Page 22 - 卫星导航2021年第1-2合期
P. 22
El‑Sheimy and Li Satell Navig (2021) 2:7 Page 12 of 23
Fig. 4 Techniques for indoor navigation
Fig. 5 Principle of position‑fxing methods
relative direction and distance to a base station that has indoors) that can be well modeled and parameterized.
a known position. Tis approach is widely used in engi- By contrast, it is more challenging to use such methods
neering surveying. For indoor PLAN, a solution is to in complex indoor and urban areas due to the existence
localize a device by its direction to a ceiling-installed AoA of error sources such as multipath, NLoS conditions,
base station (Quuppa 2020) and known ceiling height. and human-body efects. Te survey paper (Li et al.
Tis approach is reliable, and it reduces the dependence 2020a) has a detailed description of the error sources
on the number of base stations. However, the cost is high for position-fxing methods. It is difcult to alleviate
when using in wide-area applications. the device-, signal-propagation-, and base-station-
In general, geometrical position-fxing methods are related error sources by the position-fxing technique
suitable for the environments (e.g., outdoors and open itself. Tus, it is common to integrate with other PLAN
techniques, such as DR and database matching.
