How to implement the A-GPS standard?

Question

satellite navigation

The task is to make a mobile application that, by analogy with Yandex and Google maps, is able to determine the coordinates of a mobile device with some frequency and minimize the error in determining.

We use the standard getLocation to get coordinates from satellites and Yandex.locator to get coordinates from Wifi + towers. As a result, there are a couple of measurements (from GPS and from Yandex.locator), each measurement is a set of 3 values: latitude, longitude, error radius.
How to make friends these 2 measurements, having received for a given point in time one, the most accurate measurement? I understand that it is the creation of one measurement from these two that is the implementation of the A-GPS standard? Perhaps there are ready-made services for solving this problem (I did not find any)?

Answer 1

Throw out the coordinates of the towers when there is a GPS.
About A-GPS:
To start determining GPS coordinates, you need to know the coordinates of the satellites. They can either be received within 15 minutes from the satellites themselves or downloaded in a second from the Internet. This jump is what Assist GPS is doing. It has nothing to do with your topic.