• State Verified Answer
  • Replies 19 replies
  • Subscribers 74 subscribers
  • Views 5650 views
  • Users 0 members are here
Attachments (2) Download All
Nordic Case Info
  • Case ID: 239713
Options
This post is older than 2 years and might not be relevant anymore
More Info: Consider searching for newer posts

Questions about signal quality polling in nRF9160

Fredrik

Hi,

I am mapping NB-IoT and LTE-M1 indoors coverage using the nRF9160, mostly just to familiarize myself with the nRF91 DK. I have a basic application which toggles between NB and M1 mode and records the RSRP for each of them, and I have a few questions about the CEREG and CESQ commands.

Below is the log output when connecting to NB-IoT and polling CEREG and CESQ every 10 seconds. In the log, '--->' denotes commands sent to the modem, and '<---' denotes the modem response.

[00:00:01.866,394] ---> AT+CFUN=4
[00:00:01.887,420] ---> AT%XSYSTEMMODE=0,1,0,0
[00:00:01.911,285] ---> AT+CFUN=1

[00:00:01.962,219] ---> AT+CESQ
[00:00:01.976,470] <--- +CESQ: 99,99,255,255,255,255
[00:00:01.985,198] ---> AT+CEREG?
[00:00:01.999,664] <--- +CEREG: 0,4,"FFFE","FFFFFFFF",9

[00:00:12.015,777] ---> AT+CESQ
[00:00:12.030,120] <--- +CESQ: 99,99,255,255,255,255
[00:00:12.038,879] ---> AT+CEREG?
[00:00:12.053,253] <--- +CEREG: 0,4,"FFFE","FFFFFFFF",9

// some time passes

[00:01:02.250,152] ---> AT+CESQ
[00:01:02.264,495] <--- +CESQ: 99,99,255,255,255,255
[00:01:02.273,223] ---> AT+CEREG?
[00:01:02.287,628] <--- +CEREG: 0,4,"FFFE","FFFFFFFF",9

[00:01:12.297,027] ---> AT+CESQ
[00:01:12.311,370] <--- +CESQ: 99,99,255,255,19,46
[00:01:12.319,915] ---> AT+CEREG?
[00:01:12.334,320] <--- +CEREG: 0,2,"9FC5","0103A167",9

[00:01:22.343,902] ---> AT+CESQ
[00:01:22.364,318] <--- +CESQ: 99,99,255,255,19,46
[00:01:22.372,802] ---> AT+CEREG?
[00:01:22.393,463] <--- +CEREG: 0,2,"9FC5","0103A167",9

Initially, the modem status reported by the CEREG command is 4 (unknown), and then it flips to 2 (not registered, searching). At the same time I receive valid RSRP values from the CESQ command. The modem status never changes after this. Is this expected? Can I have valid RSRP, <tac> and <ci> on NB-IoT without having modem status equal to 1 or 5? Repeating the same procedure for LTE-M1 always gives initial modem status 4, then 5.

I'm on nRF Connect SDK v1.0.0, modem FW mfw_nrf9160_1.1.0. The SIM card is an iBasis SIM which was provided with the nRF9160 DK.

  • 0 in reply to Håkon Alseth

    Hi,

     

    Got confirmation from R&D that the eNB or SIM seems to be the issue.

    There is an attach reject with cause value #15 (No suitable cells in tracking area) from the home network for this SIM. This cause value means basically that you could get service from this network, either on some different area or via different access technology.

    There were no cells from other home networks tracking areas available so we also made an attempt to another vendor (the one marked with 0EDB) on the log file. That network rejects attach attempt with a cause value that includes the whole network (#14 EPS services not allowed in this PLMN).

     

    Have you tried connecting to NB1 in a different area (at work vs. at home, for instance)?

     

    Kind regards,

    Håkon

  • 0 in reply to Håkon Alseth

    I just got off the phone with Telenor who (finally) decided that the subscription I had did not support NB-IoT. My SIM does support NB, however, and we swapped my subscription to allow NB traffic. Telenor is now certain that everything looks good on their side. They also made sure that there is good coverage in my area.

    My case is starting to look similar to Terje's case as Telenor asked me to make sure I was using the telenor.iot APN. Simon's answer here indicates that PDP context should be handled by the modem firmware, and I don't know if I should mess with the APN manually.

    I'll try connecting at home over the week-end.

  • 0 in reply to Håkon Alseth

    Tried at home, same results unfortunately.

    trace-2019-12-14T11-44-48.241Z.bin

    [00:00:06.709,075] ---> AT%XMODEMTRACE=1,2
[00:00:06.732,971] ---> AT+CEREG=5
[00:00:06.755,523] ---> AT%CESQ=1
[00:00:06.824,432] ---> AT+CFUN=4
[00:00:06.850,219] ---> AT%XSYSTEMMODE=0,1,0,0
[00:00:06.877,227] ---> AT+CFUN=1
[00:00:30.016,876] <--- %CESQ: 60,3,21,3
[00:00:30.032,623] <--- +CEREG: 2,"A0F1","013DD964",9,0,0,"11100000","11100000"
[00:00:35.076,416] <--- +CEREG: 4,"A0F1","013DD964",9,0,15,"11100000","11100000"
[00:00:35.142,730] <--- %CESQ: 255,0,255,0
[00:00:35.155,181] <--- +CEREG: 4,"FFFE","FFFFFFFF",9,0,15,"11100000","11100000"
[00:00:52.689,270] <--- %CESQ: 60,3,24,3
[00:00:52.734,252] <--- +CEREG: 2,"0EDD","02100113",9,0,15,"11100000","11100000"
[00:00:54.002,990] <--- +CEREG: 2,"0EDD","02100113",9,0,14,"11100000","11100000"
[00:00:54.162,994] <--- %CESQ: 255,0,255,0
[00:00:54.171,112] <--- +CEREG: 2,"FFFE","FFFFFFFF",9,0,14,"11100000","11100000"
[00:01:00.727,142] <--- %CESQ: 60,3,19,2
[00:01:00.735,046] <--- +CEREG: 4,"A0F1","013DD964",9,0,14,"11100000","11100000"
[00:01:10.647,857] <--- %CESQ: 60,3,25,3
[00:01:15.767,974] <--- %CESQ: 60,3,20,2
[00:01:20.888,122] <--- %CESQ: 60,3,26,3
[00:01:23.448,181] <--- %CESQ: 60,3,18,2

    Telenor agreed to send me a new SIM, just in case the one I got is misconfigured somehow.

    Thanks for all your help!

  • +1

    Four SIM cards a lot of confusion later, this finally works. It was indeed an issue with the SIM card being misconfigured as suggested.

    To anyone having the same issues: Make absolutely sure that the SIM card provided by your carrier supports NB. I recieved conflicting information from customer support.

Related
Terms of service