To eliminate effect brought from the noise in underwater OFDM system for sparse multi-path channel estimation, iterative least square adaptive channel estimation method based on threshold detection is proposed. According to least-square criterion, error squares are weighted and summed by introducing weighted factor and a iterative equation is derived to execute adaptive channel estimation. The computation complexity of iterative equation is low and it can not bring out big matrix calculation. Based on the solution of LS estimation, the most significant paths of channel are detected using predetermined threshold and the non-significant paths of time channel impulse response are set zero, reducing the effect of noise for channel estimation and increasing estimation precision. At the end, the effect of variant training symbol lengths for MSE performance is discussed, at the same time, the performance simulation of the proposed method is implemented on condition that the training symbol length, threshold, and so on are prescribed and the simulation result is analyzed.%为了消除水声OFDM系统中噪声对稀疏多径信道估计的影响,提出了基于阈值探测的迭代最小二乘自适应信道估计方法.该方法根据最小方差准则引入加权因子对误差平方进行加权求和,由此导出一个迭代方程进行自适应信道估计.该迭代方程具有计算复杂度低的优点,不会带来大的矩阵运算.在该方法基础上,提出基于阈值探测的稀疏信道估计方法,探测最有效信道抽头,消除噪声干扰的影响.最后讨论了不同训练符号长度对MSE性能的影响,给出了在一定训练符号长度、阈值等参数条件下改进算法的性能仿真,并对仿真结果进行了分析.
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