摘要
A pilot pattern across two orthogonal frequency division multiplexing OFDM symbols with a special structure is designed for the channel estimation of OFDM systems with inphase and quadrature IQ imbalances at the receiver.A high-efficiency time-domain TD least square LS channel estimator and a low-complexity frequency-domain Gaussian elimination GE equalizer are proposed to eliminate IQ distortion.The former estimator can significantly suppress channel noise by a factor N/L＋1 over the existing frequency-domain FD LS where N and L＋1 are the total number of subcarriers and the length of cyclic prefix and the proposed GE requires only 2N complex multiplications per OFDM symbol.Simulation results show that by exploiting the TD property of the channel the proposed TD-LS channel estimator obtains a significant signal-to-noise ratio gain over the existing FD-LS one whereas the proposed low-complexity GE compensation achieves the same bit error rate BER performance as the existing LS one.
针对接收IQ不平衡的OFDM系统,设计了横跨2个OFDM符号的特殊训练结构.提出了一种高效的时域最小二乘(TD-LS)信道估计和一种低复杂度的频域高斯消元补偿算法来消除IQ失真.前者与传统的频域LS算法相比,信道估计噪声的影响降低了N/(L+1)倍,其中N为子载波总数,L+1为循环前缀长度;后者实现复杂度低,每个OFDM符号仅需要2N次复数乘法.仿真结果表明:由于充分挖掘了信道参数的时域特性,提出的TD-LS信道估计算法与传统的FD-LS算法相比获得了可观的信噪比增益;提出的低复杂度的GE补偿算法能够获得与基于LS的频域补偿方案几乎相同的误码性能.
基金
The Open Research Fund of National Mobile Communications Research Laboratory of Southeast University(No.2013D02)
the Fundamental Research Funds for the Central Universities(No.30920130122004)
the National Natural Science Foundation of China(No.61271230,61472190)
