In the channel estimation algorithm of MIMOOFDM system, the least squares method (LS) based on frequency domain,has the very low implementation complexity under the guarantee of certain error performance,but its error performance isn't best After comparing many pilot-symbol assisted algorithms,we designed a new pilot structure embarked from arbitrary receiving antenna, which can improve the channel estimation performance and reduce the compute complexity. In the new pilot structure, the sequences of pilot phase are mutually orthogonal and evenly distributed. In addition,being different from the existing result that the pilot matrix adopts the shape of real part and imaginary u-nit, the element of the proposed pilot matrix in this paper is real number or purely imaginary number so as to reduce the compute complexity effectively. The theoretical derivation proves that the proposed structure is the best pilot and has the minimum mean square error (MSE). The simulation results show that the proposed algorithm is better than the traditional method of least squares in mean square error, which is more obvious with the increase of signal to noise ratio (SNR). The proposed algorithm has the very low system error rate (SER) than the traditional least-square, and much better performance with increasing the number of sub-carriers in the case of big SNR.%在MIMO-OFDM系统信道估计算法中,基于频域的最小二乘法在保证一定误差性能的条件下具有较低的系统实现复杂度,但其误差性能并非最佳.在比较多种导频辅助算法后,从接收端任意天线出发,设计了一种改善信道估计性能、减小算法复杂度的新导频结构.该导频序列中相位是相互正交且均匀分布的.而且与已有研究结果中导频矩阵设计采用实部加虚部的形式不同,文中的导频矩阵元素为实数或纯虚数,从而可以有效减小运算的复杂度.理论推导证明,新提出的导频结构是最佳的,均方误差最小.仿真结果显示,新提出的算法在不增加复杂度的基础上,具有比传统的最小二乘法更小的均方误差,并随着信噪比的增大越加明显;该算法比传统的最小二乘法系统误符号率小很多;随着子载波数的增加,在大信噪比的情况下,新提出的算法性能更为优越.
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