具有时变时滞的CDMA自适应功率控制及其MATLAB仿真
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摘要
CDMA(码分多址,Code Division Multiple Access)技术是无线通信技术的重要研究方向,也是3G通信以及4G通信的关键技术,如何提高系统性能、增大用户容量是国内外专家学者研究的重大课题之一。由于CDMA本身的特点,阴影效应、角效应、多径衰落等干扰的产生是不可避免的,因此能够减少干扰、提高通信质量的多种技术逐渐的发展成熟起来,如Rake接收机技术、智能天线等技术等。功率控制技术也是CDMA移动通信系统为保证通信稳定、增大系统容量所采用的重要技术之一。
对移动台终端和基站进行良好的功率控制可以克服CDMA移动通信技术本身所特有的缺陷,更可以提高用户通信质量,减少用户的电池电量消耗。但是,通过研究CDMA移动通信系统功率控制的发展史以及其各个子方向可以看出,目前这些功率控制算法有的解决了确定系统的时滞补偿,有的解决了固定时滞的非确定系统模型辨识,而对于非确定系统的时变时滞的辨识与补偿仍未有较好的解决方案。
本文针对具有参数不确定性和时变时滞的CDMA系统的功率控制问题,提出了一种基于信道参数和时滞估计的自适应功率控制算法。该算法的建立与推导包括以下若干部分：一是分析CDMA通信系统的信噪比模型并推导出适用于最小二乘算法的广义迭代系统模型以及具有时变时滞的广义迭代系统模型；二是针对时变时滞提出时变时滞估计算法,针对参数不确定性提出系统时变参数的估计算法以及相应的控制率；三是对所提出的算法进行仿真。
仿真结果表明本文所提出的针对于CDMA移动通信系统的自适应功率控制算法可以有效地补偿参数不确定性和时变时滞的影响,能够平稳、快速地进行功率调节,满足了CDMA移动通信系统对用户功率控制平稳、超调、响应时间的需求,也满足了无线通信终端对功率控制快、平、稳的要求。
CDMA (Code Division Multiple Access) technology is one of the most important technologies in wireless communication systems, and it is the key technology for3G and4G communications. Thus, how to improve the performance of CDMA system and increase the user capacity is a hot topic in the wireless field. In order to minimize the various interferences in CDMA wireless communication system and improve the system performance, many kinds of technologies are adopted, such as RAKE receiver technology, smart antenna technology, and so on. Power control technology is also one of these technologies to improve system performance.
A better power control to the BS (base station) and MS (mobile station) can improve the communication quality and reduce the battery's consumption. However, there is little power control method which can propose a better solution to the problem of parameter uncertainty and time-varying delay.
This paper develops adaptive power control to CDMA wireless systems with uncertainty parameter and time-varying delay. The adaptive power control algorithm presented here is based on channel parameter and time delay estimations. It can estimate the time-varying delay and the parameter uncertainty effectively, and adjust the power stably as well as fleetly.
The algorithm is proposed in three steps:first, analyze the SIR mathematics model of CDMA wireless communication system, and get the generalized iteration system model which can be used in Least Squares algorithm; second, estimate the system delay time as well as the system parameters are estimated, then calculate the adaptive control law according to the estimation results; finally, do the simulation work to demonstrate the effectiveness of the proposed algorithm.
Simulation results show that the proposed algorithm can estimate and compensate for the affects of time-varying delay and parameter uncertainty rapidly. It can also adjust the transmission power smoothly and fast.
对移动台终端和基站进行良好的功率控制可以克服CDMA移动通信技术本身所特有的缺陷,更可以提高用户通信质量,减少用户的电池电量消耗。但是,通过研究CDMA移动通信系统功率控制的发展史以及其各个子方向可以看出,目前这些功率控制算法有的解决了确定系统的时滞补偿,有的解决了固定时滞的非确定系统模型辨识,而对于非确定系统的时变时滞的辨识与补偿仍未有较好的解决方案。
本文针对具有参数不确定性和时变时滞的CDMA系统的功率控制问题,提出了一种基于信道参数和时滞估计的自适应功率控制算法。该算法的建立与推导包括以下若干部分：一是分析CDMA通信系统的信噪比模型并推导出适用于最小二乘算法的广义迭代系统模型以及具有时变时滞的广义迭代系统模型；二是针对时变时滞提出时变时滞估计算法,针对参数不确定性提出系统时变参数的估计算法以及相应的控制率；三是对所提出的算法进行仿真。
仿真结果表明本文所提出的针对于CDMA移动通信系统的自适应功率控制算法可以有效地补偿参数不确定性和时变时滞的影响,能够平稳、快速地进行功率调节,满足了CDMA移动通信系统对用户功率控制平稳、超调、响应时间的需求,也满足了无线通信终端对功率控制快、平、稳的要求。
CDMA (Code Division Multiple Access) technology is one of the most important technologies in wireless communication systems, and it is the key technology for3G and4G communications. Thus, how to improve the performance of CDMA system and increase the user capacity is a hot topic in the wireless field. In order to minimize the various interferences in CDMA wireless communication system and improve the system performance, many kinds of technologies are adopted, such as RAKE receiver technology, smart antenna technology, and so on. Power control technology is also one of these technologies to improve system performance.
A better power control to the BS (base station) and MS (mobile station) can improve the communication quality and reduce the battery's consumption. However, there is little power control method which can propose a better solution to the problem of parameter uncertainty and time-varying delay.
This paper develops adaptive power control to CDMA wireless systems with uncertainty parameter and time-varying delay. The adaptive power control algorithm presented here is based on channel parameter and time delay estimations. It can estimate the time-varying delay and the parameter uncertainty effectively, and adjust the power stably as well as fleetly.
The algorithm is proposed in three steps:first, analyze the SIR mathematics model of CDMA wireless communication system, and get the generalized iteration system model which can be used in Least Squares algorithm; second, estimate the system delay time as well as the system parameters are estimated, then calculate the adaptive control law according to the estimation results; finally, do the simulation work to demonstrate the effectiveness of the proposed algorithm.
Simulation results show that the proposed algorithm can estimate and compensate for the affects of time-varying delay and parameter uncertainty rapidly. It can also adjust the transmission power smoothly and fast.
引文
[1]G.L.Stuber. Principles of Mobile Communication. Boston:MA:Kluwer,2001.
[2]吴伟陵,牛凯.移动通信原理.北京：电子工业出版社,2009.
[3]张海君.大话移动通信.北京：清华大学出版社,2011：57.
[4]与非门科技信息咨询(北京)有限公司.现代通信技术,第二章第三节_与非网.2006年,http://www.eefocus.com/html/08-11/58614s.shtml.
[5]张翔.基于模糊控制技术的CDMA功率控制算法研究：[硕士学位论文].上海：东华大学,2009.
[6]百度公司.智能天线_百度百科.百度.2011年,http://baike.baidu.com/view/150697.htm.
[7]才中喜.3G通信系统功率控制的研究：[硕士学位论文].通信与信息系统,水声工程学院.哈尔滨：哈尔滨工程大学,2007.
[8]A.J.Viterbi. CDMA Principles of Spread Spectrum Communication. NewYork Addision-Wesley,1995.
[9]J.Zander. Performance of Optimum Transmitter Power Control in Cellular Radio System. IEEE Transaction on Vehicular Technology.1,1992, Vol.1, pp.57-62.
[10]Shunsuk.Seo. SIR-based Transmit Power Control of Reverse Link for Coherent DS-CDMA Mobile Radio. IEICE Trans.Commun.1998, Vols. E81-B, pp.1508-1516.
[11]Jens.Zander. Comment on Performance of Optimum Transmitter Power Control in Cellular Radio System. IEEE Transactions on Vehicular Technology.1994, Vol.43, p.636.
[12]E.Bock. Assignment of transmitter power by linear programming. IEEE Transaction on Electromagnetic Compatibility.6,1964, pp.36-44.
[13]J.Zander. Distributed cochannel interference control in cellular radio system. IEEE Transactions on Vehicular Technology.1,1992, Vol.41, pp.305-311.
[14]Chockalingam, A. Performance of Closed-Loop Power Control in DS-CDMA Cellular Systems. IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY.3,1998, Vol.47.
[15]J.D.Herdter. Analysis of a class of distributed asynchronous power control algorithm for cellular wireless system. EEE Journal on Selected Areas in Communications.3,2000, Vol.18, pp.436-446.
[16]C.-C.Lee, R.Steele. Closed-loop power control in CDMA system. IEEE Proceedings Communications.4,1996, Vol.18, pp.231-239.
[17]J.H.Kim. Performance of sigle-bit adaptive step-size closed-looop power control scheme in DS-CDMA system. IEICE Transactions on Communications.7,1998, Vols. VUE81-B, pp. 1548-1552.
[18]RD.Yates. Intgrated power control and base station assignment. IEEE Transaction on Vehicular Technology.3,1995, Vol.44, pp.638-644.
[19]S.V.Hanly. An algorithm for combined cell-site selection and power control to maximize cellular spread spectrum capacity. IEEE Journal on Selected Areas in Communications.7, 1995, Vol.13, pp.1332-1340.
[20]B-K.Lee, H-W Chen,B-S Chen. Power Control of Cellular Radio Systems via Robust Simith Prediction Filter. IEEE Trans Wireless Commun. September 2004, Vol.3, pp. 1822-1831.
[21]F.Gunnarsson, F.Gustafssion. Control Theory Aspects of Power Control in UMTS. Control Engineering Practice. October 2003, Vol.11, pp.1113-1125.
[22]C.Y.Yang, B.S.Chen. Rubost Power Control of CDMA Cellular Radio Ssystems with Time-Varying Delays. Signal Processing.2010, Vol.90, pp.363-372.
[23]Choe, Sangho. MULTI-STEP PREDICTIVE CDMA CLOSED-LOOP POWER CONTROL SCHEME FOR TIME-VARYING FADING CHANNELS.2006.
[24]吕文渊CDMA通信系统中的鲁棒自适应功率控制算法：[硕士学位论文].上海东华大学,2010.
[25]龙晓梅CDMA系统中反向链路的功率控制技术的研究：[硕士学位论文].无出版地：南京,2010.
[26]刘党辉等.系统辨识方法及应用.北京：国防工业出版社,2010.ISBN987-118-06810-8.
[27]Cunwu Han, Dehui Sun,Jining Xu,Lisha Cao. Robust Adaptive Power Control for Cellular Communication System. World Congress on Intelligent Control and Automation (WCICA).2010.
[28]Seung-Ok Choi, Kwan-Ho You. Channnel Adaptive Power Control in the Uplink of CDMA System. Wireless Pers Commun.2008, Vol.47, pp.441-448.
[29]Robust Adaptive Power Control for Cellular Communication Systems. CW Han, Dehui Sun,Lisha Cao. Jinan,Shandong:s.n.,2010. WCICA 2010.
[30]崔智全等MATLAB 2009从入门到精通.北京:中国铁道出版社,2011.ISBN987-7-113.
[31]Bor-Sen Chen, Bore-Kuen Lee,Sheng-Kai Chen. Adaptive Power Control of Cellular CDMA System via the Optimal Predictive Model. IEEE Transactions on Wireless Communications. July 2005, pp.1914-1927.
[32]M.D.Anderson, S.Perreau. Robust Power Control for CDMA Networks subject to Modelization Errors. Acoustics,Speech,and Signal Processing.2003, Vol.4, pp.161-164.
[33]G.C.Goodwin, K.S.Sin. Adaptive Filtering Prediction and Control. Englewood Cliffs,NJ: Prentice Hall,1984.
[34]H.J.Su, E.Geraniotis. Adaptive Closed-loop Power Control with Quantized Feedback and Loop Filtering. IEEE Trans Wireless Commun.2002, Vol.1, pp.76-86.
[35]Y.L.Hsieh, C.J.Chang,Y.S.Chen. A Power Control Scheme with Link Gain Prediction using PRNN/ERLS for DS-CDMA Cellular Mobile System. IEEE Int Conf.Communications. March 2003, pp.407-411.
[2]吴伟陵,牛凯.移动通信原理.北京：电子工业出版社,2009.
[3]张海君.大话移动通信.北京：清华大学出版社,2011：57.
[4]与非门科技信息咨询(北京)有限公司.现代通信技术,第二章第三节_与非网.2006年,http://www.eefocus.com/html/08-11/58614s.shtml.
[5]张翔.基于模糊控制技术的CDMA功率控制算法研究：[硕士学位论文].上海：东华大学,2009.
[6]百度公司.智能天线_百度百科.百度.2011年,http://baike.baidu.com/view/150697.htm.
[7]才中喜.3G通信系统功率控制的研究：[硕士学位论文].通信与信息系统,水声工程学院.哈尔滨：哈尔滨工程大学,2007.
[8]A.J.Viterbi. CDMA Principles of Spread Spectrum Communication. NewYork Addision-Wesley,1995.
[9]J.Zander. Performance of Optimum Transmitter Power Control in Cellular Radio System. IEEE Transaction on Vehicular Technology.1,1992, Vol.1, pp.57-62.
[10]Shunsuk.Seo. SIR-based Transmit Power Control of Reverse Link for Coherent DS-CDMA Mobile Radio. IEICE Trans.Commun.1998, Vols. E81-B, pp.1508-1516.
[11]Jens.Zander. Comment on Performance of Optimum Transmitter Power Control in Cellular Radio System. IEEE Transactions on Vehicular Technology.1994, Vol.43, p.636.
[12]E.Bock. Assignment of transmitter power by linear programming. IEEE Transaction on Electromagnetic Compatibility.6,1964, pp.36-44.
[13]J.Zander. Distributed cochannel interference control in cellular radio system. IEEE Transactions on Vehicular Technology.1,1992, Vol.41, pp.305-311.
[14]Chockalingam, A. Performance of Closed-Loop Power Control in DS-CDMA Cellular Systems. IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY.3,1998, Vol.47.
[15]J.D.Herdter. Analysis of a class of distributed asynchronous power control algorithm for cellular wireless system. EEE Journal on Selected Areas in Communications.3,2000, Vol.18, pp.436-446.
[16]C.-C.Lee, R.Steele. Closed-loop power control in CDMA system. IEEE Proceedings Communications.4,1996, Vol.18, pp.231-239.
[17]J.H.Kim. Performance of sigle-bit adaptive step-size closed-looop power control scheme in DS-CDMA system. IEICE Transactions on Communications.7,1998, Vols. VUE81-B, pp. 1548-1552.
[18]RD.Yates. Intgrated power control and base station assignment. IEEE Transaction on Vehicular Technology.3,1995, Vol.44, pp.638-644.
[19]S.V.Hanly. An algorithm for combined cell-site selection and power control to maximize cellular spread spectrum capacity. IEEE Journal on Selected Areas in Communications.7, 1995, Vol.13, pp.1332-1340.
[20]B-K.Lee, H-W Chen,B-S Chen. Power Control of Cellular Radio Systems via Robust Simith Prediction Filter. IEEE Trans Wireless Commun. September 2004, Vol.3, pp. 1822-1831.
[21]F.Gunnarsson, F.Gustafssion. Control Theory Aspects of Power Control in UMTS. Control Engineering Practice. October 2003, Vol.11, pp.1113-1125.
[22]C.Y.Yang, B.S.Chen. Rubost Power Control of CDMA Cellular Radio Ssystems with Time-Varying Delays. Signal Processing.2010, Vol.90, pp.363-372.
[23]Choe, Sangho. MULTI-STEP PREDICTIVE CDMA CLOSED-LOOP POWER CONTROL SCHEME FOR TIME-VARYING FADING CHANNELS.2006.
[24]吕文渊CDMA通信系统中的鲁棒自适应功率控制算法：[硕士学位论文].上海东华大学,2010.
[25]龙晓梅CDMA系统中反向链路的功率控制技术的研究：[硕士学位论文].无出版地：南京,2010.
[26]刘党辉等.系统辨识方法及应用.北京：国防工业出版社,2010.ISBN987-118-06810-8.
[27]Cunwu Han, Dehui Sun,Jining Xu,Lisha Cao. Robust Adaptive Power Control for Cellular Communication System. World Congress on Intelligent Control and Automation (WCICA).2010.
[28]Seung-Ok Choi, Kwan-Ho You. Channnel Adaptive Power Control in the Uplink of CDMA System. Wireless Pers Commun.2008, Vol.47, pp.441-448.
[29]Robust Adaptive Power Control for Cellular Communication Systems. CW Han, Dehui Sun,Lisha Cao. Jinan,Shandong:s.n.,2010. WCICA 2010.
[30]崔智全等MATLAB 2009从入门到精通.北京:中国铁道出版社,2011.ISBN987-7-113.
[31]Bor-Sen Chen, Bore-Kuen Lee,Sheng-Kai Chen. Adaptive Power Control of Cellular CDMA System via the Optimal Predictive Model. IEEE Transactions on Wireless Communications. July 2005, pp.1914-1927.
[32]M.D.Anderson, S.Perreau. Robust Power Control for CDMA Networks subject to Modelization Errors. Acoustics,Speech,and Signal Processing.2003, Vol.4, pp.161-164.
[33]G.C.Goodwin, K.S.Sin. Adaptive Filtering Prediction and Control. Englewood Cliffs,NJ: Prentice Hall,1984.
[34]H.J.Su, E.Geraniotis. Adaptive Closed-loop Power Control with Quantized Feedback and Loop Filtering. IEEE Trans Wireless Commun.2002, Vol.1, pp.76-86.
[35]Y.L.Hsieh, C.J.Chang,Y.S.Chen. A Power Control Scheme with Link Gain Prediction using PRNN/ERLS for DS-CDMA Cellular Mobile System. IEEE Int Conf.Communications. March 2003, pp.407-411.