基于分块传输多址接入中的自适应技术研究
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摘要
分块传输技术目前成为宽带数字通信系统的主要支撑技术之一。频域均衡的分块传输技术包括，正交频分复用(OFDM)和单载波频域均衡(SC-FDE)。二者都具有频谱效率高，抗多径干扰强和均衡简单的优点。因此，在高速宽带通信系统中，分块传输技术受到广泛关注，如多载波码分多址(MC-CDMA)，循环前缀辅助的码分多址(CP-CDMA)，正交频分多址(OFDMA)，傅立叶扩频的正交频分多址(DFT-SOFDM)等。而这些都是分块传输技术与多址技术相结合的产物。
本文首先介绍了上述的各种多址技术，以及最优信号子空间理论和基于该理论的SC-FDE系统。同时，最优信号子空间理论也是本文提出的自适应算法的理论基础。
基于最优信号子空间理论以及每子信道回传1比特信息的自适应算法，本文提出了自适应多址通信系统，包括CP-OSS-CDMA自适应系统和自适应DFT-SOFDM系统。为了在CP-CDMA系统中应用自适应算法，首先给出了CPA-DS-CDMA系统，并在此基础上结合自适应算法给出了CP-OSS-CDMA自适应系统。由于算法实现简单并且仅回传1比特信息，基于该算法的自适应系统非常适合于移动宽带无线通信系统中。
由于上述的自适应DFT-SOFDM系统在固定的子载波分组内进行子载波选择，所以该系统无法利用多用户分集(Multiuser Diversity)从而造成了一定的频谱损失。为了利用多用户分集，本文基于最优信号子空间理论提出了一种在用户间动态分配子载波的自适应算法，有效的提高了系统性能并且频谱损失很少。由于该算法实现比较复杂并且回传信息较多，较适合于信道变化缓慢的环境中。由此，自适应DFT-SOFDM系统可将这两种算法综合应用。
Recently, block-wise transmission techniques have become a hot research field of broadband digital communication. The block-wise transmission techniques with frequency domain equalization include OFDM and SC-FDE. Both are featuring high frequency efficiency, robustness to frequency selective fading and simple equalization. The multiplexing techniques based on them have gained great interest, for example MC-CDMA, CP-CDMA, OFDMA, DFT-SOFDM and so on.
Firstly, this thesis introduces the present multiplexing techniques, Optimal Signal Subspace theory and OSS-based adaptive SC-FDE system. The Optimal Signal Subspace theory is also the foundation of the adaptive algorithm proposed in this thesis.
Secondly, this thesis proposes adaptive multiusers communication system,i.e.,adaptive CP-OSS-CDMA system and adaptive DFT-SOFDM system. These are established on Optimal Signal Subspace theory and the low-cost adaptive scheme that needs only 1 bit feedback information per subchannel. In order to employ the adaptive scheme in CP-CDMA, this thesis introduces CPA-DS-CDMA system and provides the adaptive CP-OSS-CDMA system. Because of low-cost complexity and only 1 bit feedback information per subchannel, the adaptive systems are very suitable for mobile broadband wireless communication.
Because the adaptive DFT-SOFDM system, which bases on 1 bit feedback information per subchannel, assigns the subcarriers among the given subcarriers group, the adaptive DFT-SOFDM system can not exploit the Multiuser Diversity. So the frequency efficiency reduces. In order to exploit the multiuser diversity, the paper proposes a new algorithm that assignes the subcarriers among users. This effectively improves the system performance and frequency efficiency. However, the complexity of this system is higher and the feedback information is more. So the system is fit for the slowly fading channel.
本文首先介绍了上述的各种多址技术，以及最优信号子空间理论和基于该理论的SC-FDE系统。同时，最优信号子空间理论也是本文提出的自适应算法的理论基础。
基于最优信号子空间理论以及每子信道回传1比特信息的自适应算法，本文提出了自适应多址通信系统，包括CP-OSS-CDMA自适应系统和自适应DFT-SOFDM系统。为了在CP-CDMA系统中应用自适应算法，首先给出了CPA-DS-CDMA系统，并在此基础上结合自适应算法给出了CP-OSS-CDMA自适应系统。由于算法实现简单并且仅回传1比特信息，基于该算法的自适应系统非常适合于移动宽带无线通信系统中。
由于上述的自适应DFT-SOFDM系统在固定的子载波分组内进行子载波选择，所以该系统无法利用多用户分集(Multiuser Diversity)从而造成了一定的频谱损失。为了利用多用户分集，本文基于最优信号子空间理论提出了一种在用户间动态分配子载波的自适应算法，有效的提高了系统性能并且频谱损失很少。由于该算法实现比较复杂并且回传信息较多，较适合于信道变化缓慢的环境中。由此，自适应DFT-SOFDM系统可将这两种算法综合应用。
Recently, block-wise transmission techniques have become a hot research field of broadband digital communication. The block-wise transmission techniques with frequency domain equalization include OFDM and SC-FDE. Both are featuring high frequency efficiency, robustness to frequency selective fading and simple equalization. The multiplexing techniques based on them have gained great interest, for example MC-CDMA, CP-CDMA, OFDMA, DFT-SOFDM and so on.
Firstly, this thesis introduces the present multiplexing techniques, Optimal Signal Subspace theory and OSS-based adaptive SC-FDE system. The Optimal Signal Subspace theory is also the foundation of the adaptive algorithm proposed in this thesis.
Secondly, this thesis proposes adaptive multiusers communication system,i.e.,adaptive CP-OSS-CDMA system and adaptive DFT-SOFDM system. These are established on Optimal Signal Subspace theory and the low-cost adaptive scheme that needs only 1 bit feedback information per subchannel. In order to employ the adaptive scheme in CP-CDMA, this thesis introduces CPA-DS-CDMA system and provides the adaptive CP-OSS-CDMA system. Because of low-cost complexity and only 1 bit feedback information per subchannel, the adaptive systems are very suitable for mobile broadband wireless communication.
Because the adaptive DFT-SOFDM system, which bases on 1 bit feedback information per subchannel, assigns the subcarriers among the given subcarriers group, the adaptive DFT-SOFDM system can not exploit the Multiuser Diversity. So the frequency efficiency reduces. In order to exploit the multiuser diversity, the paper proposes a new algorithm that assignes the subcarriers among users. This effectively improves the system performance and frequency efficiency. However, the complexity of this system is higher and the feedback information is more. So the system is fit for the slowly fading channel.
引文
[1] R. W. Chang and R. A. Gibby, "A Theorectical Study of Performance of an Orthogonal Multiplexing Data Transmission Scheme " IEEE Transactions on Communication Technology, vol. 16, pp. 529-540, 1968.
[2] S. B. Weinstein and P. M. Ebert, "Data Transmission by Freqeuncy-Division Multiplexing Using the Discrete Fourier Transform," IEEE Transactions on Communication Technology, vol. 19, pp. 628-634, 1971.
[3] A. Peled and A. Ruiz, "Frequency Domain Data Transmission Using Computational Reduced Algorithms," IEEE International Conference on Acoustics, Speech, and Signal Processing Proceedings vol. 5, pp. 964-967, 1980.
[4] H. Sari, G. Karam, and I. Jeanclaude, "Frequency-domain Equalization of Mobile Radio and Terrestrial Braodcast Channels," IEEE GLOBALCOM'94 pp. 1-5, 1994.
[5] H. Sari, G. Karam, and I. Jeanclaude, "Transmission Techniques for Digital Terrestrial TV Broadcasting," IEEE Communications Magazine, vol. 33, pp. 100-109, 1995.
[6] H. Witschnig, T. Mayer, A. Springer, A. Koppler, L. Maurer, M. Huemer, and R. Weigel, "A different look on cyclic prefix for SC/FDE," The 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, vol. 2, pp. 824-828, 2002.
[7] H. Witschnig, T. Mayer, A. Springer, L. Maurer, M. Huemer, and R. Weigel, "The Advantages of a Known Sequence versus Cyclic Prefix in a SC/FDE System," The 5th International Symposium on Wireless Personal Multimedia Communications, vol. 3, pp. 1328-1332, 2002.
[8] H. Witschnig, T. Mayer, M. Petit, H. Hutzelmann, A. Springer, and R. Weigel, "The advantages of a unique word for synchronisation and channel estimation in a SC/FDE system," 5th European Personal Mobile Communications Conference, pp. 436-440, 2003.
[9] J. Coon, M. Beach, J. McGeehan, and M. Sandell, "Channel and Noise Variance Estimation and Tracking Algorithms for Unique-word Based Single-carrier Systems," 1st International Symposium on Wireless Communication Systems Proceedings, pp. 51-55, 2004.
[10] M. Huemer, H. Witschnig, and J. Hausner, "Unique word based phase tracking algorithms for SC/FDE-systems," IEEE GLOBECOM'03, vol. 1, pp. 70-74, 2003.
[11] 杜岩，”分块传输系统的基本原理，”内部资料，2006．
[12] Yee, N.; Linnartz, J.-P.; "BER of multi-carrier CDMA in an indoor Rician fading channel", IEEE Signals Systems and Computers, pp: 426-430, 1993.
[13] DaSilva, V.; Sousa, E. S.;" Performance of orthogonal CDMA codes for quasi-synchronous communication systems", IEEE ICUPC, pp: 995-999, 1993.
[14] K. Fazel, S. Kaiser;' Multi-Carrier and Spread Spectrum System", Jhon Wiley, 2003.
[15] Kevin L. Baum, Timothy A. Thomas, Frederick W. Vook, Vijay Nangia, "Cyclic-Prefix CDMA: An Improved Transmission Method for Broadband DS-CDMA Cellular Systems" in Proc. IEEE WCNC, Vol. 1, pp. 183-188, March 2002
[16] Adachi, F.; Sao, T.; Itagaki, T.; "Performance of multicode DS-CDMA using frequency domain equalisation in frequency selective fading channel", IEE Electronics Letters, Vol. 39, pp. 239-241, Jan 2003
[17] M. Wahlqvist, C. Ostberg, J. Beck, O. Edfon, P. Bejesson, "A canceptoal shldy of OFDM-based multiple access schemes-Part 1: Air interface requirema," Technical report Tdoc 117196, ETSI STC SMG2 meeting no. 18, Helsinki, Finland, May'96
[18] Kevin L. Baum, Timothy A. Thomas, Frederick W. Vook, Vijay Nangia, "Cyclic-prefix CDMA with antenna diversity" in Proc. IEEE VTC 2002, vol. 2, pp. 1002-1006, May 2002
[19] Vook, F. W.; Thomas, T. A.; Baum, K. L., "Transmit array processing for cyclic-prefix CDMA" in Proc. IEEE VTC 2002, vol.1, pp. 270-274 Sept. 2002
[20] Garg, D.; Adachi, F.; "DS-CDMA with frequency-domain equalization for high speed downlink packet access" in Proc. IEEE VTC2004, Vol. 1, pp. 689-693, Sept. 2004
[21] Garg, D.; Adachi, F.; "Performance comparison of turbo-coded DS-CDMA, MC-CDMA and OFDM with frequency-domain equalization and higher-level modulation" in Proc. IEEE VTC2004, Vol. 3,pp. 2282-2286, Sept. 2004
[22] Takeda, K.; Adachi, F.; "MMSE frequency-domain equalization combined with space-time transmit diversity and antenna receive diversity for DS-CDMA" in Proc. IEEE VTC 2004, Vol. 1, pp. 464-468 May 2004
[23] Pin-Hsun Lin; Tzi-Dar Chiueh; "Low complexity frequency-domain despreading for cyclic-prefix CDMA systems", IEEE Communications Letters, Vol. 8,pp. 339-341, June 2004
[24] Tsumura, S.; Hara, S.; Hara, Y.; "Performance comparison of MC-CDMA and cyclically prefixed DS-CDMA in an uplink channel [mobile radio]" in Proc. IEEE VTC2004, Vol. 1, pp. 414-418, Sept. 2004
[25] Adachi, F.; Garg, D.; Takaoka, S.; Takeda, K.; "Broadband CDMA techniques", IEEE Wireless Communications, Vol 12, pp. 8-18, April 2005
[26] Parsaee, G.; Yarali, A., "OFDMA for the 4th generation cellular networks" in Proc. IEEE Electrical and Computer Engineering, Vol. 4, pp. 2325-2330, May 2004
[27] 3GPP R1-050971,"R1-050971 Single Carrier Uplink Options for E-UTRA: IFDMNDFT-SOFDM Discussion and Initial Performance Results", http://www.3GPP.org,Aug 2005.
[28] Sorger, U.; De Broeck, I.; Schnell, M; "Interleaved FDMA-a new spread-spectrum multiple-access scheme" i in Proceedings of the IEEE ICC, Vol. 2, pp.1013-1017,June 1998
[29] 3GPP TSG-RAN WG1 Meeting #42bis, R1-051134, San Diego, US, Oct 10-Oct 14, 2005.
[30]Schnell, M.; De Broeck, l.;"Application of IFDMA to mobile radio transmission"lEEE ICUPC, Vol 2, pp: 1267 - 1272,1998
[31]Schnelll, M.; De Broeck, I.; "Interleaved FDMA equalization and coded performance in mobile radio applications"IEEE ICC ,Vol 3, pp: 1939 -1944,1999
[32]Goto, Y.; Kawamura, T.; Atarashi, H.; Sawahashi, M.;"Variable spreading and chip repetition factors (VSCRF)-CDMA in reverse link for broadband wireless access", in Proceedings of the IEEE International Conference on PIMRC, Vol.1, pp.254 - 259,Sept. 2003
[33]Goto, Y.; Kawamura, T.; Atarashi, H.; Sawahashi, M.;" Investigations on packet error rate of variable spreading and chip repetition factors (VSCRF)-CDMA wireless access in reverse link multi-cell environment", in Proceedings of the IEEE International Conference on VTC, Vol. 2,pp.944 - 948, Sept. 2004
[34]YinLin Xu; Jianfeng Weng; Tho Le-Ngoc;"Group-orthogonal OFDMA in fast time-varying frequency-selective fading environments", IEEE VTC2004 Fall, Vol.1 ,pp:488 - 492,2004
[35]D.Hughes-Hartogs, "Emsemble Modem Structure for Inperfect Transmission Media," U.S. Patents Nos. 4,679,227(July 1987),4,731,816(March 1988), and 4,833,706(May 1989).
[36]R. F. H. Fischer and J. B. Huber, "A new loading algorithm for discrete multitone transmission," IEEE GLOBECOM '96, vol. 1, pp. 724-728,1996
[37]R. Grunheid, E. Bolinth, and H. Rohling, "A blockwise loading algorithm for the adaptive modulation technique in OFDM systems," IEEE VTC 2001 Fall, vol. 2, pp. 948-951, 2001.
[38]C. Hyung Suk and A. Chong Koo, "Bit and subcarrier allocation for OFDM transmission using adaptive modulation," KORUS.2003, vol. 2,pp. 82-85, 2003
[39]Cheong Yui Wong; Cheng, R.S.; Lataief, K.B.; Murch, R.D.;"Multiuser OFDM with adaptive subcarrier, bit, and power allocation", IEEE Journal on Selected Areas in Communications, Vol 17, pp: 1747-1758, 1999.
[40] Jiho Jang; Kwang Bok Lee; "Transmit power adaptation for multiuser OFDM", IEEE Journal on Selected Areas in Communications, Vol 21, pp: 171-178, 2003.
[41] Kwang Don Choe; Yeon u Lim; Sang Kyu Park; "Subcarrier adaptation for multiuser OFDM systems", IEEE GLOCOM Vol 2, pp: 1230-1233, 2004
[42] Rhee, W.; Cioffi, J. M.; "Increasing in capacity of multiuser OFDM system using dynamic subchannel allocation", IEEE VTC 2000-Spring, Vol 2, pp: 1085-1089, 2000
[43] Zukang Shen; Andrews, J. G.; Evans, B. L.;"Adaptive resource allocation in multiuser OFDM systems with proportional rate constraints", IEEE Transactions on Wireless Communications, Vol 4, pp: 2726-2737, 2005
[44] Mohanram, C.; Bhashyam, S.; "A sub-optimal joint subcarrier and power allocation algorithm for multiuser OFDM", IEEE Communications Letters, Vol 9, pp: 685-687, 2005
[45] Li Zhen; Zhu Geqing; Wang Weihua; Song Junde;"Improved algorithm of multiuser dynamic subcarrier allocation in OFDM system", IEEE ICCT, Vol2, pp: 1144-1147, 2003
[46] Xiaojun Sun, Yan Du, lili Wang, leilei Liu;" An adaptive DFT-SOFDM for future cellular systems", IEEE ICCCAS06, Vol. 2, pp: 1157-1160,2006
[47] Davide Dardari, "Ordered Subcarrier Selection Algorithm for OFDM-Based High-Speed WLANs", IEEE Trans. Wireless Commun, Vol. 3, pp.1452-1458, 2004
[48] Hsiao-Hwa Chen; Jun-Feng Yeh; Suehiro, N.;" A multicarrier CDMA architecture based on orthogonal complementary codes for new generations of wideband wireless communications", IEEE Communications Magazine, Vol 39, pp: 126-135, 2001
[49] 宫良，基于最优信号子空间的自适应OTDM系统的研究，山东大学硕士学位论文，2006
[50] Tsumura, S.; Hara, S.; "Design and performance of quasi-synchronous multi-carrier CDMA system"; IEEE VTC, Vol. 2, pp:843-847,2001
[2] S. B. Weinstein and P. M. Ebert, "Data Transmission by Freqeuncy-Division Multiplexing Using the Discrete Fourier Transform," IEEE Transactions on Communication Technology, vol. 19, pp. 628-634, 1971.
[3] A. Peled and A. Ruiz, "Frequency Domain Data Transmission Using Computational Reduced Algorithms," IEEE International Conference on Acoustics, Speech, and Signal Processing Proceedings vol. 5, pp. 964-967, 1980.
[4] H. Sari, G. Karam, and I. Jeanclaude, "Frequency-domain Equalization of Mobile Radio and Terrestrial Braodcast Channels," IEEE GLOBALCOM'94 pp. 1-5, 1994.
[5] H. Sari, G. Karam, and I. Jeanclaude, "Transmission Techniques for Digital Terrestrial TV Broadcasting," IEEE Communications Magazine, vol. 33, pp. 100-109, 1995.
[6] H. Witschnig, T. Mayer, A. Springer, A. Koppler, L. Maurer, M. Huemer, and R. Weigel, "A different look on cyclic prefix for SC/FDE," The 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, vol. 2, pp. 824-828, 2002.
[7] H. Witschnig, T. Mayer, A. Springer, L. Maurer, M. Huemer, and R. Weigel, "The Advantages of a Known Sequence versus Cyclic Prefix in a SC/FDE System," The 5th International Symposium on Wireless Personal Multimedia Communications, vol. 3, pp. 1328-1332, 2002.
[8] H. Witschnig, T. Mayer, M. Petit, H. Hutzelmann, A. Springer, and R. Weigel, "The advantages of a unique word for synchronisation and channel estimation in a SC/FDE system," 5th European Personal Mobile Communications Conference, pp. 436-440, 2003.
[9] J. Coon, M. Beach, J. McGeehan, and M. Sandell, "Channel and Noise Variance Estimation and Tracking Algorithms for Unique-word Based Single-carrier Systems," 1st International Symposium on Wireless Communication Systems Proceedings, pp. 51-55, 2004.
[10] M. Huemer, H. Witschnig, and J. Hausner, "Unique word based phase tracking algorithms for SC/FDE-systems," IEEE GLOBECOM'03, vol. 1, pp. 70-74, 2003.
[11] 杜岩，”分块传输系统的基本原理，”内部资料，2006．
[12] Yee, N.; Linnartz, J.-P.; "BER of multi-carrier CDMA in an indoor Rician fading channel", IEEE Signals Systems and Computers, pp: 426-430, 1993.
[13] DaSilva, V.; Sousa, E. S.;" Performance of orthogonal CDMA codes for quasi-synchronous communication systems", IEEE ICUPC, pp: 995-999, 1993.
[14] K. Fazel, S. Kaiser;' Multi-Carrier and Spread Spectrum System", Jhon Wiley, 2003.
[15] Kevin L. Baum, Timothy A. Thomas, Frederick W. Vook, Vijay Nangia, "Cyclic-Prefix CDMA: An Improved Transmission Method for Broadband DS-CDMA Cellular Systems" in Proc. IEEE WCNC, Vol. 1, pp. 183-188, March 2002
[16] Adachi, F.; Sao, T.; Itagaki, T.; "Performance of multicode DS-CDMA using frequency domain equalisation in frequency selective fading channel", IEE Electronics Letters, Vol. 39, pp. 239-241, Jan 2003
[17] M. Wahlqvist, C. Ostberg, J. Beck, O. Edfon, P. Bejesson, "A canceptoal shldy of OFDM-based multiple access schemes-Part 1: Air interface requirema," Technical report Tdoc 117196, ETSI STC SMG2 meeting no. 18, Helsinki, Finland, May'96
[18] Kevin L. Baum, Timothy A. Thomas, Frederick W. Vook, Vijay Nangia, "Cyclic-prefix CDMA with antenna diversity" in Proc. IEEE VTC 2002, vol. 2, pp. 1002-1006, May 2002
[19] Vook, F. W.; Thomas, T. A.; Baum, K. L., "Transmit array processing for cyclic-prefix CDMA" in Proc. IEEE VTC 2002, vol.1, pp. 270-274 Sept. 2002
[20] Garg, D.; Adachi, F.; "DS-CDMA with frequency-domain equalization for high speed downlink packet access" in Proc. IEEE VTC2004, Vol. 1, pp. 689-693, Sept. 2004
[21] Garg, D.; Adachi, F.; "Performance comparison of turbo-coded DS-CDMA, MC-CDMA and OFDM with frequency-domain equalization and higher-level modulation" in Proc. IEEE VTC2004, Vol. 3,pp. 2282-2286, Sept. 2004
[22] Takeda, K.; Adachi, F.; "MMSE frequency-domain equalization combined with space-time transmit diversity and antenna receive diversity for DS-CDMA" in Proc. IEEE VTC 2004, Vol. 1, pp. 464-468 May 2004
[23] Pin-Hsun Lin; Tzi-Dar Chiueh; "Low complexity frequency-domain despreading for cyclic-prefix CDMA systems", IEEE Communications Letters, Vol. 8,pp. 339-341, June 2004
[24] Tsumura, S.; Hara, S.; Hara, Y.; "Performance comparison of MC-CDMA and cyclically prefixed DS-CDMA in an uplink channel [mobile radio]" in Proc. IEEE VTC2004, Vol. 1, pp. 414-418, Sept. 2004
[25] Adachi, F.; Garg, D.; Takaoka, S.; Takeda, K.; "Broadband CDMA techniques", IEEE Wireless Communications, Vol 12, pp. 8-18, April 2005
[26] Parsaee, G.; Yarali, A., "OFDMA for the 4th generation cellular networks" in Proc. IEEE Electrical and Computer Engineering, Vol. 4, pp. 2325-2330, May 2004
[27] 3GPP R1-050971,"R1-050971 Single Carrier Uplink Options for E-UTRA: IFDMNDFT-SOFDM Discussion and Initial Performance Results", http://www.3GPP.org,Aug 2005.
[28] Sorger, U.; De Broeck, I.; Schnell, M; "Interleaved FDMA-a new spread-spectrum multiple-access scheme" i in Proceedings of the IEEE ICC, Vol. 2, pp.1013-1017,June 1998
[29] 3GPP TSG-RAN WG1 Meeting #42bis, R1-051134, San Diego, US, Oct 10-Oct 14, 2005.
[30]Schnell, M.; De Broeck, l.;"Application of IFDMA to mobile radio transmission"lEEE ICUPC, Vol 2, pp: 1267 - 1272,1998
[31]Schnelll, M.; De Broeck, I.; "Interleaved FDMA equalization and coded performance in mobile radio applications"IEEE ICC ,Vol 3, pp: 1939 -1944,1999
[32]Goto, Y.; Kawamura, T.; Atarashi, H.; Sawahashi, M.;"Variable spreading and chip repetition factors (VSCRF)-CDMA in reverse link for broadband wireless access", in Proceedings of the IEEE International Conference on PIMRC, Vol.1, pp.254 - 259,Sept. 2003
[33]Goto, Y.; Kawamura, T.; Atarashi, H.; Sawahashi, M.;" Investigations on packet error rate of variable spreading and chip repetition factors (VSCRF)-CDMA wireless access in reverse link multi-cell environment", in Proceedings of the IEEE International Conference on VTC, Vol. 2,pp.944 - 948, Sept. 2004
[34]YinLin Xu; Jianfeng Weng; Tho Le-Ngoc;"Group-orthogonal OFDMA in fast time-varying frequency-selective fading environments", IEEE VTC2004 Fall, Vol.1 ,pp:488 - 492,2004
[35]D.Hughes-Hartogs, "Emsemble Modem Structure for Inperfect Transmission Media," U.S. Patents Nos. 4,679,227(July 1987),4,731,816(March 1988), and 4,833,706(May 1989).
[36]R. F. H. Fischer and J. B. Huber, "A new loading algorithm for discrete multitone transmission," IEEE GLOBECOM '96, vol. 1, pp. 724-728,1996
[37]R. Grunheid, E. Bolinth, and H. Rohling, "A blockwise loading algorithm for the adaptive modulation technique in OFDM systems," IEEE VTC 2001 Fall, vol. 2, pp. 948-951, 2001.
[38]C. Hyung Suk and A. Chong Koo, "Bit and subcarrier allocation for OFDM transmission using adaptive modulation," KORUS.2003, vol. 2,pp. 82-85, 2003
[39]Cheong Yui Wong; Cheng, R.S.; Lataief, K.B.; Murch, R.D.;"Multiuser OFDM with adaptive subcarrier, bit, and power allocation", IEEE Journal on Selected Areas in Communications, Vol 17, pp: 1747-1758, 1999.
[40] Jiho Jang; Kwang Bok Lee; "Transmit power adaptation for multiuser OFDM", IEEE Journal on Selected Areas in Communications, Vol 21, pp: 171-178, 2003.
[41] Kwang Don Choe; Yeon u Lim; Sang Kyu Park; "Subcarrier adaptation for multiuser OFDM systems", IEEE GLOCOM Vol 2, pp: 1230-1233, 2004
[42] Rhee, W.; Cioffi, J. M.; "Increasing in capacity of multiuser OFDM system using dynamic subchannel allocation", IEEE VTC 2000-Spring, Vol 2, pp: 1085-1089, 2000
[43] Zukang Shen; Andrews, J. G.; Evans, B. L.;"Adaptive resource allocation in multiuser OFDM systems with proportional rate constraints", IEEE Transactions on Wireless Communications, Vol 4, pp: 2726-2737, 2005
[44] Mohanram, C.; Bhashyam, S.; "A sub-optimal joint subcarrier and power allocation algorithm for multiuser OFDM", IEEE Communications Letters, Vol 9, pp: 685-687, 2005
[45] Li Zhen; Zhu Geqing; Wang Weihua; Song Junde;"Improved algorithm of multiuser dynamic subcarrier allocation in OFDM system", IEEE ICCT, Vol2, pp: 1144-1147, 2003
[46] Xiaojun Sun, Yan Du, lili Wang, leilei Liu;" An adaptive DFT-SOFDM for future cellular systems", IEEE ICCCAS06, Vol. 2, pp: 1157-1160,2006
[47] Davide Dardari, "Ordered Subcarrier Selection Algorithm for OFDM-Based High-Speed WLANs", IEEE Trans. Wireless Commun, Vol. 3, pp.1452-1458, 2004
[48] Hsiao-Hwa Chen; Jun-Feng Yeh; Suehiro, N.;" A multicarrier CDMA architecture based on orthogonal complementary codes for new generations of wideband wireless communications", IEEE Communications Magazine, Vol 39, pp: 126-135, 2001
[49] 宫良，基于最优信号子空间的自适应OTDM系统的研究，山东大学硕士学位论文，2006
[50] Tsumura, S.; Hara, S.; "Design and performance of quasi-synchronous multi-carrier CDMA system"; IEEE VTC, Vol. 2, pp:843-847,2001