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  • Case ID: 292661
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Modem stuck at searching network

Martin Vitek

Hello,

I have a custom board with nRF9160. Modem FW version 1.3.2, nRF Connect SDK 2.0.0.

I'm using LTE link controller lib for connection to the NB-IoT network. The problem is that sometimes the modem gets stuck in LTE_LC_NW_REG_SEARCHING state.

This is how a standard connection looks like:

Network registration status changed: 2
LTE cell changed: Cell ID: 1359904, Tracking area: 42100
LTE_LC_EVT_LTE_MODE_UPDATE: LTE mode 9
RRC mode: Connected
Network registration status changed: 5
Connected - roaming
PSM parameter update: TAU: 28800, Active time: 4294967295
RRC mode: Idle
LTE cell changed: Cell ID: 1089312, Tracking area: 42100
LTE cell changed: Cell ID: 1359904, Tracking area: 42100
LTE cell changed: Cell ID: 1089312, Tracking area: 42100

And failed connection looks like this. And it seems that it is doing this indefinitely.

Network registration status changed: 2
LTE cell changed: Cell ID: 1089312, Tracking area: 42100
LTE_LC_EVT_LTE_MODE_UPDATE: LTE mode 9
RRC mode: Connected
RRC mode: Idle
LTE cell changed: Cell ID: 4294967295, Tracking area: 4294967295
LTE_LC_EVT_LTE_MODE_UPDATE: LTE mode 0
LTE cell changed: Cell ID: 72266582, Tracking area: 11419
LTE_LC_EVT_LTE_MODE_UPDATE: LTE mode 9
RRC mode: Connected
RRC mode: Idle
LTE cell changed: Cell ID: 4294967295, Tracking area: 4294967295
LTE_LC_EVT_LTE_MODE_UPDATE: LTE mode 0
LTE cell changed: Cell ID: 72266669, Tracking area: 65000
LTE_LC_EVT_LTE_MODE_UPDATE: LTE mode 9
RRC mode: Connected
RRC mode: Idle
LTE cell changed: Cell ID: 4294967295, Tracking area: 4294967295
LTE_LC_EVT_LTE_MODE_UPDATE: LTE mode 0

I probably got this behavior also using at_client:

*** Booting Zephyr OS build v3.0.99-ncs1  ***
The AT host sample started
AT+CFUN=1
OK
AT+CFUN?
+CFUN: 1
OK
AT+CGSN=1
+CGSN: "352656100526519"
OK
AT+CGMI
Nordic Semiconductor ASA
OK
AT+CGMM
nRF9160-SICA
OK
AT+CGMR
mfw_nrf9160_1.3.2
OK
AT+CEMODE?
+CEMODE: 0
OK
AT%XCBAND=?
%XCBAND: (1,2,3,4,5,8,12,13,17,19,20,25,26,28,66)
OK
AT+CMEE?
+CMEE: 0
OK
AT+CMEE=1
OK
AT+CNEC?
+CNEC: 0
OK
AT+CNEC=24
OK
AT+CGEREP?
+CGEREP: 0,0
OK
AT+CGDCONT?
OK
AT+CGACT?
OK
AT+CGEREP=1
OK
AT+CIND=1,1,1
OK
AT+CEREG=5
OK
AT+CEREG?
+CEREG: 5,4
OK
AT%CESQ=1
OK
AT+CESQ
+CESQ: 99,99,255,255,255,255
OK
AT%XSIM=1
OK
AT%XSIM?
%XSIM: 1
OK
AT+CPIN?
+CPIN: READY
OK
AT+CPINR="SIM PIN"
+CPINR: "SIM PIN",3
OK
AT+CIMI901288002251827
OK
%CESQ: 50,2,23,3
+CEREG: 2,"A474","00109F20",9
+CNEC_EMM: 15
+CEREG: 2,"A474","00109F20",9,0,15
%CESQ: 255,0,255,0
+CEREG: 2
%CESQ: 44,2,19,2
+CEREG: 2,"FDE8","044EB3AC",9
%CESQ: 44,2,28,4
+CNEC_EMM: 15
+CEREG: 2,"FDE8","044EB3AC",9,0,15
%CESQ: 255,0,255,0
+CEREG: 2
%CESQ: 52,2,27,3
+CEREG: 2,"2C9B","044EB356",9
+CNEC_EMM: 15
+CEREG: 2,"2C9B","044EB356",9,0,15
%CESQ: 255,0,255,0
+CEREG: 2
%CESQ: 48,2,22,3
%CESQ: 50,2,30,4
%CESQ: 51,2,25,3
%CESQ: 51,2,30,4
%CESQ: 50,2,25,3
%CESQ: 50,2,30,4
%CESQ: 48,2,23,3
%CESQ: 49,2,28,4

Parents
  • 0

    Hello Martin, 

    I'm using LTE link controller lib for connection to the NB-IoT network. The problem is that sometimes the modem gets stuck in LTE_LC_NW_REG_SEARCHING state.

    Although I cannot find LTE_LC_NW_REG_SEARCHING in the attached logs, we can find the answer here: 

    +CEREG: 2,"A474","00109F20",9,0,15
%CESQ: 255,0,255,0
+CEREG: 2
%CESQ: 44,2,19,2
+CEREG: 2,"FDE8","044EB3AC",9
%CESQ: 44,2,28,4
+CNEC_EMM: 15
+CEREG: 2,"FDE8","044EB3AC",9,0,15
%CESQ: 255,0,255,0
+CEREG: 2
%CESQ: 52,2,27,3
+CEREG: 2,"2C9B","044EB356",9
+CNEC_EMM: 15
+CEREG: 2,"2C9B","044EB356",9,0,15
%CESQ: 255,0,255,0
+CEREG: 2

    The network rejects connection attempts to different cells performed by the modem with <reject_cause> 15.  

    According to 3GPP TS 24.301:

    Cause #15 – No suitable cells in tracking area 
This EMM cause is sent to the UE if it requests service, or if the network initiates a detach request, in
a tracking area where the UE, by subscription, is not allowed to operate, but when it should find
another allowed tracking area or location area in the same PLMN or an equivalent PLMN.

    In other words, this is a subscription issue with your SIM card, and you should talk to the carrier here. 

    Regards, 

    Markus 

Reply
  • 0

    Hello Martin, 

    I'm using LTE link controller lib for connection to the NB-IoT network. The problem is that sometimes the modem gets stuck in LTE_LC_NW_REG_SEARCHING state.

    Although I cannot find LTE_LC_NW_REG_SEARCHING in the attached logs, we can find the answer here: 

    +CEREG: 2,"A474","00109F20",9,0,15
%CESQ: 255,0,255,0
+CEREG: 2
%CESQ: 44,2,19,2
+CEREG: 2,"FDE8","044EB3AC",9
%CESQ: 44,2,28,4
+CNEC_EMM: 15
+CEREG: 2,"FDE8","044EB3AC",9,0,15
%CESQ: 255,0,255,0
+CEREG: 2
%CESQ: 52,2,27,3
+CEREG: 2,"2C9B","044EB356",9
+CNEC_EMM: 15
+CEREG: 2,"2C9B","044EB356",9,0,15
%CESQ: 255,0,255,0
+CEREG: 2

    The network rejects connection attempts to different cells performed by the modem with <reject_cause> 15.  

    According to 3GPP TS 24.301:

    Cause #15 – No suitable cells in tracking area 
This EMM cause is sent to the UE if it requests service, or if the network initiates a detach request, in
a tracking area where the UE, by subscription, is not allowed to operate, but when it should find
another allowed tracking area or location area in the same PLMN or an equivalent PLMN.

    In other words, this is a subscription issue with your SIM card, and you should talk to the carrier here. 

    Regards, 

    Markus 

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