LTE Carrier Aggregation

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SoNic67
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LTE Carrier Aggregation

Post by SoNic67 » Sat Nov 16, 2019 6:30 am

I saw on some of your other boards that an LTE modem can be "forced" to work in CA mode with AT commands sent to it. But on the normal hones, that function is provisioned by the carrier.
My question is: Isn't the carrier enforce/verifies that CA compliance later?

For example, I have read that on a certain MVNO (Tello), the Samsung Galaxy 8, 9 don't get CA, but a Pixel 3 gets CA.
Is that because the Pixel ignores the provisioning by MVNO? Or is some other deal going on at the higher level (main carrier network)?

swwifty
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Re: LTE Carrier Aggregation

Post by swwifty » Sat Nov 16, 2019 8:24 am

CA is entirely controlled by the carrier, but you can limit your modem to only certain bands, but if they aren't available on the tower side theres nothing you can do about that.
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SoNic67
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Re: LTE Carrier Aggregation

Post by SoNic67 » Sat Nov 16, 2019 4:43 pm

That's what I thought. So then, Verizon allows Pixel devices to have CA even when they are on a MVNO, but not other devices?

swwifty
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Re: LTE Carrier Aggregation

Post by swwifty » Sat Nov 16, 2019 4:47 pm

SoNic67 wrote:
Sat Nov 16, 2019 4:43 pm
That's what I thought. So then, Verizon allows Pixel devices to have CA even when they are on a MVNO, but not other devices?
I don't know the exact situation here, but I have a Verizon Samsung S8 and I get 3xCA no problem.

SoNic67
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Re: LTE Carrier Aggregation

Post by SoNic67 » Sun Nov 17, 2019 5:14 pm

On a MVNO?

swwifty
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Re: LTE Carrier Aggregation

Post by swwifty » Mon Nov 18, 2019 8:18 pm

SoNic67 wrote:
Sun Nov 17, 2019 5:14 pm
On a MVNO?
No idea, I would guess they get less wireless resources since they share the infrastructure from another carrier.

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BillA
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Re: LTE Carrier Aggregation

Post by BillA » Thu Dec 19, 2019 6:40 am

I can confirm that using a Samsung S9 on an MVNO (SimpleMobile using Tmobile towers in the US), I get 3xCA during speed tests or large downloads by quickly typing *#0011# into the phone dialer to view the signal status. At the top of the screen you can see the main band, while at the bottom you can see S1 (2nd CA band) and S2 (3rd CA band). As soon as the speed test or download finishes the two additional S1/S2 CA's simply disappear till the next download session starts.

What's really cool about tethering a Samsung phone to the wireless router (instead of using a build in modem), is that you have full control over band selection from the test menu (may not work on models and all firmware versions but it doesn't hurt to try). By dialing *#2263# you can select any band or combinations you want, great for testing purposes to see which bands are available on a particular carrier, and it even shows the bandwidth of each LTE channel (5Mhz, 10Mhz, 20Mhz). The general rule of thumb is you multiply the band width by 5 to get the maximum real world Mbps download speeds of each channel when the network is not congested. Course during CA sessions those speeds usually add up, more of less.

CA sessions are controlled mainly by the tower, the only thing you can do on the phone/modem is to set the available CA channels and combinations, but not actually force a CA session unless the tower instructs your radio. I've done a lot of research and testing on this issue, so no need to waste your time trying to "force" CA. Both your equipment and the tower/carrier has to support it in order to kick in at THEIR control. So, depending on the bandwidth and the number of active CA's, you can have anywhere from around 20Mbps to 300Mbps (maybe 400Mbps if you're lucky) with three active wide band CA's on a non-congested time of the day/night. And no, you will never get 1Tbps even with a CAT-20 LTE modem in the real world, those speeds are pipe dreams, only possible in the lab under carefully controlled conditions.

By the way, if you really want to see CA being active, then start downloading a large file in another browser window (for example download iTunes.com), and while the download is still in progress switch back to the modem's status page and refresh it. Running a speed test alone, likely will not trigger CA due the relatively light and short duration data transfer, therefore a large file download is usually necessary. You will either see it active or not, depending on your modem's and your carrier's capabilities, including the availability of the second or third channel in your particular area. In other words, there are a lot of variables which all have to be true at the same time, and there's not much you can do other than provide your radio the best signal possible by either moving it around or attaching external antennas.
So I would recommend simply resetting your modem to factory settings via these AT commands and let the modem's firmware manage the connection automatically.
AT!RMARESET=1
AT!RESET
Or enter AT&F on most non-Sierra modems then do a reboot.
You many need to set up your firmware image again along with MBIM/QMI mode, and APN.

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