Issue with NB-IoT attach with BC95-G and BG77

Hi.

I am testing several Quectel’s modems:

  • BC95-G (Revision:BC95GJBR02A03)
  • BG77 (Revision: BG77LAR02A04)
  • BG96 (Revision: BG96MAR02A07M1G)

With all of them, I successfully connect in eMTC mode (LTE-M/CAT-M), but the, with NB-IoT one it just works with the BG96.

My lab setup:

  • PLMN = 00101
  • LTE Band 3
  • NB-IoT InBand mode
  • APN = internet

For connecting as CIoT, the command “AT+COPS=1,2,“00101”,9” is used.

Any suggestion what to verify what is going on and to get also the other modems attached?

Br. Stefano

Quectel_BG95&BG77_Network_Searching_Scheme_Introduction_V1.0.pdf (591.9 KB)

Hi.

Focusing on the modem BG77, I followed the instructions to get the attach in both eMTC and NB-IoT, but it is working only with eMTC.

I can confirm the NB-IoT InBand is configured and I can attach a BG96 modem.

Here are the AT commands and responses when I connect in eMTC mode:

ATI
Quectel
BG77
Revision: BG77LAR02A04

AT+CIMI
001011001002160

AT+COPS=1,2,"00101",8

AT+CGDCONT?
+CGDCONT: 1,"IP","internet","0.0.0.0",0,0,0

AT+QCFG="nwscanseq"
+QCFG: "nwscanseq",030201

AT+QCFG="band"
+QCFG: "band",0x0,0x4,0x4

AT+QCFG="iotopmode"
+QCFG: "iotopmode",0

AT+CEDRXS?
+CEDRXS: 0

AT+CPSMS?
+CPSMS: 0,,,"01100000","00000000"

AT+CFUN=1

AT+CSQ
+CSQ: 21,99

AT+CGPADDR=1
+CGPADDR: 1,10.10.0.4

But, when I try to change to NB-IoT, I don’t see any attempt from the modem at EPC side:

AT+COPS=1,2,"00101",9

AT+QCFG="iotopmode"
+QCFG: "iotopmode",1

AT+QCFG="nwscanseq"
+QCFG: "nwscanseq",030201

AT+CSQ
+CSQ: 99,99

AT+QNWINFO
+QNWINFO: No Service

Anything else I can check/verify/try?

Br. Stefano

How do you implement testing? by the test instrument? or the real radio network?

Hi Herbert. I have a lab with EPC and real eNB (Nokia).