We have been experiencing issues with cellular network registration in the UK on a previously very reliable mangOH board
The test hardware is the mangOH yellow WP7702
Sometimes times on boot the module fails to network register cycling between
at+creg?
+CREG: 0,3
OK
at+creg?
+CREG: 0,2
OK
Which I think means
When returning +CREG: 0,3 I also see
root@swi-mdm9x28-wp:~# cm radio
Power: ON
Current Network Operator: Sierra Wireless
Current RAT: Module not registered on network, RAT not available
Status: Not registered but currently searching for a new operator (LE_MRC_REG_SEARCHING)
Signal: Strong signal strength (4)
PS: Packet Switched Not registered (LE_MRC_REG_NONE)
My theory is this an NBIOT issue if I
at!entercnd="A710"
OK
AT!SELACQ?
!SELACQ:
LTE
LTE-M1
LTE-NB1
GSM
OK
AT!SELCIOT?
Current Operating Mode: 0x2
Supported Operating Modes:
LTE WB: 0x01
LTE M1: 0x02
LTE NB1: 0x04
OK
AT!SELCIOT=2
OK
AT!SELACQ=GSM,LTE-M1
OK
Wait a while
at+creg?
+CREG: 0,5
OK
and
root@swi-mdm9x28-wp:~# cm radio
Power: ON
Current Network Operator: Sierra Wireless
Current RAT: GSM network (LE_MRC_RAT_GSM)
Status: Registered to a roaming network (LE_MRC_REG_ROAMING)
Signal: Very strong signal strength (5)
PS: Packet Switched Registered to a roaming network (LE_MRC_REG_ROAMING)
We have noted this issue and it is tied to several engineering tickets in process. Restricting the RAT to GSM will help with registration times in your current geographic location.
For info - this only became an issue over the last couple of days.
I’m totally guessing (again) here - but I think that at least one network in this area may have enabled NBIOT and for whatever reason the Octave contract doesn’t work with it. I left the system on for a long time (hours) - it didn’t recover which I’m surprised about - maybe it needed a lot longer?
At the moment enabling only GSM/GPRS and LTE CAT M1 is working but of course there most likely isn’t any M1 here either so I don’t know if that tactic will work long term.
As this issue has occurred whilst we have a few folks out there field trialing Octave in the UK - is there a way to remotely make a change to their Octave system cellular config - without having to manually (locally ) intervene?
So part of the issue is that setting NB1 higher than 2G means it has to go through all of the coverage extension modes which can take literally hours. As you say them turning it on will probably mean it has to go through these before it eventually falls back to GSM. On the other hand if you set 2G higher it might never switch to NB1 if you have coverage but given there is unlikely to be any NB1 roaming for the foreseeable future that’s not necessarily a problem.
That’s a difficult question to give a hard answer to but on balance I would say no it should not cause issues.
O2 have announced an M1 network across the UK by the end of the year, generically speaking if you have an LTE roaming agreement with them (which we do) then you will be able to get onto the network and send data but until we are actually able to test it obviously there are no guarantees.
