DS-CDMA系统多用户检测技术算法的研究与性能分析
|
摘要
WCDMA、CDMA2000和TD—SCDMA都已经成为了第三代移动通信的方案，而其中的一些关键技术基本一致。CDMA通信系统的关键技术包括高效信道编译码技术、软件无线电技术、智能天线技术、多用户检测和干扰消除技术等。在直扩码分多址(DS—CDMA)系统中，多址干扰是影响系统性能和容量的重要因素之一。多用户检测是一种从接受端的设计入手的干扰抑制方法。它主要解决的问题是：如何从相互干扰的数字信息序列中可靠地解调出某个特定或全部用户的信息。多用户检测技术在传统检测技术的基础之上，充分利用所有用户信号信息对多个用户进行联合检测或从接收信号中减掉相互间干扰的方法，从理论上有效地消除多址干扰的影响，从而改善系统性能，增大系统容量。
本文从DS—CDMA的优势和存在的问题出发，引出了多用户检测的必要性。并且在对现有典型多用户检测算法进行分析和对比的基础上，提出了两种新的降低算法复杂度的多用户检测算法：“低复杂度多项式逼近算法”和“频域DFT快速分组检测算法”，并对它们的性能进行了详细分析和研究。理论分析和计算机仿真结果标明，这两种算法均显示出了优良的性能。其中，前一种算法立足多项式扩展检测的经典结论，同时将Gauss—Seidel迭代方法引入其中，最终将矩阵求逆转化为泰勒级数近似的形式。这样不但使得矩阵求逆的庞大运算量有了显著削减，而且级联结构清晰，具体实现简单。后一种算法属于“信道盲均衡”范畴，从分析最优化代价函数和约束条件着手，将IDFT的定义式引入时域输出表达式，最终推导出滤波器抽头更新系数与“输入符号”和“恒模”之间的关系。该算法在保证系统性能(误码率)的前提下，滤波器抽头系数的更新复杂度得到了大幅度降低。这两种算法都属于线性检测算法，在较恶劣信道环境下，依然能够保持优良性能和对于“远近效应”的抵抗。
WCDMA、CDMA2000 and TD-SCDMA are the scenarios on the third Generation mobile communications, some key techniques are consistent in these schemes. And including : highly effective channel encoding-decoding、software radio、smart antenna、multiuser detection and interference cancellation etc. In direct-sequence(DS) CDMA system, multi-access interference is one of the important factors that affect the systematic performance and capacity. Multiuser detection suppresses the interference at the receiver. The problem that it should solve is: How demodulate the bit information reliably of some specific user or all of the users from digital bits sequence that interference effectively by joint detection or subtract the MAI from the receiving signal according to the knowledge of sequences of all users basing on traditional detection of filter bank. Thus it can improve the performance of the system and increases capacity of the system.
This paper educed the necessity of multiuser detection by analysis the advantages and problems of the DS-CDMA system in existence. On the analysis and contrast based on existing typical algorithms on multiuser detection, two new MUD algorithms are presented for improving computing complexity: "Low complexity polynomial expansion closed" and "Fast equalization by using frequency domain block constant modulus". The performance of the new detectors is analyzed and researched in detail in this paper. Theoretical analysis and computer simulation results indicate that these two algorithms have shown a good performance. Among them, former polynomial expansion detection algorithm based on the classic conclusion ,Gauss—Seidel iterative method which will introduce the same time. Inverse matrix will eventually form into a Taylor series approximation. This not only makes a huge amount of computation matrix inversion have been significantly reduced, but cascade structure clear, simple realization. The latter algorithm is a "blind channel balancing" areas, from the analysis of the cost function and constraints optimization proceed. IDFT introduction to the time-domain-defined output expression updating filter coefficients derived ultimately tap "input symbols" and "constant modulus" the relations between them. The algorithm guarantee system performance (BER) on the premise that Tap the filter coefficient update has been significantly reduced complexity. These two algorithms are linear detection algorithm in a relatively poor channel environment, still be able to maintain good performance and for the "Near-Far" of the resistance.
本文从DS—CDMA的优势和存在的问题出发，引出了多用户检测的必要性。并且在对现有典型多用户检测算法进行分析和对比的基础上，提出了两种新的降低算法复杂度的多用户检测算法：“低复杂度多项式逼近算法”和“频域DFT快速分组检测算法”，并对它们的性能进行了详细分析和研究。理论分析和计算机仿真结果标明，这两种算法均显示出了优良的性能。其中，前一种算法立足多项式扩展检测的经典结论，同时将Gauss—Seidel迭代方法引入其中，最终将矩阵求逆转化为泰勒级数近似的形式。这样不但使得矩阵求逆的庞大运算量有了显著削减，而且级联结构清晰，具体实现简单。后一种算法属于“信道盲均衡”范畴，从分析最优化代价函数和约束条件着手，将IDFT的定义式引入时域输出表达式，最终推导出滤波器抽头更新系数与“输入符号”和“恒模”之间的关系。该算法在保证系统性能(误码率)的前提下，滤波器抽头系数的更新复杂度得到了大幅度降低。这两种算法都属于线性检测算法，在较恶劣信道环境下，依然能够保持优良性能和对于“远近效应”的抵抗。
WCDMA、CDMA2000 and TD-SCDMA are the scenarios on the third Generation mobile communications, some key techniques are consistent in these schemes. And including : highly effective channel encoding-decoding、software radio、smart antenna、multiuser detection and interference cancellation etc. In direct-sequence(DS) CDMA system, multi-access interference is one of the important factors that affect the systematic performance and capacity. Multiuser detection suppresses the interference at the receiver. The problem that it should solve is: How demodulate the bit information reliably of some specific user or all of the users from digital bits sequence that interference effectively by joint detection or subtract the MAI from the receiving signal according to the knowledge of sequences of all users basing on traditional detection of filter bank. Thus it can improve the performance of the system and increases capacity of the system.
This paper educed the necessity of multiuser detection by analysis the advantages and problems of the DS-CDMA system in existence. On the analysis and contrast based on existing typical algorithms on multiuser detection, two new MUD algorithms are presented for improving computing complexity: "Low complexity polynomial expansion closed" and "Fast equalization by using frequency domain block constant modulus". The performance of the new detectors is analyzed and researched in detail in this paper. Theoretical analysis and computer simulation results indicate that these two algorithms have shown a good performance. Among them, former polynomial expansion detection algorithm based on the classic conclusion ,Gauss—Seidel iterative method which will introduce the same time. Inverse matrix will eventually form into a Taylor series approximation. This not only makes a huge amount of computation matrix inversion have been significantly reduced, but cascade structure clear, simple realization. The latter algorithm is a "blind channel balancing" areas, from the analysis of the cost function and constraints optimization proceed. IDFT introduction to the time-domain-defined output expression updating filter coefficients derived ultimately tap "input symbols" and "constant modulus" the relations between them. The algorithm guarantee system performance (BER) on the premise that Tap the filter coefficient update has been significantly reduced complexity. These two algorithms are linear detection algorithm in a relatively poor channel environment, still be able to maintain good performance and for the "Near-Far" of the resistance.
引文
[1] 张贤达，保铮．通信信号处理．北京：国防工业出版社，2000．
[2] 樊昌信，张甫翊，徐炳祥等．通信原理(第5版)．北京：国防工业出版社，2001．
[3] 周炯槃，庞沁华，续大我等．通信原理．北京：北京邮电大学出版社，2002．
[4] 奥本海姆．信号与系统(第2版)．北京：电子工业出版社，2002．
[5] D.N.Godard, "Self-Recovering Equalization and Carrier Tracking in Two-Dimensional Data Communication Systems "IEEE Trans.Commun.vol.COM-28, no.11, pp, 1867-1875, Nov.1980.
[6] S.Verdu, Multiuser Detection, Cambridge University Press, 1998.
[7] Z.D.Lei and T.J.Lim, "Simplified polynomial-expansion linear detectors for ds-cdma systems", Electronics Letters, vol.34, no.16, pp, 1561-1563, Aug.1998.
[8] G.M.A.Sessler and F.K.Jondral, "Multiuser detection for ultra-tdd based on polynomial expansion", in Proceedings of the IEEE 54th Vehicular Technology Coference VTC 2001, vol.4
[9] 杨大成．cdma2000技术．北京：北京邮电大学出版社，2000．
[10] R.Lupas and S.Verdu, " Near-far resistance of multi-user detection in asynchronous channels", IEEE Transactions On Communications, vol.38, pp, 496-508, 1998.
[11] S.Verdu, "Minimum probability of error for asynchronous Gaussian multi-access channels", IEEE Transaction of Information Theory, vol.132, pp, 85-96, 1986.
[12] 张贤达，保铮．非平稳信号分析与处理．北京：国防工业出版社，1989．
[13] JOHNG. PROAKIS, Digital Communications (Third Edition) [M].北京：电子工业出版社(影印版)，2001.
[14] Richard E. Blahut, Fast Algorithms for Digital Processing, Addison Wesley, 1985.
[15] M. Mozaffarripour and R.Tafazolli, Fast Linear Multi-user Detector for DS-CDMA Systems, Capacity and range enhancement techniques for the third generation mobile communication and beyond, London, February.2000.
[16] General Instrument Corporation, DigiCipher HDTV System Description, Aug. 1991.
[17] D. Mansour and A.H.G.Gray, "Unconstrained Frequency-Domain Adaptive Filter", IEEE Trans.Acoust., Speech, and Signal, Proc, vol.ASSP-30, no.5, pp.726-734, Oct.1982.
[18] J.C.Lee and C.K.Un, "Performance Analysis of Frequency-Domain Block LMS Adaptive Filters", IEEE Trans.Circuits and Systems, vol.36, no.2, pp.173-189, Feb. 1989.
[19] L.N.Wong et. al., "Performance of Trellis Codes for a Class of Equalized ISI Channels", IEEETrans. onCommun., vol.36, no.12, pp.1330-1336, Dec.1988.
[20] D.S Chen and S.Roy, "An adaptive Multiuser Dereiver for CDMA Systems", IEEE Joumal on Selected Areas in communications, vol.12, no.5, pp.808-816, June. 1994.
[21] W.Lee, B.R.Vojcic and R.L.Pickholtz, "Constant Modulus Algorithm for Blind Multiuser Detection", ISSSSTA'96, Germany, pp. 1262-1266
[22] S.L.Miller, "An Adaptive Direct-Sequence Code-Division Multiple-Access Receiver for Multiuser Interference Rejection", IEEE Transaction on Communications, vol.COM-43, pp. 1746-1755, Feb/Mar/Apr. 1995.
[23] S.L.Miller, "Training Analysis of Adaptive Interference Suppression for Direct-Sequence Code-Division Multiple-Access Systems", IEEE Transactions on Communications, vol.COM-44, pp.488-495, April.1995.
[24] T.R.giallorenzi and S.GWison, " Multiuser ML sequence estimator for convolutional coded asynchronous DS-CDMA systems", IEEE Trans.Comm., vol.44, no.8, pp.997-1008, Aug.1996.
[25] J.M Luna Rivera, D.G.M.Cruickshank and J.S.Thompson, "hybrid Iternative Multiuser Receiver for a Coded DS-CMDA systems", IEEE International Symposium on Spread Spectrum Techniques and Applications (ISSSTA'02 )
[26] C.R.Johnson, JR., P.Schniter, T.J.Endres, J.D.Behrn, D.R.Brown, R.A.Casas, "Blind equalization using the constant modulus criterion: A review", Proceeding of the IEEE, vol.86, no.10, pp.1927-1949, Aug.1998.
[27] Ramjee Prassad著，朱旭红，卢学军，卓天真等译．宽带CDMA：第三代移动通信技术．北京：国防工业出版社，2001．
[28] 沈允春．扩谱技术．北京：国防工业出版社，1995．
[29] 张平．第三代蜂窝移动通信系统一WCDMA．北京：北京邮电大学出版社，2000．
[30] 吴伟陵．移动通信中的关键技术．北京：北京邮电大学出版社，2000．
[31] U.Madhow, "MMSE Interference Suppression for Timing Acquisition and Demodulation in Direct-Sequence CDMA Systems", IEEE Trans. on Commun., no.8, pp.1065-1075, 1998.
[32] L.Rusch and H.V.Poor, "Narrowband interference Suppression in spread spectrum CDMA", IEEE personal commun., vol.1 no.3, pp.14-27, Aug.1994.
[33] 张贤达．信号处理中的线性代数．北京：科学出版社，1997．
[34] Wang Xiaodong. Wireless Communication Systems[M].北京：电子工业出版社，2004.
[35] Z.DING and Y.LI., Blind Equalization and Identification, Dekker, New York, 2001.
[36] J.Miguez and L.Chambers, "A linearly constrained constant modulus approach to blind adaptive multiuser interference suppression", IEEE Commun.Lett., vol.1, no.2, pp.217-219, Aug.1998.
[37] C.Xu and G.Feng, "A linearly constrained constant modulus approach to blind adaptive multiuser interference suppression", IEEE Commun. Lett., vol.4, pp.280-282, Sept.2000.
[38] S.Verdu, B.Anderson and R.Kennedy, "Anchored blind equalization", in Proc.25th Conf. on Information Sciences and Systems, Bsltimore, MD, pp.774-779, Mar.1991.
[39] C.Papadias and A.Paulraj, "A constant modulus algorithm for multi-user signal separation in presence of delay spread using antenna arrays", IEEE Signal Processing Lett., vol.4, pp.178-181, june 1997.
[40] L.castedo, C.J.Escudero and A. Dapena, "A blind signal separation method for multiuser communications", IEEE Trans. Signal Processing, vol.45, pp. 1343-1348, June. 1997.
[41] L.J.grif ths and C.W.Jim, "An alternative approach to linearly constrained adaptive beamforming", IEEE Trans.Acoust, Speech, Signal Processing, vol.ASSP-30, pp.2737-2746, nov.1982.
[42] R.A.Horn and C.R.Johnson. Matrix Analysis. New York: Cambridge Univ.Press, 1995.
[43] 刘敏，魏玲编著．MATLAB通信仿真与应用．北京：国防工业出版社，2001．
[44] N.Zecevic and J.H.Reed, "Blind CMDA Interference Rejection in Multipath Channels", IEEEVTC'97, pp.21-25, 1997.
[45] 王艳，付永庆，孙晓岩．一种信道盲自适应多用户检测技术[J]．通信技术，2003(4)：63-65．
[2] 樊昌信，张甫翊，徐炳祥等．通信原理(第5版)．北京：国防工业出版社，2001．
[3] 周炯槃，庞沁华，续大我等．通信原理．北京：北京邮电大学出版社，2002．
[4] 奥本海姆．信号与系统(第2版)．北京：电子工业出版社，2002．
[5] D.N.Godard, "Self-Recovering Equalization and Carrier Tracking in Two-Dimensional Data Communication Systems "IEEE Trans.Commun.vol.COM-28, no.11, pp, 1867-1875, Nov.1980.
[6] S.Verdu, Multiuser Detection, Cambridge University Press, 1998.
[7] Z.D.Lei and T.J.Lim, "Simplified polynomial-expansion linear detectors for ds-cdma systems", Electronics Letters, vol.34, no.16, pp, 1561-1563, Aug.1998.
[8] G.M.A.Sessler and F.K.Jondral, "Multiuser detection for ultra-tdd based on polynomial expansion", in Proceedings of the IEEE 54th Vehicular Technology Coference VTC 2001, vol.4
[9] 杨大成．cdma2000技术．北京：北京邮电大学出版社，2000．
[10] R.Lupas and S.Verdu, " Near-far resistance of multi-user detection in asynchronous channels", IEEE Transactions On Communications, vol.38, pp, 496-508, 1998.
[11] S.Verdu, "Minimum probability of error for asynchronous Gaussian multi-access channels", IEEE Transaction of Information Theory, vol.132, pp, 85-96, 1986.
[12] 张贤达，保铮．非平稳信号分析与处理．北京：国防工业出版社，1989．
[13] JOHNG. PROAKIS, Digital Communications (Third Edition) [M].北京：电子工业出版社(影印版)，2001.
[14] Richard E. Blahut, Fast Algorithms for Digital Processing, Addison Wesley, 1985.
[15] M. Mozaffarripour and R.Tafazolli, Fast Linear Multi-user Detector for DS-CDMA Systems, Capacity and range enhancement techniques for the third generation mobile communication and beyond, London, February.2000.
[16] General Instrument Corporation, DigiCipher HDTV System Description, Aug. 1991.
[17] D. Mansour and A.H.G.Gray, "Unconstrained Frequency-Domain Adaptive Filter", IEEE Trans.Acoust., Speech, and Signal, Proc, vol.ASSP-30, no.5, pp.726-734, Oct.1982.
[18] J.C.Lee and C.K.Un, "Performance Analysis of Frequency-Domain Block LMS Adaptive Filters", IEEE Trans.Circuits and Systems, vol.36, no.2, pp.173-189, Feb. 1989.
[19] L.N.Wong et. al., "Performance of Trellis Codes for a Class of Equalized ISI Channels", IEEETrans. onCommun., vol.36, no.12, pp.1330-1336, Dec.1988.
[20] D.S Chen and S.Roy, "An adaptive Multiuser Dereiver for CDMA Systems", IEEE Joumal on Selected Areas in communications, vol.12, no.5, pp.808-816, June. 1994.
[21] W.Lee, B.R.Vojcic and R.L.Pickholtz, "Constant Modulus Algorithm for Blind Multiuser Detection", ISSSSTA'96, Germany, pp. 1262-1266
[22] S.L.Miller, "An Adaptive Direct-Sequence Code-Division Multiple-Access Receiver for Multiuser Interference Rejection", IEEE Transaction on Communications, vol.COM-43, pp. 1746-1755, Feb/Mar/Apr. 1995.
[23] S.L.Miller, "Training Analysis of Adaptive Interference Suppression for Direct-Sequence Code-Division Multiple-Access Systems", IEEE Transactions on Communications, vol.COM-44, pp.488-495, April.1995.
[24] T.R.giallorenzi and S.GWison, " Multiuser ML sequence estimator for convolutional coded asynchronous DS-CDMA systems", IEEE Trans.Comm., vol.44, no.8, pp.997-1008, Aug.1996.
[25] J.M Luna Rivera, D.G.M.Cruickshank and J.S.Thompson, "hybrid Iternative Multiuser Receiver for a Coded DS-CMDA systems", IEEE International Symposium on Spread Spectrum Techniques and Applications (ISSSTA'02 )
[26] C.R.Johnson, JR., P.Schniter, T.J.Endres, J.D.Behrn, D.R.Brown, R.A.Casas, "Blind equalization using the constant modulus criterion: A review", Proceeding of the IEEE, vol.86, no.10, pp.1927-1949, Aug.1998.
[27] Ramjee Prassad著，朱旭红，卢学军，卓天真等译．宽带CDMA：第三代移动通信技术．北京：国防工业出版社，2001．
[28] 沈允春．扩谱技术．北京：国防工业出版社，1995．
[29] 张平．第三代蜂窝移动通信系统一WCDMA．北京：北京邮电大学出版社，2000．
[30] 吴伟陵．移动通信中的关键技术．北京：北京邮电大学出版社，2000．
[31] U.Madhow, "MMSE Interference Suppression for Timing Acquisition and Demodulation in Direct-Sequence CDMA Systems", IEEE Trans. on Commun., no.8, pp.1065-1075, 1998.
[32] L.Rusch and H.V.Poor, "Narrowband interference Suppression in spread spectrum CDMA", IEEE personal commun., vol.1 no.3, pp.14-27, Aug.1994.
[33] 张贤达．信号处理中的线性代数．北京：科学出版社，1997．
[34] Wang Xiaodong. Wireless Communication Systems[M].北京：电子工业出版社，2004.
[35] Z.DING and Y.LI., Blind Equalization and Identification, Dekker, New York, 2001.
[36] J.Miguez and L.Chambers, "A linearly constrained constant modulus approach to blind adaptive multiuser interference suppression", IEEE Commun.Lett., vol.1, no.2, pp.217-219, Aug.1998.
[37] C.Xu and G.Feng, "A linearly constrained constant modulus approach to blind adaptive multiuser interference suppression", IEEE Commun. Lett., vol.4, pp.280-282, Sept.2000.
[38] S.Verdu, B.Anderson and R.Kennedy, "Anchored blind equalization", in Proc.25th Conf. on Information Sciences and Systems, Bsltimore, MD, pp.774-779, Mar.1991.
[39] C.Papadias and A.Paulraj, "A constant modulus algorithm for multi-user signal separation in presence of delay spread using antenna arrays", IEEE Signal Processing Lett., vol.4, pp.178-181, june 1997.
[40] L.castedo, C.J.Escudero and A. Dapena, "A blind signal separation method for multiuser communications", IEEE Trans. Signal Processing, vol.45, pp. 1343-1348, June. 1997.
[41] L.J.grif ths and C.W.Jim, "An alternative approach to linearly constrained adaptive beamforming", IEEE Trans.Acoust, Speech, Signal Processing, vol.ASSP-30, pp.2737-2746, nov.1982.
[42] R.A.Horn and C.R.Johnson. Matrix Analysis. New York: Cambridge Univ.Press, 1995.
[43] 刘敏，魏玲编著．MATLAB通信仿真与应用．北京：国防工业出版社，2001．
[44] N.Zecevic and J.H.Reed, "Blind CMDA Interference Rejection in Multipath Channels", IEEEVTC'97, pp.21-25, 1997.
[45] 王艳，付永庆，孙晓岩．一种信道盲自适应多用户检测技术[J]．通信技术，2003(4)：63-65．