Modem Reset Loop Restriction Reset

[Sashi]

Use case:

A moving NRF9160 modem often needs to connect and retry many times in normal operation. there are some cases where they are towers, but not allowed on them. etc. As well as conditions where you are minimally connected to a tower due to poor signal, but must use whatever signal you have to send data. 

Question:

What is the recommended strategy to maintain maximum connected state on moving devices that go between different towers/ providers/states/etc over long periods of operating time of fielded hardware.    

taking into account the modem reset loop https://docs.nordicsemi.com/bundle/nwp_042/page/WP/nwp_042/intro.html where you may be traveling with a very weak signal and dropping in and out of connection often. 

Partially related to:

 RE: Is there a way to truly hard reset the nRF9160 without power cycling? 

[Charlie]

Hi Sashi,

Modem Reset Loop Restriction is actually used to protect your device in such condition you have entered. The keep searching and reconnect process will draw a lot of power and bring unstable connection to your high level application.

In product development phase, active reset loop restriction can be removed with the %XFACTORYRESET=0 command. The command should not be used for this purpose in the final product. If %XFACTORYRESET=0 is used, all modem data, including user-configurable data, is reset.

Best regards,

Charlie 

[Sashi]

So what is the recovery process for a final product in the field?  
If a device is placed in a location with marginal signal, will it eventually hit this counter limit and be offline forever?  

[Charlie]

Hi Sashi,

Here is a more detailed explanation from our modem team:

The modem reset loop restriction serves as a safeguard against unexpected issues with the cellular modem and application. Its purpose is to protect networks in case the application or cellular modem does not behave as expected. This protection ensures that the nRF91 device does not congest the network, for example, with excessive signaling (Attach requests), which could occur if the application and modem continuously reset and attempt new connections in a loop.

There is a distinction between "reset loop protection" and "connectivity." A moving nRF91 device is not affected by the modem reset loop protection. Losing connectivity is a normal occurrence for cellular devices, and connectivity is automatically restored when possible. For mobility enhancements and power saving options, there are AT commands that could be utilized to select best possible performance for mobility and power consumption. For example see. %XCOUNTRYDATA, %CONEVAL, %XDEEPSEARCH, %PERIODICSEARCHCONF, %REDMOB and many more.

Best regards,

Charlie

[Sashi]

Is there a way in code to know that you have reached modem reset loop count? 

[Charlie]

Hi Sashi,

There is no direct count can be readout.

You can enable AT%MDMEV=1 to get %MDMEV: RESET LOOP. Then count it at your application codes.

Best regards,

Charlie