Troubleshoot GPy connect to NB-IoT



  • Hi,

    Would like to seek advise on how to troubleshoot connecting GPy to NB-IoT network.

    All firmware upgraded to the latest, and tested together with operator (Ericsson & use in-band), it seems cannot attach to the network, wonder if there is any AT command / suggested way to see whats wrong with it.

    What I have tried so far in terminal:

    from network import LTE
    lte = LTE()
    lte.send_at_cmd('AT+CFUN=0')
    '\r\nOK\r\n'
    lte.send_at_cmd('AT!="clearscanconfig"')
    '\r\n\r\nOK\r\n'
    lte.send_at_cmd('AT!="addscanfreq band=8 dl-earfcn=3741"')
    '\r\n\r\nOK\r\n'
    lte.send_at_cmd('AT!="zsp0:npc 1"')
    '\r\n\r\nOK\r\n'
    lte.send_at_cmd('AT+CGDCONT=1, "IP", "iotest"')
    '\r\nOK\r\n'
    lte.send_at_cmd('AT+CFUN=1')
    '\r\nOK\r\n'
    print (lte.isattached())
    False

    lte.send_at_cmd('AT+CEREG?')
    '\r\n+CEREG: 2,4\r\n\r\nOK\r\n'
    lte.send_at_cmd('AT+COPS=?')
    ''
    By the way, what does lte.send_at_cmd('AT!="zsp0:npc 1"') do?

    Cheers,
    Vincent



  • @vli
    did you find a way to enable scrambling?
    having the same problem here



  • Hi All,

    Simply if there is a way to enable NB-IoT Scambling Feature.

    Cheers
    vli



  • Hi @jmarcelino

    Tried by giving sufficient time after CFUN=1, still gives CEREG: 2,4.

    Further discussed with their Engineer, they had similar experience (unable to attach) with other vendor's product and is wondering if the current radio firmware on GPy do comply/implemented with the Change Request specified in the 3GPP TS 36.211 as highlighted in the following table.

    0_1522324577194_3GPP_TS_36.211_V13.6.0.PNG

    Regards,

    Vincent



  • Hi @jmarcelino

    The EARFCN in use for LTE is 3750, the in-band EARFCN for NB-IoT is 3741 - thats the one reported from another working EVB from other chipset maker. I tried both but with no luck.

    I will try again with longer wait time before checking if is attached.

    Thx!



  • Hi @vli

    I take it that your dl-earfcn=3741 is correct for the network you're using?

    Have you given sufficient time after CFUN=1 (30+ seconds)?

    The "zsp0:npc 1" are internal Sequans commands unfortunately there's no public information on those we can share.


 

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