Where to read the theory of navigation inside buildings?

Question

Electronics

I want to dive into the topic, but I can’t find anything on the road. Who can give links to some works or studies or books?
Ps.: You can not necessarily in Russian, I can also English, German and Italian

Answer 1

In reality, navigation inside buildings goes through various beacons tied to the building plan.
At present, it is very difficult to achieve high positioning accuracy. An error of 3-5 meters is the norm.

Answer 2

and here read the first 6 articles for example?
https://habrahabr.ru/search/?q=%D0%BD%D0%B0%D0%B2%...

Answer 3

Google query indoor navigation