MIMO-OFDM系统峰均比抑制问题研究及算法实现
摘要
多输入多输出正交频分复用(MIMO-OFDM)系统由于能够提高系统容量和效率并能抵抗多径衰落,频谱利用率高,成为新一代高速宽带无线通信系统的关键技术之一,并得到人们越来越多的关注。
在MIMO-OFDM系统中,由于利用IFFT变换将发送符号序列进行了OFDM调制,从而使MIMO-OFDM系统也具有峰均功率比(PAPR)过高的问题,从而严重影响MIMO-OFDM系统的性能。现有的MIMO-OFDM系统中的峰均比算法大多是将OFDM系统中的峰均比算法直接应用到各个天线上,并没有考虑MIMO-OFDM系统本身的固有特性,这样不仅计算量大而且增加了边带信息传输量,降低了有效数据的传输效率。
本文从MIMO-OFDM系统本身的固有特性出发,综合分析了MIMO-OFDM系统的峰均比抑制问题,通过借鉴目前已有的峰均比抑制方案,在证明和分析了经过正交空时编码的信号与其共轭信号具有相同的峰均功率比以及采用正交空时编码结构的发送信号在前后符号周期之间具有共轭对称性的基础上,提出了低复杂度的MIMO-OFDM系统中的选择性映射算法,并用Matlab软件对算法性能进行了仿真验证。仿真结果表明,本文提出的算法性能明显优于现有算法,不仅能显著降低算法复杂度,减少迭代运算量,同时还对峰均比抑制效果有较小的改善,从而提高了系统的性能。另外,针对空频编码MIMO-OFDM系统,将STBC MIMO-OFDM中的跨天线排序算法的原理应用到空频编码MIMO-OFDM系统中,提出了空频编码MIMO-OFDM系统中的子载波排序最优算法及其次优算法。仿真结果表明这两种算法均比原始信号具有更好的峰均比特性。
Multi-input Multi-output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) can increase the system capacity and efficiency, resists the multi-path fading, has high use ratio of frequency spectrum at the same. So it is regarded as a key technology of the fourth generation mobile communication system, and it gets more and more attention.
However, MIMO-OFDM system have the shortcoming of high peak to average power ration (PAPR) because the IFFT transform in modulation of the sending symbol sequence, this disadvantage affect the performance of MIMO-OFDM systems seriously. The existing MIMO-OFDM system PAPR algorithm is mostly apply the PAPR algorithm of OFDM system to each antenna directly without taking into account of the character of the MIMO-OFDM system, so that algorithm not only need large quantity of calculation but also increase the amount of sideband information transmission reducing transmission efficiency.
In this paper, on the base of the character of MIMO-OFDM system we mostly analyze the PAPR restrain algorithms of MIMO-OFDM system. Then the proof and analysis of the signal that through the orthogonal space-time coding has the same PAPR with its conjugate signal, and the orthogonal space-time code structure has the character of conjugate and symmetry is given firstly. Based on that and a Low-complexity PAPR reduction algorithm for MIMO-OFDM system is proposed. The simulation result shows that this algorithm is better than the present algorithm, it not only reduce computational complexity significantly and reduce the amount of iteration computation but also improved PAPR reduction effect slightly at the same time. So this algorithm can improve performance of the system. In addition, aiming at the SFBC MIMO-OFDM system, we apply the principle of cross-antenna rotation and inversion algorithm in STBC MIMO-OFDM to the SFBC MIMO-OFDM system, propose the sub-carrier rotation optimal and suboptimal algorithm in SFBC MIMO-OFDM system. The simulation result shows that algorithm have better PAPR than original signal.
在MIMO-OFDM系统中,由于利用IFFT变换将发送符号序列进行了OFDM调制,从而使MIMO-OFDM系统也具有峰均功率比(PAPR)过高的问题,从而严重影响MIMO-OFDM系统的性能。现有的MIMO-OFDM系统中的峰均比算法大多是将OFDM系统中的峰均比算法直接应用到各个天线上,并没有考虑MIMO-OFDM系统本身的固有特性,这样不仅计算量大而且增加了边带信息传输量,降低了有效数据的传输效率。
本文从MIMO-OFDM系统本身的固有特性出发,综合分析了MIMO-OFDM系统的峰均比抑制问题,通过借鉴目前已有的峰均比抑制方案,在证明和分析了经过正交空时编码的信号与其共轭信号具有相同的峰均功率比以及采用正交空时编码结构的发送信号在前后符号周期之间具有共轭对称性的基础上,提出了低复杂度的MIMO-OFDM系统中的选择性映射算法,并用Matlab软件对算法性能进行了仿真验证。仿真结果表明,本文提出的算法性能明显优于现有算法,不仅能显著降低算法复杂度,减少迭代运算量,同时还对峰均比抑制效果有较小的改善,从而提高了系统的性能。另外,针对空频编码MIMO-OFDM系统,将STBC MIMO-OFDM中的跨天线排序算法的原理应用到空频编码MIMO-OFDM系统中,提出了空频编码MIMO-OFDM系统中的子载波排序最优算法及其次优算法。仿真结果表明这两种算法均比原始信号具有更好的峰均比特性。
Multi-input Multi-output Orthogonal Frequency Division Multiplexing (MIMO-OFDM) can increase the system capacity and efficiency, resists the multi-path fading, has high use ratio of frequency spectrum at the same. So it is regarded as a key technology of the fourth generation mobile communication system, and it gets more and more attention.
However, MIMO-OFDM system have the shortcoming of high peak to average power ration (PAPR) because the IFFT transform in modulation of the sending symbol sequence, this disadvantage affect the performance of MIMO-OFDM systems seriously. The existing MIMO-OFDM system PAPR algorithm is mostly apply the PAPR algorithm of OFDM system to each antenna directly without taking into account of the character of the MIMO-OFDM system, so that algorithm not only need large quantity of calculation but also increase the amount of sideband information transmission reducing transmission efficiency.
In this paper, on the base of the character of MIMO-OFDM system we mostly analyze the PAPR restrain algorithms of MIMO-OFDM system. Then the proof and analysis of the signal that through the orthogonal space-time coding has the same PAPR with its conjugate signal, and the orthogonal space-time code structure has the character of conjugate and symmetry is given firstly. Based on that and a Low-complexity PAPR reduction algorithm for MIMO-OFDM system is proposed. The simulation result shows that this algorithm is better than the present algorithm, it not only reduce computational complexity significantly and reduce the amount of iteration computation but also improved PAPR reduction effect slightly at the same time. So this algorithm can improve performance of the system. In addition, aiming at the SFBC MIMO-OFDM system, we apply the principle of cross-antenna rotation and inversion algorithm in STBC MIMO-OFDM to the SFBC MIMO-OFDM system, propose the sub-carrier rotation optimal and suboptimal algorithm in SFBC MIMO-OFDM system. The simulation result shows that algorithm have better PAPR than original signal.
引文
[1]李建东,郭梯云,邬国扬 移动通信(第四版)[M].西安：西安电子科技大学出版社,2006.7,371-375
[2]尹长川,罗涛,乐光新多载波宽带无线通信技术[M]北京：北京邮电大学出版社,2004.7,1-9
[3]罗涛,乐光新多天线无线通信原理与应用[M]北京：北京邮电大学出版社,2005.11,4-6
[4]黄韬,袁超伟等MIMO相关技术与应用[M]北京：机械工业出版社,2007.1,205-208
[5]佟学俭,罗涛.OFDM移动通信技术原理及应用[M].北京：人民邮电出版社,2003.6,5-9
[6]Arogyaswami Paulraj, Rohit Nabar, Dhananjay Gore(著),刘伟鑫(译)空时无线通信导论[M]北京：清华大学出版社,2007.12,5-8
[7]Hamid Jafarkhani(著),任品毅(译)空时编码的理论与实践[M]西安：西安交通大学出版社,2007.8,24-30
[8]Erik G. Larsson, Petre Stoica(著),任品毅(译) 无线通信中的空时分组编码[M]西安：西安交通大学出版社,2006.5,68-70
[9]Branka Vucetic, Jinhong Yuan(著),王小海等(译)空时编码技术[M]北京：机械工业出版社,2004.8,49-55
[10]Alamouti. S. M A Simple Transmit Diversity Technique for Wireless Communications [J].IEEE Journal on Selected Areas Communication, 1998,16(8):1451-1458.
[11]V. Tarokh, H. Jafarkhani, and A. R. Calderbank. Space-time block codes from orthogonal designs [J].IEEE Transactions on Information Theory,1999,45(5):1456-1467
[12]A. V. Oppenheim, R. W. Schafer, Discrete-Time Signal Processing [M] Prentice Hall:Englewood Cliffs, Oct,1989.
[13]Ben Jmaa Ahmed Bassem. A PAPR Reduction Method for STBC MIMO-OFDM Systems Using SLM in combination with Subband Permutation[C]. Guadeloupe: The Third International Conference on Wireless and Mobile Communications, 2007:84-88.
[14]M.T. Zhou, Latinovi'c, Y. Bar-Ness. STBC MIMO-OFDM Peak-to-Average Power Ratio Reduction by Cross-Antenna Rotation and Inversion [J].IEEE Communication Letters,2005,9(7):592-594.
[15]Jankiraman M. Space-Time codes and MIMO systems [M].Newyork:Artech House, Aug,2004.
[16]Y L Lee, Y.H. You, and W.G. Jeon. Peak-to-average power ratio in MIMO-OFDM systems using selective mapping [J].IEEE Communications Letters,2003, 7(12):575-577.
[17]Rihawi B, Louet, Y., and Zabre S. PAPR Reduction Scheme with SOCP for MIMO-OFDM Wireless Communications[C].Networking and Mobile Computing,2007 Wicom 2007 International Conference 2007:271-274
[18]Harish Reddy, Duman, T.M. Space-time coded OFDM with low PAPR[C].Global T elecommunications Conference,2003:799-803
[19]Ahirwar, V., Rajan, B.S. Low PAPR full-diversity space-frequency codes for MIMO-OFDM systems[C].Global Telecommunications Conference,2005:1476-1480
[20]Alok Aggarwal, Erik R. Stauffer, and Teresa H. Meng. Optimal Peak-to-Average Power Ratio Reduction in MIMO-OFDM Systems[C]. IEEE International Conference,2006:3094-3099
[21]Young-Jin Kim, Ui-Kun Kwon, Dae Young Seol. An Effective PAPR Reduction of SFBC-OFDM for Multinode Cooperative Transmission [J]. IEEE Signal Processing Letters,2009:925-928
[22]Yung-Chih Tsai, Shang-Kang Deng, Kuan-Cheng Chen, Mao-Chao Lin. Turbo Coded OFDM for Reducing PAPR and Error Rates [J]. IEEE Transactions on Wireless Communications,2008,7(1):84-89
[23]Lee, K.F.; Williams, D.B.A space-frequency transmitter diversity technique for OFDM systems[C].Global Telecommunications Conference,2000:1473-1477.
[24]G. J. Foschini, Layered Space-Time Architecture for Wireless Communication in a Fading Environment When Using Multi-Element Antennas [J].Bell Labs Tech, 1996, 1(2):41-59
[25]I E Telatar Capacity of multi-antenna Gaussian channels [J]. European Trans Telecomm,1999,10(6):585-595
[26]A. Naguib, N.Seshadri, and A.R. Calderbank. Applications of space-time block codes and interference suppression for high capacity and high data rate wireless systems [C].The Thirty-Second Asilomar Conference,1998:1803-1810
[27]G. J. Foschini and M. J. Gans, On Limits of Wireless Communications in Fading when Using Multiple Antennas [J].Wireless Pers. Communication,1998,6(3):311-315
[28]R.van Nee and R. Prasad. OFDM for Wireless Multimedia Communications [M] Newyork:Artech House, Oct,2000.
[29]Joo Hee Moon, Young-Hwan You; Won Gi Jeon. Peak-to-Average Power Control for Multiple-AntennaHIPERLAN/2 and IEEE802.11a Systems [J].IEEE Transactions on Consumer Electronics,2003,49(4):1078-1083
[30]M. Tan and Y. Bar-Ness, OFDM peak-to-average power ratio reduction by combined symbol rotation and inversion with limited complexity [C] IEEE Global Communications Conference,2003:605-610
[31]H. Rohling, T. May, K. Bruninghaus. Broad-band OFDM radio transmission for multimedia applications [J].Proceedings of the IEEE,1999,87(10):1778-1789
[32]D. Agrawal, V. Tarokh, A. Naguib, and N. Scshadri. Space-time coded OFDM for high data-rate wireless communication over wideband channels [C].IEEE Vehicular Technology Conference,1998:2232-2236
[33]D.W. Lim, S.J. Heo, and J.S. No A new PTS OFDM scheme with low complexity for PAPR reduction [J].IEEE Transactions on Broadcasting,2006,52(1):77-82.
[34]S. H. Han, J. H. Lee. An overview of peak-to-average power ratio reduction techniques for multi-carrier transmission [J].IEEE Wireless Communications,2005, 12(2):56-65
[35]A. J. Paulraj. An Overview of MIMO Communications—a Key to Gigabit Wireless [J].Proceedings of the IEEE,2004,92(2):198-218
[36]T.C.W. Schenk, P.F. M. Smulders, and E. R. Fledderus. The application of spatial shifting for peak-to-average power ratio reduction in MIMO-OFDM systems [C] IEEE Vehicular Technology Conference,2006:1859-1863
[37]Byung Moo Lee and Rui J. P. de Figueiredo Side Information Power Allocation for MIMO-OFDM PAPR Reduction by Selected Mapping [C] ICASSP 2007, 2007:361-364
[38]Chun ming Zhao, Robert J. Baxley, and G. Tong Zhou. Peak-to-Average Power Ratio and Power Efficiency Considerations in MIMO-OFDM Systems [J]. IEEE Communication Letters,2008,12(4):268-270
[39]M. S. Baek, M. J. Kim, Y. H. You, and H. K. Song. Semi-blind channel estimation and PAR reduction for MIMO-OFDM system with multiple antennas [J].IEEE Transactions on Broadcast,2004,50(4):414-424
[40]Heechoon Lee, Daniel N. Liu, Weijun Zhu and Michael P. Fitz. Peak Power Reduction Using a Unitary Rotation in Multiple Transmit Antennas [C].IEEE International Conference,2005:2407-2411
[41]G. R. Woo and D. L. Jones. Peak power reduction in MIMO OFDM via active channel extension [C].IEEE International Conference on Communications,2005: 2636-2639.
[42]M. Vu and A. Paulraj. Optimal linear precoders for MIMO wireless correlated channels with non-zero mean in space-time coded systems [J].IEEE Transactions on Signal Processing,2006,54(6):2318-2332
[43]Amila, Pradeep, Kumara T.G. PAR Reduction in Space-Time Coded OFDM via Modified Active Constellation Extension [C].Proceedings of the 2008 IEEE Conference on Innovative Technologiesin Intelligent Systems and Industrial Applications,2008:71-75
[44]A. D. S. Jayalath, C. R. N. Athaudage. Peak Power Reduction of Space-Time Coded OFDM Signals [C].IEEE Eighth International Symposium on Spread Spectrum Techniques and Applications,2004:797-801
[45]Zoran Latinovi', Yeheskel Bar-Ness. SFBC MIMO-OFDM Peak-to-Average Power Ratio Reduction by Poly-phase Interleaving and Inversion [J] IEEE Communications Letters,2006,10(4):266-268
[46]Hlaing Minn, Yinghui Li, Naofal Al-Dhahir. PAR-Constrained Training Signal Designs for MIMO OFDM Channel Estimation in the Presence of Frequency Offsets [J] IEEE Transactions on Wireless Communication,2008,7(8):2884-2889
[2]尹长川,罗涛,乐光新多载波宽带无线通信技术[M]北京：北京邮电大学出版社,2004.7,1-9
[3]罗涛,乐光新多天线无线通信原理与应用[M]北京：北京邮电大学出版社,2005.11,4-6
[4]黄韬,袁超伟等MIMO相关技术与应用[M]北京：机械工业出版社,2007.1,205-208
[5]佟学俭,罗涛.OFDM移动通信技术原理及应用[M].北京：人民邮电出版社,2003.6,5-9
[6]Arogyaswami Paulraj, Rohit Nabar, Dhananjay Gore(著),刘伟鑫(译)空时无线通信导论[M]北京：清华大学出版社,2007.12,5-8
[7]Hamid Jafarkhani(著),任品毅(译)空时编码的理论与实践[M]西安：西安交通大学出版社,2007.8,24-30
[8]Erik G. Larsson, Petre Stoica(著),任品毅(译) 无线通信中的空时分组编码[M]西安：西安交通大学出版社,2006.5,68-70
[9]Branka Vucetic, Jinhong Yuan(著),王小海等(译)空时编码技术[M]北京：机械工业出版社,2004.8,49-55
[10]Alamouti. S. M A Simple Transmit Diversity Technique for Wireless Communications [J].IEEE Journal on Selected Areas Communication, 1998,16(8):1451-1458.
[11]V. Tarokh, H. Jafarkhani, and A. R. Calderbank. Space-time block codes from orthogonal designs [J].IEEE Transactions on Information Theory,1999,45(5):1456-1467
[12]A. V. Oppenheim, R. W. Schafer, Discrete-Time Signal Processing [M] Prentice Hall:Englewood Cliffs, Oct,1989.
[13]Ben Jmaa Ahmed Bassem. A PAPR Reduction Method for STBC MIMO-OFDM Systems Using SLM in combination with Subband Permutation[C]. Guadeloupe: The Third International Conference on Wireless and Mobile Communications, 2007:84-88.
[14]M.T. Zhou, Latinovi'c, Y. Bar-Ness. STBC MIMO-OFDM Peak-to-Average Power Ratio Reduction by Cross-Antenna Rotation and Inversion [J].IEEE Communication Letters,2005,9(7):592-594.
[15]Jankiraman M. Space-Time codes and MIMO systems [M].Newyork:Artech House, Aug,2004.
[16]Y L Lee, Y.H. You, and W.G. Jeon. Peak-to-average power ratio in MIMO-OFDM systems using selective mapping [J].IEEE Communications Letters,2003, 7(12):575-577.
[17]Rihawi B, Louet, Y., and Zabre S. PAPR Reduction Scheme with SOCP for MIMO-OFDM Wireless Communications[C].Networking and Mobile Computing,2007 Wicom 2007 International Conference 2007:271-274
[18]Harish Reddy, Duman, T.M. Space-time coded OFDM with low PAPR[C].Global T elecommunications Conference,2003:799-803
[19]Ahirwar, V., Rajan, B.S. Low PAPR full-diversity space-frequency codes for MIMO-OFDM systems[C].Global Telecommunications Conference,2005:1476-1480
[20]Alok Aggarwal, Erik R. Stauffer, and Teresa H. Meng. Optimal Peak-to-Average Power Ratio Reduction in MIMO-OFDM Systems[C]. IEEE International Conference,2006:3094-3099
[21]Young-Jin Kim, Ui-Kun Kwon, Dae Young Seol. An Effective PAPR Reduction of SFBC-OFDM for Multinode Cooperative Transmission [J]. IEEE Signal Processing Letters,2009:925-928
[22]Yung-Chih Tsai, Shang-Kang Deng, Kuan-Cheng Chen, Mao-Chao Lin. Turbo Coded OFDM for Reducing PAPR and Error Rates [J]. IEEE Transactions on Wireless Communications,2008,7(1):84-89
[23]Lee, K.F.; Williams, D.B.A space-frequency transmitter diversity technique for OFDM systems[C].Global Telecommunications Conference,2000:1473-1477.
[24]G. J. Foschini, Layered Space-Time Architecture for Wireless Communication in a Fading Environment When Using Multi-Element Antennas [J].Bell Labs Tech, 1996, 1(2):41-59
[25]I E Telatar Capacity of multi-antenna Gaussian channels [J]. European Trans Telecomm,1999,10(6):585-595
[26]A. Naguib, N.Seshadri, and A.R. Calderbank. Applications of space-time block codes and interference suppression for high capacity and high data rate wireless systems [C].The Thirty-Second Asilomar Conference,1998:1803-1810
[27]G. J. Foschini and M. J. Gans, On Limits of Wireless Communications in Fading when Using Multiple Antennas [J].Wireless Pers. Communication,1998,6(3):311-315
[28]R.van Nee and R. Prasad. OFDM for Wireless Multimedia Communications [M] Newyork:Artech House, Oct,2000.
[29]Joo Hee Moon, Young-Hwan You; Won Gi Jeon. Peak-to-Average Power Control for Multiple-AntennaHIPERLAN/2 and IEEE802.11a Systems [J].IEEE Transactions on Consumer Electronics,2003,49(4):1078-1083
[30]M. Tan and Y. Bar-Ness, OFDM peak-to-average power ratio reduction by combined symbol rotation and inversion with limited complexity [C] IEEE Global Communications Conference,2003:605-610
[31]H. Rohling, T. May, K. Bruninghaus. Broad-band OFDM radio transmission for multimedia applications [J].Proceedings of the IEEE,1999,87(10):1778-1789
[32]D. Agrawal, V. Tarokh, A. Naguib, and N. Scshadri. Space-time coded OFDM for high data-rate wireless communication over wideband channels [C].IEEE Vehicular Technology Conference,1998:2232-2236
[33]D.W. Lim, S.J. Heo, and J.S. No A new PTS OFDM scheme with low complexity for PAPR reduction [J].IEEE Transactions on Broadcasting,2006,52(1):77-82.
[34]S. H. Han, J. H. Lee. An overview of peak-to-average power ratio reduction techniques for multi-carrier transmission [J].IEEE Wireless Communications,2005, 12(2):56-65
[35]A. J. Paulraj. An Overview of MIMO Communications—a Key to Gigabit Wireless [J].Proceedings of the IEEE,2004,92(2):198-218
[36]T.C.W. Schenk, P.F. M. Smulders, and E. R. Fledderus. The application of spatial shifting for peak-to-average power ratio reduction in MIMO-OFDM systems [C] IEEE Vehicular Technology Conference,2006:1859-1863
[37]Byung Moo Lee and Rui J. P. de Figueiredo Side Information Power Allocation for MIMO-OFDM PAPR Reduction by Selected Mapping [C] ICASSP 2007, 2007:361-364
[38]Chun ming Zhao, Robert J. Baxley, and G. Tong Zhou. Peak-to-Average Power Ratio and Power Efficiency Considerations in MIMO-OFDM Systems [J]. IEEE Communication Letters,2008,12(4):268-270
[39]M. S. Baek, M. J. Kim, Y. H. You, and H. K. Song. Semi-blind channel estimation and PAR reduction for MIMO-OFDM system with multiple antennas [J].IEEE Transactions on Broadcast,2004,50(4):414-424
[40]Heechoon Lee, Daniel N. Liu, Weijun Zhu and Michael P. Fitz. Peak Power Reduction Using a Unitary Rotation in Multiple Transmit Antennas [C].IEEE International Conference,2005:2407-2411
[41]G. R. Woo and D. L. Jones. Peak power reduction in MIMO OFDM via active channel extension [C].IEEE International Conference on Communications,2005: 2636-2639.
[42]M. Vu and A. Paulraj. Optimal linear precoders for MIMO wireless correlated channels with non-zero mean in space-time coded systems [J].IEEE Transactions on Signal Processing,2006,54(6):2318-2332
[43]Amila, Pradeep, Kumara T.G. PAR Reduction in Space-Time Coded OFDM via Modified Active Constellation Extension [C].Proceedings of the 2008 IEEE Conference on Innovative Technologiesin Intelligent Systems and Industrial Applications,2008:71-75
[44]A. D. S. Jayalath, C. R. N. Athaudage. Peak Power Reduction of Space-Time Coded OFDM Signals [C].IEEE Eighth International Symposium on Spread Spectrum Techniques and Applications,2004:797-801
[45]Zoran Latinovi', Yeheskel Bar-Ness. SFBC MIMO-OFDM Peak-to-Average Power Ratio Reduction by Poly-phase Interleaving and Inversion [J] IEEE Communications Letters,2006,10(4):266-268
[46]Hlaing Minn, Yinghui Li, Naofal Al-Dhahir. PAR-Constrained Training Signal Designs for MIMO OFDM Channel Estimation in the Presence of Frequency Offsets [J] IEEE Transactions on Wireless Communication,2008,7(8):2884-2889