OFDM-WLAN系统互相关超分辨TOA估计

在正交频分复用无线局域网系统的室内场景下,针对单快拍多重信号分类的超分辨到达时间估计由于多径数估计不准确导致的到达时间估计误差偏大的问题,提出了一种未知多径数的互相关超分辨到达时间估计算法。该算法根据正交频分复用无线局域网系统的物理层协议数据单元的特点,考虑到前导码中相邻两个长正交频分复用符号的信道不变性和噪声的不相关性,首先利用两个长正交频分复用符号估计两组信道频域响应,然后,采用前后向频域平滑的方法,求两组信道频域响应的互相关矩阵,进而用所求互相关矩阵逆的高次幂近似噪声特征矩阵的乘积,最后构造伪谱函数并进行谱峰搜索,从而实现到达时间的估计。仿真结果表明,该算法估计精度高,且对噪声不敏感,具有较好的鲁棒性。

Super-Resolution TOA Estimation based on Co-Correlation for OFDM-WLAN

In the indoor WLAN(Wireless Local Area Networks) using DFDM(Orthogonal Frequency Division Multiplexing),TOA(Time of Arrival) can be estimated via MUSIC(Multiple Signal Classification) algorithm based on a single snapshot data, and aiming at the big estimation errors resulted from the incorrect estimation of multipath number, a super-resolution TOA algorithm based on co-correlation under the condition of unknown number of multipath is proposed. This algorithm makes full use of the properties of physical layer protocol data unit in OFDM-WLAN system. The invariance property of channels and the uncorrelated property of random noise are taken into consideration between two OFDM symbols in preamble. First of all, two sets of channel response in frequency domain are estimated by using two long OFDM symbols. Then, cross-correlation matrix of two sets of channel response in frequency domain is estimated by using forward and backward frequency smooths. And the inverse of cross-correlation matrix high frequency power is similar to the product of two matrices composed of noise eigenvectors. Finally, the pseudo-spectral function is constructed and used to search spectrum peak, thus to realize the estimation of TOA. Simulation results show that the proposed algorithm , with high estimation precision, and being insensitive to noise, is of good robustness.