| Re: [leshan-dev] Conceptual questions for using LWM2M with NB-IoT |
|
Hi Ralf, first at all: I use now Californium, extended by a AT-command driver over USB-serial, together with a CAT-NB modem, since this year successfully. I use DTLS-CID and for the very most cases,
my modem makes it in 4s from PSM deep-sleep into the cloud and back with a response (if the messages stay in the limit of the 330 MTU => 280 payload). I don’t use the communication patterns of LwM2M, so my device sends requests to the coap-cloud-server and
get responses back. In your case, I’m not sure, what you assume as your “traffic pattern”. 1.
Registration The LwM2M registration interface is something, where your (I guess in your case sleeping) device will report its identity (update registration) in order to exchange its data
with the server. Do you expect, that this happens only every couple of months? If you assume, that e.g. your device exchanges data say every day, then my expectation would be, that: -
You need a dtls handshake -
You need a registration update -
Your exchange your data-messages So for me, save the registration maybe not the big win.
2. Observe I guess, you search for “queue mode”, but that will be more a question for Simon. Mit freundlichen Grüßen / Best regards Von: leshan-dev-bounces@xxxxxxxxxxx <leshan-dev-bounces@xxxxxxxxxxx>
Im Auftrag von Ralf Rottmann Hi everyone, I hope you guys are doing okay during these times of the pandemic! We are currently evaluating the use of LWM2M via CoAP for low-powered NB-IoT devices. I have two key questions and would love if anybody could shed some light on those for me. 1. Registration It is my understanding that typically LWM2M devices extend their registration regularly. However, in a scenario where we have to optimize for battery life, we ideally would eliminate the need to “re-register”. Would it be possible to sort
of register devices in the factory (factory provisioning) and configure Leshan in a way that it does not require registration extending for 12 to 18 months? 2. Observe NB-IoT does not cater for cloud initiated requests to devices. Typically, NB-IoT devices wake up and send date from the device to the cloud and go back to sleep, so cloud initiated requests cannot reach them. Does that completely
rule out observe use cases for NB-IoT devices? Will LWM2M really work as expected given this “major” constraint? Thanks for taking the time to look into this. Ralf |