MC-CDMA信号的类型识别及参数盲估计
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摘要
针对MC-CDMA信号符号周期、有用数据周期、码片持续时间以及保护间隔长度等参数盲估计问题,该文提出一种改进型的循环自相关算法。首先在接收端对MC-CDMA信号求自相关函数,取傅氏变换,再在频域累积,通过检测不同切片上的谱峰间隔,可以同时估计以上多个参数。此外,根据MC-CDMA信号自身特点,提出一种新的估计符号周期方法—累加平均法,将3维图中平行于延时轴的每列谱线累加平均(间隔为符号周期),可估计出符号周期。理论推导了MC-CDMA信号的循环自相关表达式,证明加循环前缀的MC-CDMA信号具有循环平稳性。仿真实验证明了改进型的频域累积循环自相关算法的有效性,且适用于低信噪比环境。
The modified cyclic autocorrelation algorithm is proposed to estimate problems of the useful data period, entire symbol period, chip duration, and guard interval length in MC-CDMA signal. Firstly, the autocorrelation function of the received MC-CDMA signal is computed. Then, Fourier transformation and accumulation in frequency-domain are used. Finally, through detecting the interval of the peak pulses in different slices, parameters mentioned above can be estimated. In addition, a new method of estimating symbol period, the accumulative average method, is developed. By averaging amplitudes of the spectral lines in each column parallel to the delay axis, the symbol duration can be obtained. Cyclic autocorrelation expression of the MC-CDMA signal is derived theoretically, and it is proved that MC-CDMA signal with cyclic prefix has cyclostationary. The simulation results show that, the improved cyclic autocorrelation algorithm is effective in the low signal-to-noise cause.
The modified cyclic autocorrelation algorithm is proposed to estimate problems of the useful data period, entire symbol period, chip duration, and guard interval length in MC-CDMA signal. Firstly, the autocorrelation function of the received MC-CDMA signal is computed. Then, Fourier transformation and accumulation in frequency-domain are used. Finally, through detecting the interval of the peak pulses in different slices, parameters mentioned above can be estimated. In addition, a new method of estimating symbol period, the accumulative average method, is developed. By averaging amplitudes of the spectral lines in each column parallel to the delay axis, the symbol duration can be obtained. Cyclic autocorrelation expression of the MC-CDMA signal is derived theoretically, and it is proved that MC-CDMA signal with cyclic prefix has cyclostationary. The simulation results show that, the improved cyclic autocorrelation algorithm is effective in the low signal-to-noise cause.
引文
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[2]刘剑飞,石慧敏,曾详烨,等.基于小波降噪和改进ISFA的CO-OFDM信道估计方法[J].中国激光,2015,42(12):137-143.doi:10.3788/cjl201542.1205002.LIU Jianfei,SHI Huimin,ZENG Xiangye,et al.Channel estimation method based on wavelet and improved ISFA for CO-OFDM systems[J].Chinese Journal of Lasers,2015,42(12):137-143.doi:10.3788/cjl201542.1205002.
[3]钱文瑞.MC-CDMA及MC-DS-CDMA信号的参数估计[D].[硕士论文],重庆邮电大学,2016:10-20.doi:d-10617-308-(2016)-01115.QIAN W R.Parameter estimation of MC-CDMA and MC-DS-CDMA signals[D].[Master.dissertation],Chongqing University of Posts and Telecommunications,2016:10-20.doi:d-10617-308-(2016)-01115.
[4]黄敏,李兵兵.基于整体最小二乘的联合信道估计及OFDM信号检测算法[J].电子与信息学报,2014,36(6):1448-1453.doi:10.3724/sp.j.1146.2013.01327.HUANG Min and Li Bingbing.Joint channel estimation and OFDM signals detection based on total least square[J].Journal of Electronics&Information Technology,2014,36(6):1448-1453.doi:10.3724/sp.j.1146.2013.01327.
[5]张琳园,杨维.框井巷道时频编码协作MC-CDMA信道估计[J].煤炭学报,2015,40(2):481-486.doi:10.13225/j.cnki.jccs.2014.0361.ZHANG Linyuan and YANG Wei.Channel estimation of time-frequency coded cooperation MC-CDMA in mine tunnel[J].Journal of China Coal Society,2015,40(2):481-486.doi:10.13225/j.cnki.jccs.2014.0361.
[6]ZHANG Hua,LI Ye,and YI Yuanwu.Practical considerations on channel estimation for uplink MC-CDMAsystems[J].IEEE Transactions on Wireless Communications,2008,7(11):4384-4392.doi:10.1109/t-wc.2008.070761.
[7]ZABINI F,MASINI B M,CONTI A,et al.Partial equalization for MC-CDMA systems in non-ideally estimated correlated fading[J].IEEE Transactions on Vehicular Technology,2010,59(8):3818-3830.doi:10.1109/tvt.2010.2060217.
[8]ELMAHDY A E.Error probability analysis of multicarrier direct sequence code division multiple access system under imperfect channel estimation and jamming in a Rayleigh fading channel[J].IET Signal Processing,2010,4(1):89-101.doi:10.1049/iet-spr.2009.0038.
[9]钟兆根,张立民,林洪文,等.基于SMC的STBC-MC-CDMA信号扩频码及信息序列盲估计[J].电子学报,2016,44(5):1025-1031.doi:10.3969/j.issn.0372-2112.2016.05.003.ZHONG Zhaogen,ZHANG Limin,LIN Hongwen,et al.Blind estimation of spreading codes and information sequences for STBC-MC-CDMA signals based on SMC[J].Acta Electronica Sinica,2016,44(5):1025-1031.doi:10.3969/j.issn.0372-2112.2016.05.003.
[10]裴光盅,张天骐,高超,等.基于循环稳定特性的空时分组码MC-CDMA信号盲识别算法[J].系统工程与电子技术,2015,37(7):1650-1657.doi:10.3969/j.issn.1001-506x.2015.07.28.BUI Quangchung,ZHANG Tianqi,GAO Chao,et al.Blind recognition for STBC MC-CDMA signal based on cyclic stability[J].Systems Engineering and Electronics,2015,37(7):1650-1657.doi:10.3969/j.issn.1001-506x.2015.07.28.
[11]TSENG S and LEHNERT J S.LMSE-based parameter acquisition for multicarrier CDMA systems[J].IEEETransactions on Communications,2009,57(10):3113-3122.doi:10.1109/tcomm.2009.10.070265.
[12]DOBRE O A,PUNCHIHEWA A,RAJAN S,et al.On the cyclostationarity of OFDM and single carrier linearly digitally modulated signals in time dispersive channels:Theoretical developments and application[J].IEEETransactions on Wireless Communications,2008,9(8):2588-2599.doi:10.1109/twc.2010.061510.091080.
[13]ALHABASHBA A,DOBRE O A,VEDKATESAN R,et al.Second-order cyclostationarity of mobile Wi MAX and LTEOFDM signals and application to spectrum awareness in cognitive radio systems[J].IEEE Journal of Selected Topics in Signal Processing,2012,6(1):26-42.doi:10.1109/jstsp.2011.2174773.
[14]张海川,雷迎科.短循环前缀OFDM信号参数估计方法研究[J].信号处理,2016,32(12):1489-1496.doi:10.16798/j.issn.1003-0530.2016.12.014.ZHANG Haichuan and LEI Yingke.Study on parameter estimation for the short length cyclic prefix OFDM signal[J].Journal of Signal Processing,2016,32(12):1489-1496.doi:10.16798/j.issn.1003-0530.2016.12.014.
[15]LI H,BARNESS Y,ABDI A,et al.OFDM modulation classification and parameters extraction[C].International Conference on Cognitive Radio Oriented Wireless Networks&Communications,Shanghai,China,2006:1-6.doi:10.1109/crowncom.2006.363474.
[16]TANG N,LI B,LIU M,et al.A modified blind OFDMsystems parameters estimation method[C].IEEEInternational Conference on Communication Technology,Nanjing,China,2010:1279-1282.doi:10.1109/icct.2010.5689082.