Testing loss of network

[allard.p]

I want to optimize/ test the power usage of the network search after a network has been lost. I want to try different %PERIODICSEARCHCONF configurations, and measure the required power usage of the search pattern. But, how do I do this? I assume disconnecting the antenna can cause damage to the nRF9160? I do not have access to a virtual/local LTE cell, or a faraday's cage to block the signal. I'm also located very near to a cell tower, so the signal is quite strong. Any tips?

One solution that I tried is to block all networks at our provider for the SIM of the test subject. This triggered a disconnect and a search. This search became stuck, even after re-enabling all networks, the device never connected. In this stuck state I observed small peaks of 100mA every 700ms, which is very high for our low power requirements. I guess the modem was not in the normal 'searching after loss of network' state, and this is why the %PERIODSEARCHCONF profile was ignored? Will the modem ever recover from this? I can try to reproduce and create a modem log if my description is not clear.

[Elfving]

Hello Allard,

Well optimally you would use a test chamber where the device connects to a test network which can be turned off and on.

Alternatively you can try either a microwave (without turning it on of course), wrapping it in aluminum foil or taking it down in a parking garage or tunnel.

One solution that I tried is to block all networks at our provider for the SIM of the test subject.

I am not familiar with this way of doing it, but it might be that this results in a different response than if it were to simply lose signal quality.

Regards,

Elfving

[allard.p]

Is there some documentation about the behavior of the modem vs. EMM reset cause? I'm trying to reproduce the modem stuck situation,  now with modem trace enabled. I'm not able to get the modem stuck anymore, but the behavior is still a bit strange.The modem is now continuously searching for networks:

[02:39:59.125,244] <inf> cellular: Network registration status: LTE_LC_NW_REG_NOT_REGISTERED
[02:40:27.854,156] <inf> cellular: Network registration status: LTE_LC_NW_REG_SEARCHING

A new search is immediately started after failing to find a network. This is not what I configured. I set %XDATAPRFL to 0, which should mean a search pattern of:

AT%PERIODICSEARCHCONF=0,0,0,1,"0,10,40,,5","1,300,600,1800,1800,3600"

I can see the following EMM reset causes in the logs:

Cause: PLMN not allowed (11)

Cause: No Suitable Cells In tracking area (15)

Cause: EPS services not allowed in this PLMN (14)