Mikrotik LGH LTE

A look at the MikroTik LHG 2G/3G/LTE.

Some months ago I cancelled my backup ADSL line, as I hadn't needed it in years. My primary VDSL line promptly started misbehaving, suffering increasing packet loss and intermittent sync drops. This turned out to be due to a bodged overhead line repair, where someone had replaced a line section, spliced the pairs, and stuffed them into a sandwich bag taped to a tree! Recent hot weather and rainstorms proved to much for this "weatherproofing". Openreach replaced the join properly, and the stability problems went away, and I'm seeing line speeds of 20.8Mpbs down, 4.4Mbps up, which is in line with expectations given my distance from the cabinet. All in all this took weeks of fault finding, because my ISP wanted to exclude local problems, and had me change wiring, filters, and modems; but it was hard to see what did or did not help because of the intermittent nature of the fault.

I did ask the engineers about the likelihood of getting actual Fibre To The Premises. As someone who runs a business from home and uses the internet heavily, this would be of great benefit. It would be relatively easy to do, as my line is almost entirely overhead. But given that my current provision exceeds the 10Mbps download speed Universal Service Obligation, BT OpenReach won't be pro-active in installing that. It might still be possible, but will likely involve prohibitive intallation costs; and you even have to pay to get a quote. So this is not something I will pursue at the moment.

This episode did make me re-consider the need for a backup. Rather than re-instate ADSL/VDSL on the other line, I decided to evaluate mobile broadband. That would side-step BT line problems -- over the years I have had a truck damage both overhead cables, had modems damaged by lightning, and had the overhead cables damaged by shot rounds. 4/5G also promises faster upload speeds. In recent months the data costs seem to be coming down; in particular Three offers unlimited data, and they have a free SIM to check coverage.

The Three coverage checker suggested that I would get good outdoor coverage from a mast near Tacolneston some 6km away, South-South_East (bearing 147º) across fields. I don't know if it is located on the Tacolneston transmitting station masts or not, but that serves as a good landmark for aiming.

The next question is what hardware to use. I am a fan of the Mikrotik hardware, and purchased a Mikrotik LHG LTE kit (RBLHGR&R11e-LTE) from MS Distribution, as my usual supplier LinITX was out of stock. I ordered a LHG mount with it, although in hindsight I needn't have.

Assembling the unit is straightforward; there are a few components that click together. See this unboxing video. This video also gives a good overview of the device. Note that there is a single full-size SIM slot, and a single ethernet interface. I configured it to have an appropriate IP subnet for my network. I also upgraded to the current version of the OS.

Registering the free SIM with Three was a little tricky. Their normal procedure involves SMS messages for number confirmation, but there is no facility for handling texts on this device. I contacted Three customer support through their online chat, and they were able to associate the SIM with my online account. They also informed me that while the SIM has some free data, you need to apply a top-up before it would work; so I ended up paying £10.

Next question, where to site it. I initially tested it on 6m 2" aluminium tube, erected on the patio next to my office, with a laptop plugged into it. I saw 8.9Mbps down, 3.61Mbps up. I was somewhat disappointed, but it is usable. [I think the link established itself as "3G HSDSPS & HSUPA, EARFCN 2112 (band 20, bandwith 5Mhz) that time]

Obviously a pole on the patio is not ideal because of visual impact (says my wife; I think it looks cool :-). I considered moving it to the property boundary, but that would have cost some height, and would require some extra wiring effort.

I then considered adding a mast on top of the house, next to a TV Yagi and an existing TV satelite dish. During re-modelling some years ago, I had installed cat5 under the patio between the office and the house, and into the attic, so it was just a matter or crimping on a cat5 plug. As I was hooking this up, it occured to me to just try it in the attic. The roof is clay pantile and felt membrane, which should not interfere with reception too much. I suspended a short PVC pipe I had spare from a rafter. A speed test showed 25.8 Mbps down, 23 Mbps up -- that's more like it! The link established itself as "Evolved 3G (LTE), EARFCN 1392 (band 3, bandwidth 15Mhz)" that time. For now I'll leave the device in the attic; perhaps in future I'll put it ouside. If it stays in the attic long term I may mount it on a longer pipe that is supported at both ends and cut off the bolts, just for safety when crawling around up there.

It is fed by POE, injected at the patch panel. The LGH LTE supports 802.3af/at, but the switch I use at that panel doesn't offer that, so I just used the provided injector. The grey cat5 cable goes to the office router, and the thin gray cable with the barell connector is fed DC by the power supply. The black patch cable connects to the patch panel end of LGH LTE cable.

The device runs RouterOS, with its advanced configuration options. This is what the radio page looks like:

Band 3 is the 1800MHz one (1805.1-1876.7). The Absolute Radio Frequency Channel Number (ARFCN) is a unique number given to each radio channel in GSM, and per this list, 1392 is 1816.7-1831.7Mhz.

Per this page:

RSRP

The average power received from a single Reference signal, and its typical range is around -44dbm (good) to -140dbm(bad)

RSRQ

Indicates quality of the received signal, and its range is typically -19.5dB(bad) to -3dB (good)

so my values are not great, not terrible.

With a SDRplay RSP1A and SDRuno from inside the office (in the transmission path) I was able to find (part of?) the signal -- you can see in the waterfall that I started a scp half-way through, causing an increase in modulation.

The lte1 device gets a private IP address, in the 100.64.0.0/10 range, which (per RFC6598) is for "Shared Address Space to accommodate the needs of Carrier-Grade NAT (CGN) devices".

The Interfaces → LTE tab has a "LTE APNs" button, which gives:

To use it from my main router I have added a default route with a higher distance (10), using the LGE LTE's ether1 IP address. My normal default route has distance 3, so I can easily switch between lines by adjusting the distance or taking down the PPP for VDSL.

I may look at fancier failover switching, selective routing or bonding options in future. I haven't yet tried to enable IPv6 on the APN config; there are rumours Three are starting to enable that. It would also be interesting to try other providers, and then do a full price comparison. For now though, it seems this provides a workable solution.

Do you use this device in the UK? Any experience or advice, or comments on this post? Let me know.

So in summary, the LGH LTE does seem to work quite nicely with Three, in my location.