Hi,
Im having issues with low throughput from a LTE WAN connection.
Hardware is a wAP and a Quectel EC25-AU 4G LTE Cat 4 mini-PCIe card connected to a tower (5km) using B28 (700mhz).
Location is a rural beach settlement. Not a lot of interference around but possibly some other users on the tower wanting throughput.
Using a cellphone I can get throughput around 10mb/s but using the above I can only get about 2mb/s.
Wondering if antennas / signal is the issue? Using the internal LTE antennas.

Attached is details of my signal strengths. Is it normal for SINR to be so up and down? Is this a symptom of a poor RF connection or of an overloaded tower?
Will I benefit from some external antennas?

Thanks very much for any help.
Regards,
Mike

Is this a symptom of a poor RF connection or of an overloaded tower?

Signal strength (RSRP) variations and associated SINR variations may be caused by using internal antennae. That PCIe card doesn't have much space while B28 (800MHz) does require quite physically big antennae - dipole size would be 37cm. And no, RSRP of -80dBm is not exactly great, if cell tower is under load this likely means you get less than "fair share" of throughput, most cell towers are configured to (slightly) prefer clients with better radio conditions as overall tower throughput can be much higher than it would be when using "round robin" schedulling of resources.

So yes, your LTE connection would be (much?) better if you connected (decent) LTE antenna. If you decide to get one (pair!), make sure it's got decent gain figures in low frequency bands - high gain in upper frequencies won't help in your case.

Thanks MKX,

I'll get some Omni antennas (presume I need 2 for MIMO) and report back on preformance.

Regards, Mike

The EC25 while lovely compared to a r11e-lte, doesn't support carrier aggregation.

What phone are you using to get five times the throughput?

Just using an iPhone 11.
The tower im connecting to only supports B28 (703 to 748 MHz paired with 758 to 803 MHz).
Does carrier aggregation work with a single band?
Thanks.
Mike

Does carrier aggregation work with a single band?

It could if that was sensible (it is sensible e.g. in band 7 ... 2600MHz) if many 20MHz carriers were available (so yes, 2CC CA B7+B7 is there). B28 doesn't have that much capacity, whole band is only 45MHz (with FDD) and that's often divided between 2 or 3 operators, each running a single carrier.

As I wrote, that mPCIe card doesn't have space for proper antennae while a smart phone (having an order of magnitude bigger area) might have a half-decent one. It could be your iPhone supports better modulation scheme (CAT4 is up to 64QAM, higher cats are up to 256QAM, this alone increases throuput by 25% in good radio conditions), similarly for uplink, so cell tower likes it much better than your Quectel without antennae.

Your serving cell is 20MHz one, so peak cell capacity is most probably between 150Mbps (cat4 client devices) and 200Mbps (cat12 client devices). If you only get 10Mbps (using presumably decent client device), this is quite probably sign of a pretty congested cell. You may want to test it in some other time of day, often the usage low is during small hours (e.g. around 4 A.M.).

Thanks very much MKX,
Ive ordered a single directional 11dbi antenna. Will test and report back. Sounds like I should be able to get a significant improvement if the cell is not significantly overloaded.
TBH I would be happy with 10Mbs reliably so a single antenna should do I think.

You may get away with single antenna, but you have to be really careful which antenna port it needs to connect. Modem will only use single antenna for uplink (due to low category), but if you connect it to wrong port, it'll (most probably) keep using shitty on-board antenna.

For DL you would definitely benefit from using a pair of antennae, even most basic LTE category of modems (cat4) uses MIMO 2x2 in downlink. Once I tested some Fritz LTE modem by using single directional antenna (other port was connected to shitty omni antenna) and it didn't go particularly well - regardless of which antenna port was connected to directional antenna.
If you decide to go with dual antennae, it's a small magic how to mount them to get most out of them. All antennae are polarized, the best yield is if both antennae are rotated at angle of 90° (the polarizing direction[*]) ... and they are also spatially separated by a few wavelengths ... since you're after a 750MHz (plus minus) signal, that would mean spatial separation between both antennae of at least one metre (wavelength is around 40 cm). Also try to keep antenna cables as short as possible (antennae often come with some cable length attached, I wouldn't recommend to cut it shorter), cable signal loss is not exactly negligible.

[*] Something like in the picture:

(Iskra P-58 mimo)



The spatial distance shown in picture is a bit small for low frequency bands, it's fine for higher frequencies. Antenna length is slightly over a metre meaning that spatial separation is around 40cm. The distance is also mentioned in description in link provided above.

This week I set up an LHG dish with an EP06-E (in MBIM mode and ROS7.6) from Duxtel connected to a Telstra tower 16km away. It's using B3+B28 and at the time of install was getting 25M/25M with Speedtest. The signal is pretty ordinary but it's good enough for the job.

I did have trouble initially while I was seeking a signal that it locked to a closer B28 only tower and the signal and throughput was unstable and under 2Mbit. I don't think an LHG dish is big enough for 700MHz and I suspect the B3 (1800MHz) is doing most of the legwork on this link. Maybe the antennas at the focus of the LHG aren't optimal for B28 either.

I have also used Chateaus and even in a city mounted next to a window got crap speeds - so using some kind of antenna mounted outside is a must for great results. I have used Chateaus with Poynting antennas on the roof and got over 120Mbit speeds at 18km.

The point of all this is that the little antennas in the WAP might be fine for Europe with it's high density towers but not down here and they aren't big enough for good B28 use. Being a WAP try stick it up high, like on the TV mast and run the ethernet cable down to you. You might have much better luck then without needing an external antenna.

Did you order this one? https://rfshop.com.au/product/11-dbi-wi ... ntenna-nf/

Note that only MBIM mode (which you need ROS7 for) will show you any CAs being used. The default USB-ECM mode the Quectels seem to come set up with won't without using an AT command to illicit a response.

Thanks All,

Im using a single ANT-205 (like the link above but in NZ) https://www.gowifi.co.nz/specs/Ant-205.pdf
I attached this to the Main antenna connector on the EC25-AU. I disconnected the second antenna labeled Div.
Signal strength Definitely improved. See attached screenshot.
Speed however not much better.
Interestingly I tested speed with the iPhone and the mikrotik at the same time and both were poor. <10mbs. Uploads on both remain good (at approx 25mbs).

From this testing Im thinking my speeds are currently limited by capacity at the tower, not my antenna(s).

Is it worth testing with a second antenna?

Thanks. Mike.

From this testing Im thinking my speeds are currently limited by capacity at the tower, not my antenna(s).

Yeah try at sometime between 12am and 6am and compare downloads. An extra antenna might get your the other "chain" and improve download speed. Put the antennas at +45 and -45 degrees like the double Yagi in the pic above, not horizontal and vertical.

Is it worth testing with a second antenna?

In theory, second antenna should double downlink speeds in optimum radio conditions and improve stability in bad radio conditions.

And I concur with @UpRunTech (as I already wrote): test during late night, those are times when most cell towers are least congested ...