A few years back, I had a condo on Lake Washington (east of Seattle) and a buddy of mine is a microwave engineer and we were hanging out one day out on my deck with our laptops and he mentioned how amazing it was that there were so many WiFi signals and he said he had a 4 foot dish from a 2ghz MW link in the junk pile at work that they had replaced with a newer 11Ghz link. He went and got it and we put a USB WiFi dongle on the feed horn on a tripod and it was amazing, we could point it across the lake and get all these WiFi hot spots some were open. It just shows, a big antenna on one end really helps with the link budget, of course, the beam width is super narrow so it's pretty finiky on the positioning. I am not sure the distance exactly there but it had to be a mile or two.
In Australia, people are ripping out those old 11ghz tv dishes (when they remember they have them on thier roof still) now that the DVB-T free to air is somewhat decent in cities, and online streaming has taken off.
It’s not entirely unrealistic to get several and replace the LNB’s with Wifi adaptors, and set up multi diferectional internet spongeing setup.
Meanwhile I just installed three Ubiquiti APs in a ~64sqm (~700 sqft) apartment because fuck if reinforced concrete walls and thick doors are going to stand in the way of us having good WiFi coverage at home.
> Next, Paul et al. [62] reported on their observation of the WLAN link performance in open outdoor networks. The deault packet size was 1470 B for all reported measurement campaigns. They achieved a maximum range of 1800 m LOS at 148 Mbps with IEEE 802.11n links in outdoor locations for back-haul connection among WLAN APs.
I'm sure there are things here making the actual tech impressive, presumably biggest thing being power consumption and size. But just saying that the demo is not doing much when they don't provide any details of the setup.
For long distance terrestrial wireless communication on sub GHz wireless frequency, now people normally use Low Power Wide Area Network (LPWAN) solutions like LoRa, SigFox or ELTRES, but SigFox has been out of business, and ELTRES being Sony mainly limited to Japan at the moment. That leaves majority of the LPWAN installation based on LoRa.
LoRa however is not without its problem namely the spreading factor (SF) between 8 and 12 limitations, if you want to go further you really want to use the highest SF but the bandwidth goes down exponentially and instead of Kbps you have merely lowest bits/bytes speed transmission even with clear Line-of-Sight (LoS). We have tested LoRa transmission over the sea (island to mainland) and it even works for more than 20 km. That's OK if you have only IoT systems where the job is turning some remote switch or relay to be on or off.
There is a real need for efficient low power higher bandwidth transmission (Mbps range not Kbps) and this how HaLow by IEEE as inside this post come into the picture, and another cellular based Reduced Capability (RedCap) standardized in 5G release 17 standard by competing organization 3GPP. These new standards has more higher bandwidth than the existing LoRa and existing 4G/5G standards for examples NB-IoT and LTE-M but the facts the latter standards use existing 4G/5G infrastructure is a big plus and the latest RedCap standard want to capitalize on that.
Line of Sight in a mostly empty area probably gets you a lot of range but even then I find 2-3km using "regular wifi" a little hard to swallow. 1.25-1.86 mile omnidirectionally is way too far unless you have some special thing going on like your router is high up, or using a high power (1w or more) transmission, or both.
With what antenna type? IoT-like use cases often don't lend themselves towards the usage of highly-directional, large antennas and high-power transmitters.
That's exactly the problem, this demo doesn't tell anything about antennas or power levels, so it's completely impossible to say if their thing is worth anything.
The gamechanger is that they're doing it with basically a handheld tablet.
Previous long-range WLAN deployments were pretty much limited to point-to-point fixed links using high-gain directional antennas. Being able to move around in arbitrary orientations opens up dozens of new use cases.
- Video Walkie Talkies
- Drones
- Weather stations
- Sprinkler control
- Smart driveway gates
- Robot lawnmowers
One particular application I'm interested in is tracking location data and athlete performance during rowing regattas. The course is over 2km long and over 150m wide, which makes it unsuitable for regular wifi without deploying a dozen specialized APs, and directional antennas are tricky due to all the movement involved.
Being able to put a single omnidirectional antenna at the halfway point and having it Just Work would be a absolutely amazing.
well at some point, long distance wifi is just a 4G/5G antenna
of course the protocol is not the same, but it's not very different either
4g/5g might also have techniques to improve connectivity in a 3km radius when you have buildings and so many other problematic things, while wifi was designed for building interiors.
I don't know how expensive is a cheap 5G antenna, but seems like it's a tech designed for longer distance, so why use wifi?
Yeah, there are very few frequency ranges where you don’t need to be licensed and meet regulations that generally prevent a given idea from working even if technically possible.
Well in pretty much all cases you need to meet regulations. The difference is some bands allow operation without type acceptance at very low power limits.
I'm not an expert in 5G, but I was under the impression that the antennas and protocol support far more advanced beamforming than is available to other wireless tech.
I remember reading somewhere that it has a lot on common with phased array radar systems.
> This paper demonstrates the use of Unlicensed National Information Infrastructure (UNII-3), 5.725-5.825GHz, Wi-Fi frequencies, in the IEEE802.11a/n standard ... A link distance of 24.3 kilometers, the longest so far, has been achieved. An average peak throughput of 98.4Mbps has been observed ... using a TDMA based Wi-Fi radio overcomes the fundamental challenges associated with the use of the off-the-shelf Wi-Fi radio whose Media access layer is based on CDMA/CA MAC protocol.
I think what we need is cheap 4G or 5G microcells. The difference between Wifi and 4G/5G is that 4G/5G requires lots of infrastructure to run.
Then need a non-profit provider. Let's anyone sign up and manage cells. It runs in the CBRS bands. It is open to anyone. Although, might be commercial opportunity to restrict access for businesses and households.
The big difference is that it operates in a license-exempt frequency band, at transmission powers orders of magnitude less than regular cellular networks. Anyone can deploy a wifi network for a few bucks; you have to invest many millions to roll out your own 5G network.
> you have to invest many millions to roll out your own 5G network.
That's not actually true. You can get a private 5G network from AWS for just $4000 a month ( https://aws.amazon.com/private5g/pricing/ ). It operates in the unlicensed band.
You can also buy a local frequency license for your campus. They can be surprisingly cheap, around $500 a month.
This is out of range for home users, but very attractive for some large industrial customers who want to add reliable connectivity for large warehouses or factories. Mostly because WiFi reliability sucks in many environments, and it's not getting better.
People tend to forget, that if you can transmit 3km away, all the signals from everyone in that 3km circles are being received by your device too. With 2.4ghz wifi in busy apartment buildings, all the channels are overcrowded already, there is some space left on 5ghz, but not a lot, so that's why we've been going higher in frquencies for more bandwidth.
We also have other systems for unlicenced long-range communications (eg. LoRa), but once that becomes (more) popular, the spectrum will be full of that too.
> everyone in that 3km circles are being received by your device too.
This could be pretty intense. Using the below tool I had a play and found that you could have about 1.1 million people within 3km of you when in Cairo.
I was thinking that number seemed crazy, as it is closer to ~10k at 3km for me(near Cambridge, UK). However, using that site and checking a few friends houses I see Cairo isn't that unusual; ~400k in Camden, 750k in Paris' 11th. And, making a couple of guesses at denser places led me to 1.7 million in Mumbai.
If anything it makes more amazed that regular wifi works as well it does between the house and garden, and I'll try to remember that next time I'm bemoaning its magic.
Assuming it’s mostly accurate (it has errors in my area), you can find bits of Cairo that exceed 2.1 million in a 3km circle, and Mumbai I can get over 1.8 million.
I’m in New Zealand and at that density you could fit our entire population in just over 2 of these 3Km circles.
I feel irritated when people stand too close to me, but at the Cairo density there must be tens of people within a stone throw.
The paper talks about how they can get it to work in a narrow 1MHz band (though at full 1MBbit/sec speeds I am skeptical of course), but even then I'm struggling to imagine fitting the number of people on that beach into channels that isn't a disaster. Strange to not address it...
Maybe if they formed a mesh network that prioritized signals of a certain power level and had dynamic power levels to avoid losing touch with the mesh while avoiding blocking close + strong signals.
Exactly, high absorption creates the localized cells each of which is typically limited in the number of (transmitting) devices. For something like this long range IoT cell to work you would want to create temporal cells or limit them to very low power. The problem is that those require agreement between devices (and noise sources) while simple absorption doesn't (treats everything equally).
Some routers do have 3/4/5 antenna directional antenna systems. I'm not sure if there's enough room or cost margin for an IoT device. If they were only directional then, I'm not sure they would help all that much, if there were other devices in the same direction (within 3km). However, there might be very short range differential (eg quadrapole) that could have faster than r^2 fall-off. The problem is that you're relying on all other devices in-band to do the same.
I think that's one of the reasons why unlicensed (ISM in the case of WiFi) spectrum is best used where the natural cell size (due to attenuation) is small.
Barely related, but reminded me that a recent comment here linked to this DEFCON talk from a former darknet vendor. He claimed to use WiFi from a house a mile away using a Yagi antenna
With the right directional antenna you can already go like 10 miles and more. I certainly went over 1 km like 17 years ago just by using a grid reflector antenna connected to a cheap consumer 802.11b access point using legal power and a normal PCMCIA card with no external antenna on the other side. The point of the technology should be to allow long range communications with some speed restrictions but without sacrificing portability, which of course using a big directional antenna is not possible.
Yes, connecting a directional antenna is illegal because its gain "amplifies" the power in a given direction at the expense of all other directions. We of course didn't tell anyone, and back then there weren't many services that we could disrupt by pointing the antenna from the 9th floor of a building to a nearby hill:)
Using directional antennas is legal if you compensate by turning down the transmission power so that in the direction you are still transmitting the signal is no more intense than it would have been with omnidirectional antennas. That doesn't entirely defeat the purpose of using directional antennas because it still means that the receive side is focused specifically at the direction of interest and not picking up as much noise from irrelevant directions.
It's not illegal if you have a ham license, though. This allows for interesting hacks such as AREDN, which uses off-the-shelf WiFi hardware to run a mesh network, using high-gain (and usually directional) antennas to link larger nodes to each other:
Pringles can wifi hacking has been around since 2005ish. I also remember someone using a spider strainer as a cheap handheld dish with a USB stick wifi transceiver placed near the focus.
Even 20 years ago, WiFi distance records were mostly a matter of geography. The limit quickly became the curvature of Earth's surface, so the ideal geography was two mountains, separated by empty ocean in the middle, with easy access up their facing slopes.
There's troposcatter...bouncing off the troposphere. That's been around with microwave transmission for quite a long time. Requires a little more power though.
15+ years ago, my friend made a Yagi from a piece of wood and some nails, to connect to some open WiFi network from a block of flats a couple hundred meters away, in order to use it as a backup connection during semi-regular outages his ISP suffered from.
Ah, the joyful age of high school. No money or power to do things "the right way", but ample free time to skill up and hack your way around.
Vehicle to vehicle WiFi communication is standardised under the 802.11p and 802.11bd ammendments. They main difference between 11p and standard WiFi is they have halved the bit rate to increase the range and provide a way for vehicles to broadcast info outside a pre-established network context. 11bd builds on 11p adding more functionality. I don't remember the specifics of 11bd as at the time I was working with the technology 11bd hadn't finished standardisation yet.
11p and 11bd are more generally V2X comms of which there are a cellular variants (C-V2X and NR-V2X)
Unless you are far from civilization you can just use the cellular network and not need yet another radio. My Tesla gets real time updates for traffic congestion already, it's not much of a stretch to think that it could upload it's location to a server and receive relevant information concerning the surrounding vehicles through the existing channels.
Such a centralised system could also do some sanity checks. But in a peer to peer system how would one guard against malicious actors shouting false information?
Direct vehicle-to-vehicle communication can be used to provide a lot more detailed localised info (e.g. heading, speed, current position) on a lot shorter timescales (+ end to end data delivery timelines guarantees) for collision avoidance and warning systems. The current intended standard is to broadcast these basic safety messages at 10Hz but that could be higher with 802.11bd and NR-V2X. Additionally there is dedicated spectrum set aside for vehicular communications on an international level, which helps ensure there is less congestion for these safety critical applications.
Using localised peer to peer comms also eliminates some of the privacy concerns with directly sharing this info with a centralised authority as well as removing the need for any global persistent identification for this info. They also eliminate any reliance on the cellular network/internet which cannot be guaranteed to function normally for safety critical communications.
There are also alternate cellular standards for vehicle to vehicle comms called C-V2X and NR-V2X so it's entirely feasible one cellular radio could do general data comms and the P2P safety standards.
That's great but I'm still left wondering about the malicious actors problem. I thought consensus from multiple vehicles but easily spoofed. Validation against third party data but then what's the point. I can't see an easy way to improve trust, and without it I don't see the feasibility of this approach.
Right, but no one's trying to build systems that rely on precise velocity & its deritatives & related measures from nearby emitters - its implausible physically as well, your velocity can change very rapidly for reasons beyond your control.
But they are being used to build systems that are advisory or are closed systems.
Allied Media in Detroit is connecting wi-fi over long distances. They find say a church steeple to setup the base station. Then anyone who wants wi-fi they mount an antenna on their roof or balcony and point it at the steeple. I am not certain of the distances they get but I am sure it is at least a mile.
Here is an article on their project and they have published a book on the what they're building in Detroit. It is a charity that I personally support.
>Most people have probably experienced the frustration of weak Wi-Fi signals. Even getting a network to cover every corner of a fairly modest house can be a challenge
That's... not why your AP signal is weak.
It's because of laws that limit your broadcast strength.
From my experience with in-home WiFi most access points can cover a house just fine. The issue is even in the suburbs, you have dozens of other signals on the same frequency. So your signal to noise ratio is awful, leading to it being unusable in the spots farthest from the access point.
The allowed broadcast strength in the 2.4GHz band is so high that in a (sub)urban environment you won't just receive your own network, but also those of literally a dozen neighbors around you - and there are plenty of areas in your house where you can receive your neighbor's network better than your own so you end up in a shouting match.
And of course many people "solve" their poor wifi connection by adding a repeater or increasing the transmission power, which fixes the symptoms for them but makes the overall problem worse for everyone around them.
5Ghz has essentially solved the problem, simply because the signal gets killed real quick by things like walls - especially exterior ones. Your signal won't make it much beyond your house so you don't get in a shouting match with your neighbors, and adding a repeater (mostly) does what you'd expect it to.
You touched on a couple of things, but I think that the main thing you're describing here is attenuation. 5GHz transmission is much more readily-attenuated by things like walls and trees than 2.4Ghz is, and that helps allow it to actually-work in denser environments.
But it isn't so much an issue of power, I don't think: If we erased all of the existing 2.4GHz devices from the world and replaced them with devices that only transmitted 1/10th of the previous power (a 10dB reduction), then: We'd still have to contend with our neighbor's neighbors' 2.4GHz background noise.
Like in a room where everyone is shouting all at once: You can't understand what the guy across the room is shouting because of all of the noise.
But we still have the same problem in a room where everyone is carefully talking quietly all at once: You still can't understand the guy across the room because of all of the noise. The problem hasn't changed. (Sure, the noise is reduced, but the desired signal is also reduced by the same magnitude)
Signal-to-noise ratio doesn't necessarily scale with overall amplitude.
It's not an issue of SNR. Wifi isn't allowed to transmit when it detects another station is already transmitting - it has to wait for clean air. By reducing everyone's power level the competing transmitter disappears into the noise floor, freeing up air for you to transmit on. A weak-ish signal which can transmit 100% of of the time is better than a strong signal which can only transmit 5% of the time.
In theory you could indeed all shout at once, but that breaks down when your conversation partner is way closer to the other shouter - no matter how loud you shout, your message will always be overpowered and will only get through when you wait until the other shouter is silent. That's why wifi chooses to listen first.
It is a a simple issue of SNR. Even if we could somehow turn down all 2.4GHz transmitters (we cannot), that won't actually help -- it can never make things behave like 5GHz bands do.
Relatedly, hypothetically increasing the transmit power of all 5GHz devices can never make it behave like 2.4GHz does.
Walls will still attenuate the higher frequency more than the lower one, and this function of a wall is independent of transmission power.
And Wifi devices are nowhere near as polite as you proclaim. They walk all over eachother all the time, for all kinds of reasons.
(CCA improves this, but it isn't a magical antidote.)
Furthermore, not all 2.4GHz transmitters are Wifi at all. There's (still) a ton of stuff in use on that ISM band, much of which has nothing at all to do with computers or Ethernet.
A 2.4GHz video feed doesn't care about neighboring Wifi networks, for instance. It doesn't even have the ability to care. It just transmits video, using whatever modulation it uses to do that, without any regard at all for other users.
There's a lot of reasons that 2.4GHz is completely trashed in many areas -- including such offenses as leaky microwave ovens. That's just how it is, and how it is likely to remain.
If memory serves the early wrt54g replacement firmwares could go to around 2x the legal broadcast limit. I assume they still can.
Unlikely to be caught doing it, unless you live in the urban core. And for an apartment, a directional antenna likely would have sufficed for many uses, prior to MiMo ubiquity.
When you have unobstructed line of sight, a 5W handheld can reach all the way up to ISS without problem. It's very different on the ground, though, especially on high frequencies, where much smaller objects can prevent propagation.
