基于查找表的数字预失真算法研究及系统仿真
|
摘要
在欧洲第三代移动通信(3G)已经慢慢融入人们的生活,中国的第三代移动通信3G也已指日可待。第三代移动通信系统需要支持各种大量的业务类型,让用户能够在任何地方、任何时间向任何人进行通信,这就要求必须具备优良的网络传输结构及较大的数据传输量。这样一来,新型的宽带传输技术(如OFDM、WCDMA等)和高频谱效率的调制方式(如QPSK,M-QAM等)正获得越来越广泛的应用。但这些基于非恒定包络的多载波及多信道数字调制传输技术对于射频功率放大器的线性度具有很高的要求,经过非线性射频系统会产生众多的互调失真分量,形成对邻近信道的干扰。
为了解决这一问题,我们通常采用线性化的方法来对失真信号进行校正。数字预失真技术由于其精度高,适应性强,实现也相对简单,成为所有线性化技术中性价比最好的一种线性化技术。本文主要对非线性功率放大器的预失真算法进行了研究并提出了新的改进方法,并就改进的算法进行了系统仿真。主要工作包括:
(1)对非线性系统进行了分析,对常用的线性化方法进行了分析和比较,介绍了功率放大器主要技术指标。分析了几种常用的功率放大器数学模型,并以直观的方式给出了各种模型的框架图。从算法入手对自适应数字预失真方案进行分析。主要针对多项式技术和查找表方式的自适应数字预失真算法进行了分析。重点研究了LMS,RLS和离散Newton迭代法等算法从而解决功放所带来的非线性幅度相位失真问题。
(2)运用ADS对所提出的改进查找表的预失真系统进行了仿真,管子采用的是摩托罗拉的MRF21125,功放的工作频率为2.14Ghz。
(3)运用matlab软件对提出的改进的查找表方法进行了16-QAM,64-QAM调制信号的预失真仿真,同时在此基础上并对WCDMA信号的进行QAM调制和预失真处理仿真,并与没采用预失真和其他采用预失真后的相关仿真相比效。
(4)运用matlab软件在所提出的查找表方法的基础上对载波数数为128,信噪比为20dB,FFT长度采用128的OFDM系统进行了仿真。并和其他预失真方法的仿真结果进行比较,从而验证了这一设计方案的可行性,取得了预期的效果。
The third generation mobile communication(3G)has already integrated with people's life in European,which is also just been around the corner in China.The third generation mobile communication system which could support massive different kinds of services, and provide person-to-person communication service to anybody, in any place, any time needs good network architecture support. Therefore, The information transmission technology of modern communication system is developing rapidly in the direction of multi-carrier, multi-level, broad band and high Peak-Average-Ratio(PAR). New broad band digital transmission techniques(such as OFDM,WCDMA) and high spectrum efficiency modulation techniques(such as QPSK, M-QAM) are extensive used. These high efficient multi-carrier&multi-channel digital modulation transmission techniques, which are based on non-constant envelope,request high linearity of radio frequency power amplifiers(RF RAs).When signal is amplified by RF PAs, intermodulation distortion is generated, which results in spectral regrowth, then leads to adjacent channel interference.
We usually adopt linear approach to correct the distortion-signal. Among the linear approach, digital predistortion is one the best approach due to its high precision, adaptability and capability that relatively simple to achieve. This paper focuses on the algorithm and the implementation of the DPD system. Then we demonstrate the effectiveness of the novel method we have proposed by means of simulation. major work including:
1 We make fully analysis of the nonlinear systems and discuss the problems of communication system arising from the nonlinear distortion theoretically. Then, we make comparison of various commonly used linearization technique and analyse several commonly used mathematical model of the power amplifier and give a framework for a variety of model plans. The analysis of algorithm which is the core of adaptive digital predistortion technology is our research goal. The method based on Polynomial and look up table is our concern. We commit ourselves to analyse the LMS, RLS and Newton algorithm in order to solve the nonlinear problem that bring from PA.
2 We simulate the predistortion system which is base on our proposed LUT method with Agilent's software ADS.The transistor we apply is Motorola's MRF21125 which power amplifier operating frequency is 2.14Ghz..
3 We simulate the proposed predistorttion LUT method using 16-QAM and 64-QAM modulate signal under software MATLAB, then make the simulation with WCDMA signal further and make comparison with absent predistotor and other people's method.
4 We simulate the proposed lookup table method based on OFDM system which carrier numbers is 128, 20dB SNR and length of FFT is 128. we analyse and make comparison of our proposed predistortion system with constellation. Results obviously verify the practicability and advantage of our proposed method. During the test, we have been using the QAM mapping.
为了解决这一问题,我们通常采用线性化的方法来对失真信号进行校正。数字预失真技术由于其精度高,适应性强,实现也相对简单,成为所有线性化技术中性价比最好的一种线性化技术。本文主要对非线性功率放大器的预失真算法进行了研究并提出了新的改进方法,并就改进的算法进行了系统仿真。主要工作包括:
(1)对非线性系统进行了分析,对常用的线性化方法进行了分析和比较,介绍了功率放大器主要技术指标。分析了几种常用的功率放大器数学模型,并以直观的方式给出了各种模型的框架图。从算法入手对自适应数字预失真方案进行分析。主要针对多项式技术和查找表方式的自适应数字预失真算法进行了分析。重点研究了LMS,RLS和离散Newton迭代法等算法从而解决功放所带来的非线性幅度相位失真问题。
(2)运用ADS对所提出的改进查找表的预失真系统进行了仿真,管子采用的是摩托罗拉的MRF21125,功放的工作频率为2.14Ghz。
(3)运用matlab软件对提出的改进的查找表方法进行了16-QAM,64-QAM调制信号的预失真仿真,同时在此基础上并对WCDMA信号的进行QAM调制和预失真处理仿真,并与没采用预失真和其他采用预失真后的相关仿真相比效。
(4)运用matlab软件在所提出的查找表方法的基础上对载波数数为128,信噪比为20dB,FFT长度采用128的OFDM系统进行了仿真。并和其他预失真方法的仿真结果进行比较,从而验证了这一设计方案的可行性,取得了预期的效果。
The third generation mobile communication(3G)has already integrated with people's life in European,which is also just been around the corner in China.The third generation mobile communication system which could support massive different kinds of services, and provide person-to-person communication service to anybody, in any place, any time needs good network architecture support. Therefore, The information transmission technology of modern communication system is developing rapidly in the direction of multi-carrier, multi-level, broad band and high Peak-Average-Ratio(PAR). New broad band digital transmission techniques(such as OFDM,WCDMA) and high spectrum efficiency modulation techniques(such as QPSK, M-QAM) are extensive used. These high efficient multi-carrier&multi-channel digital modulation transmission techniques, which are based on non-constant envelope,request high linearity of radio frequency power amplifiers(RF RAs).When signal is amplified by RF PAs, intermodulation distortion is generated, which results in spectral regrowth, then leads to adjacent channel interference.
We usually adopt linear approach to correct the distortion-signal. Among the linear approach, digital predistortion is one the best approach due to its high precision, adaptability and capability that relatively simple to achieve. This paper focuses on the algorithm and the implementation of the DPD system. Then we demonstrate the effectiveness of the novel method we have proposed by means of simulation. major work including:
1 We make fully analysis of the nonlinear systems and discuss the problems of communication system arising from the nonlinear distortion theoretically. Then, we make comparison of various commonly used linearization technique and analyse several commonly used mathematical model of the power amplifier and give a framework for a variety of model plans. The analysis of algorithm which is the core of adaptive digital predistortion technology is our research goal. The method based on Polynomial and look up table is our concern. We commit ourselves to analyse the LMS, RLS and Newton algorithm in order to solve the nonlinear problem that bring from PA.
2 We simulate the predistortion system which is base on our proposed LUT method with Agilent's software ADS.The transistor we apply is Motorola's MRF21125 which power amplifier operating frequency is 2.14Ghz..
3 We simulate the proposed predistorttion LUT method using 16-QAM and 64-QAM modulate signal under software MATLAB, then make the simulation with WCDMA signal further and make comparison with absent predistotor and other people's method.
4 We simulate the proposed lookup table method based on OFDM system which carrier numbers is 128, 20dB SNR and length of FFT is 128. we analyse and make comparison of our proposed predistortion system with constellation. Results obviously verify the practicability and advantage of our proposed method. During the test, we have been using the QAM mapping.
引文
[1]兆龙我国3G建设情况及进展综述江苏通信-2009年6期
[2]钟章队,刘秋妍对中国GSM-R发展的研究铁路通信信号工程技术2009年1期pp.238-241
[3]钟伟21世纪第三代移动通信技术的发展模式研究通信技术期刊2008年10期pp.224-227
[4]耿光辉,张会生,16QAM解调器的FPGA实现微机处理2007年1月
[5]肖世尧李晓峰GMSK基带调制解调器的设计与实现微计算机信息2008 pp.107-113
[6]侯地哈高效率高线性基站功放的研究与设计电子科技大学2009
[7]张福洪,褚如龙,孔庆浩基于数字预失真技术的有记忆功放线性化研究计算机仿真。2009年1期pp.146-149
[8] Guel, D.,Palicot, J. Analysis and comparison of clipping techniques for OFDM Peak-to-Average Power Ratio reduction Institute of Electrical and Electronics Engineers(IEEE)2009 pp.1440-1446
[9] Hammi, O.;Carichner, S.;Vassilakis, B.;Ghannouchi, F.M. Synergetic Crest Factor Reduction and Baseband Digital Predistortion for Adaptive 3G Doherty Power Amplifier Linearizer Design. IEEE Transactions on Microwave Theory and Techniques. 2008 pp.2602-2608
[10]丘春辉,陈向东,沈冰射频功率放大器前馈线性化技术研究微电子学与计算机2008
[11] SungWon Chung,Jack W. Open-Loop Digital Predistortion Using Cartesian Feedback for Adaptive RF Power Amplifier Linearization. Holloway,Joel L. Dawson2007 pp.1449-1452
[12] Garcia, P.,de Mingo,J. Nonlinear Distortion Cancellation in a LINC Transmitter using Genetic Algorithms.外文会议Valdovinos, A. 2005 pp.66-71
[13] Young Yun Woo;Jangheon Kim;Jaehyok Yi;Sungchul Hong;Ildu Kim;Junghwan Moon;Bumman Kim. Adaptive Digital Feedback Predistortion Technique for Linearizing Power Amplifiers. IEEE Transactions on Microwave Theory and Techniques. 2007 no.5pp.932-940
[14] Thai Hoa Vo,Tho Le-Ngoc*,and Hichem Besbes. An Adaptive Baseband Digital Predistortion System For An RF Power Amplifier. Wiley Inter Science.March 2006. pp.216-225
[15] TaijunLiu,SlimBoumaiza,TaijunLiu,SlimBoumaiz. Dynamic Behavioral Modeling of 3G Power Amplifiers Using Real-Valued Time Delay Neural Networks. IEEE transactions on microwave theory and techniques. NO.3,MARCH 2004 pp.1025-1033
[16] Taijun Liu, Senior Member, IEEE, Yan Ye, Tiefeng Xu, Dongya Shen. Analysis and Decomposition of the Nonlinearities in RF Power Amplifiersand Wireless Transmitters. MTT. 2004
[17] Hsin-Hung Chen;Chili-Hung Lin;Po-Chiun Huang;Jiunn-Tsair Chen. Joint Polynomial and Look-Up-Table Predistortion Power Amplifier Linearization. IEEE Transactions on Circuits and Systems. II, Express Briefs 2006 no.8 pp.612-616
[18] Jin Zhe,Song Zhihuan,He Jiaming. Volterra series based predistortion for broadband RF power amplifiers with memory effects系统工程也电子技术(英文版)。2008年第4期pp.2155-2164
[19]陈海生TD-SCDMA预失真技术的研究与应用通信技术2009.4
[20] Jiantao Yang , Jun Gao , Shuhong Guo , Xiaotao Deng. Neural-Network-Based Predistortion Method for High-Power Amplifiers With Memory. The IET 2nd International Conference on Wireless,Mobile & Multimedia Networks.2008 pp.329-332
[21] G. Montoro,P. L. Gilabert,E. Bertran,A. Cesari,J. A. An LMS-Based Adaptive Predistorter for Cancelling Nonlinear Memory Effects in RF Power Amplifiers. Garcia. 2007
[22]贾建华,王强,JIA Jianhua,WANG Qiang一种基于RLS算法的多项式预失真技术现代电子技术2006年第16期
[24]路宁刘章发LU Ning,LIU Zhang-fa一种高线性度AB类CMOS功率放大器的设计与实现电脑知识与技术2007年第10期pp.134-136
[25] Chowdhury, D.;Reynaert, P.;Niknejad, A. M. Transformer-Coupled Power Amplifier Stability and Power Back-Off Analysis. IEEE transactions on circuits and systems. II, Express briefs. 2008 No.6
[26] Jin Zhe Volterra series based predistortion for broadband RF power amplifiers withmemory effects Engmeering and Electronics No.4,2008,pp.666-671
[27]丁元明,王甲凯模块化模型功率放大器的自适应预失真计算机工程与应用2009年29期pp.114-117
[28]曹新容,黄联芬,赵毅峰一种基于Hammerstein模型的数字预失真算法厦门大学学报(自然科学版) 2009年1期pp.47-51
[29] Li Bo, Ge Jian-hua Ai Bo. A robust power amplifier predistorter constructed using memory polynomials. The 4th International Conference on Wireless Communications, Networking and Mobile Computing 2008 pp.1323-1327
[30] AndingZhu Digital Predistortion Envelope Power Amplifiers Decomposed IEEE Transaction on Microwave Theory 2008 pp.2237-2247
[31] Zhiwen Zhu Xingping Huang Design of an LUT-based Predistorter for Power Amplifer Linearization International Conference on Advances in Satellite and Space Communications 2009.1 pp.113-116
[32]艾渤杨知行基于LUT的HPA数字基带预失真方法研究电子与信息学报2007年7月pp.1580-1584
[33] DennisR.Morgan A Generalized Memory Polynomial Model for Digital Predistortion of RF Power Amplifiers IEEE TRANSACTIONS ON SIGNAL PROCESSING oct.2006 pp.3852-3860
[34]赵新锋一种基于多项式的预失真算法电子科技2008.10 pp.41-44
[35]贺彬,陈豪基于LMS的WADPD功率放大器线性算法信息与电子工程2009年5期pp.427-431
[36] 2006 Siva D.Muruganathan A QRD-RLS-Based Predistortion Schemefor High-Power Amplifier Linearization IEEE TRANSACTIONS ON CIRCUITS AND SYSTEM Soct.2006 pp.1108-1112
[37] Compact Optichron OP4400 Digital Pre-Distortion ICs Cut Costs of Wireless frastructure Applications[Z].Optichron.2008
[38] Lei Ding ; Zhengxiang Ma ; Morgan, D.R. ; Zierdt, M. ; Pastalan, J. A least-squares/Newton method for digital predistortion of wideband signals. IEEE Transactions on Communications. 2006 No.5
[39] Xiaochen Lin,Minglu Jin An Improved Adaptive Digital Predistortion Using Discrete Newton's Method第三届IEEE无线通讯、网络技术暨移动计算国际会议2007
[40] Taijun Liu Analysis and Decomposition of the Nonlinearities in RF PowerAmplifiersand Wireless Transmitters IEEE TRANSACTIONS ON SIGNAL PROCESSING 2007.10 pp.235-241
[41] P.J.;Chin Hsia;Brazil, T.J.;Kimball, D.F.;Digital Predistortion for Envelope-Tracking Power Amplifiers Using Decomposed Piecewise Volterra Series. IEEE Transactions on Microwave Theory and Techniques 2008 No.10 pp.2408-2413
[42] ThaiHoaVo Adaptive polynomial predistorters forM-QAM transmission using non-linear power amplifiers.Wiley Inter Science 2007 pp.3207-3211
[43] Taijun Liu,Yan Ye,Xingbin Zeng, Spectral Methods for Accurate Identification and Quantification of Memory Effects of Wideband RF Power Amplifiers IEEE Xplore March 26, 2009 pp.1456-1459
[2]钟章队,刘秋妍对中国GSM-R发展的研究铁路通信信号工程技术2009年1期pp.238-241
[3]钟伟21世纪第三代移动通信技术的发展模式研究通信技术期刊2008年10期pp.224-227
[4]耿光辉,张会生,16QAM解调器的FPGA实现微机处理2007年1月
[5]肖世尧李晓峰GMSK基带调制解调器的设计与实现微计算机信息2008 pp.107-113
[6]侯地哈高效率高线性基站功放的研究与设计电子科技大学2009
[7]张福洪,褚如龙,孔庆浩基于数字预失真技术的有记忆功放线性化研究计算机仿真。2009年1期pp.146-149
[8] Guel, D.,Palicot, J. Analysis and comparison of clipping techniques for OFDM Peak-to-Average Power Ratio reduction Institute of Electrical and Electronics Engineers(IEEE)2009 pp.1440-1446
[9] Hammi, O.;Carichner, S.;Vassilakis, B.;Ghannouchi, F.M. Synergetic Crest Factor Reduction and Baseband Digital Predistortion for Adaptive 3G Doherty Power Amplifier Linearizer Design. IEEE Transactions on Microwave Theory and Techniques. 2008 pp.2602-2608
[10]丘春辉,陈向东,沈冰射频功率放大器前馈线性化技术研究微电子学与计算机2008
[11] SungWon Chung,Jack W. Open-Loop Digital Predistortion Using Cartesian Feedback for Adaptive RF Power Amplifier Linearization. Holloway,Joel L. Dawson2007 pp.1449-1452
[12] Garcia, P.,de Mingo,J. Nonlinear Distortion Cancellation in a LINC Transmitter using Genetic Algorithms.外文会议Valdovinos, A. 2005 pp.66-71
[13] Young Yun Woo;Jangheon Kim;Jaehyok Yi;Sungchul Hong;Ildu Kim;Junghwan Moon;Bumman Kim. Adaptive Digital Feedback Predistortion Technique for Linearizing Power Amplifiers. IEEE Transactions on Microwave Theory and Techniques. 2007 no.5pp.932-940
[14] Thai Hoa Vo,Tho Le-Ngoc*,and Hichem Besbes. An Adaptive Baseband Digital Predistortion System For An RF Power Amplifier. Wiley Inter Science.March 2006. pp.216-225
[15] TaijunLiu,SlimBoumaiza,TaijunLiu,SlimBoumaiz. Dynamic Behavioral Modeling of 3G Power Amplifiers Using Real-Valued Time Delay Neural Networks. IEEE transactions on microwave theory and techniques. NO.3,MARCH 2004 pp.1025-1033
[16] Taijun Liu, Senior Member, IEEE, Yan Ye, Tiefeng Xu, Dongya Shen. Analysis and Decomposition of the Nonlinearities in RF Power Amplifiersand Wireless Transmitters. MTT. 2004
[17] Hsin-Hung Chen;Chili-Hung Lin;Po-Chiun Huang;Jiunn-Tsair Chen. Joint Polynomial and Look-Up-Table Predistortion Power Amplifier Linearization. IEEE Transactions on Circuits and Systems. II, Express Briefs 2006 no.8 pp.612-616
[18] Jin Zhe,Song Zhihuan,He Jiaming. Volterra series based predistortion for broadband RF power amplifiers with memory effects系统工程也电子技术(英文版)。2008年第4期pp.2155-2164
[19]陈海生TD-SCDMA预失真技术的研究与应用通信技术2009.4
[20] Jiantao Yang , Jun Gao , Shuhong Guo , Xiaotao Deng. Neural-Network-Based Predistortion Method for High-Power Amplifiers With Memory. The IET 2nd International Conference on Wireless,Mobile & Multimedia Networks.2008 pp.329-332
[21] G. Montoro,P. L. Gilabert,E. Bertran,A. Cesari,J. A. An LMS-Based Adaptive Predistorter for Cancelling Nonlinear Memory Effects in RF Power Amplifiers. Garcia. 2007
[22]贾建华,王强,JIA Jianhua,WANG Qiang一种基于RLS算法的多项式预失真技术现代电子技术2006年第16期
[24]路宁刘章发LU Ning,LIU Zhang-fa一种高线性度AB类CMOS功率放大器的设计与实现电脑知识与技术2007年第10期pp.134-136
[25] Chowdhury, D.;Reynaert, P.;Niknejad, A. M. Transformer-Coupled Power Amplifier Stability and Power Back-Off Analysis. IEEE transactions on circuits and systems. II, Express briefs. 2008 No.6
[26] Jin Zhe Volterra series based predistortion for broadband RF power amplifiers withmemory effects Engmeering and Electronics No.4,2008,pp.666-671
[27]丁元明,王甲凯模块化模型功率放大器的自适应预失真计算机工程与应用2009年29期pp.114-117
[28]曹新容,黄联芬,赵毅峰一种基于Hammerstein模型的数字预失真算法厦门大学学报(自然科学版) 2009年1期pp.47-51
[29] Li Bo, Ge Jian-hua Ai Bo. A robust power amplifier predistorter constructed using memory polynomials. The 4th International Conference on Wireless Communications, Networking and Mobile Computing 2008 pp.1323-1327
[30] AndingZhu Digital Predistortion Envelope Power Amplifiers Decomposed IEEE Transaction on Microwave Theory 2008 pp.2237-2247
[31] Zhiwen Zhu Xingping Huang Design of an LUT-based Predistorter for Power Amplifer Linearization International Conference on Advances in Satellite and Space Communications 2009.1 pp.113-116
[32]艾渤杨知行基于LUT的HPA数字基带预失真方法研究电子与信息学报2007年7月pp.1580-1584
[33] DennisR.Morgan A Generalized Memory Polynomial Model for Digital Predistortion of RF Power Amplifiers IEEE TRANSACTIONS ON SIGNAL PROCESSING oct.2006 pp.3852-3860
[34]赵新锋一种基于多项式的预失真算法电子科技2008.10 pp.41-44
[35]贺彬,陈豪基于LMS的WADPD功率放大器线性算法信息与电子工程2009年5期pp.427-431
[36] 2006 Siva D.Muruganathan A QRD-RLS-Based Predistortion Schemefor High-Power Amplifier Linearization IEEE TRANSACTIONS ON CIRCUITS AND SYSTEM Soct.2006 pp.1108-1112
[37] Compact Optichron OP4400 Digital Pre-Distortion ICs Cut Costs of Wireless frastructure Applications[Z].Optichron.2008
[38] Lei Ding ; Zhengxiang Ma ; Morgan, D.R. ; Zierdt, M. ; Pastalan, J. A least-squares/Newton method for digital predistortion of wideband signals. IEEE Transactions on Communications. 2006 No.5
[39] Xiaochen Lin,Minglu Jin An Improved Adaptive Digital Predistortion Using Discrete Newton's Method第三届IEEE无线通讯、网络技术暨移动计算国际会议2007
[40] Taijun Liu Analysis and Decomposition of the Nonlinearities in RF PowerAmplifiersand Wireless Transmitters IEEE TRANSACTIONS ON SIGNAL PROCESSING 2007.10 pp.235-241
[41] P.J.;Chin Hsia;Brazil, T.J.;Kimball, D.F.;Digital Predistortion for Envelope-Tracking Power Amplifiers Using Decomposed Piecewise Volterra Series. IEEE Transactions on Microwave Theory and Techniques 2008 No.10 pp.2408-2413
[42] ThaiHoaVo Adaptive polynomial predistorters forM-QAM transmission using non-linear power amplifiers.Wiley Inter Science 2007 pp.3207-3211
[43] Taijun Liu,Yan Ye,Xingbin Zeng, Spectral Methods for Accurate Identification and Quantification of Memory Effects of Wideband RF Power Amplifiers IEEE Xplore March 26, 2009 pp.1456-1459