Assissted GPS - Location service - wrong Cell

[Raffael Wojtas]

Dear Nordic team,

we have a question regarding your Location Services, in particular the Assissted GPS service.
While using it, we have noticed switching locations. We investigated on our side and found out that we do two different calls against your service.

First:
https://api.nrfcloud.com/v1/location/agps?mcc=208&mnc=1&tac=52644&eci=25774343&types=6,7,8

and 

Second:
https://api.nrfcloud.com/v1/location/agps?mcc=208&mnc=1&tac=51943&eci=24855041&types=6,7,8


the difference is: 
First,  TAC: 52644 and ECI: 25774343
Second, TAC: 51943 and ECI: 24855041

The First is in Montpellier and the Second is in Paris.

We investigated further, checked the OpenCelId database and found out that the first cell was not found.
This finding makes sense, because we know that our device is in Paris (Second Cell) which exists.



Right now we are confused because we do not know how to handle this and potentially many other Assissted GPS calls.
Do you have any hints on how we can rely on or check your data?

Best regards,
Raffael Wojtas

[AndrewKostka]

Hello Raffael:
I've taken a look at the two requests. I'm wondering where you are getting that the first cell returns a location in Montpellier. When I run this request, I get the returned coordinates:

{

  "lat": 48.95999193,
  "lng": 2.27543592

}

Which maps to a location near Paris, very near to the second cell position.

[Raffael Wojtas]

Hey Andrew,

Firstly, thank you very much!

But it's strange. Now I see also the near Paris location. But I just replicated the call (executed my script after I saw your reponse). And I've got completely different data.

Did you update your database or something similar?

How can we know, if data is potentially old?

[AndrewKostka]

Data is constantly updated as, cell ID assignments can change over time. It's possible it's a newer cell that was not in the data yet. Unfortunately there is not a way to assess the age of a cell measurement, as our data vendors do not offer that information.

[Raffael Wojtas]

Yeah, I see. Thank you. Could you tell me if it makes more sense to replace the A-GPS call with the Location Cell?

Does this call tell me "I don't know", when information is old or wrong?

[AndrewKostka]

At this time, the AGPS endpoint will return the same value as the Ground Fix (recommended) or Cell Location (deprecated) endpoints. However, sometimes when a cell is not found the API may fallback to a regional position based on the cell's tracking area. In the near future, we will be adding a feature to allow you to control that fallback, to just return a 404 in that case. I am not sure if that's what was happening with your original call, but it could prevent such cases in the future.

As for your second question, the only case in which we return a 404 is if there is no known position for the cell. We don't know if data is outdated unless new data comes in for that cell, and most cells stay in one place for many years.

[Raffael Wojtas]

Oh,  that's like something we would like to have.

For our use case it makes more sense to tell our customers "Hey, nope. We don't know" instead of providing  a "wrong" / very off location.

Do you any insights into when this feature is going to be implemented?

Another, rather technical / process question - do you import the cell data from your suppliers or do you use their API to get data?

[AndrewKostka]

Hi Raffael: It's a combination, but for the most part we're using their API to get the most up-to-date data.

[AndrewKostka]

Also, as for implementation, it will be before the end of the year, although I don't have an exact timeline.

[AndrewKostka]

Hi, Raffael:
This feature will be released Thursday, 11/30. You can find more details in the API docs once it is released: https://api.nrfcloud.com/v1/