LTE connection doesn't work (v1.17.3.b1) (LTE simulator)



  • Hi,
    I upgrade the firmware to current version, and now LTE connection doesn't work.
    I was using v1.15, and I set the APN and the band in lib3GPP.c file.

    I tried to attach using lte.attach(band=3), but return False.

    I also tried to use these commands:

    lte = LTE()
    lte.send_at_cmd('AT+CFUN=0')
    lte.send_at_cmd('AT+CGDCONT=1,"IP","my.apn"')
    lte.send_at_cmd('AT+CFUN=1')

    while not lte.isattached():
    pass

    lte.connect()
    while not lte.isconnected():
    pass

    But I got no success.

    Is there another command that I have to use? Anyone got success trying to connect with LTE (Cat M1)?



  • @jmarcelino

    We got success changing "UE Modes of Operation for EPS", using this AT command: AT+CEMODE

    Supported modes are:

    0 - PS mode 2 of operation
    2 - CS/PS mode 2 of operation (default value)

    We change to PS mode (0) using AT+CEMODE=0

    This change solved the issues related to LTE-M and NB-IoT connection.

    For LTE-M:

    send_at_cmd_pretty('AT+CFUN=0')
    send_at_cmd_pretty('AT!="clearscanconfig"')
    send_at_cmd_pretty('AT!="addscanfreq band=3 dl-earfcn=1250"')
    send_at_cmd_pretty('AT+CGDCONT=1,"IP","lte.labcuritiba.br"')
    send_at_cmd_pretty('AT+CEMODE=0')
    send_at_cmd_pretty('AT+CEREG=2')
    send_at_cmd_pretty('AT+CFUN=1')
    
    while not lte.isattached():
        time.sleep(1)
        send_at_cmd_pretty('AT!="showphy"')
        send_at_cmd_pretty('AT!="fsm"')
        send_at_cmd_pretty('AT+CEREG?')
    
    lte.connect()
    while not lte.isconnected():
        pass
    

    For NB-IoT:

    send_at_cmd_pretty('AT+CFUN=0')
    send_at_cmd_pretty('AT!="clearscanconfig"')
    send_at_cmd_pretty('AT!="addscanfreq band=3 dl-earfcn=1250"')
    send_at_cmd_pretty('AT!="zsp0:npc 1"')
    send_at_cmd_pretty('AT+CGDCONT=1,"IP","lte.labcuritiba.br"')
    send_at_cmd_pretty('AT+CEMODE=0')
    send_at_cmd_pretty('AT+CFUN=1')
    

    Thank you for your support.



  • @luppi
    I can't see many options remaining other than there are some changes coming on the next firmware which may help but I don't have a planned release date to share.

    You can try addScanBand band=3 (without earfcn) instead of addscanfreq maybe that would help.



  • @jmarcelino any ideas about what is the problem? Is there another AT command that is needed? Thanks



  • @jmarcelino

    I wait for more than 3 minutes, and when the Frequency Hypothesis RF (Hz) is 6000 , RRC TOP FSM and RRC SEARCH FSM change to INITIAL, but nothing happens after this and starts again. The others output, Frequency Hypothesis RF (Hz) varies between 2000 and 4000, and RRC TOP FSM is SCANNING and RRC SEARCH FSM is WAIT_CELL_ID. The AGC/AFC parameters change every time, if you need all values and outputs, I can send by email. Thank you very much.

    DL SYNCHRO STATISTICS

    Synchro state                         : OFF
    PPU SIB1 ACQ watchdog                 : 0
    Frequency Hypothesis RF  (Hz)         : 6000
    RSRP (dBm)                            : -21474836.00
    RSRQ  (dB)                            : 0.00
    Channel estimation state (Cell-spec.) : LOW CINR
    Channel estimation state (UE-spec.)   : LOW CINR
    Channel estimation state (MBSFN)      : LOW CINR
    Channel estimation CINR               : 0.00
    Channel length                        : SHORT
    AGC
    AGC RX gain (dB)                      : 46.40
    RX PSD BO (dBFs)                      : -20.88
    RX PSD (dBm)                          : -87.16
    Noise level RS (dBm)                  : 83463.44
    Digital gain (dB)                     : 4.17
    CINR RS (dB)                          : 0.00
    NARROWBANDS
    Last DL NB                            : Central
    Last UL NB                            : 0
    AFC
    Frequency offset RF  (Hz)             : 954
    Frequency offset BB  (Hz)             : 0
    PBCH
    MIB received quantity                 : 0
    MIB timeout quantity                  : 0
    

    OK

    SYSTEM FSM

    +--------------------------+--------------------+
    |            FSM           |        STATE       |
    +--------------------------+--------------------+
    | RRC TOP FSM              |INITIAL             |
    | RRC SEARCH FSM           |INITIAL             |
    | RRC ACTIVE FSM           |NULL                |
    | PMM PLMN FSM             |PARKING             |
    | EMM MAIN FSM             |NULL                |
    | EMM AUTH FSM             |NULL                |
    | EMM CONN FSM             |NULL                |
    | EMM TAU FSM              |NULL                |
    | EMM TEST FSM             |NULL                |
    | ESM BEARER FSM           |BEARER_NULL         |
    | SMS MT FSM               |IDLE                |
    | SMS MO FSM               |IDLE                |
    | HP MAIN FSM              |IDLE                |
    | HP USIM FSM              |READY               |
    | HP SMS MO FSM            |IDLE                |
    | HP SMS MT FSM            |IDLE                |
    | HP CAT FSM               |IDLE                |
    +--------------------------+--------------------+
    

    OK

    +CEREG: 2,4

    OK



  • Thanks for that @luppi but it'd be good to know if this every changes between cycles.

    RRC TOP FSM should change to SCANNING and what's interesting is what happens afterwards.



  • @jmarcelino

    output:

    DL SYNCHRO STATISTICS

    Synchro state                         : OFF
    PPU SIB1 ACQ watchdog                 : 0
    Frequency Hypothesis RF  (Hz)         : 0
    RSRP (dBm)                            : 0.00
    RSRQ  (dB)                            : 0.00
    Channel estimation state (Cell-spec.) : LOW CINR
    Channel estimation state (UE-spec.)   : LOW CINR
    Channel estimation state (MBSFN)      : LOW CINR
    Channel estimation CINR               : 0.00
    Channel length                        : SHORT
    AGC
    AGC RX gain (dB)                      : 0.00
    RX PSD BO (dBFs)                      : 0.00
    RX PSD (dBm)                          : 0.00
    Noise level RS (dBm)                  : 0.00
    Digital gain (dB)                     : 0.00
    CINR RS (dB)                          : 0.00
    NARROWBANDS
    Last DL NB                            : 0
    Last UL NB                            : 0
    AFC
    Frequency offset RF  (Hz)             : 0
    Frequency offset BB  (Hz)             : 0
    PBCH
    MIB received quantity                 : 0
    MIB timeout quantity                  : 0
    

    OK

    SYSTEM FSM

    +--------------------------+--------------------+
    |            FSM           |        STATE       |
    +--------------------------+--------------------+
    | RRC TOP FSM              |STOPPED             |
    | RRC SEARCH FSM           |NULL                |
    | RRC ACTIVE FSM           |NULL                |
    | PMM PLMN FSM             |NULL                |
    | EMM MAIN FSM             |NULL                |
    | EMM AUTH FSM             |NULL                |
    | EMM CONN FSM             |NULL                |
    | EMM TAU FSM              |NULL                |
    | EMM TEST FSM             |NULL                |
    | ESM BEARER FSM           |BEARER_NULL         |
    | SMS MT FSM               |IDLE                |
    | SMS MO FSM               |IDLE                |
    | HP MAIN FSM              |IDLE                |
    | HP USIM FSM              |READY               |
    | HP SMS MO FSM            |IDLE                |
    | HP SMS MT FSM            |IDLE                |
    | HP CAT FSM               |IDLE                |
    +--------------------------+--------------------+
    

    OK

    +CEREG: 2,0

    OK



  • @luppi

    Can you add some debug please

    import time
    from network import LTE
    
    
    lte = LTE()
    
    def send_at_cmd_pretty(cmd):
        response = lte.send_at_cmd(cmd).split('\r\n')
        for line in response:
            print(line)
    
    send_at_cmd_pretty('AT+CFUN=0')
    send_at_cmd_pretty('AT!="clearscanconfig"')
    send_at_cmd_pretty('AT!="addscanfreq band=3 dl-earfcn=1250"')
    send_at_cmd_pretty('AT+CGDCONT=1,"IP","my.apn"')
    send_at_cmd_pretty('AT+CEREG=2')
    send_at_cmd_pretty('AT+CFUN=1')
    
    while not lte.isattached():
        time.sleep(1)
        send_at_cmd_pretty('AT!="showphy"')
        send_at_cmd_pretty('AT!="fsm"')
        send_at_cmd_pretty('AT+CEREG?') 
    

    And look at the output especially result from CEREG

    Thanks



  • @jmarcelino

    The same.
    I am using band=3 earfcn=1250, so I tried these commands too:

    lte.send_at_cmd('AT+CFUN=0')
    lte.send_at_cmd('AT!="clearscanconfig"')
    lte.send_at_cmd('AT!="addscanfreq band=3 dl-earfcn=1250"')
    lte.send_at_cmd('AT+CGDCONT=1,"IP","my.apn"')
    lte.send_at_cmd('AT+CEREG=2')
    lte.send_at_cmd('AT+CFUN=1')

    But I get stuck in attachement



  • @luppi
    As below please try adding

    lte.send_at_cmd('AT+CEREG=2')

    to your setup code (ideally after setting the APN)

    Without it it will not work.



  • @jmarcelino

    In attachment.



  • @jmarcelino

    We are using LTE band 3 on a Nokia FL17A eNB and an EPC Simulator that gives us MME/S-GW/P-GW/HSS functionality (so we can basically emulate any LTE network). Before the firmware upgrade, the connection worked normally.



  • Ok I noticed a problem, you need to add the last line as below

    lte = LTE()
    lte.send_at_cmd('AT+CFUN=0')
    lte.send_at_cmd('AT+CGDCONT=1,"IP","my.apn"')
    lte.send_at_cmd('AT+CFUN=1')
    
    lte.send_at_cmd('AT+CEREG=2')
    


  • @luppi
    Thanks, where is it "stuck" on attachment or on connect?



  • This post is deleted!


  • @luppi
    What is your operator?


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