quectel nb-iot modem is activated every hour - why? (psm is 10 hours)

lorenz

Dear iotcreators,
first of all, I really appreciate this forum. Thanks for setting it up.

I have observed a behaviour with the nb-iot modem bc95-g that I cannot explain. (using 1nce sim cards).
Event though the psm is set to 10 hours, and I am sending a packet every 1.5hours, the modem registers to the network every hour.
I asked that question to tekmodul, and they said that it might be related to the automatic network registration (i.e. at+cops=0. But I did another test with at+cops=1 (see image below) and I am still getting the connection every hour. What is the reason for that?
Could it be maybe because I am registered with roaming? +cereg: 5. (I have not found a way to select the home network though, i.e. +cereg=1)

The picture shows the output of a test run where 16 bytes are sent every 1.5 hours and it stops after 6 iterations. The crosses on the chart indicate when the packets where sent.

Here are some AT logs:

ATI
Quectel
BC95-G
Revision:BC95GJBR01A04

[2021-01-05 20:47:32.855103] AT+CSQ
[2021-01-05 20:47:32.856013] +CSQ:28,99
[2021-01-05 20:47:32.811884] at+cops=1,2,"26201"

# those are the urcs when the modem connects (15 seconds from first to last urc, which is quite a lot)
# in the graph above, this corresponds to the high skite near 01-05 23
[2021-01-05 22:47:19.038198] +CSCON:1
[2021-01-05 22:47:19.201450] +CEREG:0,0000,00000000,9,,,,
[2021-01-05 22:47:19.323469] +CSCON:0
[2021-01-05 22:47:22.309031] +CEREG:2,CB52,02992008,9,,,,
[2021-01-05 22:47:24.478155] +CSCON:1
[2021-01-05 22:47:25.997287] +CEREG:5,CB52,02992008,9,,,00000101,01000001
[2021-01-05 22:47:36.015346] +CSCON:0

# Please note that the packets did not arrive at the server because it was not running at that time. 
# here it shows that udp packets were sent successfully. 
[2021-01-05 22:17:35.039265] +CSCON:1
[2021-01-05 22:17:35.166161] +NSOSTR:1,2,1
[2021-01-05 22:17:35.296427] +CSCON:0

Thanks,
Lorenz

lorenz

quick amendment: I am connecting from Germany, so even though the network is registered with roaming, I am in the home network of 1nce.

Also, is it possible to edit previous posts? (I did not find an option for it).

Stefan de Lange

@lorenz Hi Lorenz, can you show the output of AT+CPSMS?

lorenz

@Stefan-de-Lange
Thanks for the quick answer. It is:

[2021-01-05 20:47:32.814617] AT+CPSMS=1,,,"01000001","00000101"
[2021-01-05 20:47:32.815133] OK

Unfortunately I could not add .txt files to the forum here as it is not supported. So here is the entire at command log:

[2021-01-05 20:47:32.738160] REBOOT_CAUSE_APPLICATION_AT
[2021-01-05 20:47:32.739475] Neul
[2021-01-05 20:47:32.740372] OK
[2021-01-05 20:47:32.741490] ATE1
[2021-01-05 20:47:32.742402] OK
[2021-01-05 20:47:32.744159] AT+CMEE=1
[2021-01-05 20:47:32.745102] OK
[2021-01-05 20:47:32.746136] ATI
[2021-01-05 20:47:32.747585] Quectel
[2021-01-05 20:47:32.748934] BC95-G
[2021-01-05 20:47:32.752087] Revision:BC95GJBR01A04
[2021-01-05 20:47:32.752793] 
[2021-01-05 20:47:32.753724] OK
[2021-01-05 20:47:32.755503] AT+CSCON=1
[2021-01-05 20:47:32.756412] OK
[2021-01-05 20:47:32.758180] AT+CEREG=5
[2021-01-05 20:47:32.759054] OK
[2021-01-05 20:47:32.759690] 
[2021-01-05 20:47:32.761233] +CSCON:1
[2021-01-05 20:47:32.762939] AT+CGSN=1
[2021-01-05 20:47:32.766067] +CGSN:867724030123928
[2021-01-05 20:47:32.766786] 
[2021-01-05 20:47:32.767664] OK
[2021-01-05 20:47:32.769115] AT+CIMI
[2021-01-05 20:47:32.771464] 901405101074044
[2021-01-05 20:47:32.772173] 
[2021-01-05 20:47:32.773063] OK
[2021-01-05 20:47:32.774134] AT+NCONFIG?
[2021-01-05 20:47:32.775907] +NCONFIG:AUTOCONNECT,TRUE
[2021-01-05 20:47:32.778402] +NCONFIG:CR_0354_0338_SCRAMBLING,TRUE
[2021-01-05 20:47:32.780488] +NCONFIG:CR_0859_SI_AVOID,TRUE
[2021-01-05 20:47:32.782493] +NCONFIG:COMBINE_ATTACH,FALSE
[2021-01-05 20:47:32.784590] +NCONFIG:CELL_RESELECTION,TRUE
[2021-01-05 20:47:32.786372] +NCONFIG:ENABLE_BIP,FALSE
[2021-01-05 20:47:32.788030] +NCONFIG:MULTITONE,TRUE
[2021-01-05 20:47:32.790685] +NCONFIG:NAS_SIM_POWER_SAVING_ENABLE,TRUE
[2021-01-05 20:47:32.792893] +NCONFIG:BARRING_RELEASE_DELAY,64
[2021-01-05 20:47:32.794809] +NCONFIG:RELEASE_VERSION,13
[2021-01-05 20:47:32.796204] +NCONFIG:RPM,FALSE
[2021-01-05 20:47:32.798094] +NCONFIG:SYNC_TIME_PERIOD,0
[2021-01-05 20:47:32.800239] +NCONFIG:IPV6_GET_PREFIX_TIME,15
[2021-01-05 20:47:32.801817] +NCONFIG:NB_CATEGORY,1
[2021-01-05 20:47:32.803235] +NCONFIG:RAI,FALSE
[2021-01-05 20:47:32.805192] +NCONFIG:HEAD_COMPRESS,FALSE
[2021-01-05 20:47:32.806970] +NCONFIG:RLF_UPDATE,FALSE
[2021-01-05 20:47:32.809621] +NCONFIG:CONNECTION_REESTABLISHMENT,FALSE
[2021-01-05 20:47:32.810012] 
[2021-01-05 20:47:32.810484] OK
[2021-01-05 20:47:32.811884] at+cops=1,2,"26201"
[2021-01-05 20:47:32.812354] OK
[2021-01-05 20:47:32.814617] AT+CPSMS=1,,,"01000001","00000101"
[2021-01-05 20:47:32.815133] OK
[2021-01-05 20:47:32.815474] 
[2021-01-05 20:47:32.818253] +CEREG:5,CB52,02992008,9,,,00000101,01000001
[2021-01-05 20:47:32.819766] AT+CEDRXS=2,5,"0010"
[2021-01-05 20:47:32.820254] OK
[2021-01-05 20:47:32.820588] 
[2021-01-05 20:47:32.821370] +CSCON:0
[2021-01-05 20:47:32.822284] AT+NSOCL=1
[2021-01-05 20:47:32.823503] +CME ERROR: 530
[2021-01-05 20:47:32.824486] AT+NUESTATS
[2021-01-05 20:47:32.825806] Signal power:-633
[2021-01-05 20:47:32.827070] Total power:-576
[2021-01-05 20:47:32.828163] TX power:-160
[2021-01-05 20:47:32.829145] TX time:223
[2021-01-05 20:47:32.830231] RX time:11645
[2021-01-05 20:47:32.831487] Cell ID:43589640
[2021-01-05 20:47:32.832124] ECL:0
[2021-01-05 20:47:32.832851] SNR:259
[2021-01-05 20:47:32.833831] EARFCN:3740
[2021-01-05 20:47:32.834571] PCI:463
[2021-01-05 20:47:32.835423] RSRQ:-108
[2021-01-05 20:47:32.836601] OPERATOR MODE:2
[2021-01-05 20:47:32.836954] 
[2021-01-05 20:47:32.837407] OK
[2021-01-05 20:47:32.838248] AT+CPSMS?
[2021-01-05 20:47:32.840154] +CPSMS:1,,,01000001,00000101
[2021-01-05 20:47:32.840538] 
[2021-01-05 20:47:32.841014] OK
[2021-01-05 20:47:32.841934] AT+CEDRXS?
[2021-01-05 20:47:32.843235] +CEDRXS:5,"0010"
[2021-01-05 20:47:32.843622] 
[2021-01-05 20:47:32.844088] OK
[2021-01-05 20:47:32.845047] AT+CEDRXRDP
[2021-01-05 20:47:32.846028] +CEDRXRDP:0
[2021-01-05 20:47:32.846393] 
[2021-01-05 20:47:32.846844] OK
[2021-01-05 20:47:32.847690] AT+CEREG?
[2021-01-05 20:47:32.850590] +CEREG:5,5,CB52,02992008,9,,,00000101,01000001
[2021-01-05 20:47:32.851004] 
[2021-01-05 20:47:32.851457] OK
[2021-01-05 20:47:32.852236] AT+COPS?
[2021-01-05 20:47:32.853592] +COPS:1,2,"26201"
[2021-01-05 20:47:32.853965] 
[2021-01-05 20:47:32.854412] OK
[2021-01-05 20:47:32.855103] AT+CSQ
[2021-01-05 20:47:32.856013] +CSQ:28,99
[2021-01-05 20:47:32.856366] 
[2021-01-05 20:47:32.856803] OK
[2021-01-05 20:47:32.858420] AT+NSOCR=DGRAM,17,10000
[2021-01-05 20:47:32.858824] 1
[2021-01-05 20:47:32.859150] 
[2021-01-05 20:47:32.859590] OK
[2021-01-05 20:47:33.261431] AT+NQSOS?
[2021-01-05 20:47:33.261945] OK
[2021-01-05 20:47:33.289093] AT+NSOSTF=1,10.64.220.77,6000,0x200,16,20202d31202020316262626262626262,1
[2021-01-05 20:47:33.290148] 1,16
[2021-01-05 20:47:33.290393] 
[2021-01-05 20:47:33.291522] OK
[2021-01-05 20:47:34.295223] AT+NUESTATS
[2021-01-05 20:47:34.298567] Signal power:-32768
[2021-01-05 20:47:34.301796] Total power:-32768
[2021-01-05 20:47:34.304532] TX power:-160
[2021-01-05 20:47:34.306955] TX time:223
[2021-01-05 20:47:34.309578] RX time:11795
[2021-01-05 20:47:34.312530] Cell ID:43589640
[2021-01-05 20:47:34.314104] ECL:2
[2021-01-05 20:47:34.316095] SNR:-32768
[2021-01-05 20:47:34.318875] EARFCN:4294967295
[2021-01-05 20:47:34.320765] PCI:65535
[2021-01-05 20:47:34.322853] RSRQ:-32768
[2021-01-05 20:47:34.325477] OPERATOR MODE:2
[2021-01-05 20:47:34.326327] 
[2021-01-05 20:47:34.327384] OK
[2021-01-05 20:47:34.328889] AT+CSQ
[2021-01-05 20:47:34.330859] +CSQ:99,99
[2021-01-05 20:47:34.331706] 
[2021-01-05 20:47:34.332747] OK
[2021-01-05 20:47:35.059592] 
[2021-01-05 20:47:35.061588] +CSCON:1
[2021-01-05 20:47:35.184978] 
[2021-01-05 20:47:35.187733] +NSOSTR:1,1,1
[2021-01-05 20:47:35.311728] 
[2021-01-05 20:47:35.313752] +CSCON:0
[2021-01-05 20:47:36.641977] 
[2021-01-05 20:47:36.644059] +CSCON:1
[2021-01-05 20:47:46.881091] 
[2021-01-05 20:47:46.882866] +CSCON:0
[2021-01-05 21:47:09.758089] 
[2021-01-05 21:47:09.759562] +CSCON:1
[2021-01-05 21:47:09.918467] 
[2021-01-05 21:47:09.924150] +CEREG:0,0000,00000000,9,,,,
[2021-01-05 21:47:10.045455] 
[2021-01-05 21:47:10.046897] +CSCON:0
[2021-01-05 21:47:13.022066] 
[2021-01-05 21:47:13.027566] +CEREG:2,CB52,02992008,9,,,,
[2021-01-05 21:47:15.197849] 
[2021-01-05 21:47:15.199733] +CSCON:1
[2021-01-05 21:47:16.719435] 
[2021-01-05 21:47:16.727679] +CEREG:5,CB52,02992008,9,,,00000101,01000001
[2021-01-05 21:47:26.740403] 
[2021-01-05 21:47:26.741876] +CSCON:0
[2021-01-05 22:17:33.363067] AT+NQSOS?
[2021-01-05 22:17:33.363860] OK
[2021-01-05 22:17:33.390284] AT+NSOSTF=1,10.64.220.77,6000,0x200,16,20202d31202020326262626262626262,2
[2021-01-05 22:17:33.391142] 1,16
[2021-01-05 22:17:33.391524] 
[2021-01-05 22:17:33.392117] OK
[2021-01-05 22:17:34.395625] AT+NUESTATS
[2021-01-05 22:17:34.398115] Signal power:-32768
[2021-01-05 22:17:34.400466] Total power:-32768
[2021-01-05 22:17:34.402262] TX power:-190
[2021-01-05 22:17:34.403908] TX time:202
[2021-01-05 22:17:34.405702] RX time:11039
[2021-01-05 22:17:34.407833] Cell ID:43589640
[2021-01-05 22:17:34.408759] ECL:2
[2021-01-05 22:17:34.410228] SNR:-32768
[2021-01-05 22:17:34.412471] EARFCN:4294967295
[2021-01-05 22:17:34.413881] PCI:65535
[2021-01-05 22:17:34.415456] RSRQ:-32768
[2021-01-05 22:17:34.417470] OPERATOR MODE:2
[2021-01-05 22:17:34.417845] 
[2021-01-05 22:17:34.418437] OK
[2021-01-05 22:17:34.419469] AT+CSQ
[2021-01-05 22:17:34.420844] +CSQ:99,99
[2021-01-05 22:17:34.421137] 
[2021-01-05 22:17:34.421588] OK
[2021-01-05 22:17:35.037949] 
[2021-01-05 22:17:35.039265] +CSCON:1
[2021-01-05 22:17:35.163286] 
[2021-01-05 22:17:35.166161] +NSOSTR:1,2,1
[2021-01-05 22:17:35.294941] 
[2021-01-05 22:17:35.296427] +CSCON:0
[2021-01-05 22:17:35.996565] 
[2021-01-05 22:17:35.998717] +CSCON:1
[2021-01-05 22:17:46.239367] 
[2021-01-05 22:17:46.240815] +CSCON:0
[2021-01-05 22:47:19.035467] 
[2021-01-05 22:47:19.038198] +CSCON:1
[2021-01-05 22:47:19.195954] 
[2021-01-05 22:47:19.201450] +CEREG:0,0000,00000000,9,,,,
[2021-01-05 22:47:19.321699] 
[2021-01-05 22:47:19.323469] +CSCON:0
[2021-01-05 22:47:22.303354] 
[2021-01-05 22:47:22.309031] +CEREG:2,CB52,02992008,9,,,,
[2021-01-05 22:47:24.476563] 
[2021-01-05 22:47:24.478155] +CSCON:1
[2021-01-05 22:47:25.989432] 
[2021-01-05 22:47:25.997287] +CEREG:5,CB52,02992008,9,,,00000101,01000001
[2021-01-05 22:47:36.014020] 
[2021-01-05 22:47:36.015346] +CSCON:0
[2021-01-05 23:47:28.317600] 
[2021-01-05 23:47:28.319390] +CSCON:1
[2021-01-05 23:47:28.479197] 
[2021-01-05 23:47:28.484236] +CEREG:0,0000,00000000,9,,,,
[2021-01-05 23:47:28.604820] 
[2021-01-05 23:47:28.606189] +CSCON:0
[2021-01-05 23:47:31.585180] 
[2021-01-05 23:47:31.590671] +CEREG:2,CB52,02992008,9,,,,
[2021-01-05 23:47:33.395573] AT+NQSOS?
[2021-01-05 23:47:33.396220] OK
[2021-01-05 23:47:33.422853] AT+NSOSTF=1,10.64.220.77,6000,0x200,16,20202d31202020336262626262626262,3
[2021-01-05 23:47:33.425272] +CME ERROR: 4
[2021-01-05 23:47:33.759159] 
[2021-01-05 23:47:33.760753] +CSCON:1
[2021-01-05 23:47:34.563960] AT+NUESTATS
[2021-01-05 23:47:34.566249] Signal power:-608
[2021-01-05 23:47:34.568381] Total power:-551
[2021-01-05 23:47:34.570067] TX power:-80
[2021-01-05 23:47:34.571538] TX time:84
[2021-01-05 23:47:34.573273] RX time:1288
[2021-01-05 23:47:34.575404] Cell ID:43589640
[2021-01-05 23:47:34.576329] ECL:0
[2021-01-05 23:47:34.577475] SNR:285
[2021-01-05 23:47:34.579052] EARFCN:3740
[2021-01-05 23:47:34.580196] PCI:463
[2021-01-05 23:47:34.581550] RSRQ:-108
[2021-01-05 23:47:34.583609] OPERATOR MODE:2
[2021-01-05 23:47:34.583986] 
[2021-01-05 23:47:34.584579] OK
[2021-01-05 23:47:34.585609] AT+CSQ
[2021-01-05 23:47:34.587080] +CSQ:29,99
[2021-01-05 23:47:34.587451] 
[2021-01-05 23:47:34.588042] OK
[2021-01-05 23:47:46.119337] 
[2021-01-05 23:47:46.127590] +CEREG:5,CB52,02992008,9,,,00000101,01000001
[2021-01-05 23:47:56.149028] 
[2021-01-05 23:47:56.150839] +CSCON:0
[2021-01-06 00:47:47.517554] 
[2021-01-06 00:47:47.519493] +CSCON:1
[2021-01-06 00:47:47.677925] 
[2021-01-06 00:47:47.683176] +CEREG:0,0000,00000000,9,,,,
[2021-01-06 00:47:47.803548] 
[2021-01-06 00:47:47.805375] +CSCON:0
[2021-01-06 00:47:50.866418] 
[2021-01-06 00:47:50.872370] +CEREG:2,CB52,02992008,9,,,,
[2021-01-06 00:47:52.974657] 
[2021-01-06 00:47:52.976937] +CSCON:1
[2021-01-06 00:47:54.471278] 
[2021-01-06 00:47:54.478350] +CEREG:5,CB52,02992008,9,,,00000101,01000001
[2021-01-06 00:48:04.493371] 
[2021-01-06 00:48:04.495306] +CSCON:0
[2021-01-06 01:17:33.576854] AT+NQSOS?
[2021-01-06 01:17:33.577514] OK
[2021-01-06 01:17:33.603855] AT+NSOSTF=1,10.64.220.77,6000,0x200,16,20202d31202020346262626262626262,4
[2021-01-06 01:17:33.605202] 1,16
[2021-01-06 01:17:33.605589] 
[2021-01-06 01:17:33.606206] OK
[2021-01-06 01:17:34.609876] AT+NUESTATS
[2021-01-06 01:17:34.612471] Signal power:-32768
[2021-01-06 01:17:34.614973] Total power:-32768
[2021-01-06 01:17:34.616880] TX power:-200
[2021-01-06 01:17:34.618517] TX time:212
[2021-01-06 01:17:34.620364] RX time:11081
[2021-01-06 01:17:34.622553] Cell ID:43589640
[2021-01-06 01:17:34.623553] ECL:2
[2021-01-06 01:17:34.625076] SNR:-32768
[2021-01-06 01:17:34.627375] EARFCN:4294967295
[2021-01-06 01:17:34.628776] PCI:65535
[2021-01-06 01:17:34.630400] RSRQ:-32768
[2021-01-06 01:17:34.632533] OPERATOR MODE:2
[2021-01-06 01:17:34.632928] 
[2021-01-06 01:17:34.633582] OK
[2021-01-06 01:17:34.634639] AT+CSQ
[2021-01-06 01:17:34.636164] +CSQ:99,99
[2021-01-06 01:17:34.636545] 
[2021-01-06 01:17:34.637152] OK
[2021-01-06 01:17:35.355119] 
[2021-01-06 01:17:35.357285] +CSCON:1
[2021-01-06 01:17:35.481740] 
[2021-01-06 01:17:35.483681] +NSOSTR:1,4,1
[2021-01-06 01:17:35.610867] 
[2021-01-06 01:17:35.612466] +CSCON:0
[2021-01-06 01:17:36.316238] 
[2021-01-06 01:17:36.318299] +CSCON:1
[2021-01-06 01:17:46.554074] 
[2021-01-06 01:17:46.555795] +CSCON:0
[2021-01-06 01:47:56.795231] 
[2021-01-06 01:47:56.796943] +CSCON:1
[2021-01-06 01:47:56.955605] 
[2021-01-06 01:47:56.960740] +CEREG:0,0000,00000000,9,,,,
[2021-01-06 01:47:57.081227] 
[2021-01-06 01:47:57.082832] +CSCON:0
[2021-01-06 01:48:00.145346] 
[2021-01-06 01:48:00.150251] +CEREG:2,CB52,02992008,9,,,,
[2021-01-06 01:48:02.234715] 
[2021-01-06 01:48:02.236648] +CSCON:1
[2021-01-06 01:48:03.428833] 
[2021-01-06 01:48:03.437281] +CEREG:5,CB52,02992008,9,,,00000101,01000001
[2021-01-06 01:48:13.451046] 
[2021-01-06 01:48:13.453087] +CSCON:0
[2021-01-06 02:47:33.650981] AT+NQSOS?
[2021-01-06 02:47:33.651633] OK
[2021-01-06 02:47:33.678125] AT+NSOSTF=1,10.64.220.77,6000,0x200,16,20202d31202020356262626262626262,5
[2021-01-06 02:47:33.679000] 1,16
[2021-01-06 02:47:33.679391] 
[2021-01-06 02:47:33.680340] OK
[2021-01-06 02:47:34.683998] AT+NUESTATS
[2021-01-06 02:47:34.686573] Signal power:-32768
[2021-01-06 02:47:34.689008] Total power:-32768
[2021-01-06 02:47:34.690874] TX power:-200
[2021-01-06 02:47:34.692494] TX time:170
[2021-01-06 02:47:34.694390] RX time:10846
[2021-01-06 02:47:34.696579] Cell ID:43589640
[2021-01-06 02:47:34.697538] ECL:2
[2021-01-06 02:47:34.699053] SNR:-32768
[2021-01-06 02:47:34.701358] EARFCN:4294967295
[2021-01-06 02:47:34.702765] PCI:65535
[2021-01-06 02:47:34.704435] RSRQ:-32768
[2021-01-06 02:47:34.706510] OPERATOR MODE:2
[2021-01-06 02:47:34.706902] 
[2021-01-06 02:47:34.707523] OK
[2021-01-06 02:47:34.708591] AT+CSQ
[2021-01-06 02:47:34.710107] +CSQ:99,99
[2021-01-06 02:47:34.710495] 
[2021-01-06 02:47:34.711109] OK
[2021-01-06 02:47:35.355816] 
[2021-01-06 02:47:35.357409] +CSCON:1
[2021-01-06 02:47:35.481182] 
[2021-01-06 02:47:35.483518] +NSOSTR:1,5,1
[2021-01-06 02:47:35.611556] 
[2021-01-06 02:47:35.612889] +CSCON:0
[2021-01-06 02:47:37.915551] 
[2021-01-06 02:47:37.916920] +CSCON:1
[2021-01-06 02:47:48.157139] 
[2021-01-06 02:47:48.159302] +CSCON:0
[2021-01-06 02:48:06.076203] 
[2021-01-06 02:48:06.077909] +CSCON:1
[2021-01-06 02:48:06.236569] 
[2021-01-06 02:48:06.241004] +CEREG:0,0000,00000000,9,,,,
[2021-01-06 02:48:06.363457] 
[2021-01-06 02:48:06.364936] +CSCON:0
[2021-01-06 02:48:09.422560] 
[2021-01-06 02:48:09.426772] +CEREG:2,CB52,02992008,9,,,,
[2021-01-06 02:48:11.515682] 
[2021-01-06 02:48:11.517273] +CSCON:1
[2021-01-06 02:48:13.028551] 
[2021-01-06 02:48:13.036537] +CEREG:5,CB52,02992008,9,,,00000101,01000001
[2021-01-06 02:48:23.051886] 
[2021-01-06 02:48:23.053873] +CSCON:0
[2021-01-06 03:48:15.355722] 
[2021-01-06 03:48:15.357537] +CSCON:1
[2021-01-06 03:48:15.517337] 
[2021-01-06 03:48:15.522576] +CEREG:0,0000,00000000,9,,,,
[2021-01-06 03:48:15.642961] 
[2021-01-06 03:48:15.644904] +CSCON:0
[2021-01-06 03:48:18.702072] 
[2021-01-06 03:48:18.707680] +CEREG:2,CB52,02992008,9,,,,
[2021-01-06 03:48:20.796560] 
[2021-01-06 03:48:20.797924] +CSCON:1
[2021-01-06 03:48:22.014433] 
[2021-01-06 03:48:22.023023] +CEREG:5,CB52,02992008,9,,,00000101,01000001
[2021-01-06 03:48:32.037894] 
[2021-01-06 03:48:32.039374] +CSCON:0
[2021-01-06 04:17:33.825149] AT+NQSOS?
[2021-01-06 04:17:33.825770] OK
[2021-01-06 04:17:33.852437] AT+NSOSTF=1,10.64.220.77,6000,0x200,16,20202d31202020366262626262626262,6
[2021-01-06 04:17:33.853393] 1,16
[2021-01-06 04:17:33.853777] 
[2021-01-06 04:17:33.854637] OK
[2021-01-06 04:17:34.858156] AT+NUESTATS
[2021-01-06 04:17:34.860721] Signal power:-32768
[2021-01-06 04:17:34.863087] Total power:-32768
[2021-01-06 04:17:34.864950] TX power:-190
[2021-01-06 04:17:34.866539] TX time:184
[2021-01-06 04:17:34.868344] RX time:10854
[2021-01-06 04:17:34.870481] Cell ID:43589640
[2021-01-06 04:17:34.871407] ECL:2
[2021-01-06 04:17:34.872881] SNR:-32768
[2021-01-06 04:17:34.875166] EARFCN:4294967295
[2021-01-06 04:17:34.876539] PCI:65535
[2021-01-06 04:17:34.878122] RSRQ:-32768
[2021-01-06 04:17:34.880153] OPERATOR MODE:2
[2021-01-06 04:17:34.880532] 
[2021-01-06 04:17:34.881127] OK
[2021-01-06 04:17:34.882167] AT+CSQ
[2021-01-06 04:17:34.883684] +CSQ:99,99
[2021-01-06 04:17:34.884061] 
[2021-01-06 04:17:34.884656] OK
[2021-01-06 04:17:35.676278] 
[2021-01-06 04:17:35.678207] +CSCON:1
[2021-01-06 04:17:35.800397] 
[2021-01-06 04:17:35.803314] +NSOSTR:1,6,1
[2021-01-06 04:17:35.932146] 
[2021-01-06 04:17:35.933969] +CSCON:0
[2021-01-06 04:17:36.956268] 
[2021-01-06 04:17:36.957866] +CSCON:1
[2021-01-06 04:17:47.197859] 
[2021-01-06 04:17:47.200600] +CSCON:0

Aleksandra Klinkner

Hi Lorenz,

one of the reasons for the unexpected behavior you described could be the fact that your device performs a periodic Tracking Area Update (TAU). You can read about it here and here (click on 3GPP Connectivity --> Power Saving Features --> Tracking Area Updates.

I’m not an expert on this, but it seems to me that TAU is active on your module, but please double-check. Look here for more details.

TAU timer on most of NB-IoT networks in DT footprint lays between min. 1 h - 310 h. If this value was changed by you to 0, our network will automatically change it back to the minimum value of 1 hr.
You have a possibility of adjusting this value/extending the timer, as our network supports a dynamic TAU, meaning it will accept the value proposed by your UE as long as it fits into the 1-310 h window.

Stefan de Lange

@lorenz I checked the PSM timers and everything looks good to me. You request a TAU timer of 10 hours and it is also assigned as per the correct response of +CEREG. So I cannot explain why it doesn’t follow the set timers, it is very strange.

lorenz

@Aleksandra-Klinkner
Thanks for your input.

As @Stefan-de-Lange pointed out, I am setting the PSM Tau update to 10 hours and the network acknowledges it +CEREG:5,CB52,02992008,9,,,00000101,01000001

How should I proceed now?
There is a Quectel Webinar which I will attend tomorrow where I will ask that question, but in case I don’t get an answer, is there a way to open a dedicated support ticket?

I have a bc68 (same chipset as the bc95g) where I will try it this week, but I expect the results to be the same…

Just to point it out again. If this behaviour cannot be changed, it makes it very very hard to develop battery powered applications if the device registers to the network every hour…

Thorsten Krautscheid

Hi Lorenz,

from the log in one of your previous posts it is pretty obvious, that your module is loosing its connection periodically.

What is really weird, is the fact, the the connection losses sometimes happen at times at which the module should be in PSM (e.g. reconnect 3:48 am). That suggests that the module is not even entering PSM, although the appropriate timers have been assigned by the network. You could check this by activating the URC:

AT+NPSMR=1

which provides indication for entering/leaving PSM. If the module is indeed entering PSM, this is a clear indication, that the detachment is initiated by the module, as the network would not be able to detach a module gracefully during PSM.

It is hard to say what is going on here without a trace from either the module or the network, but this is definitely erroneous behavior. There is no mechanism in the network which is causing periodic detachments, except for missing TAUs, and they seem to be fine.
However, what can be ruled out is the scan for the HPLMN in roaming, as this would not interrupt PSM and the interval for this scan is larger than 1 hour in the DT NB-IoT network. Furthermore, it would not cause a connection loss, or at least not on a correctly working module.

Unfortunately, the log does not tell whether the signal quality has changed during the test. Initially a very good signal was observed, but for the following data events the signal quality is queried too early to provide meaningful values. Maybe you can adjust your script to query the signal quality right after the +CEREG: 5,… and +NSOSTR URCs, which should always yield meaningful values.

For further troubleshooting you can collect traces on the module and send them for inspection to Quectel via your distributor. To get a dedicated support ticket for an investigation on the network side you would have to contact 1nce.

Best regards,
Thorsten

lorenz

@Thorsten-Krautscheid
Hi Thorsten,
thanks a lot for your reply. I will test the things you suggested but it might be a few days until I reply here with the results.

Regards,
Lorenz