OFDM系统中的同步算法仿真与性能分析
摘要
正交频分复用(OFDM,Orthogonal Frequency Division Multiplexing)作为多载波调制技术的之一,是当前一种非常热门的通信技术,也被公认为是第四代移动通信(4G)的核心技术之一。它具有抗多径衰落和频谱利用率高的特点,被广泛用于高速数字通信领域。
但作为一种利用正交子载波的多载波调制技术,OFDM对于频偏非常敏感,因此,如何获得可靠的同步信息成为OFDM研究中的关键。对于OFDM的同步算法而言,主要沿袭两条思路,分别是基于数据辅助型的算法和非基于数据辅助型的算法。论文的研究方向是对前一大类算法的研究和仿真分析,主要的工作有以下几点。
(1)在MATLAB/SIMULINK中构建基本OFDM系统的仿真模型。
(2)针对数据辅助型算法中最经典的最大似然估计算法(MaximumLikelihood,ML)和SC算法进行理论研究和算法仿真。先通过理论分析找出其各自的不足之处,再通过MATLAB对各个算法进行编码实现,最后仿真验证在理论推导时所取得的相关结论。
(3)通过经典算法的启示,引入介绍一种新的同步算法,此算法相对于SC算法而言在定时同步点的确定这一方面有着明显的改进。同样,先通过理论分析对该算法进行简单的推导计算,再通过MATLAB编码实现该算法,最后仿真验证其改进性能。
(4)通过定时同步图形与频偏标准差对三种算法进行比较。
Orthogonal Frequency Division Multiplexing (OFDM), a special form of multicarrier modulation (MCM), has recently received considerable attention as well as be considered as the core technique of the forth mobile communication. It's be widely used in high speed digital communication for its robustness to multipath selective fading and high bandwidth efficiency.
As a kind of multicarrier modulation using orthogonal sub carriers, OFDM is sensitive to frequency offset and the time synchronization error. The key problem is acquiring the synchronization information. There are two kinds of synchronization algorithm, basing on date and un-basing on data. This paper focus on the front one. The tasks of this paper are four points.
(1) Build a model for basic OFDM system in MATLAB/SIMULINK.
(2) Analyze ML algorithm and SC algorithm and then realize them with programming in MATLAB. Finally, find the shortcuts of them.
(3) A new improved algorithm based on SC algorithm is introduced and analyzed. As the result, the programmed algorithm will improve the time synchronization of SC algorithm.
(4) These three algorithms are compared in two aspects, the figure of time synchronization and Standard Deviation of frequency offset.
但作为一种利用正交子载波的多载波调制技术,OFDM对于频偏非常敏感,因此,如何获得可靠的同步信息成为OFDM研究中的关键。对于OFDM的同步算法而言,主要沿袭两条思路,分别是基于数据辅助型的算法和非基于数据辅助型的算法。论文的研究方向是对前一大类算法的研究和仿真分析,主要的工作有以下几点。
(1)在MATLAB/SIMULINK中构建基本OFDM系统的仿真模型。
(2)针对数据辅助型算法中最经典的最大似然估计算法(MaximumLikelihood,ML)和SC算法进行理论研究和算法仿真。先通过理论分析找出其各自的不足之处,再通过MATLAB对各个算法进行编码实现,最后仿真验证在理论推导时所取得的相关结论。
(3)通过经典算法的启示,引入介绍一种新的同步算法,此算法相对于SC算法而言在定时同步点的确定这一方面有着明显的改进。同样,先通过理论分析对该算法进行简单的推导计算,再通过MATLAB编码实现该算法,最后仿真验证其改进性能。
(4)通过定时同步图形与频偏标准差对三种算法进行比较。
Orthogonal Frequency Division Multiplexing (OFDM), a special form of multicarrier modulation (MCM), has recently received considerable attention as well as be considered as the core technique of the forth mobile communication. It's be widely used in high speed digital communication for its robustness to multipath selective fading and high bandwidth efficiency.
As a kind of multicarrier modulation using orthogonal sub carriers, OFDM is sensitive to frequency offset and the time synchronization error. The key problem is acquiring the synchronization information. There are two kinds of synchronization algorithm, basing on date and un-basing on data. This paper focus on the front one. The tasks of this paper are four points.
(1) Build a model for basic OFDM system in MATLAB/SIMULINK.
(2) Analyze ML algorithm and SC algorithm and then realize them with programming in MATLAB. Finally, find the shortcuts of them.
(3) A new improved algorithm based on SC algorithm is introduced and analyzed. As the result, the programmed algorithm will improve the time synchronization of SC algorithm.
(4) These three algorithms are compared in two aspects, the figure of time synchronization and Standard Deviation of frequency offset.
引文
[1]李彬,吴增印.OFDM原理及应用分析,空间电子技术,2005年第4期
[2]李悦.OFDM技术及仿真性能分析,山西电子技术,2006年第1期
[3]叶庆云,夏斐.OFDM物理层系统性能仿真分析,武汉理工大学学报,2006年6月
[4]张华,侯春萍.运用仿真进行OFDM性能的研究,天津工业大学学报,第21卷第1期
[5]何继爱,黎锁平,蔡志鹏.基于Simulink的OFDM系统仿真分析,现代电子技术,2006年第17期总第232期
[6]侯良芳,陈建民.突发OFDM系统中的快速符号定时同步,中国电子科技集团公司第54研究所,2006
[7]杨文东,蔡跃明,白冬林.一种改进的OFDM载波同步算法,军事通信技术,2006
[8]孙献璞,金华峰,王悦.一种新的OFDM符号定时和频率同步方案,西安电子科技大学学报,2006年12月
[9]魏波.《OFDM系统中的同步技术研究》,电子科技大学,2004
[10]倪瑛.《OFDM系统中的同步新算法研究》,南京航空航天大学,2004
[11]王巍.《OFDM系统仿真与性能分析》,南京理工大学,2005
[12]景滨.《宽带OFDM及其关键技术的研究》,2004
[13]傅民仓,冯立杰,袁俊飞.新一代宽带无线局域网系统中的OFDM技术研究,无线通信,2005
[14]P.H.Moose.A Technique for Orthogonal Frequency Division Multiplexing Frequency Offset Correction,IEEE TRANSACTIONS ON COMMUNICATIONS,VOL.42,NO.10,OCTOBER 1994
[15]Yan-Chang Chen,Wen-Jeng Lin,Jung-Shan Lin.Channel Estimation Technique with Assistance of PN-Coded Training Sequences for Wireless OFDM Communication,IEEE
[16]Jean Armstrong.Analysis of New and Existing Methods of Reducing Intercarrier Interference Due to Carder Frequency Offset in OFDM,IEEE TRANSACTIONS ON COMMUNICATIONS,VOL.47,NO.3,MARCH 1999
[17]Timothy M.Schmidl and Donald C.Cox,Fellow.Robust frequency and timing synchronization for OFDM, IEEE TRANSACTIONS ON COMMUNICATIONS, VOL.45, NO.12, DECEMBER 1997
[18] Chunlin Yan, Jiayi Fang, Youxi Tang, Shaoqian Li. OFDM Synchronization Using PN Sequence and Its Performance, The 14~(th) IEEE 2003 International Symposium on Personal, Indoor and Mobile Radio Communication Proceedings
[19] Meng Wu and Wei-Ping Zhu. A Preamble-Aided Symbol and Frequency Synchronization Scheme for OFDM Systems, IEEE, 2005
[20] Amine Laourine, Alex Stephenne. A New OFDM Synchronization Symbol for Carrier Frequency Offset Estimation, IEEE SIGNAL PROCESSING LETTERS, VOL.14, NO.5,MAY 2007
[21] Byungjoon Park, Eunseok Ko, Hyunsoo Cheon, etc. A Blind OFDM Synchronization Algorithm based on Cyclic Correlation, IEEE, 2001
[22] Hongwei Yang, Alcatel Shanghai Bell Co., Ltd. A Road to Future Broadband WirelessAccess: MIMO-OFDM-Based Air Interface, IEEE Communications Magazine, January 2005
[23] Wiley. 《OFDM-Based Broadband Wireless Networks: Design and Optimization》 , 2005
[24] ZHANG Wei. 《Issues on Broadband Wireless Communication Systems: Channel Estimation, Frequency Synchronization and Space-Time-Frequency Coding》, The Chinese University of Hong Kong, July, 2005
[25] Alan C. Brooks, Stephen J. Hoelzer. 《Design and Simulation of Orthogonal Frequency Division Multiplexing (OFDM) Signaling-Final Report》 , 2001
[26] R. van Nee, R. Prasad. 《OFDM for Wireless Multimedia Communications》 , 2000
[27] Mohinder Jankiraman. 《Space-Time Codes and MIMO Systems》, 2004
[28] Dr. Mary Ann Ingram. 《OFDM Simulation Using Matlab》 , Guillermo Acosta, 2000
[2]李悦.OFDM技术及仿真性能分析,山西电子技术,2006年第1期
[3]叶庆云,夏斐.OFDM物理层系统性能仿真分析,武汉理工大学学报,2006年6月
[4]张华,侯春萍.运用仿真进行OFDM性能的研究,天津工业大学学报,第21卷第1期
[5]何继爱,黎锁平,蔡志鹏.基于Simulink的OFDM系统仿真分析,现代电子技术,2006年第17期总第232期
[6]侯良芳,陈建民.突发OFDM系统中的快速符号定时同步,中国电子科技集团公司第54研究所,2006
[7]杨文东,蔡跃明,白冬林.一种改进的OFDM载波同步算法,军事通信技术,2006
[8]孙献璞,金华峰,王悦.一种新的OFDM符号定时和频率同步方案,西安电子科技大学学报,2006年12月
[9]魏波.《OFDM系统中的同步技术研究》,电子科技大学,2004
[10]倪瑛.《OFDM系统中的同步新算法研究》,南京航空航天大学,2004
[11]王巍.《OFDM系统仿真与性能分析》,南京理工大学,2005
[12]景滨.《宽带OFDM及其关键技术的研究》,2004
[13]傅民仓,冯立杰,袁俊飞.新一代宽带无线局域网系统中的OFDM技术研究,无线通信,2005
[14]P.H.Moose.A Technique for Orthogonal Frequency Division Multiplexing Frequency Offset Correction,IEEE TRANSACTIONS ON COMMUNICATIONS,VOL.42,NO.10,OCTOBER 1994
[15]Yan-Chang Chen,Wen-Jeng Lin,Jung-Shan Lin.Channel Estimation Technique with Assistance of PN-Coded Training Sequences for Wireless OFDM Communication,IEEE
[16]Jean Armstrong.Analysis of New and Existing Methods of Reducing Intercarrier Interference Due to Carder Frequency Offset in OFDM,IEEE TRANSACTIONS ON COMMUNICATIONS,VOL.47,NO.3,MARCH 1999
[17]Timothy M.Schmidl and Donald C.Cox,Fellow.Robust frequency and timing synchronization for OFDM, IEEE TRANSACTIONS ON COMMUNICATIONS, VOL.45, NO.12, DECEMBER 1997
[18] Chunlin Yan, Jiayi Fang, Youxi Tang, Shaoqian Li. OFDM Synchronization Using PN Sequence and Its Performance, The 14~(th) IEEE 2003 International Symposium on Personal, Indoor and Mobile Radio Communication Proceedings
[19] Meng Wu and Wei-Ping Zhu. A Preamble-Aided Symbol and Frequency Synchronization Scheme for OFDM Systems, IEEE, 2005
[20] Amine Laourine, Alex Stephenne. A New OFDM Synchronization Symbol for Carrier Frequency Offset Estimation, IEEE SIGNAL PROCESSING LETTERS, VOL.14, NO.5,MAY 2007
[21] Byungjoon Park, Eunseok Ko, Hyunsoo Cheon, etc. A Blind OFDM Synchronization Algorithm based on Cyclic Correlation, IEEE, 2001
[22] Hongwei Yang, Alcatel Shanghai Bell Co., Ltd. A Road to Future Broadband WirelessAccess: MIMO-OFDM-Based Air Interface, IEEE Communications Magazine, January 2005
[23] Wiley. 《OFDM-Based Broadband Wireless Networks: Design and Optimization》 , 2005
[24] ZHANG Wei. 《Issues on Broadband Wireless Communication Systems: Channel Estimation, Frequency Synchronization and Space-Time-Frequency Coding》, The Chinese University of Hong Kong, July, 2005
[25] Alan C. Brooks, Stephen J. Hoelzer. 《Design and Simulation of Orthogonal Frequency Division Multiplexing (OFDM) Signaling-Final Report》 , 2001
[26] R. van Nee, R. Prasad. 《OFDM for Wireless Multimedia Communications》 , 2000
[27] Mohinder Jankiraman. 《Space-Time Codes and MIMO Systems》, 2004
[28] Dr. Mary Ann Ingram. 《OFDM Simulation Using Matlab》 , Guillermo Acosta, 2000