多媒体扩频传输中关键技术研究
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摘要
扩频通信技术是一种优良的体制，多媒体传输是信息发展的要求，在第三代移动通信系统中将实现多媒体扩频通信。由于各种媒体传输的速率是不同的，与传统的移动通信系统相比较，差别主要有数据速率不同，误码率大小要求不同，时延要求不同等。传统移动通信系统所提供的数据速率一般只有几kbps，而移动多媒体通信所要求的数据速率范围为几Mbps甚至几十Mbps，在同一扩频系统内传输多媒体的扩频比也不一样，就要采用不同长度的伪码，而且伪码之间必须保证正交性或准正交性。伪码的长度，数量和正交性都是很重要的关键技术，同时也必须考虑在信道等变化时保证通信质量。
本文首先分析了第三代移动通信中(以WCDMA为例)实现多媒体扩频的方式，多速率传输技术是3G研究的重点，WCDMA中多速率传输可采用变处理增益传输(OVSF-CDMA)方案及多码(MC-CDMA)传输方案。本文在比较了这两种传输方案的基础上，讨论了变处理增益方案传输中高速率和低速率用户之间的相互关系。
WCDMA的信道扩频采用了长度可变的正交码序列，即OVSF码用作扩频码。它为WCDMA提供高度灵活的业务起了非常重要的作用。在WCDMA系统，OVSF码保证了不同物理信道之间的正交性。上行链路中扩频因子变化范围为4-256。下行链路中，扩频因子的变化范围是4-512。OVSF码作为一种无线资源，需要合理分配。本文重点研究了扩频码(OVSF)在WCDMA下行链路中的分配策略，提出了基于优先级考虑的分配策略，并进行了仿真。
最后对多媒体传输中的关键技术速率和功率的自适应技术进行了性能分析、比较和数值仿真，结果显示速率的自适应技术在某些性能方面要优于功率自适应技术。
Spread spectrum communication is an excellent system, the transmission of multimedia will be necessary in the development of mobile communication. The multimedia spread spectrum transmission will be realized in the third generation mobile communication system. The mobile multimedia communication system need to support the transmission of high-speed data and variable speed data compared with the ordinary spread spectrum communication. The data rate ranges from several Kbps to hundred Kbps for wide up to 2Mbps.In order to assure different data rate to transmission in the same spread spectrum bandwidth, we need to use different lengths and orthogonal PN codes. The lengths , numbers and orthogonality of the PN codes are important technologies.
In the thesis we analyze the methods of spread spectrum transmission of WCDMA. Two multi-rate transmission schemes are discussed and compared. And in OVSF-CDMA transmission scheme, we analyze the relationship of high velocity and low velocity users.
WCDMA use OVSF code as channel spread spectrum code. OVSF play an important role in. WCDMA which offers flexible traffics. In the up link of WCDMA the spread factor ranges from 4-256 and ranges from 4-512 in the down link of WCDMA. OVSF code is important resource, we need to assign them rightly and efficiently. We study the assignment of OVSF code in the downlink of WCDMAJn order to assure the real time traffic, the dynamic allocation method based on priority is proposed and simulated.
In the end we compare the two key technologies of the multimedia transmission. The conclusion indicates the adaptive rate technologies are better than adaptive power technologies on some issues.
本文首先分析了第三代移动通信中(以WCDMA为例)实现多媒体扩频的方式，多速率传输技术是3G研究的重点，WCDMA中多速率传输可采用变处理增益传输(OVSF-CDMA)方案及多码(MC-CDMA)传输方案。本文在比较了这两种传输方案的基础上，讨论了变处理增益方案传输中高速率和低速率用户之间的相互关系。
WCDMA的信道扩频采用了长度可变的正交码序列，即OVSF码用作扩频码。它为WCDMA提供高度灵活的业务起了非常重要的作用。在WCDMA系统，OVSF码保证了不同物理信道之间的正交性。上行链路中扩频因子变化范围为4-256。下行链路中，扩频因子的变化范围是4-512。OVSF码作为一种无线资源，需要合理分配。本文重点研究了扩频码(OVSF)在WCDMA下行链路中的分配策略，提出了基于优先级考虑的分配策略，并进行了仿真。
最后对多媒体传输中的关键技术速率和功率的自适应技术进行了性能分析、比较和数值仿真，结果显示速率的自适应技术在某些性能方面要优于功率自适应技术。
Spread spectrum communication is an excellent system, the transmission of multimedia will be necessary in the development of mobile communication. The multimedia spread spectrum transmission will be realized in the third generation mobile communication system. The mobile multimedia communication system need to support the transmission of high-speed data and variable speed data compared with the ordinary spread spectrum communication. The data rate ranges from several Kbps to hundred Kbps for wide up to 2Mbps.In order to assure different data rate to transmission in the same spread spectrum bandwidth, we need to use different lengths and orthogonal PN codes. The lengths , numbers and orthogonality of the PN codes are important technologies.
In the thesis we analyze the methods of spread spectrum transmission of WCDMA. Two multi-rate transmission schemes are discussed and compared. And in OVSF-CDMA transmission scheme, we analyze the relationship of high velocity and low velocity users.
WCDMA use OVSF code as channel spread spectrum code. OVSF play an important role in. WCDMA which offers flexible traffics. In the up link of WCDMA the spread factor ranges from 4-256 and ranges from 4-512 in the down link of WCDMA. OVSF code is important resource, we need to assign them rightly and efficiently. We study the assignment of OVSF code in the downlink of WCDMAJn order to assure the real time traffic, the dynamic allocation method based on priority is proposed and simulated.
In the end we compare the two key technologies of the multimedia transmission. The conclusion indicates the adaptive rate technologies are better than adaptive power technologies on some issues.
引文
[1] E.Dahlman, B. Gudmundson,M. Nilsson, and J. Skold, "UMTS/IMT2000 based on wideband CDMA", IEEE Communication Magazine,vol.36,,Sep 1998, pp70-80.
[2] 毕厚杰编著，“多媒体信息的传输与处理”，人民邮电出版社
[3] Wideband DS-CDMA for next generation mobile communications systems",IEEE Commun. Mag, Sep 1998,pp56-69
[4] Per.K.Enge, "Spread spectrum multiple access performance of orthogonal codes: Linear receivers", IEEE Trans. Commun.,vol35,Dec 1987, pp1309-1319.
[5] 常永红编著，“第三代移动通信系统与技术”，人民邮电出版社
[6] Tony Ottosson and Ame Svensson, "On schemes for multirate support in ds-cdma systems",http://www.google.com
[7] Fettweis G, "On multicarrier code division multiple access(MC-CDMA) modem design".IEEE Veh Tech Conference,1994.
[8] Leta K.B, "Multicode high-speed transmission for wireless mobile communication",ICC'95.
[9] Ottosson T, Svensson A, "Performance of different multi-rate schemes in DS/CDMA systems", proc. NRS ceminar on Radio communication networks, Sweden, 1994, pp15-18.
[10] Z. Guo, K.B. Letaief, "Performance of VSG-CDMA and MC-CDMA in multirate systems. Proc. IEEE Vehicular Technology Cgnference, Greece, May 2001.
[11] 阮永红，祁玉生，“DS-CDMA移动通信系统地址码的正交性”，南京邮电学院学报vol．17 Jun 1997
[12] Thit Minn, Kai-Yeung Siu, "Dynamic assignment of orthogonal variable spreading factor codes in WCDMA", IEEE Journal Selected Areas in Comm, Aug 2000, pp1429-1440.
[13] R.-G. Cheng and P.Lin, "OVSF code channel assignment for IMT-2000",in proc. of 51~(st) IEEE Vehicular Technology Society Conference,vol.3,,2000, pp2188-2192.
[14] Y.C. Tseng,C.-M. Chao, and S.-L. Wu, "Code placement and replacement strategies for wideband CDMA OVSF code tree management", in proceedings of IEEE Glob,vol. 1, ,2001, pp562-566.
[15] F.Adashi, M. Sawahashi, and K. Okawa, "Tree structured generation of orthogonal spreading codes with different lengths for forward link of DS-CDMA mobile radio", Electronic Letters,vol.33, Jan 1997, pp27-28.
[16] A.N. Rouska, D.N.Skoutas, "OVSF codes assignment and reassignment at the forward link of WCDMA 3G systems",PIMRC, 2002, pp2404-2408.
[17] W.-T.Chen,Y.-P.Wu, "A novel code assignment scheme for wcdma systems", in proc.
of 54~(th) IEEE Vehicular Technology Society Coference,vol.2,2001, pp1182-1186.
[18] 刘铁，项梅格，“一种灵活的DS-CDMA系统多速率支持方案”，通信技术，1998．6
[19] 朱春梅，“基于OVSF码动态有序分配算法的呼叫公平性研究”，计算机工程与应用，2003．2
[20] A.J.Goldsmith, Soon-Ghee Chua, "Variable-rate Variable-power MQAM for fading channels", IEEE Transactions on communications,vol.45.1997, pp1219-1227.
[21] Yun L, "Variable quality of service in CDMA systems by statistical power control", IEEE ICC'95, pp713-719.
[22] N.Guo, S.morgera, "The grade of service for integrated voice/data wireless DS-CDMA networks",Proc IEEE ICC'94, pp1104-1110.
[23] 变速率调制在宽带瑞利衰落中的性能分析，北邮学报 2001．3
[24] S.W.Kin, "Adaptive rate and power ds/cdma communication in fading channels[J] IEEE Comm. Letters pp85-87,1999.3.
[25] S.J.oh and K.M. Wasserman, "Dynamic spreading gain control in multiservice CDMA networks, IEEE JSA in commun., 1999, pp918-927
[26] S.Kandu, S.Boyd, "Simultaneous rate and power control in multirate multimedia cdma systems, IEEE 6~(th) Int Symp on Spread-spectrum Tech&Appli, 2000,pp570-574
[27] T. offosson and A.Svensson, "On schemes for multirate support in DS-CDMA systems, Wireless personal communications, 1998,pp265-287.
[28] A wireless multimedia cdma system based on transmission power control,"IEEE Journal on selected areas in communication,vol14,,May 1996, pp683-691.
[29] "A new power control function for multirate ds-cdma systems, IEEE Trans on communJune 1999,pp896-904.
[30] changliangcheng, "performance analysis of closed-loop rate adaptation scheme for a ds/cdma cellular system". http://www.goole.com
[31] A.J.Goldsmith, "The capacity of downlink fading channels with variable rate and power",IEEE Transactions on vehicular, Aug. 1997,pp569-580.
[32] W.T.Webb, R.Steele, "Variable rate QAM for mobile radio",IEEE Trans comm., 1995,pp2223-2230.
[33] J.K.Cavers, "Variable-rate transmission for Rayleigh fading channels[J].IEEE Trans. Commun.,Vol.com-20,,Feb. 1972,pp 15-22.
[34] On the capacity of a cellular CDMA system, IEEE Trans. on vehicular technolgy,,may 1991,.pp303-312.
[35] S.W.Kim, Andrea.J.Goldsmith, "Truncated power control in code division multiple
access communications",IEEE Trans. On vehicular tech.,may 2000, pp965-972.
[36] 雷春娟，DS-CDMA系统的速率自适应技术，电信快报2002．2
[37] A. J. Viterbi著，李世鹤译，CDMA扩频通信原理，北京，人民邮电出版社．
[38] 范影乐 杨胜天 李铁编著，“Matlab仿真应用详解”，人民邮电出版社
[39] 胡健栋 郑朝晖等编著，“码分多址与个人通信”，人民邮电出版社
[40] 王月清 柴远波等编著，“宽带CDMA移动通信原理”，电子工业出版社
[41] 彭林等编著，“第三代移动通信技术”，电子工业出版社
[42] 唐宝民等编著，“电信网技术基础”，人民邮电出版社
[43] 概率论与数理统计教程，华东师范大学数学系编
[44] Proakis著，张力军等译，数字通信 第四版 电子工业出版社
[45] 张平等编著，“第三代峰窝移动通信系统WCDMA"，北京邮电大学出版社
[46] 李子孺等，CDMA反向闭环功率控制仿真研究，无线通信技术1999．1
[47] 胡捍英等编，“第三代移动通信系统”，人民邮电出版社，2001．
[48] 李建东 杨家玮编著，“个人通信”，人民邮电出版社
[49] 任世岩，宽带 CDMA移动通信并行多码方案及同步系统的研究，北京邮电大学硕士论文
[50] 吴伟陵编，“移动通信中的关键技术”，北京邮电大学出版社．2000．9
[2] 毕厚杰编著，“多媒体信息的传输与处理”，人民邮电出版社
[3] Wideband DS-CDMA for next generation mobile communications systems",IEEE Commun. Mag, Sep 1998,pp56-69
[4] Per.K.Enge, "Spread spectrum multiple access performance of orthogonal codes: Linear receivers", IEEE Trans. Commun.,vol35,Dec 1987, pp1309-1319.
[5] 常永红编著，“第三代移动通信系统与技术”，人民邮电出版社
[6] Tony Ottosson and Ame Svensson, "On schemes for multirate support in ds-cdma systems",http://www.google.com
[7] Fettweis G, "On multicarrier code division multiple access(MC-CDMA) modem design".IEEE Veh Tech Conference,1994.
[8] Leta K.B, "Multicode high-speed transmission for wireless mobile communication",ICC'95.
[9] Ottosson T, Svensson A, "Performance of different multi-rate schemes in DS/CDMA systems", proc. NRS ceminar on Radio communication networks, Sweden, 1994, pp15-18.
[10] Z. Guo, K.B. Letaief, "Performance of VSG-CDMA and MC-CDMA in multirate systems. Proc. IEEE Vehicular Technology Cgnference, Greece, May 2001.
[11] 阮永红，祁玉生，“DS-CDMA移动通信系统地址码的正交性”，南京邮电学院学报vol．17 Jun 1997
[12] Thit Minn, Kai-Yeung Siu, "Dynamic assignment of orthogonal variable spreading factor codes in WCDMA", IEEE Journal Selected Areas in Comm, Aug 2000, pp1429-1440.
[13] R.-G. Cheng and P.Lin, "OVSF code channel assignment for IMT-2000",in proc. of 51~(st) IEEE Vehicular Technology Society Conference,vol.3,,2000, pp2188-2192.
[14] Y.C. Tseng,C.-M. Chao, and S.-L. Wu, "Code placement and replacement strategies for wideband CDMA OVSF code tree management", in proceedings of IEEE Glob,vol. 1, ,2001, pp562-566.
[15] F.Adashi, M. Sawahashi, and K. Okawa, "Tree structured generation of orthogonal spreading codes with different lengths for forward link of DS-CDMA mobile radio", Electronic Letters,vol.33, Jan 1997, pp27-28.
[16] A.N. Rouska, D.N.Skoutas, "OVSF codes assignment and reassignment at the forward link of WCDMA 3G systems",PIMRC, 2002, pp2404-2408.
[17] W.-T.Chen,Y.-P.Wu, "A novel code assignment scheme for wcdma systems", in proc.
of 54~(th) IEEE Vehicular Technology Society Coference,vol.2,2001, pp1182-1186.
[18] 刘铁，项梅格，“一种灵活的DS-CDMA系统多速率支持方案”，通信技术，1998．6
[19] 朱春梅，“基于OVSF码动态有序分配算法的呼叫公平性研究”，计算机工程与应用，2003．2
[20] A.J.Goldsmith, Soon-Ghee Chua, "Variable-rate Variable-power MQAM for fading channels", IEEE Transactions on communications,vol.45.1997, pp1219-1227.
[21] Yun L, "Variable quality of service in CDMA systems by statistical power control", IEEE ICC'95, pp713-719.
[22] N.Guo, S.morgera, "The grade of service for integrated voice/data wireless DS-CDMA networks",Proc IEEE ICC'94, pp1104-1110.
[23] 变速率调制在宽带瑞利衰落中的性能分析，北邮学报 2001．3
[24] S.W.Kin, "Adaptive rate and power ds/cdma communication in fading channels[J] IEEE Comm. Letters pp85-87,1999.3.
[25] S.J.oh and K.M. Wasserman, "Dynamic spreading gain control in multiservice CDMA networks, IEEE JSA in commun., 1999, pp918-927
[26] S.Kandu, S.Boyd, "Simultaneous rate and power control in multirate multimedia cdma systems, IEEE 6~(th) Int Symp on Spread-spectrum Tech&Appli, 2000,pp570-574
[27] T. offosson and A.Svensson, "On schemes for multirate support in DS-CDMA systems, Wireless personal communications, 1998,pp265-287.
[28] A wireless multimedia cdma system based on transmission power control,"IEEE Journal on selected areas in communication,vol14,,May 1996, pp683-691.
[29] "A new power control function for multirate ds-cdma systems, IEEE Trans on communJune 1999,pp896-904.
[30] changliangcheng, "performance analysis of closed-loop rate adaptation scheme for a ds/cdma cellular system". http://www.goole.com
[31] A.J.Goldsmith, "The capacity of downlink fading channels with variable rate and power",IEEE Transactions on vehicular, Aug. 1997,pp569-580.
[32] W.T.Webb, R.Steele, "Variable rate QAM for mobile radio",IEEE Trans comm., 1995,pp2223-2230.
[33] J.K.Cavers, "Variable-rate transmission for Rayleigh fading channels[J].IEEE Trans. Commun.,Vol.com-20,,Feb. 1972,pp 15-22.
[34] On the capacity of a cellular CDMA system, IEEE Trans. on vehicular technolgy,,may 1991,.pp303-312.
[35] S.W.Kim, Andrea.J.Goldsmith, "Truncated power control in code division multiple
access communications",IEEE Trans. On vehicular tech.,may 2000, pp965-972.
[36] 雷春娟，DS-CDMA系统的速率自适应技术，电信快报2002．2
[37] A. J. Viterbi著，李世鹤译，CDMA扩频通信原理，北京，人民邮电出版社．
[38] 范影乐 杨胜天 李铁编著，“Matlab仿真应用详解”，人民邮电出版社
[39] 胡健栋 郑朝晖等编著，“码分多址与个人通信”，人民邮电出版社
[40] 王月清 柴远波等编著，“宽带CDMA移动通信原理”，电子工业出版社
[41] 彭林等编著，“第三代移动通信技术”，电子工业出版社
[42] 唐宝民等编著，“电信网技术基础”，人民邮电出版社
[43] 概率论与数理统计教程，华东师范大学数学系编
[44] Proakis著，张力军等译，数字通信 第四版 电子工业出版社
[45] 张平等编著，“第三代峰窝移动通信系统WCDMA"，北京邮电大学出版社
[46] 李子孺等，CDMA反向闭环功率控制仿真研究，无线通信技术1999．1
[47] 胡捍英等编，“第三代移动通信系统”，人民邮电出版社，2001．
[48] 李建东 杨家玮编著，“个人通信”，人民邮电出版社
[49] 任世岩，宽带 CDMA移动通信并行多码方案及同步系统的研究，北京邮电大学硕士论文
[50] 吴伟陵编，“移动通信中的关键技术”，北京邮电大学出版社．2000．9