Performance of the Adaptive Coding and Modulation(ACM) strongly depends on the retrieved Channel State Information(CSI),which can be obtained using the channel estimation techniques relying on pilot symbol transmissio...Performance of the Adaptive Coding and Modulation(ACM) strongly depends on the retrieved Channel State Information(CSI),which can be obtained using the channel estimation techniques relying on pilot symbol transmission.Earlier analysis of methods of pilot-aided channel estimation for ACM systems were relatively little.In this paper,we investigate the performance of CSI prediction using the Minimum Mean Square Error(MMSE)channel estimator for an ACM system.To solve the two problems of MMSE:high computational operations and oversimplified assumption,we then propose the Low-Complexity schemes(LC-MMSE and Recursion LC-MMSE(R-LC-MMSE)).Computational complexity and Mean Square Error(MSE) are presented to evaluate the efficiency of the proposed algorithm.Both analysis and numerical results show that LC-MMSE performs close to the wellknown MMSE estimator with much lower complexity and R-LC-MMSE improves the application of MMSE estimation to specific circumstances.展开更多
针对正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统中最小均方误差(Minimum Mean Squared Error,MMSE)信道估计算法误码率(BER)高的问题,提出一种平均最小均方误差(Averaged-Minimum Mean Squared Error,A-MMSE)...针对正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统中最小均方误差(Minimum Mean Squared Error,MMSE)信道估计算法误码率(BER)高的问题,提出一种平均最小均方误差(Averaged-Minimum Mean Squared Error,A-MMSE)信道估计算法。该算法首先基于802.11n标准而构造了一种新的导频结构,收发两端分别进行降采样和过采样处理,利用已知训练序列和导频获得信道频域响应。仿真结果表明,所提出的A-MMSE信道估计算法与传统的MMSE算法相比,在BER为10^(-3)时,信噪比改善了约8dB。因而所提出的信道估计算法能明显改善系统的BER性能。展开更多
The turbo equalization approach is studied for Orthogonal Frequency Division Multiplexing （OFDM） system with combined error control coding and linear precoding. While previous literatures employed linear precodcr of...The turbo equalization approach is studied for Orthogonal Frequency Division Multiplexing （OFDM） system with combined error control coding and linear precoding. While previous literatures employed linear precodcr of small size for complexity reasons, this paper proposes to use a linear precoder of size larger than or equal to the maximum length of the equivalent discrete-time channel in order to achieve full frequency diversity and reduce complexities of the error control coder/decoder. Also a low complexity Linear Minimum Mean Square Error （LMMSE） turbo equalizer is derived for the receiver. Through simulation and performance analysis, it is shown that the performance of the proposed scheme over frequency selective fading channel reaches the matched filter bound; compared with the same coded OFDM without linear precoding, the proposed scheme shows an Signal-to-Noise Ratio （SNR） improvement of at least 6dB at a bit error rate of 10 6 over a multipath channel with exponential power delay profile. Convergence behavior of the proposed scheme with turbo equalization using various type of linear precoder/transformer, various interleaver size and error control coder of various constraint length is also investigated.展开更多
针对现有的正交时频空(Orthogonal Time Frequency Space,OTFS)调制系统中最大比合并(Maximal Ratio Combining,MRC)均衡算法收敛速度慢、误码率高的问题,提出一种基于水声OTFS系统的分块线性最小均方误差的最大比合并(Maximal Ratio Co...针对现有的正交时频空(Orthogonal Time Frequency Space,OTFS)调制系统中最大比合并(Maximal Ratio Combining,MRC)均衡算法收敛速度慢、误码率高的问题,提出一种基于水声OTFS系统的分块线性最小均方误差的最大比合并(Maximal Ratio Combining Based on Block Linear Minimum Mean Square Error,BLMMSE-MRC)均衡算法。该算法基于水声信道的稀疏性,利用分块线性最小均方误差算法进行预处理,将输出结果作为MRC检测的初始估计值,然后在延迟多普勒空间中估计发射信号的多径分量,并利用MRC进行合并检测。实验结果表明,与已有零填充最大比合并算法(Maximal Ratio Combining Based on Zero Padding,ZP-MRC)和零填充块线性最小均方误差算法(Block Linear Minimum Mean Square Error Based on Zero Padding,ZP-BLMMSE)相比,所提算法能快速收敛,在10-4误码率条件下,信噪比提升了2 dB以上。展开更多
在采用多天线高阶QAM的MIMO通信系统中,现有基于信道分组并行检测算法虽然接近最优检测性能但以牺牲计算效率为代价.针对这一问题,本文提出一种MMSE准则下基于信道分组的并行检测算法,不但有效降低计算复杂度,而且仍保证检测性能.该算...在采用多天线高阶QAM的MIMO通信系统中,现有基于信道分组并行检测算法虽然接近最优检测性能但以牺牲计算效率为代价.针对这一问题,本文提出一种MMSE准则下基于信道分组的并行检测算法,不但有效降低计算复杂度,而且仍保证检测性能.该算法采用MMSE准则下格归约算法改进分组后条件较好子信道矩阵特性,并在消除参考信号基础上利用改进的子信道矩阵对剩余信号以非线性方式进行检测.仿真结果表明:对4@4和6@6MIMO系统,该算法检测性能达到最优,对于8@8 MIMO系统,比最优算法所需信噪比提高约1dB.复杂度分析表明:相比现有信道分组检测算法,相同检测性能下该算法在6@6 M IMO系统中复杂度降低90%以上,在8@8 MIMO系统中复杂度降低98%以上.展开更多
针对采用最小均方误差(minimum mean square error,MMSE)检测算法在MIMO系统接收端进行检测时,需要进行大量伪逆运算导致检测复杂度增加的问题,提出了用一种基于迭代QR分解的MMSE V-BLAST算法,避免了伪逆运算,有效地降低了检测算法的复...针对采用最小均方误差(minimum mean square error,MMSE)检测算法在MIMO系统接收端进行检测时,需要进行大量伪逆运算导致检测复杂度增加的问题,提出了用一种基于迭代QR分解的MMSE V-BLAST算法,避免了伪逆运算,有效地降低了检测算法的复杂度,使系统检测性能得到了明显改善.在多散射物无线通信环境下进行仿真实验,结果表明,与传统的算法相比,提案算法在保证相同信噪比,误码率没有显著变化的前提下,系统检测复杂度明显改善.理论分析证明,系统中有效天线数目越多,所提出的算法优越性越明显.展开更多
非线性码间干扰是影响卫星通信的重要因素之一,需要有效消除或降低这种影响。在用Volterra级数分解表示非线性信道基础上,提出了基于线性MMSE(Minimum Mean Square Error)的Turbo均衡算法,以解决非线性码间干扰问题。通过对基于线性MMSE...非线性码间干扰是影响卫星通信的重要因素之一,需要有效消除或降低这种影响。在用Volterra级数分解表示非线性信道基础上,提出了基于线性MMSE(Minimum Mean Square Error)的Turbo均衡算法,以解决非线性码间干扰问题。通过对基于线性MMSE的Turbo均衡算法作无先验信息和低复杂度的MMSE近似处理,在不降低均衡性能的前提下,既能同时消除线性和非线性干扰,又能大大降低计算复杂度。仿真验证了该算法的有效性。展开更多
基金supported by the 2011 China Aerospace Science and Technology Foundationthe Certain Ministry Foundation under Grant No.20212HK03010
文摘Performance of the Adaptive Coding and Modulation(ACM) strongly depends on the retrieved Channel State Information(CSI),which can be obtained using the channel estimation techniques relying on pilot symbol transmission.Earlier analysis of methods of pilot-aided channel estimation for ACM systems were relatively little.In this paper,we investigate the performance of CSI prediction using the Minimum Mean Square Error(MMSE)channel estimator for an ACM system.To solve the two problems of MMSE:high computational operations and oversimplified assumption,we then propose the Low-Complexity schemes(LC-MMSE and Recursion LC-MMSE(R-LC-MMSE)).Computational complexity and Mean Square Error(MSE) are presented to evaluate the efficiency of the proposed algorithm.Both analysis and numerical results show that LC-MMSE performs close to the wellknown MMSE estimator with much lower complexity and R-LC-MMSE improves the application of MMSE estimation to specific circumstances.
文摘针对正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统中最小均方误差(Minimum Mean Squared Error,MMSE)信道估计算法误码率(BER)高的问题,提出一种平均最小均方误差(Averaged-Minimum Mean Squared Error,A-MMSE)信道估计算法。该算法首先基于802.11n标准而构造了一种新的导频结构,收发两端分别进行降采样和过采样处理,利用已知训练序列和导频获得信道频域响应。仿真结果表明,所提出的A-MMSE信道估计算法与传统的MMSE算法相比,在BER为10^(-3)时,信噪比改善了约8dB。因而所提出的信道估计算法能明显改善系统的BER性能。
基金Supported by the National High Technology ResearchDevelopment Program of China (863 Program)(No.2001AA 123014)
文摘The turbo equalization approach is studied for Orthogonal Frequency Division Multiplexing （OFDM） system with combined error control coding and linear precoding. While previous literatures employed linear precodcr of small size for complexity reasons, this paper proposes to use a linear precoder of size larger than or equal to the maximum length of the equivalent discrete-time channel in order to achieve full frequency diversity and reduce complexities of the error control coder/decoder. Also a low complexity Linear Minimum Mean Square Error （LMMSE） turbo equalizer is derived for the receiver. Through simulation and performance analysis, it is shown that the performance of the proposed scheme over frequency selective fading channel reaches the matched filter bound; compared with the same coded OFDM without linear precoding, the proposed scheme shows an Signal-to-Noise Ratio （SNR） improvement of at least 6dB at a bit error rate of 10 6 over a multipath channel with exponential power delay profile. Convergence behavior of the proposed scheme with turbo equalization using various type of linear precoder/transformer, various interleaver size and error control coder of various constraint length is also investigated.
文摘针对现有的正交时频空(Orthogonal Time Frequency Space,OTFS)调制系统中最大比合并(Maximal Ratio Combining,MRC)均衡算法收敛速度慢、误码率高的问题,提出一种基于水声OTFS系统的分块线性最小均方误差的最大比合并(Maximal Ratio Combining Based on Block Linear Minimum Mean Square Error,BLMMSE-MRC)均衡算法。该算法基于水声信道的稀疏性,利用分块线性最小均方误差算法进行预处理,将输出结果作为MRC检测的初始估计值,然后在延迟多普勒空间中估计发射信号的多径分量,并利用MRC进行合并检测。实验结果表明,与已有零填充最大比合并算法(Maximal Ratio Combining Based on Zero Padding,ZP-MRC)和零填充块线性最小均方误差算法(Block Linear Minimum Mean Square Error Based on Zero Padding,ZP-BLMMSE)相比,所提算法能快速收敛,在10-4误码率条件下,信噪比提升了2 dB以上。
文摘在采用多天线高阶QAM的MIMO通信系统中,现有基于信道分组并行检测算法虽然接近最优检测性能但以牺牲计算效率为代价.针对这一问题,本文提出一种MMSE准则下基于信道分组的并行检测算法,不但有效降低计算复杂度,而且仍保证检测性能.该算法采用MMSE准则下格归约算法改进分组后条件较好子信道矩阵特性,并在消除参考信号基础上利用改进的子信道矩阵对剩余信号以非线性方式进行检测.仿真结果表明:对4@4和6@6MIMO系统,该算法检测性能达到最优,对于8@8 MIMO系统,比最优算法所需信噪比提高约1dB.复杂度分析表明:相比现有信道分组检测算法,相同检测性能下该算法在6@6 M IMO系统中复杂度降低90%以上,在8@8 MIMO系统中复杂度降低98%以上.
文摘针对采用最小均方误差(minimum mean square error,MMSE)检测算法在MIMO系统接收端进行检测时,需要进行大量伪逆运算导致检测复杂度增加的问题,提出了用一种基于迭代QR分解的MMSE V-BLAST算法,避免了伪逆运算,有效地降低了检测算法的复杂度,使系统检测性能得到了明显改善.在多散射物无线通信环境下进行仿真实验,结果表明,与传统的算法相比,提案算法在保证相同信噪比,误码率没有显著变化的前提下,系统检测复杂度明显改善.理论分析证明,系统中有效天线数目越多,所提出的算法优越性越明显.
文摘非线性码间干扰是影响卫星通信的重要因素之一,需要有效消除或降低这种影响。在用Volterra级数分解表示非线性信道基础上,提出了基于线性MMSE(Minimum Mean Square Error)的Turbo均衡算法,以解决非线性码间干扰问题。通过对基于线性MMSE的Turbo均衡算法作无先验信息和低复杂度的MMSE近似处理,在不降低均衡性能的前提下,既能同时消除线性和非线性干扰,又能大大降低计算复杂度。仿真验证了该算法的有效性。
