802.11ah Wi-Fi HaLOW: The 1 Kilometer WiFi Standard
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This is English dubbed Russian video of extending WiFi with proper antenna. There are series of these videos by Kreosan. They improve antennas over time. I believe they achieved range of a few kilometers. Wi-Fi frequency and chip are standard, antenna is the only component improved.
Aside from that, a much simpler antenna is this one, which can be built from a metal can + connector + wire stub. Directionality is likely a bit worse but I've used it successfully over a distance a bit lower than a kilometer. https://web.archive.org/web/20060516103023/http://www.saunal...
Made a GIF of the transit of the milky way using this software on a raspberry pi with some SDR/RF equipment. https://github.com/byggemandboesen/H-line-software
Unfortunately I only have some images on my phone right now, a git page is on my todo.
If you are in the USA, and you have the appropriate Amateur License (Tech class or higher), and you choose channels that are in the Ham Bands, Then it's perfectly fine to use these as ham radio links. https://www.arednmesh.org/
https://www.nytimes.com/2015/07/18/world/europe/in-bleak-ukr...
Perhaps most unusual about the pair is that in a war that has deeply divided Ukraine, where no one is indifferent, the two say they are neutral. Rather, the conflict is part of a landscape that emerges in rare moments, like the distant reports of artillery fire at the end of one video.
That neutrality is not a calculated stance to avoid offending viewers. It is one of faith.
“The lord Jesus Christ does not take sides, and we must strive to act in his image,” Mr. Kryukov said. “We study the Bible, and our members, we call them brothers and sisters, live in Russia and Ukraine. If we picked a side, we would become an enemy to someone. And we don’t want to be enemies with our brothers and sisters.”
They apparently has left Ukraine since the full-scale war broke out, and travelling around the world: Thailand, India, Kazakhstan, etc.
The fact that they have themselves fled the war zone if anything makes it worse. They are hypocrites as well as cowards.
Please.
LoRA is amazing but its max datarate is 27kbps for the sub GHz version and 254kbps for the 2.4GHz version and it's half duplex --you need to implement time multiplexing on your own or use multiple radios if you want two-way communication. It's great for something you would do over a serial cable but not great for networking.
802.11ah is however great for networking because you can buy an adapter and use TCP/IP just like ad-hoc wifi, although most products released so far use it internally and provide some other interface, like the one in the video. There is at least one access point available, and I'm kind of annoyed that's it is an unpopular way to use the technology. I'm afraid that 802.11ah won't take-off if most devices are proprietary bridges instead of following the wifi model of any device being able to connect to any access point.
Normal wifi works well globally with minor differences in power/range, and uses basically the same frequencies and bandwidths everywhere, with a channel or two excluded in some regions. And, normal wifi devices automatically conform to the region of routers. 802.11ah is restricted to use significantly different power, frequencies, bandwidths and duty cycles in at least 10 different regions. As a result, in Indonesia, it supports a few Mbps. In Europe and Japan it supports about 12Mbps. Only in North America does it support 78Mbps.
So far devices are usually only certified for use in North America, if at all. You have to go out of your way to even change settings to the correct region, if it's even possible. And since the most popular devices so far are proprietary bridges, users will buy a pair and unknowingly operate them illegally in Europe or elsewhere. The most likely outcome is import bans on devices not certified for a region. If I recall correctly using the wrong region setting can in some cases overlap with emergency services, broadcast TV and mobile networks so it will be taken seriously. I think the only realistic way for 802.1ah to "take-off" is for it to become a feature of normal wifi routers and have all the regional requirements locked on the router just like it is for the other wifi standards.
I think in a new product that integrates an RF module, you still have to at least do testing for unintentional emissions. And if you do something like change the antenna, in my understanding it's possible to update the FCCID instead of recertifying and getting a new FCCID but you'd need support from the original vendor which is probably unlikely. It is obvious that lots of small companies do not do any testing/certification and a lot of webshops practically encourage you to mix and match radios and antennas so I don't think this is well-enforced anywhere.
One funny thing is you're actually not supposed to change antenna types as an end user either. Radio module manufacturers are supposed to use proprietary connectors or integrated antennas to avoid this so the end user can't just buy a high gain antenna and connect it. Unfortunately (or fortunately) this usually means they use reverse polarity SMA connectors instead of SMA connectors. RPSMA connectors became so popular that today it's easier to buy an RPSMA antenna than an SMA antenna.
SparkFun for example definitely is aware: https://www.sparkfun.com/tutorials/398
It’s a shame it isn’t more popular. There are many situations where I’d love to be able to chat with people a few hundred meters away without a network connection: Friends sitting in a different row on an airplane/train, supermarkets with bad cell signal, when hiking…
There are three Bluetooth transmission power classes, and traditionally, most devices (including headphones and headsets) used to be Class 2, which has a range of roughly 10 meters, but Airpods are Class 1, which has 10 times that.
There's no real signal processing magic happening other than (significantly, due to the inverse square law involved) bumping up the maximum transmit power from 2.5 to 100 mW.
Both ends of a connection need to support Class 1 for that to work, but at least Apple's devices have consistently done so for many years now as far as I know.
Now almost everything can do at least 25mW or so, and with dynamic TX power it's not like having too many mW is a problem, it will just turn it down if not needed.
It's a shame because the necessary technologies and protocols have all existed for a decade or more: XMPP over mDNS-announced endpoints and wifi in ad-hoc mode was supported by Pidgin many years ago.
The basic problem is that LTE base stations assign time slots to devices when to access the spectrum - that doesn’t work well when by regulation you need to play nice with other technology on the same band.
Is there good source to read more on this? Based on quick Wikipedia reading, Wifi traditionally (and including this 802.11ah) uses OFDM in sort of TDMA arrangement, which also includes AP assigning time-slots to stations if I understand it correctly (which I very much might not). LTE is based on OFDMA/SCFDMA which (again afaik) are just further refinements on the concept, but similarly rely on allocating resources (time-slots on sub-carriers). And later Wifi standards have also started to use OFDMA. So on surface-level its not super clear what here makes Wifi more suitable for unlicensed use... something maybe on how those time-slots are allocated, but its difficult to compare the two especially when they use somewhat confusingly (for an outsider) different terminology.
„Supporting LTE over unlicensed bands is not trivial. The key challenge is how to achieve har- monious coexistence between LTE and other sys- tems that are already operating in these bands. Conventional LTE cannot operate in unlicensed spectrum as it has no concern for cross-technol- ogy coexistence. For example, transmissions in an LTE radio access network (RAN) are continuous in time, and subject to centralized scheduling at the eNodeB (eNB). Even in the absence of data traffic, control and reference signals are transmit- ted over the air (at the OFDM symbol level) and are ubiquitous over time and its channel band- width.“
From Huang, Yan, et al. "Recent advances of LTE/WiFi coexistence in unlicensed spectrum.", use https://doi.org/10.1109/MNET.2017.1700124 in sci-hub.
And the fresnel zone of 900 MHz is much larger than 5 GHz so in it requires more height above terrain than 5 GHz. Not great. Tropospheric ducting is so transient and rare it does not matter for this application. And it doesn't really help getting your signal across town.
I regret investing in a bunch of 900 MHz transceivers, bidirectional amps, filters, etc.
Watch your Fresnel Zone!
This compares to other WiFi standards which tend to proliferate quite extensively within a year or two of release. And LoRA (which HaLOW competes against) had a decent number of products available for far cheaper within the first few years after release (~2-3 years before HaLOW).
What I mean by actually low powered 802.11ah is most of the time people 347 Mb/s max speed, ignoring that's peak for for a 4x4 16 MHz channel. That's almost a different world, not even high performance laptop chips find 4x4 worth the power budget, let alone something built for IoT. If you go to the real IoT client hardware in a realistic use case of 1x1 8 MHz suddenly your realistic goodput of 10s of megabits per second but that doesn't really enable too many additional use cases and comes with the aforementioned loss of coverage area and efficiency (it's more efficient than normal Wi-Fi but it's still Wi-Fi based).
Take that into consideration and what you have is a bunch of people getting excited about high speed 900 MHz when the standard was actually designed around IoT use case and demand, losing out to competitors which do it better, cheaper, farther, and came first.
Related: There are bunch of other weird sub 1 GHz standards from 802, even some under 802.11. They tend to take advantage of the TV spectrum. I don't think any have been popular, partially because that's a more complicated spectrum to participate in.
https://github.com/Ysurac/openmptcprouter https://www.openmptcprouter.com/
I mentored the port of MPTCP to OpenWRT years ago, and OpenMPTCPRouter took some of this work in their port.