Hello,
I'm doing some initial investigation with the nrf9160 DK and after some reading and testing, it's clear that significant part of the low-power capabilities is determined by the SIM Card itself and not nrf9160 alone.
For example, the iBasis SIM card shipped together with the DK doesn't seem to like PSM mode when in roaming (Australia, Telstra Network in my case).
But the real issue seems to be the missing capability of a SIM Card to be turned OFF during the eDRX "quiet" periods. For example, in my case, the floor power consumption for PSM mode is around 6uA while the floor consumption in eDRX is above 50uA.
By measuring the SIM_1V8 line (TP20 in my DK 0.8.3 board) voltage it's easy to note that the eDRX mode is not powering the SIM Card off, even when setting it to very long intervals (1100b or 1310.72 seconds).
Moving forward I would like to know how I can identify if a SIM Card supports being powered OFF during eDRX apart from running a connection test? Is there any command I can use to read the SIM Card capabilities?
I can see some comments on this topic: https://devzone.nordicsemi.com/nordic/cellular-iot-guides/b/hardware-design/posts/measuring-psm-idle-current-on-the-nrf91-dk, where Timo Vayrynen mention this is specified at 3gpp 31.102 Chapter 4.2.18, but I'm not sure how to request such feature for my SIM Card provider/Mobile Telecom?
In a realistic scenario, how likely is to find SIM Cards that support being powered OFF in an eDRX cycle under 81.92 seconds?
Any help/guidance is appreciated.
Regards,
Mike M.