A-GPS: how to send every 5 seconds to cloud

[visu]

Hi folks,

I am playing around with the A-GPS sample.

I am trying to send the fix every five seconds to the cloud. This should be possible according to the webinar last Tuesday (02.March 2021).

Is it right that I have to use the continuous mode since the periodic mode only supports interval with min. 10 seconds?

How do I handle the "multiplexing" of GPS/LTE?  (turning off GPS, turn on LTE, send to the cloud, turn on GPS etc.?)

[Carl Richard]

Hi, Visu!

I must check with the developers/presenters on this, but judging from the documentation you are correct that continuous mode must be used.

We have documentation on concurrent GPS and LTE operation in the Thingy:91 documentation and in the A-GPS sample documentation. There we recommend to use one of the LTE power saving mechanisms PSM or eDRX to allow enough time for GPS operation. For your use case I suggest configuring eDRX getting GPS fixes in the sleep interval and then uploading every 5 seconds. You should not need to turn on and off GPS/LTE.

Good luck!

Best regards,
Carl Richard

[visu]

Thanks for your qick reply! Should this work with NB-IoT and LTE-M?

I am considering to use LTE-M

[Carl Richard]

Hi!

GPS operation is supported for both NB-IoT and LTE-M, but I would recommend using LTE-M due to limited support for mobility on NB-IoT networks.

Best regards,
Carl Richard

[visu]

Hi,

By uploading data to the cloud, the nRF9160 gets into RRC Connected Mode.
The time transition from RRC Connected to RRC Idle is dependent on the network.

I read that indicating RRC Release with AT%XRAI is only possible with NB-IoT, so I guess my application with 5seconds interval will only work with NB-IoT?

Or is there another way to get this work with LTE-M?

[Carl Richard]

Hi again!

As the documentation states the transition time from RRC Connected to RRC Idle will vary with the network, and it can be as as low as a couple of seconds. Hence, I would recommend checking what value your network uses before you decide to not use LTE-M.

XRAI is currently only supported on NB-IoT, so that is an alternative if the RRC Inactive timer is too long for your application.

Best regards,
Carl Richard