OFDM中频信号处理系统设计
摘要
OFDM(正交频分复用)是一种多载波调制技术,其核心思想是将串行高速的数据流转换成并行低速的数据流进行传输。它具有频谱利用率高、抗多径环境、抗频率选择性衰落或窄带干扰等优点,适用于无线信道中的高速数据传输,具有广泛的应用前景,被普遍认为是下一代移动通信系统中的关键技术。
本设计详细的研究了OFDM基带通信系统的基本工作原理,对OFDM的调制解调以及其中涉及的关键技术做了相关的分析,并对OFDM通信系统进行了仿真。
根据设计的需求,自行设计了一款开放式的软件无线电硬件平台,并在平台上实现OFDM基本的基带设计和中频设计。该硬件平台采用Xilinx公司生产的Spartan3A-DSP FPGA作为数字信号处理芯片,平台上同时包括高速DAC,高速ADC及UART, USB等诸多外围接口设备。
本设计使用System Generator来实现OFDM调制与解调算法的设计。System Generator是Xilinx公司开发的系统级建模工具,允许工程师在进行FPGA设计时使用Matlab下的Simulink平台。本设计中OFDM调制端的内容包括QPSK映射、训练序列的插入、IFFT、循环前缀插入等模块的设计。解调端的内容包括信号同步、循环前缀删除、FFT、QPSK解映射等。
在此基础上,本设计通过数字信号发生器、数字混频器和插值滤波器的设计,将基带信号进行了数字变频。最后,本设计通过对比发送和接收的数据,证明本设计的可行性。
OFDM (Orthogonal frequency division multiplexing) is a multi-carrier modulation technology. The main opinion is to convert the high speed serial data stream to the parallel low-speed data stream. It has lots of advantage, such as high spectrum utilization, strong multipath effects resistance. It can also work well in frequency selective fading or narrowband interference etc. OFDM is suitable for the high speed data transmission in wireless channel. OFDM have widespread application prospect, which is generally considered to be the key technology of the next generation of mobile communication system.
This paper studies the basic working principle of the OFDM communication system. At the same time, this paper also analyzes the modulation and demodulation of OFDM, including the key technologies. This paper also contains a comprehensive simulation of the OFDM system.
According to the design requirements, an open-planed software defined radio hardware platform is designed in this project. The Xilinx FPGA Spartan3A-DSP is selected as the main digital signal processing chip. High speed ADC, high speed DAC and many peripheral interface equipment are all designed and tested in this hardware platform..
This project makes the implementation of a whole OFDM modulation and demodulation based on System Generator. The modulation module contains QPSK mapping, training sequence insertion, IFFT, cyclic prefix insertion. The demodulation contains the OFDM synchronization, delete of the cyclic prefix, FFT, QPSK de-mapping. Based on this achievement, down conversation and up conversation is designed also by System Generator. Finally, by comparing the related data, it is proved that the design is working correctly.
本设计详细的研究了OFDM基带通信系统的基本工作原理,对OFDM的调制解调以及其中涉及的关键技术做了相关的分析,并对OFDM通信系统进行了仿真。
根据设计的需求,自行设计了一款开放式的软件无线电硬件平台,并在平台上实现OFDM基本的基带设计和中频设计。该硬件平台采用Xilinx公司生产的Spartan3A-DSP FPGA作为数字信号处理芯片,平台上同时包括高速DAC,高速ADC及UART, USB等诸多外围接口设备。
本设计使用System Generator来实现OFDM调制与解调算法的设计。System Generator是Xilinx公司开发的系统级建模工具,允许工程师在进行FPGA设计时使用Matlab下的Simulink平台。本设计中OFDM调制端的内容包括QPSK映射、训练序列的插入、IFFT、循环前缀插入等模块的设计。解调端的内容包括信号同步、循环前缀删除、FFT、QPSK解映射等。
在此基础上,本设计通过数字信号发生器、数字混频器和插值滤波器的设计,将基带信号进行了数字变频。最后,本设计通过对比发送和接收的数据,证明本设计的可行性。
OFDM (Orthogonal frequency division multiplexing) is a multi-carrier modulation technology. The main opinion is to convert the high speed serial data stream to the parallel low-speed data stream. It has lots of advantage, such as high spectrum utilization, strong multipath effects resistance. It can also work well in frequency selective fading or narrowband interference etc. OFDM is suitable for the high speed data transmission in wireless channel. OFDM have widespread application prospect, which is generally considered to be the key technology of the next generation of mobile communication system.
This paper studies the basic working principle of the OFDM communication system. At the same time, this paper also analyzes the modulation and demodulation of OFDM, including the key technologies. This paper also contains a comprehensive simulation of the OFDM system.
According to the design requirements, an open-planed software defined radio hardware platform is designed in this project. The Xilinx FPGA Spartan3A-DSP is selected as the main digital signal processing chip. High speed ADC, high speed DAC and many peripheral interface equipment are all designed and tested in this hardware platform..
This project makes the implementation of a whole OFDM modulation and demodulation based on System Generator. The modulation module contains QPSK mapping, training sequence insertion, IFFT, cyclic prefix insertion. The demodulation contains the OFDM synchronization, delete of the cyclic prefix, FFT, QPSK de-mapping. Based on this achievement, down conversation and up conversation is designed also by System Generator. Finally, by comparing the related data, it is proved that the design is working correctly.
引文
[1]Guifen Gu, Guili Peng, The survey of GSM wireless communication system, Computer and Information Application (ICCIA), 2010 International Conference on, On page(s):121 124
[2]K. Pahlavan et al., "Handoff in Hybrid Mobile Data Networks" IEEE Pers. Commun., Apr. 2000.
[3]G. J. Pottie, "System Design Choices in Personal Communications", IEEE Pers. Commun., vol.2, no.5, pp.50-67 1995
[4]Groe, J. A Multimode Cellular Radio,Circuits and Systems II:Express Briefs, IEEE Transactions on, On page(s):269-273 Volume:55, Issue:3, March 2008
[5]E. Mino Diaz et al., "The WINNER Project:Research for NewRadio Interfaces for Better Mobile Services," IEICE Trans.,Japan, vol. E87-A, no.10, Oct.2004, pp.2592-98.
[6]Weinstein, S. Data Transmission by Frequency Division Multiplexing Using the Discrete
[7]Fourier Transform [J]. IEEE Transaction on. Communication Technology,1971:628-634. J. Mitola, Cognitive Radio:making software radios more personal. IEEE Personal Communications, Aug.1999.
[8]A. Pinomaa, Utilization of Software-Defined Radio in Power Line Communication between Motor and Frequency Converter. IEEE International Symposium on Power Line Communications and Its Applications (ISPLC),2010
[9]A. Chouly, A. Brajal and S. Jourdan, "Orthogonal Multicarrier Techniques Applied to Direct Sequence Spread Spectrum CDMA Systems," Proc. of/E€€ GLOBECOM'93. Houston, USA, Nov.1993, pp.1723-28.
[10]Chimini, L.J., "Analysis and simulation of a digital mobile channel using orthogonal frequency division multiplexing". IEEE Transactions on Communication, vol. COM-33, no.7, pp.665-675, July 1986.
[11]Tufvesson, F., M. Faulkner, P. Hoeher, O. Edfors, "OFDM Time and Frequency Synchronization by Spread Spectrum Pilot Technique",8th IEEE Communication Theory Mini Conference in conjunction to ICC'99, Vancouver, Canada. June 7-10,1999, pp.115-119.
[12]Xilinx System Generator for DSP Reference Guide [EB/OL] .http://www.xilinx.com/support/documentation/sw_manuals/xilinx 11/sysgen_ref.pdf. [2010-01-01],
[13]CARDELLS T F,VALLS C A. Optimized FPGA-implementation of quadrature DDS[C]. Proc. IEEE International Symposium on Circuitsand Systems. IEEE Press, 2002,:369-372.
[14]肖乾友,黄晓革,骆志敏.一种数字中频接收机的设计与实现[J].电讯技术,2006,(04).
[15]王水,吴继华.数字中频与FPGA[J]电子设计技术,2007,(09).
[16]赵国栋,郭德淳.基于FPGA的数字中频接收系统[J].军民两用技术与产品,2006,(01).
[17]李振军,曾凌云,郑善贤.基于FPGA的中频数字接收机设计与实现[J].计算技术与自动化,2009,(02).
[18]何勤,束永江.一种通用中频数字化接收机的实现[J].现代电子技术,2009,(11).
[19]冯振伟,武小冬,梅顺良.基于FPGA的数字中频接收机设计与实现[J].通信技术,2010,(04).
[20]李云飞,宋虎,周希辰.基于System Generator的数字下变频实现[J].雷达与对抗,2008,(04).
[21]Mohamed K. Nezami. RF Architectures & Digital Signal Processing Aspects of Digital Wireless Transceivers.2003:322-325
[22]Yunho Jung, Hongil Yoon, Jaeseok Kim. New Efficient FFT Algorithm and Pipeline Implementation Result for OFDM/DMT Applications. IEEE Transactions on Comsumer Electronice Vol.49.No.1 2003:223-226
[23]刘占线.基于System Generator的QPSK数字调制器设计[J].电子科技,2011,(08)
[24]元静,刘萍.基于System Generator的字符分割算法的并行实现[J].现代电子技术,2009,(14).
[26]冯昭,吴尽昭.基于System Generator数字中频接收机的设计[J].电视技术,2010,(S1).
[27]Sherif Kishk, Ahmed Mansour, Mohy Eldin. Implementation of an OFDM System Using FPGA.26th-National Radio Science Conference.March 17-19,2009
[28]WEInstein, S. Data Transmission by Frequency Division Multiplexing Using the Discrete Fourier Transform [J]. IEEE Transaction on. Communication Technology,1971:628-634.
[29]Joaquin Garcia. Rene Cumplido. On the design of an FPGA-Based OFDM modulator for IEEE 802.11a.2nd International Conference on Electrical and Electronics Engineering (ICEEE) and XI Conference on Electrical Engineering.2005:112-116
[30]Mery, H. Digital Communication Receivers:Synchronization and Channel Estimation Algorithms[M]. New York:John Wiley&Sons,1997:18-19
[31]Aghamhammadi, A. Adaptive Synchronization and Channel Parameter Estimation Using an Extended Klaman Filer [J]. IEEE Transaction on. Communication,2004:1025-1026
[32]Morelli, M. Mengali, U. A Comparison of Pilot-Aided Channel Estimation Methods for OFDM Systems [J]. IEEE Transaction on Signal Processing,2000,49(4):1207-1215
[33]Muquet, B. Zhengdao Wang. Cyclic Prefixing or Zero Padding for Wireless Multi-Carrier Transmissions [J]. IEEE Transactions on. Communications, 2002:2136-3148
[2]K. Pahlavan et al., "Handoff in Hybrid Mobile Data Networks" IEEE Pers. Commun., Apr. 2000.
[3]G. J. Pottie, "System Design Choices in Personal Communications", IEEE Pers. Commun., vol.2, no.5, pp.50-67 1995
[4]Groe, J. A Multimode Cellular Radio,Circuits and Systems II:Express Briefs, IEEE Transactions on, On page(s):269-273 Volume:55, Issue:3, March 2008
[5]E. Mino Diaz et al., "The WINNER Project:Research for NewRadio Interfaces for Better Mobile Services," IEICE Trans.,Japan, vol. E87-A, no.10, Oct.2004, pp.2592-98.
[6]Weinstein, S. Data Transmission by Frequency Division Multiplexing Using the Discrete
[7]Fourier Transform [J]. IEEE Transaction on. Communication Technology,1971:628-634. J. Mitola, Cognitive Radio:making software radios more personal. IEEE Personal Communications, Aug.1999.
[8]A. Pinomaa, Utilization of Software-Defined Radio in Power Line Communication between Motor and Frequency Converter. IEEE International Symposium on Power Line Communications and Its Applications (ISPLC),2010
[9]A. Chouly, A. Brajal and S. Jourdan, "Orthogonal Multicarrier Techniques Applied to Direct Sequence Spread Spectrum CDMA Systems," Proc. of/E€€ GLOBECOM'93. Houston, USA, Nov.1993, pp.1723-28.
[10]Chimini, L.J., "Analysis and simulation of a digital mobile channel using orthogonal frequency division multiplexing". IEEE Transactions on Communication, vol. COM-33, no.7, pp.665-675, July 1986.
[11]Tufvesson, F., M. Faulkner, P. Hoeher, O. Edfors, "OFDM Time and Frequency Synchronization by Spread Spectrum Pilot Technique",8th IEEE Communication Theory Mini Conference in conjunction to ICC'99, Vancouver, Canada. June 7-10,1999, pp.115-119.
[12]Xilinx System Generator for DSP Reference Guide [EB/OL] .http://www.xilinx.com/support/documentation/sw_manuals/xilinx 11/sysgen_ref.pdf. [2010-01-01],
[13]CARDELLS T F,VALLS C A. Optimized FPGA-implementation of quadrature DDS[C]. Proc. IEEE International Symposium on Circuitsand Systems. IEEE Press, 2002,:369-372.
[14]肖乾友,黄晓革,骆志敏.一种数字中频接收机的设计与实现[J].电讯技术,2006,(04).
[15]王水,吴继华.数字中频与FPGA[J]电子设计技术,2007,(09).
[16]赵国栋,郭德淳.基于FPGA的数字中频接收系统[J].军民两用技术与产品,2006,(01).
[17]李振军,曾凌云,郑善贤.基于FPGA的中频数字接收机设计与实现[J].计算技术与自动化,2009,(02).
[18]何勤,束永江.一种通用中频数字化接收机的实现[J].现代电子技术,2009,(11).
[19]冯振伟,武小冬,梅顺良.基于FPGA的数字中频接收机设计与实现[J].通信技术,2010,(04).
[20]李云飞,宋虎,周希辰.基于System Generator的数字下变频实现[J].雷达与对抗,2008,(04).
[21]Mohamed K. Nezami. RF Architectures & Digital Signal Processing Aspects of Digital Wireless Transceivers.2003:322-325
[22]Yunho Jung, Hongil Yoon, Jaeseok Kim. New Efficient FFT Algorithm and Pipeline Implementation Result for OFDM/DMT Applications. IEEE Transactions on Comsumer Electronice Vol.49.No.1 2003:223-226
[23]刘占线.基于System Generator的QPSK数字调制器设计[J].电子科技,2011,(08)
[24]元静,刘萍.基于System Generator的字符分割算法的并行实现[J].现代电子技术,2009,(14).
[26]冯昭,吴尽昭.基于System Generator数字中频接收机的设计[J].电视技术,2010,(S1).
[27]Sherif Kishk, Ahmed Mansour, Mohy Eldin. Implementation of an OFDM System Using FPGA.26th-National Radio Science Conference.March 17-19,2009
[28]WEInstein, S. Data Transmission by Frequency Division Multiplexing Using the Discrete Fourier Transform [J]. IEEE Transaction on. Communication Technology,1971:628-634.
[29]Joaquin Garcia. Rene Cumplido. On the design of an FPGA-Based OFDM modulator for IEEE 802.11a.2nd International Conference on Electrical and Electronics Engineering (ICEEE) and XI Conference on Electrical Engineering.2005:112-116
[30]Mery, H. Digital Communication Receivers:Synchronization and Channel Estimation Algorithms[M]. New York:John Wiley&Sons,1997:18-19
[31]Aghamhammadi, A. Adaptive Synchronization and Channel Parameter Estimation Using an Extended Klaman Filer [J]. IEEE Transaction on. Communication,2004:1025-1026
[32]Morelli, M. Mengali, U. A Comparison of Pilot-Aided Channel Estimation Methods for OFDM Systems [J]. IEEE Transaction on Signal Processing,2000,49(4):1207-1215
[33]Muquet, B. Zhengdao Wang. Cyclic Prefixing or Zero Padding for Wireless Multi-Carrier Transmissions [J]. IEEE Transactions on. Communications, 2002:2136-3148