Location fingerprinting is a technique employed when Global Positioning System (GPS) positioning breaks down within indoor environments. Since Location Service Providers (LSPs) would implicitly have access to such information, preserving user privacy has become a challenging issue in location estimation systems. This paper proposes a low-complexity k-anonymity approach for preserving the privacy of user location and trajectory, in which real location/trajectory data is hidden within k fake locations/trajectories held by the LSP, without degrading overall localization accuracy. To this end, three novel location privacy preserving methods and a trajectory privacy preserving algorithm are outlined. The fake trajectories are generated so as to exhibit characteristics of the user’s real trajectory. In the proposed method, no initial knowledge of the environment or location of the Access Points (APs) is required in order for the user to generate the fake location/trajectory. Moreover, the LSP is able to preserve privacy of the fingerprinting database from the users. The proposed approaches are evaluated in both simulation and experimental testing, with the proposed methods outperforming other well-known k-anonymity methods. The method further exhibits a lower implementation complexity and higher movement similarity (of up to 88%) between the real and fake trajectories.

当全球定位系统（GPS）定位在室内环境中发生故障时，使用定位指纹技术。由于位置服务提供商（LSP）将隐式访问此类信息，因此在位置估计系统中，保护用户隐私已成为一个具有挑战性的问题。本文提出了一种低复杂度的k-匿名方法来保护用户位置和轨迹的隐私，其中真实位置/轨迹数据隐藏在k中LSP保留的虚假位置/轨迹，而不会降低整体定位精度。为此，概述了三种新颖的位置隐私保护方法和轨迹隐私保护算法。生成伪轨迹以展现用户真实轨迹的特征。在所提出的方法中，不需要环境或接入点（AP）的位置的初始知识即可使用户生成伪造的位置/轨迹。而且，LSP能够保护指纹数据库对用户的隐私。在仿真和实验测试中对所提出的方法进行了评估，所提出的方法的性能优于其他已知的k-匿名方法。该方法还表现出较低的实现复杂度和真实轨迹与伪轨迹之间的较高运动相似性（高达88％）。