to use OFDM,so
researchers recently focus on it．
This paper simply introduces the emergence，development,basic working theory,
characteristics and the merits of OFDM systems．Four calTier frequency offset estimation
algorithms are respectively discussed about their chief theories，classical algorithms and
problems that they have．Then it proposes some new modified methods to estimate CalTier
frequency offset．
With the basic MLE，SCA algorithms and MUSIC-Like，ESPRIT-Like which belong to
the subspace cartierfrequency Offset estimation algorithms being researched,they are simulatedrespectively．Then this paper modified the combination method,itfirst attains more exact timingestimation based on MLE，then estimates entire frequency offset based on SCA．Simulation results show that this new method is of better precision and little computation．Two Novel algorithms belonging to classical subspace method,LS—ESPRIT and TLS-ESPRIT,are also proposed to estinaate carrier frequency offset．They have the same even better estimation performance as ESPRIT-Like．At the end ofthis paper a simple simulation about appfication estimation algorithms to OFDM systems shows that they are feasible and efficient to maintain good system performance．
本文简单介绍了OFDM系统的产生、发展，及其基本工作原理、特点和技术优势。在此基础上讨论了四类载波频率偏移估计算法的主要思想和各自的优缺点，并提出了一些改进方法。
作者研究了MLE、SCA及其改进方法和两种基于子空间的算法：类
MUSIC和类ESPRIT算法．分析了它们的主要思想、实现方法和各自的优缺点．并分别进行了仿真；改进了MLE结合SCA的方法，提出了在得到较准确的帧定时后使用SCA算法进行整个粗细频偏估计的方法，仿真结果表明它有更好的估计精度和较小的计算量；创造性地采用两种经典的ESPRIT方法(LS．ESPRIT和TLS—ESPRIT)估计载波频率偏移，也达到了与类ESPRIT算法相近甚至更好的估计性能；最后作者把频偏估计算法应用于一个设计的OFDM系统中，仿真表明应用频偏估计及校正方法很好地消除了载频偏移的影响，保证了良好的系统性能。
Orthogonal Frequency Division Multiplexing(OFDM)has been extensively used in the
areaofradio communication systems，itwillbethebasictechniqueofthefuturebroadband radio
access system，and also has been considered as the core technique of future mobile
communication system．Cartier frequency offset is the key problem to use OFDM,so
researchers recently focus on it．
This paper simply introduces the emergence，development,basic working theory,
characteristics and the merits of OFDM systems．Four calTier frequency offset estimation
algorithms are respectively discussed about their chief theories，classical algorithms and
problems that they have．Then it proposes some new modified methods to estimate CalTier
frequency offset．
With the basic MLE，SCA algorithms and MUSIC-Like，ESPRIT-Like which belong to
the subspace cartierfrequency Offset estimation algorithms being researched,they are simulatedrespectively．Then this paper modified the combination method,itfirst attains more exact timingestimation based on MLE，then estimates entire frequency offset based on SCA．Simulation results show that this new method is of better precision and little computation．Two Novel algorithms belonging to classical subspace method,LS—ESPRIT and TLS-ESPRIT,are also proposed to estinaate carrier frequency offset．They have the same even better estimation performance as ESPRIT-Like．At the end ofthis paper a simple simulation about appfication estimation algorithms to OFDM systems shows that they are feasible and efficient to maintain good system performance．
引文
[1] Elena Costa,Silvano Pupolin. M-QAM-OFDM System Performance in the Presence of a Nonlinear Amplifier and Phase Noise. IEEE Trans,2002,50(3):462～472
[2] Yupingzhao and Sven-Gustav Haggman. BER Analysis of OFDM Communication System with Intercarrier Interference. ICCT’98 ,S38-02-1～S38-02-5
[3] T.Pollet,M.Van. Bladel,M.Moeneclaey. BER Sensitivity of OFDM Systems to Carriers Frequency Offset and Wiener Phase Noise.IEEE Trans,1995,43:191～193
[4] Jean Armstrong. Analysis of New and Existing Methods of Reducing Intercarrier Interference Due to Carrier Frequency Offset in OFDM.
IEEE Trans,1999,47(3): 365～369
[5] Van de Beek J J,Sandell M,Borjesson P O. ML Estimation of Time and Frequency Offset in OFDM Systems. IEEE Trans,1997,45(7): 1800～1805
[6] Timothy M.Schmidl,Donald C.Cox. Robust Frequency and Timing Synchronization for OFDM. IEEE Trans,1997,45(12):1613～1621
[7] YHN H K,Young Hahm. An Efficient Frequency Offset Estimator for Timing and Frequency Synchronization in OFDM Systems. IEEE Trans,2001,50(5):580～583
[8] M.Morelli,U.Mengali. An Improved Frequency Offset Estimator for OFDM Appplications IEEE Trans ,1999,106～109
[10] Hui Liu,Ufuk Tureli. A High-Efficiency Carrier Estimator for OFDM Communications
IEEE Trans,1998,2(4):104～106
[11] Tureli U,Liu H,Zoltowski M D. OFDM Blind Carrier Offset Estimation:ESPRIT
IEEE Trans,2000,48(9):1459～1461
[12] Paul H.Moose. A Technique for Orthogonal Frequency Division Multiplexing Frequency Offset Correction. IEEE Trans,1994,42(10):2908～2914
[13] Macro Luise,Ruggero Reggiannini. Carrier Frequency Acquisition and Tracking for OFDM Systems. IEEE Trans,1996,44(11):1590～1598
[14] Giovanni Santella. A Frequency and Symbol Synchronization System for OFDM Signal:Architecture and Simulation Results. IEEE Trans,2000,49(1):254～275
[15] Macro Luise,Macro Marselli,Ruggero Reggiannini. Low-Complexity Blind Carrier Frequency Recovery for OFDM Signals over Frequency-Selective Radio Channels.
IEEE Trans,2002,50(7):1182～1188
[16] Ferdinand Classen,Heinrich Meyr. Frequency Synchronization Algorithms for OFDM
Systems Suitable for Communication over Frequency Selective Fading Channels
IEEE Trans,1994,1655～1659
[17] R.Roy,A.Paulraj,T.Kailath. ESPRIT-A Subspace Ratation Approach to Estimation of Parameters of Cisoids in Noise. IEEE Trans,1986,34(5):1340～1342
[18] 王电平等.多载波调制(MCM)系统及其性能分析.
重庆邮电大学学报,1998,10(1):30～33
[19] 赵亚红,李伟华等.正交多载波调制(OFDM)技术及应用.电讯技术,2001,(1)
[20] 吴俊,赵建平等.多载波CDMA在第三代移动通信中的应用.
移动通信,1998,(2):26～29
[21] 阮象华.基于OFDM传输中的频率偏移和信道估计.电视广播与传输,2001,(5)
[22] 曾璐,葛建华.利用叠加导频技术进行OFDM系统同步的算法.
通信技术,2002,(5):20～25
[23] 周一青,胡爱群.利用训练帧进行OFDM系统统的新算法.通信学报,2001,(4):13～18
[24] 冯爱刚,殷勤业等.正交频分复用码分多址系统盲自适应频率同步算法.
西安交通大学学报,2002,(8):834～838
[25] 严春林等.一种利用PN序列的OFDM频率同步.
电子科技大学学报,2003,(10):495～498
[26] 王亚莉等.一种适用于瑞利衰落信道的有效的OFDM时频同步体制.
通信学报,2003,(1):18～24
[27] 欧阳喜,葛临东等.一种基于代价函数的正交频分复用中符号同步与频偏估计算法.
电讯技术,2002,(3):22～26
[28] 李思伟,张建超.正交频分复用的原理及应用.
中国民航学院学报,1999,(10):35～39
[29] 叶中付,一种快速TLS-ESPRIT算法.信号处理,1998,14(2):146～149
[30] 张贤达,保铮著.通信信号处理.北京:国防工业出版社,2000
[31] 张贤达,信号处理中的线性代数.北京:科学出版社?1997
[32] 王曙,周希朗.阵列信号波达方向与频率的同时估计方法.??
上海交通大学学报,1999,33(1):40～42
[2] Yupingzhao and Sven-Gustav Haggman. BER Analysis of OFDM Communication System with Intercarrier Interference. ICCT’98 ,S38-02-1～S38-02-5
[3] T.Pollet,M.Van. Bladel,M.Moeneclaey. BER Sensitivity of OFDM Systems to Carriers Frequency Offset and Wiener Phase Noise.IEEE Trans,1995,43:191～193
[4] Jean Armstrong. Analysis of New and Existing Methods of Reducing Intercarrier Interference Due to Carrier Frequency Offset in OFDM.
IEEE Trans,1999,47(3): 365～369
[5] Van de Beek J J,Sandell M,Borjesson P O. ML Estimation of Time and Frequency Offset in OFDM Systems. IEEE Trans,1997,45(7): 1800～1805
[6] Timothy M.Schmidl,Donald C.Cox. Robust Frequency and Timing Synchronization for OFDM. IEEE Trans,1997,45(12):1613～1621
[7] YHN H K,Young Hahm. An Efficient Frequency Offset Estimator for Timing and Frequency Synchronization in OFDM Systems. IEEE Trans,2001,50(5):580～583
[8] M.Morelli,U.Mengali. An Improved Frequency Offset Estimator for OFDM Appplications IEEE Trans ,1999,106～109
[10] Hui Liu,Ufuk Tureli. A High-Efficiency Carrier Estimator for OFDM Communications
IEEE Trans,1998,2(4):104～106
[11] Tureli U,Liu H,Zoltowski M D. OFDM Blind Carrier Offset Estimation:ESPRIT
IEEE Trans,2000,48(9):1459～1461
[12] Paul H.Moose. A Technique for Orthogonal Frequency Division Multiplexing Frequency Offset Correction. IEEE Trans,1994,42(10):2908～2914
[13] Macro Luise,Ruggero Reggiannini. Carrier Frequency Acquisition and Tracking for OFDM Systems. IEEE Trans,1996,44(11):1590～1598
[14] Giovanni Santella. A Frequency and Symbol Synchronization System for OFDM Signal:Architecture and Simulation Results. IEEE Trans,2000,49(1):254～275
[15] Macro Luise,Macro Marselli,Ruggero Reggiannini. Low-Complexity Blind Carrier Frequency Recovery for OFDM Signals over Frequency-Selective Radio Channels.
IEEE Trans,2002,50(7):1182～1188
[16] Ferdinand Classen,Heinrich Meyr. Frequency Synchronization Algorithms for OFDM
Systems Suitable for Communication over Frequency Selective Fading Channels
IEEE Trans,1994,1655～1659
[17] R.Roy,A.Paulraj,T.Kailath. ESPRIT-A Subspace Ratation Approach to Estimation of Parameters of Cisoids in Noise. IEEE Trans,1986,34(5):1340～1342
[18] 王电平等.多载波调制(MCM)系统及其性能分析.
重庆邮电大学学报,1998,10(1):30～33
[19] 赵亚红,李伟华等.正交多载波调制(OFDM)技术及应用.电讯技术,2001,(1)
[20] 吴俊,赵建平等.多载波CDMA在第三代移动通信中的应用.
移动通信,1998,(2):26～29
[21] 阮象华.基于OFDM传输中的频率偏移和信道估计.电视广播与传输,2001,(5)
[22] 曾璐,葛建华.利用叠加导频技术进行OFDM系统同步的算法.
通信技术,2002,(5):20～25
[23] 周一青,胡爱群.利用训练帧进行OFDM系统统的新算法.通信学报,2001,(4):13～18
[24] 冯爱刚,殷勤业等.正交频分复用码分多址系统盲自适应频率同步算法.
西安交通大学学报,2002,(8):834～838
[25] 严春林等.一种利用PN序列的OFDM频率同步.
电子科技大学学报,2003,(10):495～498
[26] 王亚莉等.一种适用于瑞利衰落信道的有效的OFDM时频同步体制.
通信学报,2003,(1):18～24
[27] 欧阳喜,葛临东等.一种基于代价函数的正交频分复用中符号同步与频偏估计算法.
电讯技术,2002,(3):22～26
[28] 李思伟,张建超.正交频分复用的原理及应用.
中国民航学院学报,1999,(10):35～39
[29] 叶中付,一种快速TLS-ESPRIT算法.信号处理,1998,14(2):146～149
[30] 张贤达,保铮著.通信信号处理.北京:国防工业出版社,2000
[31] 张贤达,信号处理中的线性代数.北京:科学出版社?1997
[32] 王曙,周希朗.阵列信号波达方向与频率的同时估计方法.??
上海交通大学学报,1999,33(1):40～42