光码分多址通信系统中的关键技术问题研究
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摘要
光纤通信技术继续保持迅速的发展，从点到点的信息传输到网络应用，从干线网到用户网，正逐渐深入到通信的各个领域，各种新技术得到开发利用。码分多址技术在无线通信领域成功地得到大规模商品化应用，在光纤通信通信网中码分多址技术的应用近年来也吸引了许多研究者的兴趣，展现了很好的应用潜质。本文对码分多址技术在光纤通信系统中应用作了历史回顾与综合分析，总结出了若干关键技术问题，并作了深入的理论研究。
本文突破了以往在HFC系统中使用CDMA扩频技术通信时，通常都采用Gold序列来作为地址码的惯例，分析和提出了在HFC的特定环境中，使用同一m序列在某时刻具有的不同相移序列，来构成一个小区的地址编码，能够达到多用户通信时比使用Gold序列进行通信具有更好的相关特性。这种地址码的安排，要求用户间严格同步，使得原本为一个m序列的自相关函数，在各个用户相位差恒定的条件下，分割成用户间的自相关和互相关函数。论文在提出地址码设计方案后，通过计算机仿真实验，模拟一个用户数为100的小区，使用论文设计的地址码方案进行S-CDMA综合业务通信，已预先知道每个用户通信的信息，在计算机仿真通信处理完成后，检验在接收端的用户信息。通过验证每个用户在仿真处理后均能够恢复原始信息，证明了方案的正确性和可行性。
由于地址码的设计方案对用户间的地址码相位要求严格，本文对地址码相位同步问题也进行了深入的研究。论文所提出的方案是通过前端发射固定的导频信号，并且在前端和用户端都把用户地址码相位捆绑在导频相位上，使得用户在同步捕获和跟踪导频相位后，间接得到用户的地址码相位。我们成功设计了导频参考时间点0的电路图，从而解决了S-CDMA系统对同步的严格要求。同时，我们还提出了用两次停留搜索方法代替一次串行搜索进行同步的方法，使导频的同步搜索效率得以提高，并通过计算机仿真实验进行了验证。
本文还对光码分多址通信系统中的光纤非线性效应进行了深入研究。论
哈尔滨工程大学硕士学位论文
文推导综合了各种非线性效应的非线性薛定愕方程;并提出了当各种非线性
效应都作为微扰时，它们的影响可以简单地将各自的作用加到方程之中，这
样就可以得到总结性的方程。然后本文又继续讨论各种非线性效应在不同实
际情况中影响的大小及对方程的简化。根据综合研究非线性效应的考虑，本
文研究了自相位调制及交叉相位调制对四波混频相位匹配的影响，在一定的
简化下得到了解析的结果。结果表明相位调制对四波混频的效率会有影响，
用四波混频进行波长转换时该情况有很大作用。如果忽略相位调制的影响(光
功率很小时)，那么效率公式就回复到通常的仅由色散及频道间隔决定的情
况。
Optical fiber communication keeps in rapid development, from trunk lines to subscriber networks , stepping into more and more areas of the modern communication . While code-division multiple-access technology has been employed commercially world wide , its application in fiber-optic network become attractive . In this dissertation , the researches on the application of CDMA in fiber-optic communication systems have been reviewed , and several key techniques in the application are proposed with theoretical analysis.
In traditional researches and applications of the HFC CDMA communication system , the GOLD sequence was used as the users' address code . In this paper , we analyze the characteristics of the m sequence in detail . Then , the address code can be designed by different phase sequence of an m sequence . Our studied method can attain better communication quality than before case . Of course , synchronization among all users is requested , i.e., our method is a S-CDMA communication . The self-correlation function of the m sequence is divided into the self-correlation between all same address users and the mutual-correlation between all different address users . A computer simulation experiment , which 100 users are communicating under our method , is given in this paper . The information of every user is known before the processing of S-CDMA communication start . After S-CDMA processing , the demodulated information and the original information of the same users are equally . We found that they are same in every user and prove the right of our method .
In our communication method , synchronization between all users is requested . The key is that the Head-end emits the guide m sequence , which is non-correlative with any users' address code . The phase of all users address code and the Head-end address code are combined with the guide m sequence . Every
user address code phase can attain after the guide m sequence phase is searched and tracked . After the circuit that can offer the point "0" of time coordinate is designed by myself, the most difficulty of our S-CDMA communication system is solved . In search processing of synchronization , one time search processing is improved by two time search processing . Therefore , the time spend on synchronization is saved , not only in the theory analysis but also in the computer simulation experiment are shown in this paper .
The nonlinear effect has also been researched deeply in this paper . The nonlinear Schrodinger Equation (NLS) that consider all kinds of the nonlinear effects is derived . When every nonlinear effect is processed as perturbation , they can be simply put in the equation altogether . Then the different influence of each effect is discussed under different condition . By following the way of studying the nonlinear effect as a whole , the influence of the SPM and XPM to the phase matching condition of FWM is studied . From the achieved analytical expression it can be seen that the phase modulation can change the efficiency of the FWM . It is very important to the wavelength conversion through FWM . The result shows that a shorter fiber is necessary to get an enough efficiency when employing high optical energy.
本文突破了以往在HFC系统中使用CDMA扩频技术通信时，通常都采用Gold序列来作为地址码的惯例，分析和提出了在HFC的特定环境中，使用同一m序列在某时刻具有的不同相移序列，来构成一个小区的地址编码，能够达到多用户通信时比使用Gold序列进行通信具有更好的相关特性。这种地址码的安排，要求用户间严格同步，使得原本为一个m序列的自相关函数，在各个用户相位差恒定的条件下，分割成用户间的自相关和互相关函数。论文在提出地址码设计方案后，通过计算机仿真实验，模拟一个用户数为100的小区，使用论文设计的地址码方案进行S-CDMA综合业务通信，已预先知道每个用户通信的信息，在计算机仿真通信处理完成后，检验在接收端的用户信息。通过验证每个用户在仿真处理后均能够恢复原始信息，证明了方案的正确性和可行性。
由于地址码的设计方案对用户间的地址码相位要求严格，本文对地址码相位同步问题也进行了深入的研究。论文所提出的方案是通过前端发射固定的导频信号，并且在前端和用户端都把用户地址码相位捆绑在导频相位上，使得用户在同步捕获和跟踪导频相位后，间接得到用户的地址码相位。我们成功设计了导频参考时间点0的电路图，从而解决了S-CDMA系统对同步的严格要求。同时，我们还提出了用两次停留搜索方法代替一次串行搜索进行同步的方法，使导频的同步搜索效率得以提高，并通过计算机仿真实验进行了验证。
本文还对光码分多址通信系统中的光纤非线性效应进行了深入研究。论
哈尔滨工程大学硕士学位论文
文推导综合了各种非线性效应的非线性薛定愕方程;并提出了当各种非线性
效应都作为微扰时，它们的影响可以简单地将各自的作用加到方程之中，这
样就可以得到总结性的方程。然后本文又继续讨论各种非线性效应在不同实
际情况中影响的大小及对方程的简化。根据综合研究非线性效应的考虑，本
文研究了自相位调制及交叉相位调制对四波混频相位匹配的影响，在一定的
简化下得到了解析的结果。结果表明相位调制对四波混频的效率会有影响，
用四波混频进行波长转换时该情况有很大作用。如果忽略相位调制的影响(光
功率很小时)，那么效率公式就回复到通常的仅由色散及频道间隔决定的情
况。
Optical fiber communication keeps in rapid development, from trunk lines to subscriber networks , stepping into more and more areas of the modern communication . While code-division multiple-access technology has been employed commercially world wide , its application in fiber-optic network become attractive . In this dissertation , the researches on the application of CDMA in fiber-optic communication systems have been reviewed , and several key techniques in the application are proposed with theoretical analysis.
In traditional researches and applications of the HFC CDMA communication system , the GOLD sequence was used as the users' address code . In this paper , we analyze the characteristics of the m sequence in detail . Then , the address code can be designed by different phase sequence of an m sequence . Our studied method can attain better communication quality than before case . Of course , synchronization among all users is requested , i.e., our method is a S-CDMA communication . The self-correlation function of the m sequence is divided into the self-correlation between all same address users and the mutual-correlation between all different address users . A computer simulation experiment , which 100 users are communicating under our method , is given in this paper . The information of every user is known before the processing of S-CDMA communication start . After S-CDMA processing , the demodulated information and the original information of the same users are equally . We found that they are same in every user and prove the right of our method .
In our communication method , synchronization between all users is requested . The key is that the Head-end emits the guide m sequence , which is non-correlative with any users' address code . The phase of all users address code and the Head-end address code are combined with the guide m sequence . Every
user address code phase can attain after the guide m sequence phase is searched and tracked . After the circuit that can offer the point "0" of time coordinate is designed by myself, the most difficulty of our S-CDMA communication system is solved . In search processing of synchronization , one time search processing is improved by two time search processing . Therefore , the time spend on synchronization is saved , not only in the theory analysis but also in the computer simulation experiment are shown in this paper .
The nonlinear effect has also been researched deeply in this paper . The nonlinear Schrodinger Equation (NLS) that consider all kinds of the nonlinear effects is derived . When every nonlinear effect is processed as perturbation , they can be simply put in the equation altogether . Then the different influence of each effect is discussed under different condition . By following the way of studying the nonlinear effect as a whole , the influence of the SPM and XPM to the phase matching condition of FWM is studied . From the achieved analytical expression it can be seen that the phase modulation can change the efficiency of the FWM . It is very important to the wavelength conversion through FWM . The result shows that a shorter fiber is necessary to get an enough efficiency when employing high optical energy.
引文
[1] 张海滨，黄培中，宋文涛．实现光码分多址系统的关键技术．光通信技术．1999，4：257-260页
[2] Nikos Karafols, et al. Optical fiber code division multiple access networks a review. Optical Fiber Technology. 1996,2:149
[3] Ohtsuki T, et al. Effects of hard-limiter and error correction coding on performance of direct-detection optical CDMA systems with PPM signaling. in Proc. ICC' 95, Seattle, WA, 1995:1307
[4] 吉建华，范戈．光码分多址通信系统中的地址码．光通信技术．2002，1：20-23页
[5] Guu-Chung Yang. Variable-Weight Optical Orthogonal Codes for CDMA Networks with Multiple Performance Requirments. IEEE Trans Commun, 1996,44(1):47-55P
[6] Svetislav V. Maric, Oscar Moreno, Carlos J. Corrada. Multimedia Tran smission in Fiber-Optical LANs Using Optical CDMA. Journal of Light wave Technology. 1996,14(10):2149-2159P
[7] 于金辉，范戈．降低 OCDMA 系统多用户干扰的技术研究．光纤与电缆及其应用技术．2001，6：4-8页
[8] OHTSUKI T. Performance analysis of direct-detection optical asy nchronous CDMA systems with double optical hard-limiters. IEEE Journal of Lightwave Technology. 1997,15(3):452-457P
[9] OHTSUKI Y. Channel interference cancellation using electrooptic swich and optical CDMA systems. IEEE Journal of Lightwave Technology. 1998,16(4):520-526P
[10] LIN C L, WU J S. A synchronous fiber-optic CDMA system using adaptive optical hard-limiter. IEEE Journal of Lightwave Technology.1998, 16(8): 1393-1403P
[11] LIN C L, WC J S. Chanel inference reduction using random Manchester codes for both synchronous fiber-optic CDMA systems. IEEE Journal of Lightwave Technology. 2000,18(1):26-33P
[12] 沈成彬，范戈．光码分多址技术及其编解码器的研究．光通信技术．2000，4：299-303页
[13] Fathallah H. Rusch L A. Passive optical fast frequency-hop CDMA communications system. J. Lightwave Technology. 1999,17:397-405P
[14] Cho Y. Lee J H. On the performance of an optical decorrelating receiver for optical orthogonal code-division multiple-access systems. IEEE Inter. Sympo. Personal Indoor Mobile Radio Comm.'98 Proc. 1998,2:718-721P
[15] 李晓滨，赵晓晖等．全光码分多址通信系统地址码研究．长春邮电学院学报．1999，17(2)：6-1页1
[16] 刘国驷，周浩强等．一种新的光码分多址技术．光通信研究．1999，5：14-18
[17] 张宝富，朱勇，李玉权．光纤扩频通信系统中的光编码器的研究[J]．通信学报．1998，7：35-41页
[18] 薛余网，陈景韶．光纤码分多址技术研究．上海交大学报．1996，11：45-51
[19] 张宝富，李玉权．光纤 CDMA 系统的方案设计及关键技术的实现．电信科学．1998，9：29-31页
[20] Yang G C. Variable-weight optical orthogonal codes for CDMA network with multiple performance requirements. IEEE Transaction on communicat ions, 1996,44(1):47-55P
[21] David Faulfner, Rajendrakumar Mistry, etc. The Full Services Access Netw orks Initiative, IEEE Communications Magazine. 1997,3:58-68P
[22] Rajendrakumar Mistry, Phil Savill, etc. OA & M for Full Services Access Networks, IEEE Communications Magazine. 1997,3:70-77P
[23] Niels Engell Andersen, etc. Broadbandloop: A full-service access network for residential and small business users. IEEE Communications Magzine. 1997,12:325-336P
[24] 王延尧．SDH/SONET同步光通信基础．天津科学技术出版社．1996
[25] Eugenio Guarene, etc. IP and ATM Integration Perspectives. IEEE Comm unications Magazine. 1998,1:74-80P
[26] Philip Dumortier. Toward a new IP over ATM routing paradigm. IEEE Co mmunications Magzine. 1998,1:82-86P
[27] Koichi Asatani, Yoichi Maeda. Access network architectural issues for future telecommunication networks, IEEE Communications Magzine. 1998, 8:110-114P
[28] 孙玲芬等．现代Internet接入方式—ADSL Moderm与Cable Moderm．通信工程学院学报．1998，9：56-62页
[29] 查开德．宽带综合业务HFC网．电视技术．1998,9：15-22页
[30] George Abe．PESIDENTIAL BROADBAND，电子工业出版社．1998
[31] IEEE P 802.14 Working Group, "IEEE Project 802.14/a Draft Revision 1" . 1998,4
[32] Ying-Dar Lin, etc. Allocation and scheduling Algorithms for IEEE 802.14 and MCNS in hybrid fiber coaxial networks. IEEE Transaction on Broadcasting. 1998,12:324-332P
[33] Chatschik Bisdikian, etc. MLAP: A MAC level access protocol for the HFC 802.14 network. IEEE Communication Magazine. 1996,3:114-121P
[34] 黄永进，宋文涛．HFC网络中的宽带接入技术．电讯技术．1998，12：54-58
[35] 吴承治，徐敏毅．光接入网工程．人民邮电出版社．1998
[36] 付军，罗元，党明瑞．关于光纤电缆混合上行信道传输问题的分析．重庆邮电学院学报．1998，6：1-5页
[37] Yvo L. C. de Jong etc. A CDMA based bi-directional Communication System for Hybrid Fiber-Coax CATV Networks. IEEE Trans. on Broadcasting. 1997,9:329-338P
[38] 饶小毛，付岚．同步码分多址技术与宽带光纤同轴电缆混合网．现代电信科技．1997，5：37-39页
[39] 任长虹，范戈．同步码分多址技术在光纤同轴混合网中的应用．光纤与电缆及其应用技术．1998，5：21-24页
[2] Nikos Karafols, et al. Optical fiber code division multiple access networks a review. Optical Fiber Technology. 1996,2:149
[3] Ohtsuki T, et al. Effects of hard-limiter and error correction coding on performance of direct-detection optical CDMA systems with PPM signaling. in Proc. ICC' 95, Seattle, WA, 1995:1307
[4] 吉建华，范戈．光码分多址通信系统中的地址码．光通信技术．2002，1：20-23页
[5] Guu-Chung Yang. Variable-Weight Optical Orthogonal Codes for CDMA Networks with Multiple Performance Requirments. IEEE Trans Commun, 1996,44(1):47-55P
[6] Svetislav V. Maric, Oscar Moreno, Carlos J. Corrada. Multimedia Tran smission in Fiber-Optical LANs Using Optical CDMA. Journal of Light wave Technology. 1996,14(10):2149-2159P
[7] 于金辉，范戈．降低 OCDMA 系统多用户干扰的技术研究．光纤与电缆及其应用技术．2001，6：4-8页
[8] OHTSUKI T. Performance analysis of direct-detection optical asy nchronous CDMA systems with double optical hard-limiters. IEEE Journal of Lightwave Technology. 1997,15(3):452-457P
[9] OHTSUKI Y. Channel interference cancellation using electrooptic swich and optical CDMA systems. IEEE Journal of Lightwave Technology. 1998,16(4):520-526P
[10] LIN C L, WU J S. A synchronous fiber-optic CDMA system using adaptive optical hard-limiter. IEEE Journal of Lightwave Technology.1998, 16(8): 1393-1403P
[11] LIN C L, WC J S. Chanel inference reduction using random Manchester codes for both synchronous fiber-optic CDMA systems. IEEE Journal of Lightwave Technology. 2000,18(1):26-33P
[12] 沈成彬，范戈．光码分多址技术及其编解码器的研究．光通信技术．2000，4：299-303页
[13] Fathallah H. Rusch L A. Passive optical fast frequency-hop CDMA communications system. J. Lightwave Technology. 1999,17:397-405P
[14] Cho Y. Lee J H. On the performance of an optical decorrelating receiver for optical orthogonal code-division multiple-access systems. IEEE Inter. Sympo. Personal Indoor Mobile Radio Comm.'98 Proc. 1998,2:718-721P
[15] 李晓滨，赵晓晖等．全光码分多址通信系统地址码研究．长春邮电学院学报．1999，17(2)：6-1页1
[16] 刘国驷，周浩强等．一种新的光码分多址技术．光通信研究．1999，5：14-18
[17] 张宝富，朱勇，李玉权．光纤扩频通信系统中的光编码器的研究[J]．通信学报．1998，7：35-41页
[18] 薛余网，陈景韶．光纤码分多址技术研究．上海交大学报．1996，11：45-51
[19] 张宝富，李玉权．光纤 CDMA 系统的方案设计及关键技术的实现．电信科学．1998，9：29-31页
[20] Yang G C. Variable-weight optical orthogonal codes for CDMA network with multiple performance requirements. IEEE Transaction on communicat ions, 1996,44(1):47-55P
[21] David Faulfner, Rajendrakumar Mistry, etc. The Full Services Access Netw orks Initiative, IEEE Communications Magazine. 1997,3:58-68P
[22] Rajendrakumar Mistry, Phil Savill, etc. OA & M for Full Services Access Networks, IEEE Communications Magazine. 1997,3:70-77P
[23] Niels Engell Andersen, etc. Broadbandloop: A full-service access network for residential and small business users. IEEE Communications Magzine. 1997,12:325-336P
[24] 王延尧．SDH/SONET同步光通信基础．天津科学技术出版社．1996
[25] Eugenio Guarene, etc. IP and ATM Integration Perspectives. IEEE Comm unications Magazine. 1998,1:74-80P
[26] Philip Dumortier. Toward a new IP over ATM routing paradigm. IEEE Co mmunications Magzine. 1998,1:82-86P
[27] Koichi Asatani, Yoichi Maeda. Access network architectural issues for future telecommunication networks, IEEE Communications Magzine. 1998, 8:110-114P
[28] 孙玲芬等．现代Internet接入方式—ADSL Moderm与Cable Moderm．通信工程学院学报．1998，9：56-62页
[29] 查开德．宽带综合业务HFC网．电视技术．1998,9：15-22页
[30] George Abe．PESIDENTIAL BROADBAND，电子工业出版社．1998
[31] IEEE P 802.14 Working Group, "IEEE Project 802.14/a Draft Revision 1" . 1998,4
[32] Ying-Dar Lin, etc. Allocation and scheduling Algorithms for IEEE 802.14 and MCNS in hybrid fiber coaxial networks. IEEE Transaction on Broadcasting. 1998,12:324-332P
[33] Chatschik Bisdikian, etc. MLAP: A MAC level access protocol for the HFC 802.14 network. IEEE Communication Magazine. 1996,3:114-121P
[34] 黄永进，宋文涛．HFC网络中的宽带接入技术．电讯技术．1998，12：54-58
[35] 吴承治，徐敏毅．光接入网工程．人民邮电出版社．1998
[36] 付军，罗元，党明瑞．关于光纤电缆混合上行信道传输问题的分析．重庆邮电学院学报．1998，6：1-5页
[37] Yvo L. C. de Jong etc. A CDMA based bi-directional Communication System for Hybrid Fiber-Coax CATV Networks. IEEE Trans. on Broadcasting. 1997,9:329-338P
[38] 饶小毛，付岚．同步码分多址技术与宽带光纤同轴电缆混合网．现代电信科技．1997，5：37-39页
[39] 任长虹，范戈．同步码分多址技术在光纤同轴混合网中的应用．光纤与电缆及其应用技术．1998，5：21-24页