Howto "AT^SXRAT" (Cinterion specific)

[Aleksander Morgado]

Hey Norbert,

Giacinto, added you in CC, in case you have some suggestion.

>
> We're using a Cinterion ELS61-E R2 and seem to suffer from a lot of
> "packet data disconnects" and cell/rat/MO switching.
> We're advised to force the modem to use 3G/2G (or 4G/2G) Radio Access
> Technology with the AT^SXRAT command.
> We've been told the "AT+COPS=0" may reset SXRAT settings.
>
> I've tried to do this via:
> mmcli -m 0 --set-allowed-modes='2g|4g' --set-preferred-mode='4g'
>
> but it doesn't work and even if it would, I'm not sure this means the
> "AT^SXRAT" command alwaysf ollows "AT+COPS=0" nicely.
>
> I see no "AT^SXRAT" in the source code, so I guess "AT^SXRAT" is a
> Cinterion specific command that isn't supported yet.
>
> I do like to use the "AT^SXRAT" command.
>
> So I'd like to do a "AT^SXRAT" after each "AT+COPS=0". This involves
> changing modem_3gpp_register_in_network, is this the right thing to do?
>
> If not, how to best use the "AT^SXRAT" command?
>

The Cinterion plugin currently uses AT+COPS also to configure access
technology; e.g. if 4G-only is requested, we would run AT+COPS=,,,7

Does this COPS based logic to configure access tech not work in the
ELS61? Is ^SXRAT the only way to do that in the ELS61? If ^SXRAT is
the only way to do it, we could upgrade the Cinterion plugin to use
it. But I'm not sure that sending the SXRAT after each COPS would make
much sense; is there no other way to do that?

Also, if COPS=0 resets the desired access tech, I wonder if the same
is currently happening with our already available COPS based access
tech selection logic.

-- 
Aleksander
https://aleksander.es