Lowest Power Communication Protocol

[rytabb]

I am looking to use the nRF9160 in eDRX intervals of 2.7 minutes (no PSM). The goal of the device is to be dormant until receiving a command to begin transmitting its location. I am looking for a way to initiate that command over the network in the way that would be most power effective considering this command may only be send once every few months. One idea that comes to mind is SMS. Would that be any more efficient than the alternatives as the device won't have to establish a connection to an MQTT or HTTP server and check for a message every time it goes through an eDRX cycle?

Thanks!! 

[Carl Richard]

Hi, Rytabb!

I do believe SMS would be the most efficient option for your case. Could I also ask, what are you latency requirements? If you don't expect the signal more often than every few months it could be a good idea to consider a longer eDRX interval, as waking up every 2.7 minutes can be quite power demanding.

Best regards,
Carl Richard

[rytabb]

Hi Carl,

Thanks for the reply. Having latency under 5 minutes is very important and that is why we went with those settings. Glad to know SMS is the way to go. I appreciate your help.

-Ryan

[Carl Richard]

Hi again!

Then it's very understandable. Best of luck with the project!

Best regards,
Carl Richard

[rytabb]

Hi Carl,

I actually have a follow up question if you don't mind.

I am looking at using a Hologram SIM for this project, and they offer two different SMS messaging protocols.

One is circuit-switched SMS (old school, requires a dedicated number for the device) and SMS via Hologram Cloud, which is sent over data. Are either of these options, to your knowledge, fine?

My goal is to allow the network to tell the device that there is a message when it cycles, rather than having the device connect and check as I mentioned previously.

Thanks again for your help.

-Ryan

[Carl Richard]

Hi again!

I'm not very familiar with Hologram and their SMS messaging protocols, but from what I see when I read about them the SMS via Hologram Cloud requires the establishment of a TCP/IP link. This can be quite demanding when it comes to power consumption. Hence, I believe the circuit-switched SMS is the way to go.

On the note of circuit-switched SMS: We support SMS over SGs (service gateways), i.e. LTE way of implementing "circuit switched" services for SMS. Our default configuration is to attempt registration using combined procedures, i.e. by default we make an attempt to do registration also to SMS over SGs. SMS should work with our device, given that Hologram has SMS service activated in local LTE network that is providing the radio interface for Hologram(roaming agreements between Hologram and local LTE carrier).

I'm not exactly sure how the above applies to Hologram, but I recommend that you send an inquiry to them regarding this.

Best regards,
Carl Richard