[BG77] NB-IoT triangulation to calculate location

Hello,

We are using the Quectel BG77 module in our project. We are using the GNSS function of the module but we would like to implement a fallback method in case the GNSS does not work (indoors for example). We were thinking about gathering the RSSI values of the near LTE cell towers and use them to calculate the location with triangulation.

Is this possible with the BG77 module? Unfortunately I could not find an AT command which can query the RSSI of the near cell towers. (I only found “AT+CSQ” which returns the RSSI of the cell tower that the module is connected to.)

An AT command which returns a list of the near cell tower IDs would be also fine.

Thank you for your help.

Best regards,
Bence

If I understand correctly, Quectel offers a paid localization service “QuecLocator” which works in the way you described. However it does not support NB network.

Hi everyone,

I am very interested in this service: QuecLocator.

Does anyone know where I can get more infromation?

Best regards.

https://forums.quectel.com/t/bg95-m3-queclocator-2-0/4570

https://forums.quectel.com/t/pricing-queclocator/4952

Hello,

Thank you for suggesting QuecLocator.

Unfortunately NB-IoT is the only option for us. Actually we don’t need an external service to compute the location, we only need an AT command to query a [cell tower ID] - [RSSI] list for every near cell tower. Do you think this is available in BG77?

Thank you,
Bence

AT+QCSQ Query and Report Signal Strength
The command is used to query and report the signal strength of the current service network. If the MT is
registered on multiple networks in different service modes, customers can query the signal strength of
networks in each mode.
AT+CEREG EPS Network Registration Status
The command queries the network registration status

Tracking indoor and outdoor by GNSS and cell ID


Enjoy the reading.

http://wiki.opencellid.org/wiki/API

Hello,

I’ve just read in the BG77 module specification that BG77 supports the QuecLocator service.

Can somebody (a Quectel employee I suppose) confirm, that this really works at the moment on BG77 using NB-IoT?

Thank you very much.

Best regards,
Bence

Hello,

Could somebody answer the question? It is quite urgent and it will be used in a mass product.

Thank you.

Best regards,
Bence

Hi Bence,

See if this helps-
I use Queclocator with BG77 using LTE Cat M1. Its a simple AT command which does an HTTP request in the background, so I think it should work with Cat NB2 as well. A Quectel engineer should confirm this for you.
I believe NB2 coverage is not as widespread, so triangulation accuracy is something to test out and see if it is acceptable. With Cat M1 in USA, in urban areas I get accuracy of ~1 mile and in remote areas I saw accuracy of ~5 miles.

-Kunal

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Hi Kunal,

Thank you very much for your answer.

In the meantime, I’ve applied for a trial token for Queclocator. I’ve received it, and tried it but no success unfortunately. :frowning:

AT+QCFG=“iotopmode”,1,1
AT+COPS=1,2,“21670”,9
AT+QICSGP=1,1,“XY.com”,“user”,“password”,1
AT+QIACT=1
AT+QIACT? // —> this returns the IP address of the modem registered to NB-IoT network, so the connection is OK

AT+QLBSCFG=“token”,“ABCDEFGH123” /// until this command everything is fine, the response is always OK

AT+QLBS /// <— this command returns “+CME ERROR 730”

I cannot figure out why the “AT+QLBS” AT command does not work. The application note (QuecLocator
Application Note) says it does not have any parameters.

I checked the QuecLocator default server (queclocator.com:80) with my PC browser, but it returns 404 page not found error. Maybe this is the issue?

Can you please send the AT commands that you use, Kunal? And also the QuecLocator server URL that you use. (If it’s not private)

Thank you very much for your help.

Best regards,
Bence

Bence,

Error 730 is HTTP error for invalid parameter. I remember getting that error when I was playing with AT+QLBSCFG parameters. If you have changed any default settings then try undoing them. I use default queclocator server. I use these commands at startup:
AT+QLBSCFG=“token”,“my_token”
AT+QLBSCFG=“timeout”,10
And I query location using:
AT+QLBS

Your steps look correct. Can you query and check if token is set correctly?
AT+QLBSCFG=“token”
+QLBSCFG: “token”,"****************"
OK

This is the actual response. I have not replaced the token with ******.
If you have trial token then you must have an account here: https://iot.quectel.com/login.html If not then make an account and login to see Queclocator tab in the account.

Firstly, ask your Quectel contact to confirm whether Queclocator works with NB2.

-Kunal

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Hi Kunal,

Thank you very much for your help.

I’ve contacted the Quectel support team and I’ll copy their answer here, as this could be useful for somebody trying to use QuecLocator with NB-IoT:

Seems our database for location does not have much NB base stations to be used.
We are working now with 3rd party to get more data, but this will take some unknown time.
For now, NB can only be used for transport of data and for location you need to input manually WiFi address to get a location (if you have such info, of course)

Best regards,
Bence

QuecLocator does not work with NB-IoT. And with NB-IoT you can basically get only the serving cell info - AT+QENG="servingcell". Because of the nature of NB-IoT the module (most of the time) does not know about neighbour cells.

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