单载波频域均衡系统中关键技术的研究与实现
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摘要
单载波频域均衡(SC-FDE)技术，不仅可以有效对抗信道的频率选择性衰落，实现高速率、大容量的通信传输，而且能够避免单载波时域均衡(SC-TDE)复杂度大和正交频分复用(OFDM)技术峰均比高的不足，是宽带无线接入系统物理层的重要组成技术。近几年来，关于单载波频域均衡的讨论日渐增多，并且已经被纳入IEEE802.16(WIMAX)标准中，然而目前对SC-FDE的研究大多还只是集中在理论仿真阶段，很少有实际的系统实现。
本文首先对SC-FDE传输系统的建立进行了可行性分析。在信道容量，信号峰值平均功率比以及理论误码性能方面，与传统的OFDM传输系统进行了比较分析。经过分析，在一般的情况下，SC-FDE系统的信道容量更小，具有更低的峰均比。在信噪比较高的情况下，与OFDM系统相比，SC-FDE系统具有较低的误码率；而在信噪比较低的情况下，OFDM系统在误码率方面要略优于SC-FDE系统。
经过可行性分析论证，本文对SC-FDE系统中的关键技术：同步技术(包括帧同步，位同步及载波同步)，频域均衡算法进行了研究。然后在ADS仿真平台上进行了基于迫零算法的SC-FDE系统的建模和仿真。由仿真结果分析得出，经过SUI-3无线信道后的数据在经过基于迫零算法的频域均衡模块后可以得到很好的恢复，整个SC-FDE传输模型具有较低的误码率。
随后，本文在基于TMS320C6713的DSP开发平台上完成了SC-FDE系统发送和接收各个子模块的调试，初步建立了一个SC-FDE实现系统。另外，本文设计的硬件实现系统还使用了EDMA传输技术实现了音频数据传输在SC-FDE系统中的应用。
最后，本文针对理论分析和仿真结果，结合实际系统硬件实现中遇到的问题，探讨了今后的改进方法。
SC-FDE (Single Carrier-Frequency Domain Equalization) allows anadvantageous of high-speed data transmission in frequency-selective fading channel.It avoids the complexity of SC-TDE (Single Carrier-Time Domain Equalization) andthe high PAPR (Peak Average Power Ratio) of OFDM (Orthogonal FrequencyDivision Multiplexing) as well. It becomes one of the most important components ofthe wideband wireless access technique. In recent years, there is more and morediscussion about SC-FDE, including been brought into the IEEE802.16 (WIMAX)protocol. However, most of research work still focuses on theories and simulation ofparts or whole system, and less implementation in real hardware platform.
First, the thesis analyzes the feasibility of building SC-FDE system. It comparesthe SC-FDE system with OFDM system in the following aspects, such as channelcapability, PAPR and BER (Bit Error Rate) in theory. By analysis, SC-FDE systemhas smaller channel capability and lower PAPR normally. Compared with OFDMsystem, SC-FDE has lower BER with high SNR (Signal Noise Ratio), while SC-FDEhas higher BER with low SNR.
Through the analysis of feasibility, the thesis begins to research on the keytechniques of SC-FDE system, including frame synchronization, bit synchronization,carrier synchronization and frequency domain equalization algorithm. Then itcompletes the simulation of SC-FDE system based on the Zero-Forcing algorithm onADS simulation platform. After analyzing the result of simulation, it can recover thedata well which are sent to SUI-3 channel and through the frequency domainequalization module based on ZF algorithm at receiver. The result proves that thewhole SC-FDE system of simulation has low BER.
Then, the author completes the debugging of submodules of SC-FDE system attransmitter and receiver on the DSP platform based on TMS320C6713 chip. Inaddition, it implements the audio data transmission in SC-FDE system by usingEDMA transmission technique.
Finally, according to the limitation of the SC-FDE system designed both insimulation and implementation, some ideas are discussed to improve the performancefor the future.
本文首先对SC-FDE传输系统的建立进行了可行性分析。在信道容量，信号峰值平均功率比以及理论误码性能方面，与传统的OFDM传输系统进行了比较分析。经过分析，在一般的情况下，SC-FDE系统的信道容量更小，具有更低的峰均比。在信噪比较高的情况下，与OFDM系统相比，SC-FDE系统具有较低的误码率；而在信噪比较低的情况下，OFDM系统在误码率方面要略优于SC-FDE系统。
经过可行性分析论证，本文对SC-FDE系统中的关键技术：同步技术(包括帧同步，位同步及载波同步)，频域均衡算法进行了研究。然后在ADS仿真平台上进行了基于迫零算法的SC-FDE系统的建模和仿真。由仿真结果分析得出，经过SUI-3无线信道后的数据在经过基于迫零算法的频域均衡模块后可以得到很好的恢复，整个SC-FDE传输模型具有较低的误码率。
随后，本文在基于TMS320C6713的DSP开发平台上完成了SC-FDE系统发送和接收各个子模块的调试，初步建立了一个SC-FDE实现系统。另外，本文设计的硬件实现系统还使用了EDMA传输技术实现了音频数据传输在SC-FDE系统中的应用。
最后，本文针对理论分析和仿真结果，结合实际系统硬件实现中遇到的问题，探讨了今后的改进方法。
SC-FDE (Single Carrier-Frequency Domain Equalization) allows anadvantageous of high-speed data transmission in frequency-selective fading channel.It avoids the complexity of SC-TDE (Single Carrier-Time Domain Equalization) andthe high PAPR (Peak Average Power Ratio) of OFDM (Orthogonal FrequencyDivision Multiplexing) as well. It becomes one of the most important components ofthe wideband wireless access technique. In recent years, there is more and morediscussion about SC-FDE, including been brought into the IEEE802.16 (WIMAX)protocol. However, most of research work still focuses on theories and simulation ofparts or whole system, and less implementation in real hardware platform.
First, the thesis analyzes the feasibility of building SC-FDE system. It comparesthe SC-FDE system with OFDM system in the following aspects, such as channelcapability, PAPR and BER (Bit Error Rate) in theory. By analysis, SC-FDE systemhas smaller channel capability and lower PAPR normally. Compared with OFDMsystem, SC-FDE has lower BER with high SNR (Signal Noise Ratio), while SC-FDEhas higher BER with low SNR.
Through the analysis of feasibility, the thesis begins to research on the keytechniques of SC-FDE system, including frame synchronization, bit synchronization,carrier synchronization and frequency domain equalization algorithm. Then itcompletes the simulation of SC-FDE system based on the Zero-Forcing algorithm onADS simulation platform. After analyzing the result of simulation, it can recover thedata well which are sent to SUI-3 channel and through the frequency domainequalization module based on ZF algorithm at receiver. The result proves that thewhole SC-FDE system of simulation has low BER.
Then, the author completes the debugging of submodules of SC-FDE system attransmitter and receiver on the DSP platform based on TMS320C6713 chip. Inaddition, it implements the audio data transmission in SC-FDE system by usingEDMA transmission technique.
Finally, according to the limitation of the SC-FDE system designed both insimulation and implementation, some ideas are discussed to improve the performancefor the future.
引文
[1] 张贤达，保铮著．通信信号处理[M]．北京：国防工业出版社，2000年．
[2] 仇佩亮著．信息论与编码，第1版[M]．北京：高等教育出版社，2003年12月．
[3] Liu Oian-lei, Yang Lv-xi. Theoretic Comparison of BER Performance between Single-Carder Frequency-Domain Equalization and Multi-carrier OFDM [J]. Journal of Electronics & Information Technology, 2005, 27(3):411-414.
[4] Gusmao A, Dinis R, Conceicao J, et al. Comparison of Two Modulation Choices for Broadband Wireless Communications, 2000:1300-1305.
[5] John GProakis著，张力军，张宗橙，郑宝玉等译．数字通信，第4版．北京：电子工业出版社，2003年6月．
[6] 奇怀亮、汪仲仙、张新政、吴秀珍著．数字通信．北京：电子工业出版社，1988年．
[7] 丁玉美、高西全、彭学愚著．数字信号处理．西安：西安电子科技大学出版社，1994年．
[8] Wiener N. Extrapolation, interpretation, and smoothing of stationary time series. New York: MIT Press and Wiley, 1949.
[9] Kalman R.E.A new approach to linear filtering and prediction problems. Trans. ASME.J. Basic Eng, 1960, 82:35-45.
[10] Dention M, McCool J, Widrow B. Adaptive filtering in the frequency domain. Proc. IEEE, 1978, 66(12): 1658-1659.
[11] Ferrara E R Jr. Frequency-domain adaptive filtering. In Adaptive filters, Edited by Cowan C.EN. and Grant PM, New Jersey: Prentice-Hall, Englewood Cliffs, 1985.
[12] H.Witschnig, T.Mayer, A.Springer. A different look on cysclic prefix for sc/fde. Communications Magazine, IEEE, 2002.
[13] Luc Deneire. Training sequence versus cyclic prefix-A new look on single carder communication. Communications Magazine, IEEE, January 9, 2001.
[14] Mario Huemer, Harald Witschnig, Josef Hausner. Unique word based phase tracking algorithms for sc/fde_systems. Globecom, 2003.
[15] Andreas Czylwik. Comparison between adaptive OFDM and single carrier modulation with frequency domain equalization. Communications Magazine, IEEE, 1997.
[16] S.U.H.Qureshi. Adaptive Equalization, Proc. IEEE, Vol.73, No.9, Sept, 1985, pp. 1349-1387.
[17] D.D.Falconer and ER.Magee, Jr. Adaptive Channel Memory Truncation for Maximum-Likelihood Sequence Estimation. Bell System Tech. November 1973, pp. 1541-1562.
[18] D.G Messerschmitt. Design of a Finite Impulse Response for the Viterbi Algorithm and Decision Feedback Equalizer, Proc. ICC 74, Minneapolis, June 1974, pp. 37D-1—37D-5.
[19] M.V.Clark. Adaptive Frequency-Domain Equalization and Diversity Combining for Broadband Wireless Communications. IEEE JSAC, Vol.16, NO.8, Oct.1998, pp.1385-1395.
[20] 杨大成著．移动传播环境——理论基础．分析方法和建模技术．北京：机械工业出版社，2003年．
[21] Erceg V, Had K VS, Smith M S, et al. Channel Models for Fixed wireless Applications [S]. Contribution IEEE802.16a-03/01, [S.I.]: IEEE, 2003.
[22] IEEE Std 802.11a-1999, I.AN Medium Access Control (MAC) and Physical Layer (PHY) specifications: High-speed Physical Layer in the 5GHZ Band [S]. [S.I.]: IEEE, 1999.
[23] Schmidle T M, Cox, D C. Robust frequency and timing synchronization for OFDM [J]. IEEE Transactions on Communications, 1997, 45(12):1613-1621.
[24] Gardner F M. Interpolation in Digital Modems-Part Ⅰ: Fundamentals [J]. IEEE Trans On Communications, 1993, 41(3):501-507.
[25] Erup L, Gardner F M, Harris R A. Interpolation in Digital Modems-Part Ⅱ: Implementation and Performance [J]. IEEE Transactions on Communications, 1993, 41(6):998-1008.
[26] Gardner F M. A BPSK/QPSK Timing-Error Detector for Sampled Receivers [J]. IEEE Trans On Communications, 1986, 34(5):423-429.
[27] 郑大春，项海格．一种全数字化载波频偏估计器算法[J]．电子学报，1999，27(1)：78-80．
[28] 张厥盛，曹丽娜著．锁相与频率合成技术[M]．成都：电子科技大学出版社，1998．
[29] 万心平著．锁相技术[M]．西安：西安电子科技大学出版社，1990．
[30] 李方慧，王飞，何佩琨著．TMS320C6000系列DSPs原理与应用，第2版．北京：电子工业出版社，2003年6月．
[31] 周霖著．DSP通信工程技术应用．湖南：国防工业出版社，2004年．
[32] 张雄伟，陈亮，徐光辉著．DSP芯片的原理与开发应用．北京：电子工业出版社，2003年．
[2] 仇佩亮著．信息论与编码，第1版[M]．北京：高等教育出版社，2003年12月．
[3] Liu Oian-lei, Yang Lv-xi. Theoretic Comparison of BER Performance between Single-Carder Frequency-Domain Equalization and Multi-carrier OFDM [J]. Journal of Electronics & Information Technology, 2005, 27(3):411-414.
[4] Gusmao A, Dinis R, Conceicao J, et al. Comparison of Two Modulation Choices for Broadband Wireless Communications, 2000:1300-1305.
[5] John GProakis著，张力军，张宗橙，郑宝玉等译．数字通信，第4版．北京：电子工业出版社，2003年6月．
[6] 奇怀亮、汪仲仙、张新政、吴秀珍著．数字通信．北京：电子工业出版社，1988年．
[7] 丁玉美、高西全、彭学愚著．数字信号处理．西安：西安电子科技大学出版社，1994年．
[8] Wiener N. Extrapolation, interpretation, and smoothing of stationary time series. New York: MIT Press and Wiley, 1949.
[9] Kalman R.E.A new approach to linear filtering and prediction problems. Trans. ASME.J. Basic Eng, 1960, 82:35-45.
[10] Dention M, McCool J, Widrow B. Adaptive filtering in the frequency domain. Proc. IEEE, 1978, 66(12): 1658-1659.
[11] Ferrara E R Jr. Frequency-domain adaptive filtering. In Adaptive filters, Edited by Cowan C.EN. and Grant PM, New Jersey: Prentice-Hall, Englewood Cliffs, 1985.
[12] H.Witschnig, T.Mayer, A.Springer. A different look on cysclic prefix for sc/fde. Communications Magazine, IEEE, 2002.
[13] Luc Deneire. Training sequence versus cyclic prefix-A new look on single carder communication. Communications Magazine, IEEE, January 9, 2001.
[14] Mario Huemer, Harald Witschnig, Josef Hausner. Unique word based phase tracking algorithms for sc/fde_systems. Globecom, 2003.
[15] Andreas Czylwik. Comparison between adaptive OFDM and single carrier modulation with frequency domain equalization. Communications Magazine, IEEE, 1997.
[16] S.U.H.Qureshi. Adaptive Equalization, Proc. IEEE, Vol.73, No.9, Sept, 1985, pp. 1349-1387.
[17] D.D.Falconer and ER.Magee, Jr. Adaptive Channel Memory Truncation for Maximum-Likelihood Sequence Estimation. Bell System Tech. November 1973, pp. 1541-1562.
[18] D.G Messerschmitt. Design of a Finite Impulse Response for the Viterbi Algorithm and Decision Feedback Equalizer, Proc. ICC 74, Minneapolis, June 1974, pp. 37D-1—37D-5.
[19] M.V.Clark. Adaptive Frequency-Domain Equalization and Diversity Combining for Broadband Wireless Communications. IEEE JSAC, Vol.16, NO.8, Oct.1998, pp.1385-1395.
[20] 杨大成著．移动传播环境——理论基础．分析方法和建模技术．北京：机械工业出版社，2003年．
[21] Erceg V, Had K VS, Smith M S, et al. Channel Models for Fixed wireless Applications [S]. Contribution IEEE802.16a-03/01, [S.I.]: IEEE, 2003.
[22] IEEE Std 802.11a-1999, I.AN Medium Access Control (MAC) and Physical Layer (PHY) specifications: High-speed Physical Layer in the 5GHZ Band [S]. [S.I.]: IEEE, 1999.
[23] Schmidle T M, Cox, D C. Robust frequency and timing synchronization for OFDM [J]. IEEE Transactions on Communications, 1997, 45(12):1613-1621.
[24] Gardner F M. Interpolation in Digital Modems-Part Ⅰ: Fundamentals [J]. IEEE Trans On Communications, 1993, 41(3):501-507.
[25] Erup L, Gardner F M, Harris R A. Interpolation in Digital Modems-Part Ⅱ: Implementation and Performance [J]. IEEE Transactions on Communications, 1993, 41(6):998-1008.
[26] Gardner F M. A BPSK/QPSK Timing-Error Detector for Sampled Receivers [J]. IEEE Trans On Communications, 1986, 34(5):423-429.
[27] 郑大春，项海格．一种全数字化载波频偏估计器算法[J]．电子学报，1999，27(1)：78-80．
[28] 张厥盛，曹丽娜著．锁相与频率合成技术[M]．成都：电子科技大学出版社，1998．
[29] 万心平著．锁相技术[M]．西安：西安电子科技大学出版社，1990．
[30] 李方慧，王飞，何佩琨著．TMS320C6000系列DSPs原理与应用，第2版．北京：电子工业出版社，2003年6月．
[31] 周霖著．DSP通信工程技术应用．湖南：国防工业出版社，2004年．
[32] 张雄伟，陈亮，徐光辉著．DSP芯片的原理与开发应用．北京：电子工业出版社，2003年．