Cannot connect my board :-(

NB-IoT
1

Hello, I have never been able to connect:

(nbiot.connect(“oceanconnect.t-mobile.nl”, “172.16.14.22”, “20416”)) from arduino sketch examples.

AT passthrough does work, for example:

AT+NRB

REBOOTING
AT+NRB

REBOOTING
REBOOT_CAUSE_APPLICATION_AT
Neul
OK

AT+NCONFIG?

+NCONFIG:AUTOCONNECT,FALSE
+NCONFIG:CR_0354_0338_SCRAMBLING,FALSE
+NCONFIG:CR_0859_SI_AVOID,TRUE

OK
AT+NCDP=172.16.14.22

OK
AT+CGDCONT=1,“IP”,“oceanconnect.t-mobile.nl”

OK
AT+CFUN=1

OK
AT+NBAND=8

OK
AT+COPS=1,2,“20416”

OK
AT+CSQ

+CSQ:2,99

OK
AT+CSQ

+CSQ:2,99

OK
AT+CSQ

+CSQ:2,99

OK
AT+CGATT?

+CGATT:1

OK
AT+NPING=172.16.14.22

OK

+NPING:172.16.14.22,125,1601
AT+NSMI=1

OK
AT+COPS=1,2,“20416”

OK
AT+CGMM

Neul Hi2110

OK
AT+NUESTATS

Signal power:-1161
Total power:-1076
TX power:23
TX time:1352
RX time:61648
Cell ID:153701
DL MCS:0
UL MCS:0
DCI MCS:1
ECL:1
SNR:57
EARFCN:3747
PCI:456

OK

Do you have a hint?

Edit: the shield is sitting on e Leonardo
Edit2: my location is 52°51’58.49 N , 6°22’32.37 E

2

You have a very low signal strenght.
In the library we check if the signal is -93 dBm or better.

3

Indeed this check should be removed signal = signal.

My current experience is that the default minimal signal quality of the library is higher than is required. I have set an other minimal signal quality to the lowest possible value in my sketch. The original value (-93) was likely based on LTE standards we expect additional 20 dB coverage extension for NB-IOT.

nbiot.init(MODEM_STREAM, 7);
nbiot.setDiag(DEBUG_STREAM);
nbiot.setMinRSSI(-113);

This is not a minimum value in theory, just the lowest value the library allows. what the real value should be is another interesting topic. It would be a good idea to remove this check completely and rely on the UE to tell us whether there is signal to connect to (CSQ <> 99)

4 
 nbiot.setMinRSSI(-113);

Yes, thank you, this fixes my problem.

5

@Jan I want to ask you to urgently updated the libraries according to this suggestion. The T-Mobile network has far better performance than is suggested in the Sodaq libraries. The fact that the reason for not connecting is not returned worsens the perception. Thanks in advance Eric Barten (T-Mobile IOT)

6

We will fix this issue in the next update.

Regards,
Jan