A new sparse channel estimation method of orthogonal frequency division multiplexing（OFDM） system based on intercarrier interference（ICI） self-cancellation is investigated. Firstly,based on the characteristic that...A new sparse channel estimation method of orthogonal frequency division multiplexing（OFDM） system based on intercarrier interference（ICI） self-cancellation is investigated. Firstly,based on the characteristic that the ICI generated by a subcarrier to the two adjacent subcarriers is approximately equal, a data pair with opposite sign and equal magnitude is modulated onto two adjacent subcarriers as pilot pair to eliminate the effect of ICI on pilots. Secondly, a new OFDM channel estimation model based on linear time-varying（LTV） model and compressed sensing（CS） is constructed, which obtains the mean of the gains of the multipath.Finally, a pilot pair optimization algorithm based on two layers loop is used to realize the minimization of the mutual coherence of the measurement matrix. For time-varying channel scenes with different numbers or delay of multipath and maximum Doppler frequency shift, the performances of several channel estimation methods are verified by simulation. The result shows that the new method has obvious advantage in both the performance of the channel estimation and the spectral efficiency.展开更多
在基于分段线性模型的正交频分复用(orthogonal frequency division multiplexing,OFDM)时变信道估计中,存在模型参数估计精度受到载波间干扰(inter-carrier interference,ICI)影响的问题。为此,本文采用ICI自消除技术,抑制了导频子载波...在基于分段线性模型的正交频分复用(orthogonal frequency division multiplexing,OFDM)时变信道估计中,存在模型参数估计精度受到载波间干扰(inter-carrier interference,ICI)影响的问题。为此,本文采用ICI自消除技术,抑制了导频子载波的ICI,改善了模型参数的估计性能。此外,还推导了单抽头Jakes信道条件下模型参数估计均方误差的表达式,理论分析表明,与基本的分段线性模型方法相比,本文方法可以使均方误差下降约13dB。仿真结果验证了在多抽头信道和大的多普勒扩展条件下,本文方法也能明显提高ICI抑制能力,从而得到更好的系统误码性能。展开更多
针对正交频分复用(OFDM)系统中由频率偏移引起的子载波间干扰(ICI)的问题,提出了一种基于对称子载波的ICI自消除算法。该算法将互为相反数的发送符号映射到对称的子载波上,并在接收端将解调信号进行线性组合。为了进一步降低ICI,将基于...针对正交频分复用(OFDM)系统中由频率偏移引起的子载波间干扰(ICI)的问题,提出了一种基于对称子载波的ICI自消除算法。该算法将互为相反数的发送符号映射到对称的子载波上,并在接收端将解调信号进行线性组合。为了进一步降低ICI,将基于对称子载波的ICI自消除算法与时域加窗相结合,即在发送数据符号之前,与升余弦函数相乘。对算法进行仿真实验,相对于相邻符号自消除算法,该算法减小了子载波间的干扰系数;加窗后OFDM符号频谱的边瓣衰减速度快,最大可衰减至-40 d B;对于系统的信号干扰比性能(SIR),加窗后的算法同相邻符号自消除算法相比可提高8 d B左右;在信噪比较大的情况下,改善了系统的误码率。仿真结果表明,所提算法能够抑制ICI,提高系统抗干扰性能。展开更多
针对采用GFDM(Generalized Frequency Division Multiplex)多载波调制的移动通信系统中,非正交性引起的ICI(Inter Carrier Interference)、OOBE(Out of Band Emission)问题,以及在衰落信道条件下存在的时域、频域选择性衰落问题,提出了...针对采用GFDM(Generalized Frequency Division Multiplex)多载波调制的移动通信系统中,非正交性引起的ICI(Inter Carrier Interference)、OOBE(Out of Band Emission)问题,以及在衰落信道条件下存在的时域、频域选择性衰落问题,提出了根据干扰信号能量预估值来调整原型滤波器参数以降低干扰的方法.在此基础上,采用结合了压缩感知的低复杂度预编码算法,在降低计算复杂度的同时能进一步提高频谱效率.使用Matlab软件搭建模型验证上述方法,仿真结果表明,采用上述降低干扰的方法可以将GFDM系统BER(Bit Error Rate)控制在较低水平.展开更多
基金supported by the National Natural Science Foundation of China(61571368)
文摘A new sparse channel estimation method of orthogonal frequency division multiplexing（OFDM） system based on intercarrier interference（ICI） self-cancellation is investigated. Firstly,based on the characteristic that the ICI generated by a subcarrier to the two adjacent subcarriers is approximately equal, a data pair with opposite sign and equal magnitude is modulated onto two adjacent subcarriers as pilot pair to eliminate the effect of ICI on pilots. Secondly, a new OFDM channel estimation model based on linear time-varying（LTV） model and compressed sensing（CS） is constructed, which obtains the mean of the gains of the multipath.Finally, a pilot pair optimization algorithm based on two layers loop is used to realize the minimization of the mutual coherence of the measurement matrix. For time-varying channel scenes with different numbers or delay of multipath and maximum Doppler frequency shift, the performances of several channel estimation methods are verified by simulation. The result shows that the new method has obvious advantage in both the performance of the channel estimation and the spectral efficiency.
文摘在基于分段线性模型的正交频分复用(orthogonal frequency division multiplexing,OFDM)时变信道估计中,存在模型参数估计精度受到载波间干扰(inter-carrier interference,ICI)影响的问题。为此,本文采用ICI自消除技术,抑制了导频子载波的ICI,改善了模型参数的估计性能。此外,还推导了单抽头Jakes信道条件下模型参数估计均方误差的表达式,理论分析表明,与基本的分段线性模型方法相比,本文方法可以使均方误差下降约13dB。仿真结果验证了在多抽头信道和大的多普勒扩展条件下,本文方法也能明显提高ICI抑制能力,从而得到更好的系统误码性能。
文摘针对正交频分复用(OFDM)系统中由频率偏移引起的子载波间干扰(ICI)的问题,提出了一种基于对称子载波的ICI自消除算法。该算法将互为相反数的发送符号映射到对称的子载波上,并在接收端将解调信号进行线性组合。为了进一步降低ICI,将基于对称子载波的ICI自消除算法与时域加窗相结合,即在发送数据符号之前,与升余弦函数相乘。对算法进行仿真实验,相对于相邻符号自消除算法,该算法减小了子载波间的干扰系数;加窗后OFDM符号频谱的边瓣衰减速度快,最大可衰减至-40 d B;对于系统的信号干扰比性能(SIR),加窗后的算法同相邻符号自消除算法相比可提高8 d B左右;在信噪比较大的情况下,改善了系统的误码率。仿真结果表明,所提算法能够抑制ICI,提高系统抗干扰性能。
文摘针对采用GFDM(Generalized Frequency Division Multiplex)多载波调制的移动通信系统中,非正交性引起的ICI(Inter Carrier Interference)、OOBE(Out of Band Emission)问题,以及在衰落信道条件下存在的时域、频域选择性衰落问题,提出了根据干扰信号能量预估值来调整原型滤波器参数以降低干扰的方法.在此基础上,采用结合了压缩感知的低复杂度预编码算法,在降低计算复杂度的同时能进一步提高频谱效率.使用Matlab软件搭建模型验证上述方法,仿真结果表明,采用上述降低干扰的方法可以将GFDM系统BER(Bit Error Rate)控制在较低水平.
