Signal Dropping Issue MC7455 / WE826

[hw1353]

I recently built a LTE modem with WE826 and MC7455.

I got my verizon service activated, setup some antennas, and the LTE Router/Modem combo works great, for about 6-8 hours.

Around 8 hours, my signal will drop from 80% to about 40%, and stay there. Clear Sunny Day/ Clear nights, same result.

If I reboot the modem, the signal strength goes back to ~80% for about 6-8 hours.

If I disconnect the antennas for about 3-4 minutes without rebooting, and then reconnect them, the signal comes back to 80% for a few hours.

If I do nothing, the signal stays at 40~% indefinitely. Brings my upload to a 1/3 of what it is at 80%, as well as dropping download about 15-20%.

I have a Dual Yagi(Plastic Covered)wilson antenna setup, both are 700-2700 50ohm antennas. I've tried a few different configurations of these antennas, but it doesn't have any affect. I've also tried a PCTEL Broadband MIMO Omni Directional antenna, my max signal strength is around 60-70% with it, but the same thing happens after a few hours, the signal drops to 40% and stays there.

But when I reboot or disconnect antennas briefly, my signal goes back to 80%...my speeds are still pretty good at 40%, but I'm more curious than anything as to why I'm seeing this behavior.

Running WiFiX / GoldenOrb_2020-03-07

Thanks in advance for any suggestions.

[bjames]

It is possible the carrier/network is placing the modem in idle state to preserve its resources.

Do this seem to happen when there is not much activity on the router?

Run and post the results of AT!GSTATUS? while signals are good, and after they drop.

[hw1353]

Not really, I've seen it degrade while the wife is streaming 1080p netflix and while I'm browsing the web on the PC. Since I set this up I keep the wifix page up most times while using the computer to monitor things and make sure it stays stable before I cancel my DSL service.

If it were going into idle state, wouldn't the signal/power bounce back when the network becomes loaded again?

I've attached the GSTATUS for the High/low times.

It was showing 54% at the time of this screenshot, I know I said 40%, most times its 40-45%, but this time degraded to 50%, at any rate, this kinda shows what I'm seeing.

Even at 40-50% I'm still getting 40mbps down/ 2mbps up. So its not horrible.

During the 77-80% signal strength, I see 70mbps down / 11 up.

I also see the Band Aggregation going up and down. Sometimes within a given 10 minute period, Band Aggregation will go up and down on B4&B13...and then sometimes no band aggregation. Not sure if thats related, although I'm not showing aggregation in either screenshot.

[bjames]

What you are seeing is most likely the modem changing bands--and the signal strength is reading the primary (RxM) carrier LTE band.

Notice how the RSRP is better (less negative) on Band 13 regardless of whether it is being used as the Primary or Secondary band.

You will not see CA active unless you are downloading data. Even running a speed test from another browser will cause it to kick in to active state.

[bjames]

The AT!GSTATUS? results are always easier to explain if you copy and paste the results, rather than an image.

[hw1353]

I'm following you on the CA and the band changing. I tested this, and I do see the CA show up while streaming or running a speed test.

I want to say that I've seen B13 with very similar signal quality that wasn't represented well in this dataset. I'll keep an eye on it and repost screen shots in a few hours if it degrades again.

Next repost I'll copy and paste

Thanks for the help btw.

[hw1353]

Is it possible to force it to keep B13 as the primary band? Is that what bandlocking does? Can I set it to have B13 primary but still aggregate with B4 while downloading?

[bjames]

You can lock the modem to band 13 or lock the band to 4 but this would prevent the modem from doing CA.

You can create a group of bands consisting of band 13 and band 4, but you have no control over which band it uses as the primary or secondary.

You may try watching the AT!GSTATUS? read out while relocating/positioning the router. Sometimes a little move can substantially increase or decrease the signals.

[hw1353]

I guess I'm just not understanding why it would prefer B4 over B13 if B13 has higher signal strength.

[bjames]

That I cannot answer.

[BillA]

I guess I'm just not understanding why it would prefer B4 over B13 if B13 has higher signal strength.

The modem's firmware looks mainly at the RSRQ (quality) not so much at the RSSI (strength), so even if you have a lower signal strength on a particular band, the modem may still pick another one based on signal quality. The only thing you can do, is lock the modem to a particular band, course then you have to give up any chance of CA, unless you define a list of bands.
You could try popping in another carrier's sim card just to see if the degradation is still present, which would point to the modem rather than the network.