There is some information here: https://forum.iotcreators.com/topic/733/how-long-will-a-downlink-message-stay-in-the-network-queue
Posts made by Stefan de Lange
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RE: No downlink messages received after closing and reopening connection.
@hans-liefting Hi Hans.
Our device registers itself every hour at the network, after which it will send an uplink message.
What protocol are you using? I would definitely not recommend to register every hour. Registering with the network is very costly energy consumption wise since many messages are exchanged. So unless your module has a very poor PSM mode the tradeoff is not worth it. Operators also generally don’t like it since it creates more load on the network.
When the device sends the uplink message, our backend replies with a downlink message that is delayed by a maximum of 3 minutes.
I am not entirely sure but I don’t think this will work since the downlink message has to be queued before you sent the uplink… but t-mobile will know the details on that.
After the uplink message has been successfully sent, the modem waits for 10 seconds for a downlink message. Afterward, it closes the connection and shutdown the modem (we use the Telit modem ME310G1-WW).
My guess is that when the modem deregisters itself from the network, the downlink message queue is cleared. But again t-mobile has to confirm this…
Note that for energy reasons, our device does not go to PSM but actually shuts down.
Can you please try again without shutting down but staying in PSM mode?
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RE: Edit forum posts, after posting
@Florian-Duecker said in Edit forum posts, after posting:
Would be happy to get some feedback if this works.
Doesn’t work yet unfortunately.
@Florian-Duecker said in Edit forum posts, after posting:
within the first hour after posting.
Why only within the first hour?
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RE: How to know if queued downlinks are retrieved
@magnatron It can work ofcourse but in general NB-IoT was not designed to handle so much data
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RE: How to know if queued downlinks are retrieved
@magnatron Because 75KB is too much for NB-IoT. It’s better suited for LTE-M
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RE: How to know if queued downlinks are retrieved
@magnatron if you have 75KB to send to a device you should probably switch to LTE-M…
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RE: Edit forum posts, after posting
Editing never worked, also deleting never worked
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RE: Collegial roaming?
@magnatron said in Collegial roaming?:
The signal quality hovers at 99,99 when a modem doesn’t find an MT to connect to. Once it finds an MT and is able to connect the signal quality will indicate RSSI and QUAL.
I understand. But CSQ tells you nothing about the ability to connect, it’s just an indication that there is a signal.
In my experience, on band 8 this is no problem and happens almost instantly. Tested in The Netherlands and in Germany.
I have also not had any problems. Perhaps it is a modem issue? You can try u-blox or nRF91, those are very reliable in my experience.
But on band 20, in NL only available through VL, auto-COPS (
AT+COPS=0
) doesn’t work. The device will only connect when COPS is specified viaAT+COPS=1,2,"20404"
.You mean you are trying to roam on band 20 VFNL NB-IoT using a T-Mobile sim?
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RE: Collegial roaming?
@magnatron Is this for NB-IoT? As far as I know T-Mobile NB-IoT is not available on band 20 in NL.
@magnatron said in Collegial roaming?:
On band 8 auto-COPS works fine but on band 20 I have to set COPS to 1,2,“20404” before the CSQ goes below 99,99.
I don’t understand this part, the COPS command will force it to vodafone. What do you mean by CSQ goes below 99,99?
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RE: Batch import Excel/csv
@Uta I agree with Lauwie007. It’s a little misleading, since ‘Excel file’ (.xlsx) and csv are both file formats…
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RE: Beginner: BG96 cannot read SIM and don't know how to find GPS location
@Cher Hi, looking at your screenshot, I think there is a bug in the modem firmware. If you look at the logs on the right you can see:
+CPIN: RE DY
This means the sim card is detected and ready. However, one letter is missing. This is supposed to be +CPIN READY. So I think the serial tool is therefore failing to interpet the correct string.
Can you query the CCID/IMSI? If it returns a number then the sim card is for sure working. You can also try updating the firmware
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RE: Using NB-IOT for citizen-science
@MarPi said in Using NB-IOT for citizen-science:
Right - not right…to high - to low? It always depends. Which value exactly you doubt?
Or maybe there is a chance to improve your values?The difference between nonIP and UDP is more than factor 2. The difference between nonIP and nonIP with RAI is negligible. This makes no sense. I suspect you used RAI for both nonIP cases?
To be fair, UDP + RAI will be in the area of fourhundred something.
I have achieved around 70 uWh (or 0.070 mWh) using nRF9160 using NB-IoT, UDP + RAI. 400 seems pretty high.
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RE: Using NB-IOT for citizen-science
@MarPi Those numbers can’t be right. I thi
@MarPi said in Using NB-IOT for citizen-science:
Hi @Stefan-de-Lange …from my point of view it might not be such a big difference if you look at a single shot.
It was averaged over 100’s of measurements. There was no difference.
nonIP + RAI --> 0,303mWh nonIP --> 0,314mWh UDP --> 0,647mWh (20Byte IP + 8Byte UDP header overhead)
But that might differ between different setups and scenarios.
Those numbers can’t be right. What modem is this?
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RE: Using NB-IOT for citizen-science
@MarPi Although you are right I doubt the 20 bytes of IP header will make much of a difference. I have done some tests using various packet sizes and 10 or 100 bytes did not make a notable difference in power consumption.
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RE: Data does not arrive at second application URL
@magnatron aka ‘he who must not be named’
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RE: Data does not arrive at second application URL
@Cees-Meijer your picture is not loading
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RE: RSSI and SNR in JSON response from API
@Uta You don’t need to derive it from the tower, the UE will measure those anyway (and I think it’s part of power control mechanisms). The tower also measures it’s own RSSI, not sure which one @MeneerJacco is referring to.
Anyway, it’s only a couple of bytes so doesn’t make a huge difference if it’s transmitted by the UE
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RE: RRC inactivity timer duration for NB-IoT and LTE-M
@David-Micallef I hope so. If you need professional help in developing/testing I can give you the contact info of my (ex) colleague. He is a real expert on this topic, together we tested many many modules/usecases. It’s how I aquired most of my knowledge on this topic. Just send me a private message if you are interested
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RE: RRC inactivity timer duration for NB-IoT and LTE-M
@David-Micallef Yes, you are right, RAI is not supported for LTE-M. Even if you find a module that supports it for LTE-M you will be out of luck because as far as I am aware there are currently no networks that support it either. This leads to some significant powerconsumption in the PSM case for LTE-M. The nRF9160 however, has extremely low idle/active currents. During C-DRX the module may go as low as 70 uA. Thus the effect of the C-DRX phase on energy consumption is limited, compared to some other modules.
Disabling the radio (CFUN…) is also not ideal because the attaching process is still costly from a battery perspective.
Also true. But it is a gray area and depends on several parameters. For example, the nRF9160 can attach/detach very quickly. Thus you may find that if you do uplink once an hour turning off/on the radio can still save you some energy. Operators may not like it if you detach/attach frequently, but that’s the world they have created as it stands today
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RE: RRC inactivity timer duration for NB-IoT and LTE-M
@David-Micallef Hi David, I have tested several modules including SARA N2/N3. I would recommend testing the Nordic nRF9160 as it showed superior power consumption for all usecases. It also fully supports RAI for NB-IoT. I have tested RAI for UDP, LWM2M and confirmed/non-confirmed CoAP on nRF9160. It works in all cases. See also section 8.13 in the nRF91 AT command manual: https://infocenter.nordicsemi.com/pdf/nrf91_at_commands_v1.6.pdf
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RE: What is the difference of NB-IoT and LTE-M?
@HaraldNaumann With your incredible bias towards LTE I do not trust your results anymore
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RE: What is the difference of NB-IoT and LTE-M?
@HaraldNaumann This is exactly why I never ask you, because you immediately try to sell me things