AGPS startup via NB-IoT on nrf9160-DK

[paul_tanner]

I took the APGS example and switched in to NB-IoT as I can't easily test with LTE/M at the moment

2021-03-15T16:25:39.226Z DEBUG modem << I: A-GPS sample has started
2021-03-15T16:25:39.246Z DEBUG modem << I: Connecting to LTE network. This may take minutes.
2021-03-15T16:25:39.249Z DEBUG modem << I: PSM mode requested
2021-03-15T16:25:42.194Z DEBUG modem << +CEREG: 2,"1BE8","00334D15",9,0,0,"11100000","11100000"
2021-03-15T16:25:42.900Z DEBUG modem << +CSCON: 1
2021-03-15T16:25:45.571Z DEBUG modem << +CEREG: 5,"1BE8","00334D15",9,,,"00000010","00011111"
2021-03-15T16:25:45.605Z DEBUG modem << I: Connected to LTE network
2021-03-15T16:25:45.606Z DEBUG modem << D: MAGPIO set: AT%XMAGPIO=1,0,0,1,1,1565,1586
2021-03-15T16:25:45.607Z DEBUG modem << D: COEX0 set: AT%XCOEX0=1,1,1565,1586
2021-03-15T16:25:45.610Z DEBUG modem << D: GPS socket created, fd: 1232491587
2021-03-15T16:25:45.611Z DEBUG modem << I: CLOUD_EVT_CONNECTING
2021-03-15T16:25:46.400Z DEBUG modem << I: CLOUD_EVT_CONNECTING

I tried this a few times and waiting several minutes in each case.  No more output seen.
Are there other things I need to change? apart from:

#CONFIG_LTE_NETWORK_MODE_LTE_M_GPS=y
CONFIG_LTE_NETWORK_MODE_NBIOT_GPS=y

Suggestions welcome.  Thx.

[Øyvind]

Hello, 

Sorry for the delayed answer. I will have a look at your case and get back to you before end of the day.

Kind regards,
Øyvind

[paul_tanner]

?

[Øyvind]

Hello, 

My apologies for the blunt answer yesterday. I contacted the RSM for the UK to get a better overview of the network situation, and this is her response:

The UK have LTE-m coverage in the EAST, via O2 (Telefonica). Customers can check the coverage in their area using this website: https://www.o2.co.uk/business/solutions/iot/lte-m

Please note that the last time I checked the low-power modes (eDRX and PSM) were not available to roaming SIMs (like iBasis) so he would need a SIM from O2 (with a data allowance) to get the GPS demo on the Thingy:91 working.

Should he wish to try NB-IoT, then this is also possible where he lives, however he will need to get specific SIM cards that are enabled for NB-IoT. I would advise contacting Arkessa for these as they are a preferred partner of Vodfone, however the SIMs that Arkessa supply in their trial pack are NOT whitelisted – which makes development a whole lot easier especially when using AWS!

If you are interested in getting a trial package from Arkessa, please let me know and I will forward the contact information.

NB-IoT coverage is ALMOST the whole of the country (with notable exceptions like East Anglia), and the density of coverage should be improving.

Please let me know if you have any further questions on this.

Are you using the iBasis SIM for testing or do you use another SIM from one of the network providers? 

Kind regards,
Øyvind

[paul_tanner]

I'm using NB-IoT SIMs from Vodafone.  I also have an iBasis LTE/M SIM but had similar coverage issues with that.  I know that at this stage of UK rollouts we have to travel a little to get in range.  However, we have plenty of development work yet to do before we'll be ready to deploy.

So the question remains: why does the AGPS example stall?  Is some further customisation needed to enable the necessary cloud connection?

I see that nrfCloud can generate a device certificate.  No mention of that in the README but I wondered if that could be required in the build?

[Øyvind]

paul_tanner said:

why does the AGPS example stall?  Is some further customisation needed to enable the necessary cloud connection?

 No, there shouldn't be any other customisations needed to enable anything. What I am afraid of is the NB-IoT connection. Are you able to try with a new SIM from Arkessa? https://www.arkessa.com/

If that does not help, can you please try running the Asset Tracker sample to see if that is able to connect nRF Cloud?

Thank you.
-Øyvind

[paul_tanner]

I was thinking that the SIMs must be OK as they are working with other examples such as UDP.

It could take a while to get SIMs from another source.  However, I realised that the Vodafone SIMs I have may be restricted in terms to the IPs they can access.  I have asked them to support a connection to supl.google.com in addition to the IP they are already accessing.

[paul_tanner]

OK. I got some O2 SIMs from Arkessa.

Changed the code to select LTE-M but not getting a connection.

Looking at the config I see that I have CONFIG_LTE_LEGACY_PCO_MODE=y

Could that be a cause of non-connection?

Regards.

[Øyvind]

Hi Paul, 

Yes, this may cause a connection issue as Legacy Protocol Configuration Options (PCO) is an older protocol compared to extended Protocol Configuration Options (ePCO), and intended for NB-IoT

The Digital Matter blog https://www.digitalmatter.com/nb-iot-update-pco-support/ has a good explanation:

Device manufacturers, module manufacturers, and networks all need to quickly adapt when deploying new networks. In the case of NB-IoT, not every network has got it right first try.

The 3GPP standard (standard specification for mobile networks globally) specifies that NB-IoT networks support ePCO (extended protocol configuration options).

Many networks globally instead offer PCO. When a device attempts to connect expecting ePCO, it will not be able to get online. The two messages are different, so the device and the network don’t understand each other properly.

Did you try to remove this configuration?

Kind regards,
Øyvind

[paul_tanner]

I'm certain I already replied to this. Anyway:

Yes. removing CONFIG_LTE_LEGACY_PCO_MODE=y made no difference.

Regards.