RUTX50 - Locking 5G-NSA CA bands manually

NETWORKING SOLUTIONS
1

Hi,

My RUTX50 is struggling to maintain my desired 5G-NSA CA configuration.

Using a directional antenna, I have tested a lot of configurations with my local cell tower and have concluded that a Triple CA of B7+B7+N78 is optimal for me.

I have configured my Mobile settings as follows:

Network Type: “4G+5G”
Band Selection: “Manual”
LTE Bands: “B7”
5G Bands: “78”

When my router is configured to Band Selection: “Auto”, it achieves a Multi CA of B1+B3+B3+B7+N78. This is suboptimal for me as bands B1 and B3 have a lot of interference which impacts the quality of my network.

When I configure my Manual band selection by clicking Save and Apply, the configuration is enabled successfully, and I have tested this by running gsmctl -A 'AT+QCAINFO' in an SSH shell.

I get:

PCC: “LTE BAND 7”
SCC: “LTE BAND 7”
SCC: “NR5G BAND 78”

However, after approximately 3-4 hours, the RUTX50 defaults back to 4G in Single CA mode with “LTE BAND 7”.

In order for me to re-enable my desired 5G-NSA CA configuration, I need to set the Band Selection to “Auto”, save and apply which enables 5G again, and then set it back to “Manual” with my selected bands.

Then the cycle repeats.

Obviously this is very suboptimal because I don’t want to have to do this every 4 hours.

Is there any way to force the RUTX50 to honour the Manual 5G-NSA CA band configuration I set? So rather than simply selecting the bands, to lock onto the specific configuration I want (i.e. B7+B7+N78)?

I have inferred that this is unrelated to my service provider as when I perform this “Auto” → “Manual” cycle, the 5G-NSA CA configuration is applied successfully and my network speeds/latency remain extremely good until the RUTX50 defaults to 4G within 3-4 hours, at which point I have to change it manually again.

Thank you, any help would be appreciated. I am comfortable with using the CLI, so any configuration I could apply from there would be great. I thought about potentially setting up an automated job to do this cycle of “Manual” → “Auto”, but figured the must be a smarter / more elegant way.

I haven’t been able to find any documentation on this here
https://wiki.teltonika-networks.com/view/Gsmctl_commands

And also, for what it’s worth, this page is very out of date as it’s only for firmware R_00.06.08.3 and below.

Thank you!

2 Likes
2

Also, it’s worth nothing that I cannot get my preferred 5G-NSA CA configuration to be applied if I reboot the modem when the connection is downgraded to 4G.

I have to literally cycle through selecting the mode of “Manual” → “Auto”.

Some useful links I’ve been able to find:
https://wiki.teltonika-networks.com/view/AT_Commands
https://wiki.teltonika-networks.com/view/Band_Lock

But no luck.

This is an interesting command from the latter link:
gsmctl –A AT+QCFG=“band“, [<bandval>,<ltebandval>,<tdsbandval>[,<effect>]]

With this:
0x40 LTE Band 7 2600MHz

But not sure how I would apply it for a B7+B7+N78 configuration.
Perhaps it would need to be 0x80, as per the example (eg.: 0x15=0x1(LTE B1)+0x4(LTE B3)+0x10(LTE B5))

Any help would be appreciated.

3

CC @Daumantas @AndzejJ

One last thing worth mentioning, is that even when the Network Type and Bands are set to Auto, the RUTX50 will always eventually lose the 5G NSA connection, downgrade to 4G, and never negotiate back to 5G unless there’s manual intervention.

Is there any way to fix abd sustain the 5G NSA mode, and honour a single CA configuration consistenly?

If not, can I at at least set up a job using the CLI for the RUTX50 to attempt this on a recurring basis?

This constant downgrading to 4G is impacting my experience. The problem is that it never negotiates back to 5G unless I intervene manually…

4

Hello,

Since the carrier uses 5G NSA configuration, it may be hard to force the device to stay on 5G. However, what you can do, is lock the device onto 4G cells that have 5G availability and hope that the device stays connected to 5G. Run the command gsmctl -A 'AT+QCAINFO' when you are connected to the correct cells, and note the EARFCN and PCI of the LTE cells.
Then remove all of the band locks, but leave the service mode on 4G+5G. Run this command with the number of B7 cells, their EARFCN and PCI information filled in:
+QNWLOCK: "common/4g",<num of cells>,[[<EARFCN>,<PCI>],...]
An example could look like so:
gsmctl -A '+QNWLOCK: "common/4g",2,6400,354,6400,348'

Let me know if this helps!

5

Thank you, @Daumantas, this looks promising.

I will try it as soon as possible and report my results.

Three quick follow up questions:

  1. You mention to keep the Network Type as 4G+5G and to remove any band lock. Does this mean setting the Band Selection mode to Auto on the WebUI? What if I want to revert this configuration that is inputted from the CLI? Do I need to run another command or simply setting the bands manually via the WebUI will overwrite this?

  2. Is there any reason why I cannot lock onto the N78 band in the same way as I would for the two B7 bands? When I run the CAINFO command, the N78 is listed as a standalone carrier.

  3. If the RUTX50 downgrades to 4G for some reason, will it automatically renegotiate 5G NSA when/if it becomes available? My problem now is that it stays at 4G when downgraded and only goes back to 5G with manual intervention.

Thank you very much.

6

You mention to keep the Network Type as 4G+5G and to remove any band lock. Does this mean setting the Band Selection mode to Auto on the WebUI? What if I want to revert this configuration that is inputted from the CLI? Do I need to run another command or simply setting the bands manually via the WebUI will overwrite this?

A simple modem reboot will remove the cell lock (this is what the provided command does). If you’d like the change to stay, I recommend placing it into the System → Custom Scripts page so that it gets executed every time the device boots up.

Is there any reason why I cannot lock onto the N78 band in the same way as I would for the two B7 bands? When I run the CAINFO command, the N78 is listed as a standalone carrier.

You could try by substituting the 4g in common/4g with common/5g, although I’m not sure if this will work or have the intended behaviour. The n78 is listed in a seperate line simply because it uses different technology. Use the command gsmctl -A 'AT+QENG="servingcell"' to determine if SA or NSA is used. However, the simple fact that QCAINFO returns both 4G and 5G cells indicates that you are using 5G NSA, as standalone 5G will operate without connecting to 4G bands.

If the RUTX50 downgrades to 4G for some reason, will it automatically renegotiate 5G NSA when/if it becomes available? My problem now is that it stays at 4G when downgraded and only goes back to 5G with manual intervention.

Hard to say. My current guess is that the RUTX50 is connecting to a different cell with better signal/lower load, and that this cell does not support 5G. However, this is only a theory, thus I recommend testing the provided command and if the issue persists we can look for a different solution.

Best regards,
Daumantas

7

Got it, @Daumantas, this is extremely helpful.

I will be testing this and report results as soon as possible.

One last thing to confirm, the reason I cannot lock onto the N78 5G band in the same way as the B7+B7 LTE bands is because it’s NSA and therefore depends on the negotiation which occurs by the tower itself once you’re connected on LTE?

In the command you provided, is the only option common/4G and common/5G? Is there no way to specify a locked 4G+5G configuration where the router always seeks the B7+B7+N78 configuration from the locked cell?

Thanks so much.

8

One last thing to confirm, the reason I cannot lock onto the N78 5G band in the same way as the B7+B7 LTE bands is because it’s NSA and therefore depends on the negotiation which occurs by the tower itself once you’re connected on LTE?

I’m not very familiar with the technicalities from the mobile side, so I don’t want to mislead you, but yes, I believe this is the case. When you connect to a 4G cell, your carrier gives you a “green light” to connect to the 5G cell, and if you lock the device on 5G cell, it might not be able to establish the proper communication. But I’d recommend testing this if you have some time to do so.

In the command you provided, is the only option common/4G and common/5G? Is there no way to specify a locked 4G+5G configuration where the router always seeks the B7+B7+N78 configuration from the locked cell?

Correct, 5G-NSA is supposed to only be used for transition from 4G to 5G, thus very extensive feature set for locking onto bands from both technologies will most likely not be available. Either way, all of the commands that I have provided are executed on the modem software, and not our developed tools, thus even if there are any issue, we will most likely not be able to help, as the modem manufacturer does not even provide this command in the manuals.

Let me know how it goes!

9

Hey @Daumantas, got lots of updates to share!

I experimented with using QNWLOCK, there’s a few things to point out.

  1. In your post, the example command you shared had slightly incorrect syntax gsmctl -A '+QNWLOCK: "common/4g",2,6400,354,6400,348'. It’s actually supposed to be gsmctl -A '+QNWLOCK="common/4g",2,6400,354,6400,348'.

  2. Additionally, you mentioned that I should remove my locked bands via the WebUI when apply this command. When I removed the locks, the command did seem like it was locking the cell I wanted as a primary carrier, (which was the B7 band I wanted), however it still connected with B1 and B3 for CA. I observed that using a Band lock in the WebUI with B7 and N78 and using QNWLOCK allowed me to lock the configuration B7+B7+N78 as reliably as possible.

  3. Your hypothesis was completely correct. After watching the logs, I observed that I was connecting to a B7 from a different cell, which although had very high RSSI, it doesn’t support 5G ENDC. Locking to my preferred cell with QNWLOCK has so far proved successful. I’m really happy about this.

  4. When there’s a reboot, the lock is always removed, so I set it up to be applied on system init in the Custom Script as you advised. Sometimes even when there’s no reboot, the lock seems to be removed. One can assess which lock is currently active on the modem by running gsmctl -A 'AT+QNWLOCK="common/4g"'. Since the Custom Script is executing Bash, I wrote a while loop which every hour after system initialisation checks the cell lock on the modem. If the returned string is not what I expect, I simply apply it again. Otherwise, the script does nothing.

For reference, here is the code I wrote:

gsmctl -A 'AT+QNWLOCK="common/4g",2,6400,354,6400,348'
sleep 5

(
while true
do
OUTPUT=$(gsmctl -A 'AT+QNWLOCK="common/4g"')
if [[ $OUTPUT != '+QNWLOCK: "common/4g",2,6400,354,6400,348' ]]; then
gsmctl -A 'AT+QNWLOCK="common/4g",2,6400,354,6400,348'
fi
sleep 3600
done
) &

exit 0

I’ve supplied the example cells you shared in the example above. Logs suggest that this is working well, and using the & operator I run it in a shell subprocess so that the init script can exit successfully.

Overall, I’m happy!

Will be testing this more and report back within a week or so. If 5G remains consistent I will consider this solved. Hopefully the code above and the details will help future lurkers looking to do the same thing.

Thanks!

10

Hello,

Yes, sorry, just noticed that I provided the incorrect syntax.
As for the secondary bands, they indeed cannot be locked onto, so yes, in your case band lock may still be needed, sorry about that.
As for the modem losing the cell lock, it may be that the modem itself reboots to regain connection or something similar, and then the cell lock becomes ineffective. Your script seems like a great solution for this.
Glad to see that it is working so far! Update us with the results.

Best regards,
Daumantas G.

11

Hi @Daumantas

Just wanted to update here that everything has been working perfectly and as expected.
I’m happy to mark this as solved for future lurkers as well.

In fact, my speeds have never been better.
I’m now able to hit 400Mbps down / 100Mbps up in ideal conditions, and I average around 200Mbps down / 50Mbps even on the busiest of times during the day.

I wonder if the fact that I’m locking onto to specific bands on a specific cell is allowing my ISP to better optimise my traffic which is effectively improving my experience.

Latency is also very low at around 25ms.

Very happy!

Thanks for all your help and suggesting to use the QNWLOCK command.

I think this would be a great feature for the WebUI along with with Band Lock for other folks whom maybe are not as comfortable with writing code.

1 Like
12

We do have a cell lock example on our Wiki for other devices: Locking Devices to a Mobile Cell - Teltonika Networks Wiki
However, the RUTX50 modem does not officially support cell locking, thus it is not included in the Wiki. Additionally, locking to a cell is not advisable, as the carrier may need to move your device to a less congested cell, and this will simply not be possible if you are locked onto a specific PCI.
I’m happy this solution works for you!

Best regards,

16

@Daumantas Is my issue Any updates on the 5G NSA? related?

17

Hello,

I’ve left a reply on your thread.