多业务OFDMA系统中无线资源优化分配研究
|
摘要
本文主要研究了OFDMA及认知OFDM系统中的无线资源管理技术。
文中首先介绍了OFDM及认知无线电的基本原理;其次,对OFDM系统中无线资源分配技术进行了详细的研究,分析了Jang, Yin, Rhee, Shen, Wong等几种经典的子载波-比特-功率分配算法;最后,介绍了一种基于公平约束下的改进的整数比特资源分配算法,该改进的整数比特资源分配算法能有效提高系统吞吐量。
在此基础上,给出话音业务与数据业务共存系统模型下的多业务资源优化分配方案。在该方案中,首先,对于时间敏感业务而言,系统优先为其分配资源以保证其对时延的要求,通过为其分配子载波簇以降低所需反馈信息量,通过增加子载波簇上的功率来降低其占用的频带宽度;其次,将剩余资源灵活地分配给数据业务,实现子载波-功率-整数比特分配,同时着重考虑整比特分配后所产生的剩余功率重分配问题,从而进一步提高系统的吞吐量。仿真结果表明,本文多业务资源优化算法相对于固定载波分配算法和最大吞吐量算法达到较好的频谱利用率和较小的掉线率。
最后,研究了一种认知OFDM系统中认知用户资源分配方案。在该方案中,通过功率上限的控制,在不干扰授权用户通信的前提下进行子载波-功率分配。仿真结果表明,在满足系统服务质量(QoS)要求的前提下,本文认知用户资源分配算法相对于自适应资源分配算法使频谱资源的利用率有较大提高。
Radio Resource Management (RRM) in adaptive OFDMA networks and OFDM based Cognitive Radio Systems is considered in the thesis.
Firstly, the basic principles of OFDM and Cognitive Radio are introduced. Secondly, RRM in OFDM Systems is analyzed particularly in this paper. Performances of some typical subcarrier-bit-power allocation algorithms, including Jang algorithm, Yin, Rhee, Shen and Wong algorithm, are analyzed. Thirdly, under the constraints of integer bit allocation and the proportionnatily among the different users’throughput, a subcarrier- power-integer bits allocation scheme is analyzed. This allocation scheme can maximized the throughput of OFDMA Systems.
Meanwhile, the scheme of allocating OFDMA radio resource to multiple service,i.e., time sensitive services and time insensitive services, with different Quality of Service (QoS) , is designed in detail. In this scheme, the time sensitive services, with high priority to get the necessary resources to meet their time delay requirements, gain subcarrier clusters to lower the feedbacks and a little more power on each subcarrier cluster to reduce the occupancy of the bandwidth. Then the remaining resources after the first step are adaptively assigned to time insensitive services to realize the subcarrier-power-integer bits allocation to maximize the throughput of the time insensitive services, with the help of remaining power reallocation. Simulation results indicated that drop rate of our method can be decreased greatly compared with the Maximum throughput scheme and Fixed allocation schmem; meanwhile the throughput of our method is simaliar to that of the Maximum throughput scheme and greater than the Fixed allocation schmem.
Finally for OFDMA-based cognitive radio system, the radio resource management for cognitive users and primary users are considered with the constraint that no interferences are induced to the primary users by the cognitive users. The simulations verify the performance of the proposed scheme, and the spectrum efficiency of the cognitive system is increased greatly.
文中首先介绍了OFDM及认知无线电的基本原理;其次,对OFDM系统中无线资源分配技术进行了详细的研究,分析了Jang, Yin, Rhee, Shen, Wong等几种经典的子载波-比特-功率分配算法;最后,介绍了一种基于公平约束下的改进的整数比特资源分配算法,该改进的整数比特资源分配算法能有效提高系统吞吐量。
在此基础上,给出话音业务与数据业务共存系统模型下的多业务资源优化分配方案。在该方案中,首先,对于时间敏感业务而言,系统优先为其分配资源以保证其对时延的要求,通过为其分配子载波簇以降低所需反馈信息量,通过增加子载波簇上的功率来降低其占用的频带宽度;其次,将剩余资源灵活地分配给数据业务,实现子载波-功率-整数比特分配,同时着重考虑整比特分配后所产生的剩余功率重分配问题,从而进一步提高系统的吞吐量。仿真结果表明,本文多业务资源优化算法相对于固定载波分配算法和最大吞吐量算法达到较好的频谱利用率和较小的掉线率。
最后,研究了一种认知OFDM系统中认知用户资源分配方案。在该方案中,通过功率上限的控制,在不干扰授权用户通信的前提下进行子载波-功率分配。仿真结果表明,在满足系统服务质量(QoS)要求的前提下,本文认知用户资源分配算法相对于自适应资源分配算法使频谱资源的利用率有较大提高。
Radio Resource Management (RRM) in adaptive OFDMA networks and OFDM based Cognitive Radio Systems is considered in the thesis.
Firstly, the basic principles of OFDM and Cognitive Radio are introduced. Secondly, RRM in OFDM Systems is analyzed particularly in this paper. Performances of some typical subcarrier-bit-power allocation algorithms, including Jang algorithm, Yin, Rhee, Shen and Wong algorithm, are analyzed. Thirdly, under the constraints of integer bit allocation and the proportionnatily among the different users’throughput, a subcarrier- power-integer bits allocation scheme is analyzed. This allocation scheme can maximized the throughput of OFDMA Systems.
Meanwhile, the scheme of allocating OFDMA radio resource to multiple service,i.e., time sensitive services and time insensitive services, with different Quality of Service (QoS) , is designed in detail. In this scheme, the time sensitive services, with high priority to get the necessary resources to meet their time delay requirements, gain subcarrier clusters to lower the feedbacks and a little more power on each subcarrier cluster to reduce the occupancy of the bandwidth. Then the remaining resources after the first step are adaptively assigned to time insensitive services to realize the subcarrier-power-integer bits allocation to maximize the throughput of the time insensitive services, with the help of remaining power reallocation. Simulation results indicated that drop rate of our method can be decreased greatly compared with the Maximum throughput scheme and Fixed allocation schmem; meanwhile the throughput of our method is simaliar to that of the Maximum throughput scheme and greater than the Fixed allocation schmem.
Finally for OFDMA-based cognitive radio system, the radio resource management for cognitive users and primary users are considered with the constraint that no interferences are induced to the primary users by the cognitive users. The simulations verify the performance of the proposed scheme, and the spectrum efficiency of the cognitive system is increased greatly.
引文
[1] J. Mitola et al., Cognitive radio: Making software radios more personal, IEEE Pers. Commun., vol. 6, no. 4, Aug, 1999, pp. 13–18.
[2] J. Mitola, Cognitive Radio for Flexible Mobile Multimedia Communications, MoMuC , nov 1999, pp 3-10.
[3] W. Mohr, W.Konhuser. Access Network Evolution Beyond Third Generation Mobile Communications, IEEE Commun. Mag., vol.38, no.12, Dec.2000, pp .122-133.
[4] S.Ohmori,Y.Yamao, and N. Nakajima, The Future Generations of Mobile Communications Based on Broadband Access Technologies, IEEE Commun. Mag.,vol.38, no.12, Dec.2000, pp.134-142.
[5] R.van Nee et al. New High-rate Wireless LAN Standards,IEEE Commun. Mag.,vol.37, no.12, Dec.1999, pp.82-88.
[6] J.Chuang and N. Sollenberger. Beyond 3G; Wideband wireless data access based on OFDM and synamic packet assignment. IEEE Commun. Mag., vol.38, no.7, July 2000, pp.78-87.
[7] J.Chuang,Jr L. J. Cimini, G. Y. Li, B. McNair, N. Sollenberger, H. Zhao, L. Lin, and M. Suzuki, High speed wireless data access based on combing EDGE withwiddeband OFDM, IEEE Commun. Mag., vol. 37, no.11, nov. 1999, pp. 92-98.
[8] L. J. Cimini, Analysis and Simulation of a Digital Mobile Channel Using Orthogonal Frequency Division Multiplexing, IEEE Trans. Commun., vol. 33, 1985, pp. 665-675.
[9] S.Kaiser, OFDM code-division multiplexing in fading channels, IEEE Transactions on, Commun. vol. 50, Aug. 2002, pp. 1266-1273.
[10] N.Benvenuto, S.Tomasin, L.Tomba, Equalization methods in OFDM and FMT systems for broadband wireless communications, IEEE Transactions, Commun. vol. 50, Sept. 2002 , pp.1413-1418.
[11] R.Negi, J.M.Cioffi,Blind OFDM symbol synchronization in ISI channels, IEEE Trans., Commun. vol. 50, Sept. 2002 , pp.1525-1534.
[12] D.Hughes-Hartogs. Ensemble modem structure for imperfect transmission media, U.S. Patents Nos.4 679 227, July 1987; 4 731 816, Mar. 1988; and 4 833 796, May 1989.
[13] John G.Proakis著,张军力等译,Digital Communications (Fourth Edition),北京:电子工业出版社,2004。
[14] Webb, W.T., Steele, R., Variable rate QAM for mobile radio.Communications, IEEE Transactions on , vol.43 , July 1995 , pp.2223 - 2230.
[15] Matsuoka, H.; Sampei, S.; Morinaga, N.; Kamio, Y., Adaptive modulation system with punctured convolutional code for high quality personal communication systems. Universal Personal Communications. 1995. Record., 1995 Fourth IEEE International Conference on , 6-10 .nov. 1995, pp.2 - 26.
[16] Yuanrun Teng, Nagaosa, T.; Mori, K., Kobayashi, H.,Grouping adaptive modulation method for burst mode OFDM transmission system. 2002 IEEE Region 10 Conference on Computers, Communications, Control and Power Engineering , vol. 2, 28-31, Oct. 2002 , pp.929 - 932.
[17] Adaptive Techniques for Multiuser OFDM, PhD. Exit Seminar, Eric Lawrey, 26 th June 2001, At James Cook University, Townsville, Australia.
[18] J Mitola, David Chester, Shinichiro Haruyama, etal. Globalization of Software Radio. IEEE Communication Magazine. Feb 1999.
[19]杨小牛,楼才义,徐建良.软件无线电原理与应用。北京:电子工业出版社,2001.1。
[20]佟学俭,罗涛. OFDM移动通信技术原理与应用.北京:人民邮电出版社,2003.6。
[21]伊长川,罗涛,乐光新.多载波宽带无线通信技术。北京:北京邮电大学出版社,2004.7。
[22] Lawrey E.,“Multiuser OFDM,”Proc. IEEE Intermational Symposium on Signal Processing and its Applications, vol.2, Aug.1999, pp.761-764.
[23] Wong C.Y., Cheng R.S., Letaief K.B.,“Multuser OFDM with Adaptive Subcarrier, Bit, and Power Allocation,”IEEE Journal on Selected Aress in Communications, vol.17, no.10, October 1999, pp. 1747-1758.
[24] Wong C.Y., Tsui C.Y., Cheng R.S., Letaief.K.B., R.D.Murch,“Multiuser Subcarrier Allocation for OFDM Transmission using Adaptive Modulation,”In Proc. Vtc, 1999, pp.479-483.
[25] Wong C.Y., Tsui C.Y., Cheng R.S., Letaief.K.B.,“A Real-time Subcarrier Allocation Scheme for Multiple Access Downlink OFDM Transmission,”In Proc.of IEEE Vtc’99, pp.1124-1128.
[26] Pietrzyk Slawomir, Janssen J.M.Gerard,“Multiuser subcarrier Allocation for QoS Provision in the OFDMA Systems,”In Procceeding of IEEE VTC’02 Fall, vol. 2, 24-28 , Sept.2002, pp.1077-1081.
[27] Pietrzyk Slawomir, Janssen J.M.Gerard,“Subcarrier and Power Allocation for QoS-aware OFDMA Systems Using Embedded Modulation,”IEEE Communications Society, vol.6, 20-24, June 2004, pp.3202-3206.
[28] Rhee W., Cioffi J.M.,“Increasing in Capacity of Multiuser OFDM System Using Dynamic Subchannel Allocation,”Vehicular Technology Conference Proceedings, 2000. IEEE 51s t, vol.2, Vtc-2000 Spring Tokyo, pp.1085-1089.
[29] Kim I., Lee H.L., Kim B., Lee Y.H.,“On the use of linear Programming for Dynamic Subchannel and Bit Allocation in Multiuser OFDM,”Global Telecommunications Conference, 2001, Globecom’01, vol. 6, 25-29, Nov. 2001, pp.3648-3652.
[30] Zhang Ying Jun, Letaief K.B.,“Multiuser Subcarrier and Bit Allocation along With Adaptive Cell Selection for OFDM transmission”ICC 2002, vol.2, 28 , April-2 May 2002, pp.861-865.
[31] J.,Lee K.B.,“Transmit Power Adaptation for Multiuser OFDM Systems,”IEEE Journal on Selected Areas in Communicationa, vol.21, Feb.2003, pp.171-178.
[32] Shen Zukang, Andrews G Jeffrey, Evans L. Brian,“Optimal Power Allocation in Multiuser OFDM Systems”, Globecom 2003, vol.1, 1-5, Dec. 2003, pp.337-341.
[33] Zhang Ying Jun, Letaief K.B.,“Multiuser Adaptive Subcarrier-and-Bit Allocation with Adaptive Cell Selection for OFDM Systems,”IEEE Transactions on Wireless Communications, vol.3, no.5, Sept.2004, pp.1566-1575.
[34] Song Guocong, Li Ye (Geoffrey),“Utility-Based Joint Physical-MAC Layer Optimization in OFDM”, Globecom 2002, vol. 1, 17-21, nov. 2002, pp.671-675.
[35] Song Guocong, Li Ye (Geoffrey),“Adalptive Subcarrier and Power Allocation in OFDM Based on Maximizing Utility”, Vtc 2003, vol.2, 22-25, April 2003, pp.905-909.
[36] Pollet T., Moeneclaey M.,“Synchronizability of OFDM Signals,”In Proceedings of Globecom’95, vol.3, Singapore, nov.1995, pp.2054-2058.
[37] Zogakis T.N., Cioffi J.M.,“The Effect of Timing Jitter on the Performance of a Discrete Multitone System,”IEEE Transactions on Communication, vol.44, no.7, 1996, pp.799-808.
[38] Schmidl T.M., Cox D.C.,“Robust frequency and timing synchronization for OFDM,”IEEE Transaction on Communications, vol.45, no.12, 1997, pp.1613-1621.
[39] Jan-Jaap van de Beek,“A Time and Frequency Synchronization Scheme for multiuser OFDM,”IEEE Journal on Slected Areas in Communications, vol.17, no.11, nov. 1999, pp.1900-1914.
[40] Landatrom D, Wilsom S.K., van de Beek J-J, Borjesson P.O.,“Symbol time offset estimation in coherent OFDM systems,”IEEE Transactions on Communications, 2002, vol.50, no.4, pp.5345-549.
[41]侯晓林,“宽带无线移动通信系统中信道估计的研究”,北京邮电大学,2005.4。
[42] J.-J. van de Beek, Edfors O., Sandell M., Wilson S.K., et al.,“On Channel Estimation in OFDM Systems,”in Proc. IEEE Vtc’95, vol.2, pp.815-819.
[43] Sandell M., Edfors O.,“A comparative study of pilot-based channel estimators for wireless OFDM,”Research Report, Sep.1996.
[44] Hoeher P., Kaiser S., Robertson P.,“Two-dimensional pilot-symbol-aided channel estimation by Wiener filtering,”in Proc.IEEE Icassp’97, vol.3, 21-24, Apr. 1997, pp.1845-1848.
[45] Schafhuber D., Matz G, Hlawatsch F.,“Adaptive prediction of time-varying channels for coded OFDM systems,”in Proc. IEEE Icassp’02, vol.3, 13-17, May 2002, pp.2549-2552.
[46] Jang J., Lee K.B.,“Transmit power adaptation for multiuser OFDM systems,”IEEE J.Sel. Areas Commun., vol.21, Feb.2003, pp.171-178.
[47] Li Guoqing, Liu Hui,“On the Optimality of the OFDMA Network,”IEEE Communications Letters, vol.9, no.5, May 2005, pp.438-440.
[48] Simon Haykin, Life Fellow, IEEE Cognitive Radio: Brain-Empowered Wireless Communications IEEE Journal on Selected Areas in Communications, vol.23, no.2, Feb. 2005.
[49] J.Jang and K.G.Lee,“Transmit Power Adaptation for Multiuser OFDM Systems,”IEEE J.Select.Areas Commun, vol.21, Feb 2003, pp.171-178.
[50] H.Yin and H.Liu,“An Efficient Multiuser Loading Algorithm for OFDM-based Broadband Wireless Systems,”in Proc. IEEE Global Telecommunications Conference, vol. 1, 2000, pp. 103-107.
[51] Z. Shen, J.G. Andrews, and B. L. Evans,“Adaptive Resource Allocation in Multiuser OFDM Systems With Proportional Fairness,”IEEE Trans. Wireless Commun, vol. 4, lssue6, nov. 2005, pp. 2726-2737.
[52] Kang Shen, Jeffrey G. Andrews, and Brian L. Evans. Adaptive Resource Allocation in Multiuser OFDM Systems with Proportional Fairness [J], IEEE Trans.Wireless Commun, 2005, pp. 2726-2737.
[53] Zhang, KB Letaief. Multiuser adaptive subcarrier-and-bit allocation with adaptive cell selection for OFDM systems [J]. IEEE Transactions on Wireless Commun, 2004, pp. 1566-1575.
[2] J. Mitola, Cognitive Radio for Flexible Mobile Multimedia Communications, MoMuC , nov 1999, pp 3-10.
[3] W. Mohr, W.Konhuser. Access Network Evolution Beyond Third Generation Mobile Communications, IEEE Commun. Mag., vol.38, no.12, Dec.2000, pp .122-133.
[4] S.Ohmori,Y.Yamao, and N. Nakajima, The Future Generations of Mobile Communications Based on Broadband Access Technologies, IEEE Commun. Mag.,vol.38, no.12, Dec.2000, pp.134-142.
[5] R.van Nee et al. New High-rate Wireless LAN Standards,IEEE Commun. Mag.,vol.37, no.12, Dec.1999, pp.82-88.
[6] J.Chuang and N. Sollenberger. Beyond 3G; Wideband wireless data access based on OFDM and synamic packet assignment. IEEE Commun. Mag., vol.38, no.7, July 2000, pp.78-87.
[7] J.Chuang,Jr L. J. Cimini, G. Y. Li, B. McNair, N. Sollenberger, H. Zhao, L. Lin, and M. Suzuki, High speed wireless data access based on combing EDGE withwiddeband OFDM, IEEE Commun. Mag., vol. 37, no.11, nov. 1999, pp. 92-98.
[8] L. J. Cimini, Analysis and Simulation of a Digital Mobile Channel Using Orthogonal Frequency Division Multiplexing, IEEE Trans. Commun., vol. 33, 1985, pp. 665-675.
[9] S.Kaiser, OFDM code-division multiplexing in fading channels, IEEE Transactions on, Commun. vol. 50, Aug. 2002, pp. 1266-1273.
[10] N.Benvenuto, S.Tomasin, L.Tomba, Equalization methods in OFDM and FMT systems for broadband wireless communications, IEEE Transactions, Commun. vol. 50, Sept. 2002 , pp.1413-1418.
[11] R.Negi, J.M.Cioffi,Blind OFDM symbol synchronization in ISI channels, IEEE Trans., Commun. vol. 50, Sept. 2002 , pp.1525-1534.
[12] D.Hughes-Hartogs. Ensemble modem structure for imperfect transmission media, U.S. Patents Nos.4 679 227, July 1987; 4 731 816, Mar. 1988; and 4 833 796, May 1989.
[13] John G.Proakis著,张军力等译,Digital Communications (Fourth Edition),北京:电子工业出版社,2004。
[14] Webb, W.T., Steele, R., Variable rate QAM for mobile radio.Communications, IEEE Transactions on , vol.43 , July 1995 , pp.2223 - 2230.
[15] Matsuoka, H.; Sampei, S.; Morinaga, N.; Kamio, Y., Adaptive modulation system with punctured convolutional code for high quality personal communication systems. Universal Personal Communications. 1995. Record., 1995 Fourth IEEE International Conference on , 6-10 .nov. 1995, pp.2 - 26.
[16] Yuanrun Teng, Nagaosa, T.; Mori, K., Kobayashi, H.,Grouping adaptive modulation method for burst mode OFDM transmission system. 2002 IEEE Region 10 Conference on Computers, Communications, Control and Power Engineering , vol. 2, 28-31, Oct. 2002 , pp.929 - 932.
[17] Adaptive Techniques for Multiuser OFDM, PhD. Exit Seminar, Eric Lawrey, 26 th June 2001, At James Cook University, Townsville, Australia.
[18] J Mitola, David Chester, Shinichiro Haruyama, etal. Globalization of Software Radio. IEEE Communication Magazine. Feb 1999.
[19]杨小牛,楼才义,徐建良.软件无线电原理与应用。北京:电子工业出版社,2001.1。
[20]佟学俭,罗涛. OFDM移动通信技术原理与应用.北京:人民邮电出版社,2003.6。
[21]伊长川,罗涛,乐光新.多载波宽带无线通信技术。北京:北京邮电大学出版社,2004.7。
[22] Lawrey E.,“Multiuser OFDM,”Proc. IEEE Intermational Symposium on Signal Processing and its Applications, vol.2, Aug.1999, pp.761-764.
[23] Wong C.Y., Cheng R.S., Letaief K.B.,“Multuser OFDM with Adaptive Subcarrier, Bit, and Power Allocation,”IEEE Journal on Selected Aress in Communications, vol.17, no.10, October 1999, pp. 1747-1758.
[24] Wong C.Y., Tsui C.Y., Cheng R.S., Letaief.K.B., R.D.Murch,“Multiuser Subcarrier Allocation for OFDM Transmission using Adaptive Modulation,”In Proc. Vtc, 1999, pp.479-483.
[25] Wong C.Y., Tsui C.Y., Cheng R.S., Letaief.K.B.,“A Real-time Subcarrier Allocation Scheme for Multiple Access Downlink OFDM Transmission,”In Proc.of IEEE Vtc’99, pp.1124-1128.
[26] Pietrzyk Slawomir, Janssen J.M.Gerard,“Multiuser subcarrier Allocation for QoS Provision in the OFDMA Systems,”In Procceeding of IEEE VTC’02 Fall, vol. 2, 24-28 , Sept.2002, pp.1077-1081.
[27] Pietrzyk Slawomir, Janssen J.M.Gerard,“Subcarrier and Power Allocation for QoS-aware OFDMA Systems Using Embedded Modulation,”IEEE Communications Society, vol.6, 20-24, June 2004, pp.3202-3206.
[28] Rhee W., Cioffi J.M.,“Increasing in Capacity of Multiuser OFDM System Using Dynamic Subchannel Allocation,”Vehicular Technology Conference Proceedings, 2000. IEEE 51s t, vol.2, Vtc-2000 Spring Tokyo, pp.1085-1089.
[29] Kim I., Lee H.L., Kim B., Lee Y.H.,“On the use of linear Programming for Dynamic Subchannel and Bit Allocation in Multiuser OFDM,”Global Telecommunications Conference, 2001, Globecom’01, vol. 6, 25-29, Nov. 2001, pp.3648-3652.
[30] Zhang Ying Jun, Letaief K.B.,“Multiuser Subcarrier and Bit Allocation along With Adaptive Cell Selection for OFDM transmission”ICC 2002, vol.2, 28 , April-2 May 2002, pp.861-865.
[31] J.,Lee K.B.,“Transmit Power Adaptation for Multiuser OFDM Systems,”IEEE Journal on Selected Areas in Communicationa, vol.21, Feb.2003, pp.171-178.
[32] Shen Zukang, Andrews G Jeffrey, Evans L. Brian,“Optimal Power Allocation in Multiuser OFDM Systems”, Globecom 2003, vol.1, 1-5, Dec. 2003, pp.337-341.
[33] Zhang Ying Jun, Letaief K.B.,“Multiuser Adaptive Subcarrier-and-Bit Allocation with Adaptive Cell Selection for OFDM Systems,”IEEE Transactions on Wireless Communications, vol.3, no.5, Sept.2004, pp.1566-1575.
[34] Song Guocong, Li Ye (Geoffrey),“Utility-Based Joint Physical-MAC Layer Optimization in OFDM”, Globecom 2002, vol. 1, 17-21, nov. 2002, pp.671-675.
[35] Song Guocong, Li Ye (Geoffrey),“Adalptive Subcarrier and Power Allocation in OFDM Based on Maximizing Utility”, Vtc 2003, vol.2, 22-25, April 2003, pp.905-909.
[36] Pollet T., Moeneclaey M.,“Synchronizability of OFDM Signals,”In Proceedings of Globecom’95, vol.3, Singapore, nov.1995, pp.2054-2058.
[37] Zogakis T.N., Cioffi J.M.,“The Effect of Timing Jitter on the Performance of a Discrete Multitone System,”IEEE Transactions on Communication, vol.44, no.7, 1996, pp.799-808.
[38] Schmidl T.M., Cox D.C.,“Robust frequency and timing synchronization for OFDM,”IEEE Transaction on Communications, vol.45, no.12, 1997, pp.1613-1621.
[39] Jan-Jaap van de Beek,“A Time and Frequency Synchronization Scheme for multiuser OFDM,”IEEE Journal on Slected Areas in Communications, vol.17, no.11, nov. 1999, pp.1900-1914.
[40] Landatrom D, Wilsom S.K., van de Beek J-J, Borjesson P.O.,“Symbol time offset estimation in coherent OFDM systems,”IEEE Transactions on Communications, 2002, vol.50, no.4, pp.5345-549.
[41]侯晓林,“宽带无线移动通信系统中信道估计的研究”,北京邮电大学,2005.4。
[42] J.-J. van de Beek, Edfors O., Sandell M., Wilson S.K., et al.,“On Channel Estimation in OFDM Systems,”in Proc. IEEE Vtc’95, vol.2, pp.815-819.
[43] Sandell M., Edfors O.,“A comparative study of pilot-based channel estimators for wireless OFDM,”Research Report, Sep.1996.
[44] Hoeher P., Kaiser S., Robertson P.,“Two-dimensional pilot-symbol-aided channel estimation by Wiener filtering,”in Proc.IEEE Icassp’97, vol.3, 21-24, Apr. 1997, pp.1845-1848.
[45] Schafhuber D., Matz G, Hlawatsch F.,“Adaptive prediction of time-varying channels for coded OFDM systems,”in Proc. IEEE Icassp’02, vol.3, 13-17, May 2002, pp.2549-2552.
[46] Jang J., Lee K.B.,“Transmit power adaptation for multiuser OFDM systems,”IEEE J.Sel. Areas Commun., vol.21, Feb.2003, pp.171-178.
[47] Li Guoqing, Liu Hui,“On the Optimality of the OFDMA Network,”IEEE Communications Letters, vol.9, no.5, May 2005, pp.438-440.
[48] Simon Haykin, Life Fellow, IEEE Cognitive Radio: Brain-Empowered Wireless Communications IEEE Journal on Selected Areas in Communications, vol.23, no.2, Feb. 2005.
[49] J.Jang and K.G.Lee,“Transmit Power Adaptation for Multiuser OFDM Systems,”IEEE J.Select.Areas Commun, vol.21, Feb 2003, pp.171-178.
[50] H.Yin and H.Liu,“An Efficient Multiuser Loading Algorithm for OFDM-based Broadband Wireless Systems,”in Proc. IEEE Global Telecommunications Conference, vol. 1, 2000, pp. 103-107.
[51] Z. Shen, J.G. Andrews, and B. L. Evans,“Adaptive Resource Allocation in Multiuser OFDM Systems With Proportional Fairness,”IEEE Trans. Wireless Commun, vol. 4, lssue6, nov. 2005, pp. 2726-2737.
[52] Kang Shen, Jeffrey G. Andrews, and Brian L. Evans. Adaptive Resource Allocation in Multiuser OFDM Systems with Proportional Fairness [J], IEEE Trans.Wireless Commun, 2005, pp. 2726-2737.
[53] Zhang, KB Letaief. Multiuser adaptive subcarrier-and-bit allocation with adaptive cell selection for OFDM systems [J]. IEEE Transactions on Wireless Commun, 2004, pp. 1566-1575.