基于改进二维 MUSIC 算法的蓝牙信号到达角估计

蓝牙技术联盟在蓝牙 5. 1 规范引入寻向功能,为大幅提升蓝牙定位技术的精度提供了新的解决途径,但并未对信号的 角度测量算法提供统一方案。 针对低功耗蓝牙在室内环境多径干扰下到达角估计困难这一问题,提出了一种面向矩形阵列的 改进二维 MUSIC 算法,通过对矩形阵列天线阵元进行二次划分,采用前后向平滑的方法修正一维子阵的协方差矩阵,再利用接 收信号矩阵的广义逆求出各个子阵协方差的关系,从而修正整个阵列接收信号的协方差矩阵。 该算法在没有降低信号协方差 矩阵维数的同时,恢复了信号协方差矩阵的秩,有效抑制室内多径信源引起的干扰。 经过仿真实验,证明了本文算法在低快拍 数、低信噪比的情况下对角度估计的精度有着较大改善。 并设计了相应的硬件系统进行室内与室外的实验,结果表明在多径干 扰严重的室内定位时定位精度改善更为明显,室内定位圆概率误差降低了 26. 75% ~ 60. 25%。 仿真和现场定位实验证明了本 文提出角度估计算法的有效性,该算法对其他应用领域的来波方向估计也具有重要参考意义。

Estimation of arrival angle of Bluetooth signals based on improved 2D-MUSIC algorithm

The Bluetooth SIG announced support for angle of arrival ( AoA) and angle of departure ( AoD) in the Bluetooth 5. 1 specification, which provides a new solution to greatly improve the precision of Bluetooth positioning. However, the Bluetooth 5. 1 does not provide a unified algorithm for angle calculation. An improved two-dimensional MUSIC algorithm based on rectangular array was proposed to solve the problems of angle calculation caused by serious multipath interference in indoor environment. The antenna array is divided twice, and the covariance matrix of one-dimensional subarray is corrected by the method of forward and backward smoothing, and the covariance matrix of the whole array is corrected by the generalized inverse of the received signals matrix. This algorithm restores the rank of the signals covariance matrix without reducing the dimension of the signals covariance matrix, interference caused by indoor multipath sources can be effectively suppressed. Through the simulation experiment, it is proved that the proposed algorithm can greatly improve the accuracy of angle estimation under the condition of low fast beat number and low SNR. Positioning system is designed for indoor and outdoor experiments. The results show that the improvement of location accuracy is more obvious in indoor location. The circular probability error of stationary location is reduced by 26. 75% ~ 60. 25% in the indoor environment. Simulation and indoor positioning experiments show the effectiveness of the angle estimation algorithm proposed in this paper, this algorithm also has important reference significance for direction of arrival estimation in other application fields.