基于自适应MEDLL的伪卫星室内多径估计算法

Indoor pseudolite multipath estimation algorithm based on adaptive MEDLL

在室内环境下,室内伪卫星定位系统受多径效应影响严重。针对该问题,提出一种基于自适应多径估计延迟锁定环路(multipath estimating delay lock loop,MEDLL)的伪卫星室内多径估计算法。该算法在MEDLL的基础上增加了一个参考相关器,用参考相关器相关值的标准差作为衡量标准,与其他相关器经过MEDLL算法消除所有信号后的噪声相关值的标准差进行比较,进而得到多径条数。实验结果表明,所提算法对不同时延、幅值的多径适应性都较好,在低信噪比条件下仍能正确估计多径条数。直射信号幅值估计误差均方根相比网格化MEDLL算法最高可以降低59%,相比Teager-Kaiser(TK)-MEDLL算法最高可以降低43%,更加适用于伪卫星室内定位系统抗多径。

In the indoor environment,the indoor pseudolite positioning system is seriously affected by multipath effect.To solve this problem,an indoor pseudolite multipath estimation algorithm based on adaptive multipath estimating delay lock loop(MEDLL)is proposed.In this algorithm,a reference correlator is added based on the MEDLL,whose output is used as a benchmark,and the noise correlation values of other correlators are compared with the output values of the reference correlator after all signal influence is eliminated by MEDLL,so as to obtain the accurate estimation of the number of multipath signals.Experiments’result show that the proposed algorithm has good adaptability to multipath with different delay and amplitude,and can still estimate the number of multipath correctly under low signal to noise ratio.The root mean square of direct signal amplitude estimation error can be reduced by 59%compared with the grid MEDLL algorithm and 43%compared with Teager-Kaiser(TK)-MEDLL algorithm,proving that it is more suitable for indoor pseudolite positioning system to anti-multipath.