T-MMB解调算法的研究
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摘要
随着社会和信息技术的不断发展,人们希望在任何地方,任何时间都能获得多媒体的信息服务,手机电视/移动多媒体设备应运而生。陆地移动多媒体广播(Terrestrial Mobile Multimedia Broadcasting简称T-MMB)标准是我国手机电视/移动多媒体的国家标准,具有一定的自主知识产权。因此,对基于该标准的接收系统进行研究,具有十分重大的意义。
解调是数字接收机必须完成的关键功能。本文通过研究T-MMB系统的帧结构和差分OFDM系统,在复杂的多径信道下提出并仿真实现了一整套适用于T-MMB的解调算法,希望籍此为T-MMB数字接收机的设计提供一定的借鉴。
本论文深入研究了T-MMB中的解调算法,详细分析了各种非理想同步对T-MMB系统的影响。分析表明,T-MMB系统对于各种误差非常敏感,符号误差和采样时钟偏差将会引入码间干扰,载波偏差导致子载波间干扰的发生,帧同步误差会导致发送端和接收端的信息起始位置的不一致。
最后本文提出了一套适合于T-MMB系统的同步方案,包括:帧同步、载波同步、符号同步和采样时钟同步。帧同步算法是利用能量比的方法,检测T-MMB帧中的空符号。载波频率同步算法包括小数倍频偏粗估计、整数倍频偏估计和小数倍频偏细估计。符号同步也包括符号粗同步和符号细同步。其中小数倍频偏粗估计和符号粗同步算法是利用循环前缀的最大似然估计。整数倍频偏估计、符号细同步和采样时钟同步是在频域下利用相位参考符号进行的数据辅助估计。小数倍频偏细估计是在时域下利用相位参考符号进行的估计。
通过对各部分算法性能的仿真,我们可以得到如下结论:帧同步算法稳定,有很好的抗多径性能;载波频偏估计算法性能优越,估计误差的方差与克拉美罗界比较接近;符号和采样时钟同步算法都是基于相位参考符号,二者可以并行、独立地估计相应的同步参数,缩短了捕获周期,实现了通信的高效传输。各部分算法估计准确,便于数字化实现,本文设计的解调算法具有很强的抗多径衰落的特性。
As the development of society and information technology, people want to access to the multimedia service wherever and whenever, so the mobile multimedia equipment comes out. Terrestrial Mobile Multimedia Broadcast standard is the national mobile phone TV/mobile multimedia standard. Because of the independent intellectual property rights in some degree, it is important for us to develop receive system based on this standard.
Demodulation is the key function of digital receiver. This paper implements the T-MMB demodulation and synchronization algorithm in multi-path channels by studying the frame structure of T-MMB and differential OFDM system.
This paper studies demodulation algorithm deeply. The paper discusses some non-ideal synchronization effects on the performance of T-MMB digital system in detail. The study shows that the T-MMB system is very sensitive to synchronization errors, symbol offset and sampling offset would introduce inter-symbol interference, and frequency offset of carrier would result in inter-carrier interference, and errors in frame synchronization would lead to the difference in starting signals between the transmitter and receiver.
This paper also proposes a synchronization method that fits T-MMB system well, it includes: frame synchronization, carrier synchronization, symbol and sample synchronization. Frame synchronization algorithm is in use of the null symbol, using the power ratio method ; fine carrier offset and coarse symbol offset are estimated by using maximum likelihood estimation based on cyclic prefix; the phase reference symbol is used in integer carrier offset, fine symbol offset and sample offset estimation.
The result of simulation indicates that the frame synchronization algorithm is robust to multi-path; carrier frequency estimation algorithm has advanced performance, the error variance is close to MCRB; the symbol and sample synchronization algorithm are based on phase reference symbol, they can work independently, in this way, the capture period is shortened and high efficiency of communication is implemented. The estimation algorithm is convenient to realize in digital. The demodulation algorithm in the paper is stable to multi-path.
解调是数字接收机必须完成的关键功能。本文通过研究T-MMB系统的帧结构和差分OFDM系统,在复杂的多径信道下提出并仿真实现了一整套适用于T-MMB的解调算法,希望籍此为T-MMB数字接收机的设计提供一定的借鉴。
本论文深入研究了T-MMB中的解调算法,详细分析了各种非理想同步对T-MMB系统的影响。分析表明,T-MMB系统对于各种误差非常敏感,符号误差和采样时钟偏差将会引入码间干扰,载波偏差导致子载波间干扰的发生,帧同步误差会导致发送端和接收端的信息起始位置的不一致。
最后本文提出了一套适合于T-MMB系统的同步方案,包括:帧同步、载波同步、符号同步和采样时钟同步。帧同步算法是利用能量比的方法,检测T-MMB帧中的空符号。载波频率同步算法包括小数倍频偏粗估计、整数倍频偏估计和小数倍频偏细估计。符号同步也包括符号粗同步和符号细同步。其中小数倍频偏粗估计和符号粗同步算法是利用循环前缀的最大似然估计。整数倍频偏估计、符号细同步和采样时钟同步是在频域下利用相位参考符号进行的数据辅助估计。小数倍频偏细估计是在时域下利用相位参考符号进行的估计。
通过对各部分算法性能的仿真,我们可以得到如下结论:帧同步算法稳定,有很好的抗多径性能;载波频偏估计算法性能优越,估计误差的方差与克拉美罗界比较接近;符号和采样时钟同步算法都是基于相位参考符号,二者可以并行、独立地估计相应的同步参数,缩短了捕获周期,实现了通信的高效传输。各部分算法估计准确,便于数字化实现,本文设计的解调算法具有很强的抗多径衰落的特性。
As the development of society and information technology, people want to access to the multimedia service wherever and whenever, so the mobile multimedia equipment comes out. Terrestrial Mobile Multimedia Broadcast standard is the national mobile phone TV/mobile multimedia standard. Because of the independent intellectual property rights in some degree, it is important for us to develop receive system based on this standard.
Demodulation is the key function of digital receiver. This paper implements the T-MMB demodulation and synchronization algorithm in multi-path channels by studying the frame structure of T-MMB and differential OFDM system.
This paper studies demodulation algorithm deeply. The paper discusses some non-ideal synchronization effects on the performance of T-MMB digital system in detail. The study shows that the T-MMB system is very sensitive to synchronization errors, symbol offset and sampling offset would introduce inter-symbol interference, and frequency offset of carrier would result in inter-carrier interference, and errors in frame synchronization would lead to the difference in starting signals between the transmitter and receiver.
This paper also proposes a synchronization method that fits T-MMB system well, it includes: frame synchronization, carrier synchronization, symbol and sample synchronization. Frame synchronization algorithm is in use of the null symbol, using the power ratio method ; fine carrier offset and coarse symbol offset are estimated by using maximum likelihood estimation based on cyclic prefix; the phase reference symbol is used in integer carrier offset, fine symbol offset and sample offset estimation.
The result of simulation indicates that the frame synchronization algorithm is robust to multi-path; carrier frequency estimation algorithm has advanced performance, the error variance is close to MCRB; the symbol and sample synchronization algorithm are based on phase reference symbol, they can work independently, in this way, the capture period is shortened and high efficiency of communication is implemented. The estimation algorithm is convenient to realize in digital. The demodulation algorithm in the paper is stable to multi-path.
引文
[1]何晓华,手机电视实现方式与标准的发展[J],中国有线电视,2006(53),2280~2282
[2]B.R. Saltzberg,“Performance of an efficient parallel data transmission”[J], IEEE Trans. Commun. Technol.vol. COM-15, Dec. 1967. 805-813
[3]李旭明,OFDM差分调制技术的研究与应用[D],南京:东南大学,2008年
[4]中华人民共和国国家标准,手机电视/移动多媒体广播传输系统帧结构、信道编码、调制及复用[P],2008年
[5]鄂一鸣,数字移动多媒体广播系统的同步技术[D],南京:东南大学,2007年
[6]啜钢,王文博,常永宇等,移动通信原理与系统[M],北京:北京邮电大学出版社,2005.16~55
[7]邝育军,OFDM无线传输系统中定时同步和信道估计的研究[D],北京:北京邮电大学,2003年
[8]李栋,数字声音广播[M],北京:北京广播学院出版社,2001年,318~357
[9]严添明,浅谈OFDM原理及其应用[J],西部广播电视,2004年第2期,14~18
[10]李冬梅,DVB-H发射端信道内码和调制部分的FPGA设计和实现[D],上海:同济大学,2007年
[11]沈保锁,侯春萍,现代通信原理[M],北京:国防工业出版社,2002年,154~194
[12]张健,数字广播中的OFDM关进技术及其应用[D],南京:东南大学,2007年
[13]崔小准,OFDM系统同步技术[D],上海:上海交通大学,2003年
[14]朱江,OFDM系统中同步技术的研究与仿真分析[D],重庆:重庆邮电大学,2004年
[15]饶志华,OFDM系统同步技术的研究[D],重庆:重庆邮电大学,2007年
[16]杨征帆,DAB接收机中OFDM系统的同步[D],北京:北京交通大学,2007年
[17] Jeong-Ki Min and Hyoung-Kyu Song, Frequency Synchronization for Digital Audio Broadcasting[J],IEEE Transactions on Consumer Electronics, Vol. 49, No. 2, MAY 2003
[18] Hui Lu and Zaiwang Dong,CARRIER FREQUENCY OFFSET ESTIMATION OF DAB RECEIVER BASED ON PHASE REFERENCE SYMBOL[J],IEEETransactions on Consumer Electronics, Vol. 46, No. 2, FEB 2000
[19] Dong Kyu Kim, Sang Hyun Do and Hong Bae Cho,A NEW JOINT ALGORITHM OF SYMBOLTIMING RECOVERY AND SAMPLING CLOCK ADJUSTMENT FOR OFDM SYSTEMS[J], IEEE Transactions on Consumer Electronics, Vol. 44, No. 3, AUGUST 1998
[20] Jaehee Cho, Namshin Cho, Keukjoon Bang, Myunghee Park, Heeyoung Jun, Hyuncheol Park, PC-Based Receiver for Eureka-147 Digital Audio Broadcasting[J], IEEE TRANSACTIONS ON BROADCASTING, VOL. 47, NO. 2, JUNE 2001
[21] Flavio Daffara and Antoine Chouly, Maximum Likelihood Frequency Detectors for Orthogonal Multicarrier Systems[J],IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 45, NO. 7, JULY 1997
[22] Jan-Jaap van de Beek, ML Estimation of Time and Frequency Offset in OFDM Systems[J], IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 45, NO. 7, JULY 1997
[23]Kenichi Taura, et al, A Digital Audio Broadcasting receiver[J], IEEE Trans on Consumer Electronics, Vol 42, No.3, Aug.1996
[24] Keukjoon Bang, Namshin Cho, Jaehee Cho, et al, A Coarse Frequency Offset Estimation in an OFDM System Using the Concept of the Coherence Phase Bandwidth[J], IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 49, NO. 8, AUGUST 2001
[25] Navid Lashkarian and Sayfe Kiaei, Class of Cyclic-Based Estimators for Frequency-Offset Estimation of OFDM Systems[J], IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 48, NO. 12, DECEMBER 2000
[26] Timothy M. Schmidl and Donald C. Cox, Robust Frequency and Timing Synchronization for OFDM[J], IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 45, NO. 12, DECEMBER 1997
[27] DAVID C. RIFE AND ROBERT R. BOORSTYN, Single-Tone Parameter Estimation from Qiscrete-Time Observations[J],IEEE TRANSACTIONS ON INFORMATION THEORY, VOL. IT-20, NO. 5, SEPTEMBER 1974
[28] Guangliang Ren, Yilin Chang and Huining Zhang Synchronization Method Based on a New Constant Envelop Preamble for OFDM Systems[J],IEEE TRANSACTIONS ON BROADCASTING, VOL. 51, NO. 1, MARCH 2005
[29] Byungjoon Park, Hyunsoo Cheon and Changeon Kang, A Novel Timing Estimation Method for OFDM Systems[J], IEEE COMMUNICATIONS LETTERS, VOL. 7, NO. 5, MAY 2003
[30]贾岳,郑宝辉,DAB接收机中载波频偏估计[J],信息传输与接入技术,2006年第11期,22~24
[31] Baoguo YANG,B. Letaief,t Roger S. Cheng,t and Zhigang,An Improved Combined Symbol and Sampling Clock Synchronization Method for OFDM Systems[J], IEEE COMMUNICATIONS LETTERS, VOL. 7, NO. 5, MAY 2003
[32]齐志强,蒋佳,DAB接收机的样机设计[J],今日电子,2006年12月84~87
[33]黄灵芝,董在望,数字音频广播接收机载波同步电路设计及实现[J],电声技术,2003年第11期,60~63
[34]葛建明,李兵兵,王雯芳,基于DAB/DMB系统的模式检测及帧同步技术[J],电视技术,2006年第12期,10~13
[35]吕晖,叶兵,董在望,一种实用化DAB接收机综合同步方法[J],广播与电视技术,2000年第3期143~146
[2]B.R. Saltzberg,“Performance of an efficient parallel data transmission”[J], IEEE Trans. Commun. Technol.vol. COM-15, Dec. 1967. 805-813
[3]李旭明,OFDM差分调制技术的研究与应用[D],南京:东南大学,2008年
[4]中华人民共和国国家标准,手机电视/移动多媒体广播传输系统帧结构、信道编码、调制及复用[P],2008年
[5]鄂一鸣,数字移动多媒体广播系统的同步技术[D],南京:东南大学,2007年
[6]啜钢,王文博,常永宇等,移动通信原理与系统[M],北京:北京邮电大学出版社,2005.16~55
[7]邝育军,OFDM无线传输系统中定时同步和信道估计的研究[D],北京:北京邮电大学,2003年
[8]李栋,数字声音广播[M],北京:北京广播学院出版社,2001年,318~357
[9]严添明,浅谈OFDM原理及其应用[J],西部广播电视,2004年第2期,14~18
[10]李冬梅,DVB-H发射端信道内码和调制部分的FPGA设计和实现[D],上海:同济大学,2007年
[11]沈保锁,侯春萍,现代通信原理[M],北京:国防工业出版社,2002年,154~194
[12]张健,数字广播中的OFDM关进技术及其应用[D],南京:东南大学,2007年
[13]崔小准,OFDM系统同步技术[D],上海:上海交通大学,2003年
[14]朱江,OFDM系统中同步技术的研究与仿真分析[D],重庆:重庆邮电大学,2004年
[15]饶志华,OFDM系统同步技术的研究[D],重庆:重庆邮电大学,2007年
[16]杨征帆,DAB接收机中OFDM系统的同步[D],北京:北京交通大学,2007年
[17] Jeong-Ki Min and Hyoung-Kyu Song, Frequency Synchronization for Digital Audio Broadcasting[J],IEEE Transactions on Consumer Electronics, Vol. 49, No. 2, MAY 2003
[18] Hui Lu and Zaiwang Dong,CARRIER FREQUENCY OFFSET ESTIMATION OF DAB RECEIVER BASED ON PHASE REFERENCE SYMBOL[J],IEEETransactions on Consumer Electronics, Vol. 46, No. 2, FEB 2000
[19] Dong Kyu Kim, Sang Hyun Do and Hong Bae Cho,A NEW JOINT ALGORITHM OF SYMBOLTIMING RECOVERY AND SAMPLING CLOCK ADJUSTMENT FOR OFDM SYSTEMS[J], IEEE Transactions on Consumer Electronics, Vol. 44, No. 3, AUGUST 1998
[20] Jaehee Cho, Namshin Cho, Keukjoon Bang, Myunghee Park, Heeyoung Jun, Hyuncheol Park, PC-Based Receiver for Eureka-147 Digital Audio Broadcasting[J], IEEE TRANSACTIONS ON BROADCASTING, VOL. 47, NO. 2, JUNE 2001
[21] Flavio Daffara and Antoine Chouly, Maximum Likelihood Frequency Detectors for Orthogonal Multicarrier Systems[J],IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 45, NO. 7, JULY 1997
[22] Jan-Jaap van de Beek, ML Estimation of Time and Frequency Offset in OFDM Systems[J], IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 45, NO. 7, JULY 1997
[23]Kenichi Taura, et al, A Digital Audio Broadcasting receiver[J], IEEE Trans on Consumer Electronics, Vol 42, No.3, Aug.1996
[24] Keukjoon Bang, Namshin Cho, Jaehee Cho, et al, A Coarse Frequency Offset Estimation in an OFDM System Using the Concept of the Coherence Phase Bandwidth[J], IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 49, NO. 8, AUGUST 2001
[25] Navid Lashkarian and Sayfe Kiaei, Class of Cyclic-Based Estimators for Frequency-Offset Estimation of OFDM Systems[J], IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 48, NO. 12, DECEMBER 2000
[26] Timothy M. Schmidl and Donald C. Cox, Robust Frequency and Timing Synchronization for OFDM[J], IEEE TRANSACTIONS ON COMMUNICATIONS, VOL. 45, NO. 12, DECEMBER 1997
[27] DAVID C. RIFE AND ROBERT R. BOORSTYN, Single-Tone Parameter Estimation from Qiscrete-Time Observations[J],IEEE TRANSACTIONS ON INFORMATION THEORY, VOL. IT-20, NO. 5, SEPTEMBER 1974
[28] Guangliang Ren, Yilin Chang and Huining Zhang Synchronization Method Based on a New Constant Envelop Preamble for OFDM Systems[J],IEEE TRANSACTIONS ON BROADCASTING, VOL. 51, NO. 1, MARCH 2005
[29] Byungjoon Park, Hyunsoo Cheon and Changeon Kang, A Novel Timing Estimation Method for OFDM Systems[J], IEEE COMMUNICATIONS LETTERS, VOL. 7, NO. 5, MAY 2003
[30]贾岳,郑宝辉,DAB接收机中载波频偏估计[J],信息传输与接入技术,2006年第11期,22~24
[31] Baoguo YANG,B. Letaief,t Roger S. Cheng,t and Zhigang,An Improved Combined Symbol and Sampling Clock Synchronization Method for OFDM Systems[J], IEEE COMMUNICATIONS LETTERS, VOL. 7, NO. 5, MAY 2003
[32]齐志强,蒋佳,DAB接收机的样机设计[J],今日电子,2006年12月84~87
[33]黄灵芝,董在望,数字音频广播接收机载波同步电路设计及实现[J],电声技术,2003年第11期,60~63
[34]葛建明,李兵兵,王雯芳,基于DAB/DMB系统的模式检测及帧同步技术[J],电视技术,2006年第12期,10~13
[35]吕晖,叶兵,董在望,一种实用化DAB接收机综合同步方法[J],广播与电视技术,2000年第3期143~146