SIM shutdown does not happen during the e-DRX cycle greater than 60 seconds on NRF9151 DK

[mnjLC]

We recently got the NRF9151-DK and were trting to measure the e-DRX current on the system working on CAT-M1 network. The NRF9151 DK is loaded with Serial LTE Modem application ( Default application that it was shipped with )and Modem firmware v2.0.0 ( Default FW that it was shipped with ). According to this post we have set the follwing at commands 

at+cfun=0

AT%XDATAPRFL=0 // sets the low power mode

AT+SSRDA=0,1,0 // sim shut shutdown

at+cfun=1

at+cedrx=2,4,”0101”

We are still seeing 35uA of floor current during e-DRX cycle. We feel this is a bug in the pre lodaed FW. Can someone from nordic try it on their NRF9151-DK and share the results?. I all attaching the PPK2 trace with this post.

Thanks!

nrf9151_eDRX_80_PTW_1_1NCE_NoShutoff.ppk

[Didrik Rokhaug]

papatel said:

After further research I believe that Noridic is offering access to its SoftSIM platform to everyone who wants it.  It's just that this is not likely a standard that will be widely accepted outside of Nordic (not GSMA adopted) so it's hard for MVNO's and carriers to justify the implementation work until there is a critical mass of adopters.

As far as I know (I will try to get this confirmed though) there is no standard interface for SoftSIMs. Though even if it were, there would probably be some porting needed anyway, to adapt a particular SoftSIM solution to the relevant HW and SW platform.

papatel said:

Onomondo may just be the first instance and more will follow with time.  Either way, this is super concerning and I'm not sure we will use Nordic's SoftSIM offering.  My company is looking 5 years down the line and having several million devices deployed on a dead SoftSIM platform doesn't seem particularly appealing.

If you haven't already, I recommend you take this up with your local sales representative. They should have a better overview of any other potentila SoftSIM providers. If you don't know how to contact your local sales representative, you can send me a private message with your location, and I will provide the contact details.

papatel said:

Or when we have connectivity problems we don't get support from network providers.

In my experience, Onomondo is quite helpful when it comes to looking into connectivity problems, and on their web platform you can get network logs. Though as an MVNO, they of course only cover the core network. If you are thinking of RAN problems, you will have the same problem with any MVNO regardless of the type of SIM, and similarly if you use an MNO, but are roaming on a different network.

papatel said:

Regarding the response from your SIM expert, I'm trying to read between the lines that proper implementations of suspend don't actually wear out the flash while SIM shutfoff certainly can.  Can you please check that this assumption is correct? 

I will check and come back to you.

[Didrik Rokhaug]

Didrik Rokhaug said:

As far as I know (I will try to get this confirmed though) there is no standard interface for SoftSIMs.

Our SIM expert also doesn't know of any standard interface for SoftSIMs.

Didrik Rokhaug said:

papatel said:

Regarding the response from your SIM expert, I'm trying to read between the lines that proper implementations of suspend don't actually wear out the flash while SIM shutfoff certainly can.  Can you please check that this assumption is correct? 

I will check and come back to you.

"Suspend uses flash to store the internal state of SIM card, so I think that a proper implementation could be expected to tolerate large number of write cycles. Such SIM card should not wear out too soon due to use of suspend functionality for power saving."