室内伪卫星载波多径误差抑制方法研究

Carrier multipath error mitigation method for the indoor pseudolite system

为提升伪卫星在室内多径环境中的定位精度,根据室内伪卫星载波多径的时空变化特征建立了一种基于用户空间位置的多径误差改正模型。首先提取静态采样点的载波双差多径误差值,以采样点的三维坐标为输入、多径误差为输出,采用基于径向基核函数的支持向量回归进行误差模型训练,并借助留一法交叉验证获得模型的最优超参数。在该模型基础上,通过迭代不断修正载波双差观测方程,使得位置解能够最大程度地逼近真实坐标,从而达到抑制多径的目的。强多径室内环境下静态相对定位实验表明,多径改正后的整体平面定位精度提升到厘米-分米级,垂直精度提升到1 m以内。该方法无需对系统进行改造,适用于结构化室内环境中的伪卫星高精度定位。

To improve pseudolite positioning accuracy in the indoor multipath-contaminated environment,a multipath error correction model based on the user space position is formulated,which utilizes the spatio-temporal variation characteristics of indoor pseudolite carrier multipath.To be specific,the double-differenced carrier multipath errors of the static sampling points are extracted,and the three-dimensional coordinates of these points are taken as the input and the multipath error as the output.The error model is trained by the support vector regression based on the radial basis kernel function,and the optimal hyperparameters of the model are achieved by the leave-one-out cross-validation method.On the basis of this model,the double-differenced carrier observation equations are modified continuously through iteration.The position solutions can approximate the real coordinates to the greatest extent.Thus,the multipath is mitigated.The static relative positioning experiments in the strong-multipath-contaminated indoor environment show that the overall horizontal positioning accuracy after multipath correction is improved to the centimeter-decimeter level.The vertical accuracy within 1 m.This method can be implemented without system transformation,which is suitable for pseudolite high-precision positioning in the structured indoor environments.