[Ovmsdev] 3G / 2G fallback on SIM5360 Europe?

Mon Aug 3 18:21:02 HKT 2020

Chris,

we don't tell the modem to restrict itself in any way. Bugs in the modem
firmware are likely, but I think a serious bug like this would have been
solved early.

I've read the pilot description now, and you need to pay attention to
this section:

> statt der üblichen drei Dienste LTE, UMTS und GSM kommen in
> Kirchfarrnbach "nur" LTE 800 und LTE 900 für die Datenversorgung sowie
> GSM für Sprachdienste und SMS zum Einsatz. Auf UMTS haben die
> Funknetzplaner hier verzichtet, weil bereits LTE und GSM alle
> Anforderungen der Bevölkerung erfüllen.

…translated…
> Instead of the usual three services LTE, UMTS and GSM, "only" LTE 800
> and LTE 900 are used in Kirchfarrnbach for data supply as well as GSM
> for voice services and SMS. The radio network planners have dispensed
> with UMTS here because LTE and GSM already meet all the requirements
> of the population.

So you have neither UMTS nor EDGE. GSM is only available for voice
streams and SMS. Data is only available via LTE.

Your only option is to tell them they're a bunch of … outstanding
economical visionaries, who could possibly consider rethinking their IoT
compatibility ;-)

Regards,
Michael

Am 03.08.20 um 11:33 schrieb Chris van der Meijden:
> I did some more reading on the SIM5360 and also digged a bit through
> the simcom source. Found loads of AT-commands there :-)
>
> I could not find an AT command to restrict the selection to 2g.
> Perhaps I did not look deep enough, but if someone knows the command ...
>
> I'm still thinking why the automatic fallback to 2g does not happen.
>
> - The transmitter offers only 2g (GSM 900 mHz) and LTE (800 or 1800).
> No 3g.
> - I have a signal strength of -110 to -100 dBm
> - AT+COPS? gives me an empty response.
>
> Could it be possible, that somewhere in the code something like
>
> - I don't have 3g
> - I do have LTE
> - Lets try LTE
> - I see LTE
> - I have no hardware for LTE
> - OK, don't do anything
>
> happens? So somehow fallback to 2g never happens?
>
> Just guessing around ...
>
> Regards
>
> Chris
>
> Am Montag, den 03.08.2020, 10:10 +0800 schrieb Mark Webb-Johnson:
>> The SIM5360E should auto-switch between 2G and 3G. It supports the
>> following frequency bands:
>>
>>     GSM/GPRS/EDGE 850/900/1800/1900MHz;
>>     UMTS/HSPA+ 900/2100MHz
>>
>>
>> There are SIMCOM options/commands to restrict the selection, but the
>> default is automatic.
>>
>> Regards, Mark
>>
>>> On 2 Aug 2020, at 6:40 PM, Chris van der Meijden <chris at arachnon.de
>>> <mailto:chris at arachnon.de>> wrote:
>>>
>>> Hey Michael
>>>
>>> Thanx for the help :-)
>>>
>>> The AT commands are working now, but as expected no connection at
>>> all. So also no fallback to 2g. Or no GPRS offered on 2g ...
>>>
>>> Here some (German) information on the "site lite" transmitters:
>>>
>>> https://www.telekom.com/de/blog/netz/artikel/standort-light-pilotprojekt-552152
>>>
>>> I also did not find any AT command for the SIM5360 to force 2g. I
>>> will play a bit around with the modem in the next days. Will also
>>> try congstar, I do have a congstar SIM laying around here ...
>>>
>>> Greetinx
>>>
>>> Chris
>>>
>>>
>>> Am Sonntag, den 02.08.2020, 10:59 +0200 schrieb Michael Balzer:
>>>> Chris,
>>>>
>>>> how to send modem commands and read the responses:
>>>>
>>>> OVMS# log level debug simcom
>>>> Logging level for simcom set to debug
>>>> OVMS# simcom cmd AT+COPS?
>>>> SIMCOM command has been sent.
>>>> D (164488782) simcom: tx mcmd ch=4 len=10  : AT+COPS?
>>>> D (164488792) simcom: rx line ch=4 len=23  : +COPS: 0,0,"congstar",2
>>>> D (164488802) simcom: rx line ch=4 len=2   : OK
>>>>
>>>> Now let's see if we have 3G:
>>>>
>>>> OVMS# simcom cmd AT+CPSI?
>>>> SIMCOM command has been sent.
>>>> D (164693462) simcom: tx mcmd ch=4 len=10  : AT+CPSI?
>>>> D (164693482) simcom: rx line ch=4 len=85  : +CPSI:
>>>> WCDMA,Online,262-01,0x16C3,7824927,WCDMA IMT
>>>> 2000,454,10836,0,7.5,104,18,8,500
>>>> D (164693482) simcom: rx line ch=4 len=2   : OK
>>>>
>>>> Yes. Well, no surprise, Telekom network :-).
>>>>
>>>> The SIM5360 is supposed to automatically fall back to 2G if 3G
>>>> isn't available. On a quick browse through the manual, I didn't
>>>> find a command to force 2G, just one to lock to a specific 2G cell…
>>>> you could do that depending on your location, but maybe you should
>>>> first inspect your modem status now.
>>>>
>>>> Regards,
>>>> Michael
>>>>
>>>>
>>>> Am 02.08.20 um 09:39 schrieb Chris van der Meijden:
>>>>> Hi all
>>>>>
>>>>> I'm trying to understand some principals of the SIM connection
>>>>> methods of OVMS.
>>>>>
>>>>> Reason is that I recently moved from "the big city" Munich to the
>>>>> very much rural village Thalham. In Thalham we have so called
>>>>> "lite" mobile transmitters. These transmitters are installed, as
>>>>> far as I understood, to safe money and to prepare the transition
>>>>> of the providers to 4g / 5g. They are forcing the frequencies
>>>>> towards the 4g band with those.
>>>>>
>>>>> So these transmitters seem to offer only 2g and 4g, but no more 3g
>>>>> (really ???).
>>>>>
>>>>> I don't have any network connection with the SIM in my OVMS here
>>>>> in Thalham. In the next village Zolling I have connection. In
>>>>> Zolling they don't have the "lite" transmitters, but still have
>>>>> full 3g support. The antenna of my OVMS is working well (-100 dBm
>>>>> to -70 dBm).
>>>>>
>>>>> Now my questions ...
>>>>>
>>>>> Does OVMS have a fallback on SIM5360 Europe to 2g (EDGE) if 3g is
>>>>> not available?
>>>>>
>>>>> I also did some reading in the modem documentation and tried to
>>>>> send some AT commands. Goal is to try to force the SIM into 2g
>>>>> mode. I tried i.e.
>>>>>
>>>>> simcom muxtx 2 AT+COPS?
>>>>>
>>>>> to get some information from the SIM, but I don't get an answer on
>>>>> that command at all. No matter what channel I try. Am I missing
>>>>> something there?
>>>>>
>>>>> Thanx for input.
>>>>>
>>>>> Regards
>>>>>
>>>>> Chris
>>>>>
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-- 
Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26

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