NB-IOT in nomadic mode


  • We’re doing an experiment where our wearable NB-IoT device is ‘walked’ around the village by a test person. We want to sent (Tx) a measurement every minute. Obviously, the device will see different cells when walking around. To save battery, we do not want to reregister to the network every Tx. Instead we would like to stay connected to one cell as long as possible, but detect if the current cell is out of range and then connect to the nearest cell. Question: how to detect when a signal is lost? CGATT or COPS do not seem to provide reliable information for this. Any suggestions ?



  • If I understand your question correctly: yes, this should be possible. with Long Periodic TAU: https://forum.iot.t-mobile.nl/topic/41/power-saving-met-nb-iot/

    @Jasper @Richard-Marijs @Eric-Barten @ericbarten

    Do you know when we will support Long Periodic TAU?



  • @afzal_m From recent experiments we noticed that automatic cell hand-over seems to work now, see separate treat on “Interessante RSSI metingen in de auto”. I.e. the system (modem + network) seems to be able to connect to a ‘better’ cell when moving around, even at high speed (80km/h), without intervention from the application software on the crowduino.

    Still interesting to learn:

    • Will this also work abroad and with other MNO’s (NB-IOT interoperability question) ?

    • What if connection is lost after all, e.g. due to a bad signal, how to detect that in a reliable manner? Using parameters CSQ=99 or RSRP=0 does not seem to be reliable. Is there a white paper that describes a solid solution?

    • NB-IOT provides various parameters to minimize power consumption; T3314, T3324, etc. I’m wondering how to apply those parameters in the most efficient way. And also what the impact is, e.g. on responsiveness, when changing these parameters. Is there a white paper that demonstrates adequate use of these parameters. And when will they be supported (roadmap question), as experiments have shown that these parameters currently seem to have no noticeable effect.



  • @felixdonkers said in NB-IOT in nomadic mode:

    Will this also work abroad and with other MNO’s (NB-IOT interoperability question) ?

    Definitely 3gpp standard will be inter operable across all operators global…
    The latest non-backwards compatible change happened during rel 13… but this is a rare event… Not all operators have this change implemented but this will be resolved in the next couple of months… And this has only some effects on PSM I believe.

    Today read: "GSMA counts 31 NB-IoT launches to date… " As far as I can see is the NB-Iot rollout pace a lot faster than Cat-M1…

    What if connection is lost after all, e.g. due to a bad signal, how to detect that in a reliable manner? Using parameters CSQ=99 or RSRP=0 does not seem to be reliable. Is there a white paper that describes a solid solution?

    I would assume that connection only gets lost when after device misses its periodic registration requirements…
    AT+CGATT? if returns 1 the device is attached.

    NB-IOT provides various parameters to minimize power consumption; T3314, T3324, etc. I’m wondering how to apply those parameters in the most efficient way. And also what the impact is, e.g. on responsiveness, when changing these parameters. Is there a white paper that demonstrates adequate use of these parameters. And when will they be supported (roadmap question), as experiments have shown that these parameters currently seem to have no noticeable effect.

    AT+CPSMS command influences this.

    White paper covering these topics:
    NB-IoT Deployment Guide to Basic Feature set Requirements.pdf

    regards,


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