Is support for nRF91 "Full modem FOTA update" required by Nordic or cellular carriers?

[droberson]

Hello,

We are in the feasibility phase of updating a product to include a nRF9151 modem connected to a nRF52840 via a single UART. The modem will operate in SLM (Serial LTE Modem) mode. This must fit on our existing PCB board size which is already quite small, so board space is limited. In regard to nRF91 modem FOTA, my understanding is that in order to perform a "full modem" FOTA update (as opposed to delta FOTA update), an external flash of 4 MB or larger is required to be connected directly to the nRF91 modem to store the downloaded firmware image. It is also my understanding that delta FOTA updates support updating only from one minor version to another (For example, 1.1.1 to 1.1.2), and full modem updates are required to update from one major version to another (For example, 1.1.x to 1.2.x). We are trying to determine if we can do away with the 4 MB flash and the need to support full modem FOTA updates, and only support delta FOTA updates.

Question: Is there some requirement by Nordic or cellular carriers to support full modem FOTA updates?

For example, will a carrier required bugfix ever require a major firmware version change (full modem FOTA update)?

Question: If full modem FOTA is not required, do you see any issues with not supporting it?

For example, will Nordic stop providing bugfixes for products stuck on an old 'major' firmware version that would otherwise require an update to a new 'major' version?

We don't necessarily care about new features, just bugfixes. For FDA approved products, they are required to have the ability to apply any new critical bugfixes that are deemed a cybersecurity threat.

Thanks,

Derek

[dejans]

Hi,

Question: Is there some requirement by Nordic or cellular carriers to support full modem FOTA updates?

For example, will a carrier required bugfix ever require a major firmware version change (full modem FOTA update)?

There are no such requirements from the carrier. On our side there are no 2 modem firmware versions with different major version number which can be run on the same device.

Question: If full modem FOTA is not required, do you see any issues with not supporting it?

For example, will Nordic stop providing bugfixes for products stuck on an old 'major' firmware version that would otherwise require an update to a new 'major' version?

We provide fixes only in the bugfix versions, not in the new major firmware versions. Delta firmware updates are provided for these bugfix versions. 

Best regards,
Dejan

[droberson]

Hey Dejan,

dejans said:

On our side there are no 2 modem firmware versions with different major version number which can be run on the same device.

Using the nRF9160 as an example, it does indeed have 2 or more modem firmware versions with a different major version that can run on the same device.

Some nRF9160 firmware versions include:

1.1.5

1.2.8

1.3.7

The major version jumps from 1 to 2 then to 3. What am I missing in regard to your comment? From my understanding, Nordic uses the second number (in bold above) as the "major" version, and not the first number per industry standard.

Source: https://docs.nordicsemi.com/bundle/comp_matrix_nrf9160/page/COMP/nrf9160/nrf9160_modem_fw.html

"Nordic's current nrF91 modem FOTA is designed to fix bugs and corrections to keep devices in the field running. These are differential updates that can update minor updates, i.e from 1.1.x to 1.1.x+1. It is correct that this will not cover major updates and feature additions, i.e transitions from 1.1.x to 1.2.x."

Source: https://devzone.nordicsemi.com/f/nordic-q-a/56357/nrf9160-modem-fw-fota-updates

"This means you can't jump from a minor version to major one. So from 1.3.x to 1.4.x you would need to do a full modem FOTA"

Source: https://devzone.nordicsemi.com/f/nordic-q-a/98169/nrf9160-fota-modem-updates/417859

Thanks,

Derek