The "100x bandwidth" claim needs to be substantiated.
There are some significant regulatory issues with the current popular mesh network protocols in the USA, namely that neither MeshCore or Meshtastic are compliant with the actual FCC regulations. 100x bandwidth because you're breaking the rules isn't the same as 100x bandwidth legally.
I never understood the popularity of these protocols, because when I looked at the legal duty cycles and multiplied that by time in a day and instantaneous bitrate, the result was a disappointing amount of data per day...
So many spectrum rules are totally weird though: should they be interpreted per radio device? or per user?
What -apart from cost- prevents a user who wants more bandwidth from installing 10 devices in parallel and alternate each radio so none of the radios exceed their allowed transmit duty cycle?
These things aren't "Internet Access", they're an easy way to get service that is bandwidth-equivalent to SMS, MMS, IRC or walkie talkie, over complex and distant terrain, without any central coordinating authority. Potentially even acting as last-mile to repeater nodes that pass through the actual Internet.
> What -apart from cost- prevents a user who wants more bandwidth from installing 10 devices in parallel and alternate each radio so none of the radios exceed their allowed transmit duty cycle?
Folks with badges knocking on the user’s door. It is pretty trivial to locate stationary signals.
The issue you linked to is about MeshCore using channels that are too narrow. A mesh system claiming to offer 100x bandwidth is probably not violating regulations in that particular way.
Correct. The LoRa configurations mentioned which offer 100× the speed of Meshtastic/Core operate at 800 kHz and 1.6 MHz bandwidth, which are permitted by the FCC in 15.247.
As far as I know there's not actually anything particular to 2.4 GHz allowing higher throughput for LoRa than that the corresponding Semtech chip happens to support wider bandwidths. (I.e. no legal barrier.)
The tradeoff is less range due to lower link budget. Doubly so because 2.4 GHz has higher free-space path loss. You're not going to get outside your house with these speeds. The primary use (as stated in the original post) is likely through clear space with a directed antenna.
(The 2.4 GHz band is better suited to this use since you can use antennas with higher than 6 dBi gain. If my math is correct, anything higher than 11 dBi is a win even accounting for FSPL and the power derating the FCC imposes.)
At least in Europe the 868 Band is is in contrast to 2.4 allowed only for low duty cycle applications that do not actually occupy the channel for more than 1% afaik (given space multiplexing). I also remember also that the free to us band was quite narrow by design (we built sensor nodes bit banging a PHY transceiver that were in the grey area of unenforced rules, 20 years ago .l)
What issues does it create for others to use too narrow of a bandwidth? Why “should” the FCC care if someone is only using a small portion of the spectrum that would otherwise be fine fr them to use?
The legal power limit in these bands is 1 W. If you spread that out over 500 kHz, that signal is weaker than background noise at any given frequency for anyone more than about a city block away. (Give or take many factors.)
But, if you compress that 1 W into, say, 12.5 kHz (typical for FM voice), your signal is now detectable (and will interfere with other, possibly licensed, users) at over 6 times the distance.
There are probably other factors. For example, it's not legally sufficient to simply reduce your power by a corresponding factor. I suspect it may simply be the FCC's goal to reduce conflict between users by mandating spread-spectrum technologies for unlicensed use.
Note also that 47 CFR 15.247(e) [1] gives a spectral power limit which corresponds approximately with the 1 W max / 500 kHz min specified in (b)(3) and (a)(2).
Final side note – https://docs.fcc.gov/public/attachments/FCC-02-151A1.pdf is interesting reading as to how the current form of 15.247 came to be. Specifically it changed the rule from specifically DSSS to digital modulation generally, which in turn allowed the transition from 802.11b (DSSS) to 802.11g (OFDM) on 2.4 GHz.
The idea with either requiring very wide band or frequency hopping on the 900Mhz band is to make it so that usages of the 900Mhz band 1. are tolerant to some loss (ie: by temporary collision) and 2. don't collide continuously (by using wide band or frequency hopping).
It's a mechanism to try to make the 900Mhz band more useful to uncoordinated users.
Our local discord questions the use of 2.4ghz for longer than 50 feet, between WiFi and Bluetooth, microwaves, and millions of "2.4 GHz (nonspec) wireless devices", the spectrum is just trashed.
i am just reading "its not allowed" "rules are being broken" "not premitted" lol. how should you invoate and break free from the current ISP model, if everythig is not premitted?
In the U.S. I believe the FCC has federal authority to knock down your door, if they can pinpoint an illegal interference emanating from within your home. Intent is not particularly a factor in that, since interference can have a large radius and be unintentional. Seems like an awful time to be intentionally emanating ‘de facto unenforceable’ illegal signals.
Correct me if I am wrong but I thought the primary appeal of LoRa was range? Also isn't the primary factor in making long range radio go through things is the frequency? So 2.4ghz is the same frequency as consumer wifi right and thus would propagate about the same right?
It doesn't seem like this would be that useful except that the protocol is LoRa so you can have higher bandwidth between two devices if they happen to be close enough together.
LoRa would go much farther than Wifi on 2.4ghz. Lora uses Chirp Spread Spectrum (CSS) modulation while wifi uses OFDM (Orthogonal Frequency Division Multiplexing). The first being designed for extreme range while the latter for bandwidth. At 2.4ghz you could probably get LoRa connections up to 6 miles with the right antenna height.
6 miles seems a very optimistic estimation: 2.4Ghz propagation is very reduced by obstacles like buildings or trees and at that frequency the atmospheric water (fog, rain, humidity) have a big impact on propagation. And you need also to consider that 2.4Ghz is a very polluted band, then the noise floor is significatevly higher than in the 865/915 Mhz.
Moreover at 2.4Ghz the Fresnel window is smaller and the risk of multipath fading is higher.
LORA uses a sub noise-floor link budget. It allows some pretty crazy performance, at the expense of massive speed losses. Like 203kbps for LoRa vs 1,376,000kbps for WiFi lol.(max phy speeds, ymmmv).
WiFi sensitivity is about -90dB, while LoRa sensitivity is around-150dB…. So that’s about a million times more sensitive. So you need about a million times more signal strength to use low bandwidth WiFi (still impossibly fast by LoRa standards) than to use low bandwidth LoRa.
Those are radio specifications. Real links require about 10db more to get any kind of reliability, but the comparison stands.
> 2.4Ghz propagation is very reduced by obstacles like buildings
I never did much 2.4ghz stuff because that was what rich people did, or people mad enough to modify microwave oven magnetrons. However I was always under the impression that freespace loss on 2.4 was terrible. but it turns out its "only" ~9db more than 865
When I worked in the Trimble Navigation radio group, 2.4 GHz was tried but its real world range sucked compared to ~900 MHz and CB ~450 MHz bands of existing solutions. It's simply limitations of physics that lower frequencies propagate farther (at lower bandwidth) than higher frequencies.
even 900mhz sux vs 433. the lower the better it penetrates matter for the same amplitude.
lower than 430 you start to run into severe bandwidth issues though. and its not allowed to transmit lora/dss on 430 in the us without license hence the 900mhz
at 2.4ghz the real world usage is limited. might as well use wifi. the only advantage is short range bandwidh while keeping lora compat.
FSP loss for 915 MHz at 10 kms is ~ -111.67 dB while for 2.4 GHz is -120 dB.
That is a 9 dB loss which is significant. It could mean the difference between a copy or just plain static though the LoRa is supposed to be copyable down to -140 dBm.
The max tx power is around 150 mW (21.76 dBm), so at 10 kms, the RSSI is 21.76-120 = -98.24 dBm which is above the -140 dBm limit.
This calculation is assuming there is no loss due to vegetation or humidity or other barriers.
"Going through things" isn't always necessary / is avoidable in some deployments. And 2.4GHz signals can propagate an okay distance between nodes if there aren't things to go through. (Globalstar's emergency SOS satellite constellation uses the n53 band, which is right above the 2.4GHz "wi-fi" band, and it propagates between handsets and LEO through 1400km of air just fine.)
So you could probably pull off a 2.4GHz mesh outdoors in rural areas? It'd be feasible in the same places a microwave-laser hilltop-to-hilltop link would, but instead of "fast but point-to-point" it's "slow but meshed" (and with much larger tolerance for slop — you don't need to put everything on fixed masts so they have perfect line-of-sight, you can just stick them on the tops of trees or whatever and if they wave in the wind it still works.)
Mind you, the authors' motivating use-case for the hardware seems to be their project (https://github.com/datapartyjs/MeshTNC) to (AFAICT) bridge LoRa (or some specific LoRa L2 protocol — Meshtastic, probably?) to packet radio, i.e. digital packet-switched signalling over amateur (HAM) radio bands.
In that context, the tradeoff of high throughput for low propagation makes sense. Insofar as you're working with LoRa, and want to build and experiment with a bunch of site-local devices that mesh between themselves and interoperate with LoRa data-link protocols, you'd likely be speaking something like LoRA over 2.4GHz (LoRa itself doesn't spec a way to do that, but you could make it happen within the closed ecosystem of your own home/office.)
And in that context, you could use a MeshTNC device as something like "LoRaLAN" router. It'd be something you'd keep somewhere central in your house (like a wi-fi router), plugged into power + an antenna (internal to your house, like a wi-fi router) and plugged into a packet-radio transceiver with its own even-bigger antenna, outside your house. (Like a wi-fi router being plugged into a gateway modem on its upstream WAN port.)
This MeshTNC device would then pick up signals from:
- regular LoRaWAN IoT devices and Meshtastic handsets in your building
- more custom devices in your building†, that you've built yourself, that use another MeshTNC module; where these other devices do their part of the meshing only on the 2.4GHz band, which means they don't need big fiddly external antennas like LoRa devices do, but can be quite compact
- and possibly, a separate bidirectional LoRa repeater (made from any existing "high-gain" LoRa module, i.e. the kind used in mains-powered LoRaWAN base stations) — which brings in LoRa mesh traffic from outside your building, and picks up and carries away "destined for elsewhere in this area" LoRa mesh traffic that your "LoRaLAN" device has emitted (either due to forwarding it from your 2.4GHz-only mesh handsets/devices, or due to forwarding it after receiving it from packet radio.)
Though keep in mind you only need that complexity for the 2.4GHz-only mesh devices, since there isn't an existing mesh to forward those packets. But this whole setup is still also a regular LoRa mesh, and so you can still use regular LoRa (e.g. meshtastic) handsets, and put out packets that make their way through your regional mesh, back to the packet-radio bridge in your building; and from there to who-knows-where.
† To be clear, the 2.4GHz mesh handsets would only work reliably inside your building (if the 2.4GHz antenna is inside your building); but knowing HAMs, half the point would be seeing how far away you could get from your house/office and have your 2.4GHz mesh handsets keep working. (You'd probably want to have a second MeshTNC "base station" with a building-external antenna to try that. Pleasantly, that doesn't complicate the topology; it's all still just mesh, so you can just drop that in.)
It sucks how everything feels like a toy. I think meshtastic is the closest thing to a “product”. They made a bunch of bad architectural decisions that are haunting them now like how nodes broadcast its info.
Because they are toys. For real work it makes so much more sense to use the internet. With the new satellite tech you can reach the internet everywhere.
Mesh radio is a fun way to chat with radio nerds in your area. Not a serious infrastructure.
So what’s the real solution for when Starlink is too expensive and too high power? I really want to solution for remote mountaineering communication that’s not just GMRS. And what about remote weather sensors? I really don’t need a full internet connection just to send a tiny payload every 5 minutes.
Meshtastic should be the obvious answer for this but in my limited experience the app(s) and code are buggy on even the most typical hardware. Wish it wasn’t the case but it is.
If you're talking about a few miles/KMs between nodes, plain old LoRaWAN might be more than sufficient, esp. for the sensor use case. The nice thing about using LoRaWAN is that's it's literally providing an IPv6 overlay so you can run e.g. MQTT or a text-based messaging protocol designed for regular TCP/IP use. UDP is preferable to avoid frequent session resets and keepalive traffic chewing up your available bandwidth.
Meshtastic and MeshCore can theoretically provide "infinite" range so long as there are peers between the nodes you want to connect. Theoretically, mobile peers can also serve as store-and-forward nodes so that reachability doesn't need to be constant, just frequent enough to handle the messaging you want to do.
I would absolutely not rely on either for a safety-critical application, though. If you want emergency comms in case something happens while you're out on the mountain, use a satellite communicator. There are a ton of these marketed for outdoor/portable use, and they have much more robust "SOS" capabilities (up to and including direct dispatch of search-and-rescue).
Depends what exactly it is you want. But phones these days can communicate with satellites for emergency messaging.
I think people need to think more about what the actual scenario they have in mind is because it seems most people think of mesh radio as some backup for the government shutting the internet down. When in reality it’s almost useless for that since it’s so easy to jam or flood mesh radio.
We may see a day when the internet is not available, or when interacting with it represents an unacceptable risk. It's a good idea to know how to set up your own.
It's a different jamming scenario however. Starlink is comparatively centralised, and reliant on both terrestrial (ground stations) and satellite communication. While the terminals themselves are sparse and widely distributed, the backbone infrastructure is far less so. It's possible to target the satellites, ground stations and critical service dependencies (e.g. GPS) rather than needing to target the hundred of thousands/millions of terminals directly.
The mesh networks are dealing with, by definition, a sparse and widely distributed set of devices which are independently configured and controlled, and in their current widely available form are only dealing with terrestrial communication. Without that point of centralisation you would need to focus on targetted regional jamming, as from a practical standpoint you cannot perform wideband RF jamming over an entire country - signal jammers don't scale that well, and geographic features come into play. As an example you might effectively block mesh networks from operating reliably in a given city, but if people were to move outside of that area then the mesh would operate again.
Geography is both a strength and a weakness here: a mountain range will impede direct communication with someone on the other side, but it will also have the same effect on jammers which will vastly increase the cost to deploy them in a ubiquitous fashion.
I suspect jamming LoRa could be a lot easier than most radio though. LoRa signals are incredibly weak and long range. A jammer which jams at a massively higher power level could cover a massive area. You can also just flood the network with messages that nodes will happily relay further for you.
That's a DoS attack, not "jamming". RF jamming usually relies on flooding frequencies with garbage which doesn't get interpreted as valid protocol traffic but does "crowd out" legitimate use.
The protocol-aware class of attack you describe does require some knowledge of the radio parameters being used, since LoRa runs on very narrow bands and uses both time and frequency-hopping to avoid congestion on any one virtual channel. They even apply (very basic) encryption to messages to prevent unknown senders from flooding the channel.
Unfortunately, both systems come preconfigured out of the box to use a default configuration which most users never override. So like cheap FRS/GMRS walkie talkies, all it takes is a few jerks who don't care about common use to overwhelm everyone with bogus messages. If you fire up a new device running the default Meshtastic firmware in any kind of dense urban environment, odds are it will more or less immediately get inundated with spam: "ping", "test", "hello from <neighborhood>", etc.
And since MT + MC both flood the shared channels to push messages across intermediary nodes, they pretty much self-DDoS by doing...nothing.
That’s really the killer for survivalist mesh ideas. It’s trivially easy to jam, and if it’s open it’s also easy to DDOS.
Jamming is done in military scenarios too, but in that case it’s limited by the fact that a jammer is a big transmitter painting itself with a big sign that says “fire missile here.” Civilian mesh doesn’t have that fallback.
Neglect is a bigger killer than active denial. If the Internet goes down it will likely be because a few execs decided to replace competent network admins with AI, or because all the competent network admins decided to quiet-quit because they aren't being paid jack compared to the folks hawking AI vaporware.
Battlestar Galactica opened my eyes to this problem more than electronic warfare in games of the day did. It's freaky (read: terrifying) that we're getting to a point that people are starting to take "embedded information (and decision)" systems serious enough to deploy them into meat space.
I've been tinkering with the tech to make city-wide flrc meshes joined together over the internet, my estimates are that it should be at least able to support thousands of users per region.
This has been tried with mqtt bridges in Meshtastic. But it’s ultimately kind of pointless because if you are planning some kind of internet alternative, you don’t want to build something that falls over the moment the internet goes down.
That works with just basic mesh radio. The internet bridges thing is tempting but ultimately a bit useless and doesn't push people to extend the mesh natively.
Don't get me wrong, I like the mesh/* ideas around everyone being able to prop up a router/repeater, but I've seen what that can do in an urban environment... unfortunately for some, I don't plan on letting every tom dick and harry to set up their own towers.
It doesn't surprise me. This is a deep networking problem and very few CS people know anything about networking or how to design clean, fast, low-overhead network protocols and systems.
If IP were designed today the packets would have 500+ bytes of plain text JSON as headers and the spec would support hundreds of extensions.
It's a fundamentally really hard problem that looks easy on the surface. There is no solution that works well beyond the small scale. Many people have tried. It's the same kind of thing that draws people to try to write IPv8.
And also them calling out Andy for they key? Stupid.
The official Android app (blessed by the "community") still has in-app purchases up. It gates the remote repeater management, afair one of the things Andy's MeshOS app for TDeck is gating.
The underlying protocol is open source, but the companion app isn't.
Yes, in the current version of Meshcore app it's possible to manage the repeater without the key, after a wait period, but that changed recently and they still nudge towards in-app purchase.
Similarly Andy's firmware* can be used for free, without purchasing a key, unless the user wants the full functionality.
*is it even his, considering it's been AI-generated?
A big mess. Also the network is a big mess, now I understand why.
That stuff is good for drone warfare, mesh networks already been used in Ukraine
E.g. drones geographically organize themselves into a chain with each of them serving as a mesh-network node, then each of them, including the tip of a chain, can be controlled by operators, and the whole setup is a closed network which works without requiring Internet access
The bandwidth of LoRa networks is really low. Anything beyond a environment sensors is stretching the design, especially on mesh networks.
Meshing two digit number of drones on a military grade reliability is a real uphill battle with chirp based protocols, as the high ToA reaches congestion fast.
might have worked for a bit in the past, but is easily disrupted by jammers, and forced a switch to fiber-optic in-theater. People have learned from that and don't bother with radio anymore, even in new theaters.
Fiber optic tethers limit range and target conditions. You can't go into a forest or even an urban canyon, you basically need to run the drone along roads and fields. And you have to drag it with you, which reduces what you can carry. The fiber itself is very light weight and has a habit of getting sucked up into the props on quadcopters.
There's a lot of frequency hopping and chirp systems being used now, with a mix between analog radios mostly for FPV and digital radios or Starlink for larger ISR drones or larger gliders. Digital still gets used a lot for FPV because of how readily available it is, but good drone FPV pilots want the lower latency of analog and will take it if they can get it.
the flip side of that is that your operator can be miles away, and using repeaters, hundreds of miles away. As the operator is the difficult to replace part, its a fair tradeoff.
Frequency hopping is nice, as is spread spectrum but its still easily detectable, as is the operator.
Seems like this would support institutional/campus environments or changing environments where the sensors at the edge are sending higher bandwidth ultimately back to an Internet node using LoRA mesh--instead of directional WiFi?
I'm trying to envision the application of a mesh like this. These could be examples?
- interconnected nodes need to share data (like images)
- interconnected nodes are acting as a collective array of sensors (eg. geolocation)
- interconnected mesh nodes provide redundant pathways back to the central node
- interconnected mesh nodes provide spatial diversity in case of interference or jamming
- nodes are mobile (eg. drone or vehicle) and mesh provides alternative connectivity based on node location and RF attenuation (also provides longer range with mesh connectivity)
> an Internet node using LoRA mesh--instead of directional WiFi?
not really, the reason why Wifi is useful is that its reasonably efficient and high bandwidth. Unless you need to cover hectares of land without any buildings, its easier just to use decent wifi (ie unfi)
Mesh networking with multi-path is really hard to tune for bandwidth efficiency, throughput and power efficiency at the same time
Gonna reply here, but this isn't about you or this post:
HN has a lot of us that have ~0 idea what you'd use this for, even when we steelman, all we can do is vaguely handwave about easier to setup wireless internet on a vast compound we own.
Would be really cool if someone could hop in and just give a couple one off examples, i guess? Only other one handwave I can think of is IOT x assembly line stuff for businesses, but I'm real curious why individuals are so into it -- or maybe they're not, and that's why the codebase quality is so poor? Idk.
You'll read a lot of illusions and wishful intentions.
In the end: LoRa is only good for very short text messages at somewhat long distance (up to 10km without special setup) and without bad conditions (obstacles on line of sight, rain/fog). There is an ongoing fight between each of the two frequencies to be used as default and this publication adds another frequency into the battle.
There is WiFi HaLow, a relatively new WiFi protocol which seems to solve the low bandwidth issues with LoRa on relatively confortable distance (likely up to 8km, same as with LoRa in regards to Line of Sight), albeit slightly less affected by weather conditions. The advantage here is permitting to send images and binary data in general, but think about something being sent at the speed levels from 2005 (which in any case is good speed for most usable things).
Then there are other relevant mesh protocols yet to mention here like ESPnow which is my personal favorite. Whereas the other two options above are exotic and with transceivers around the 50 EUR and above. With ESPnow you just need any cheap ESP32 embedded device with an optional antenna to increase range for about 3 EUR (antenna included). With that you get similar returns to WiFi HaLow with less range (about 3 kilometers max on my experiments) but cheap like heck.
To setup internet on a vast compound, WiFi HaLow might be a good investment. If you are with a constrained budget, then ESP32 is your friend. To remember, long distance is limited so if you are considering more than 8 devices exchanging heavy data, you should just go for proper WiFi long range transmitters.
Assuming you mean mesh in general:
Meshtastic like projects
- emergency communication
- low power data transfer for sensors
- low data rate data transfer for mobile groups. Air softers use it to transmit information to each other while playing.
HaLow:
- "high" data rate over shorter range, though much higher range than 2.4 wifi
- data sharing between mobile groups like above, but high enough bandwidth for low quality video
I build environmental and structural sensor networks for work and this has my wheels spinning, but honestly I can’t think of many uses for the additional bandwidth. You could packet additional metadata maybe? GPS or network info? I’ll get one and play with it but off the top of the dome I think sub-Ghz is sufficient for most everything I do.
How are they increasing the bandwidth? It's a hardware limitation of the radios. Even if you run the lowest spread factor (SF) and highest bandwidth setting on the radio, it's still not great. And the radio buffer is 255 bytes. I'm also curious why they're starting a new project with the SX1276 instead of SX1262.
I think I can give it a pretty nice use: distributed ring signature over long distances. We can distribute people over different regions for redundancy and form long distance encryption channel to deliver a signature of some data, and use it to make consensus with enough provenance. Kind of like e-voting but with stronger assumptions.
By using a long distance communication device this eliminates the proximity strike problem. This could easily be extended to say like distributing the voting rights to different generals at different regions, and given that the device is genuine and not modified, can be a hardware voting key to say like launch the nuke in secrecy or not.
Whether adversarials can use the radio signals that it emits to triangulate you and thus track you is another story, though.
Not much. While this is technically LoRa on 2.4GHz (which is not new), most people will associate LoRa with significantly longer range and LoRa 2.4 can do.
I know it’s all open source and I’m not paying for anything so I cant be choosy. But after playing with a bunch of Lora peer to peer chat systems. All I wish is a chat service that uses haloW. Since it uses wifi backend, regular wifi should work as well.
Is the design for this open source? I’m not an rf guy so it would be really handy to be able to reuse some parts of this in my sensor network on our farm. I can do the digital and sensor part all day, but I respect the skill of rf engineering in getting decent performance out of tiny pcbs.
Is the poster maybe confusing bandwidth (range of frequencies over which a single board can work) with bandwidth (data transfer speeds in bits per second)?
Cue xkcd on standards. I've been interested in mesh radio, and I keep hoping that a winner will emerge. Probably won't until a large commercial vendor gets interested and picks one.
Sounds like bs. Why would someone pay $50 for almost 10 years old hardware when there are plenty of well-supported and cheaper options like MuziWorks Duo / Ebyte / etc with newer LR1121 or LR2021 which combine both 2.4G and SubG bands in single and modern chip at 1/2 of the cost less? SX1281 and SX1281 are relics.
I’m struggling to see the value here. At $50, this seems hard to justify given the availability of cheaper, well-supported options like MuziWorks Duo, Ebyte, and other newer LR1121/LR2021-based designs. Those chips offer both 2.4 GHz and sub-GHz support in a single modern package, often at roughly half the price, which makes the SX1281 feel fairly outdated.
Metricom Ricochet used dual-band radios, operating in 900MHz and 2.4GHz, to form a routable mesh that delivered internet access and other services, in 1999.
They used repeaters on street lights as part of the infrastructure, and even after the company went belly up people were able to use the repeaters for private networks. Pretty slick for the mid 90s.
There are some significant regulatory issues with the current popular mesh network protocols in the USA, namely that neither MeshCore or Meshtastic are compliant with the actual FCC regulations. 100x bandwidth because you're breaking the rules isn't the same as 100x bandwidth legally.
Here is the issue discussing this in the MeshCore repository: https://github.com/meshcore-dev/MeshCore/issues/945
So many spectrum rules are totally weird though: should they be interpreted per radio device? or per user?
What -apart from cost- prevents a user who wants more bandwidth from installing 10 devices in parallel and alternate each radio so none of the radios exceed their allowed transmit duty cycle?
Folks with badges knocking on the user’s door. It is pretty trivial to locate stationary signals.
As far as I know there's not actually anything particular to 2.4 GHz allowing higher throughput for LoRa than that the corresponding Semtech chip happens to support wider bandwidths. (I.e. no legal barrier.)
The tradeoff is less range due to lower link budget. Doubly so because 2.4 GHz has higher free-space path loss. You're not going to get outside your house with these speeds. The primary use (as stated in the original post) is likely through clear space with a directed antenna.
(The 2.4 GHz band is better suited to this use since you can use antennas with higher than 6 dBi gain. If my math is correct, anything higher than 11 dBi is a win even accounting for FSPL and the power derating the FCC imposes.)
(Aside, I am the author of that MeshCore ticket.)
Thanks for educating us!
The legal power limit in these bands is 1 W. If you spread that out over 500 kHz, that signal is weaker than background noise at any given frequency for anyone more than about a city block away. (Give or take many factors.)
But, if you compress that 1 W into, say, 12.5 kHz (typical for FM voice), your signal is now detectable (and will interfere with other, possibly licensed, users) at over 6 times the distance.
There are probably other factors. For example, it's not legally sufficient to simply reduce your power by a corresponding factor. I suspect it may simply be the FCC's goal to reduce conflict between users by mandating spread-spectrum technologies for unlicensed use.
Note also that 47 CFR 15.247(e) [1] gives a spectral power limit which corresponds approximately with the 1 W max / 500 kHz min specified in (b)(3) and (a)(2).
Final side note – https://docs.fcc.gov/public/attachments/FCC-02-151A1.pdf is interesting reading as to how the current form of 15.247 came to be. Specifically it changed the rule from specifically DSSS to digital modulation generally, which in turn allowed the transition from 802.11b (DSSS) to 802.11g (OFDM) on 2.4 GHz.
[1] https://www.ecfr.gov/current/title-47/part-15/section-15.247...
It's a mechanism to try to make the 900Mhz band more useful to uncoordinated users.
In the end, won't be used.
Thank you for the update.
I guess you have never encountered the anger and wrath of a retiree who's into ham radio and has the regulatory office on speed dial.
There are other countries in the world.
And there are also places where there is no electromagnetic policies (think about over the oceans).
It doesn't seem like this would be that useful except that the protocol is LoRa so you can have higher bandwidth between two devices if they happen to be close enough together.
https://www.thethingsnetwork.org/article/new-lora-world-reco...
But, that's receiving 3 of maybe thousands of packets.
There's work on bouncing of LoRA signals off the moon:
https://engprojects.tcnj.edu/lora-eme/
Yes, but Joe Shmoe won't see this on their home setup trying to talk to a buddy 2 miles away behind a hill.
WiFi sensitivity is about -90dB, while LoRa sensitivity is around-150dB…. So that’s about a million times more sensitive. So you need about a million times more signal strength to use low bandwidth WiFi (still impossibly fast by LoRa standards) than to use low bandwidth LoRa.
Those are radio specifications. Real links require about 10db more to get any kind of reliability, but the comparison stands.
I never did much 2.4ghz stuff because that was what rich people did, or people mad enough to modify microwave oven magnetrons. However I was always under the impression that freespace loss on 2.4 was terrible. but it turns out its "only" ~9db more than 865
> Wifi HaLow 802.11ah. LoRa is another level. It works down to -146dBm. 802.11ah dies around -100dBm.
https://news.ycombinator.com/item?id=47890598
LoRa looks like someone is dropping a saw wave on the spectrum. It so clearly looks like such a blunt force user of spectrum. Just wild.
lower than 430 you start to run into severe bandwidth issues though. and its not allowed to transmit lora/dss on 430 in the us without license hence the 900mhz
at 2.4ghz the real world usage is limited. might as well use wifi. the only advantage is short range bandwidh while keeping lora compat.
And if you don't have line of sight then no you're not getting 6 miles
https://radionor.no/solution/cre-2-series/
No. Free space loss increases with frequency.
FSP loss for 915 MHz at 10 kms is ~ -111.67 dB while for 2.4 GHz is -120 dB.
That is a 9 dB loss which is significant. It could mean the difference between a copy or just plain static though the LoRa is supposed to be copyable down to -140 dBm.
The max tx power is around 150 mW (21.76 dBm), so at 10 kms, the RSSI is 21.76-120 = -98.24 dBm which is above the -140 dBm limit.
This calculation is assuming there is no loss due to vegetation or humidity or other barriers.
So you could probably pull off a 2.4GHz mesh outdoors in rural areas? It'd be feasible in the same places a microwave-laser hilltop-to-hilltop link would, but instead of "fast but point-to-point" it's "slow but meshed" (and with much larger tolerance for slop — you don't need to put everything on fixed masts so they have perfect line-of-sight, you can just stick them on the tops of trees or whatever and if they wave in the wind it still works.)
Mind you, the authors' motivating use-case for the hardware seems to be their project (https://github.com/datapartyjs/MeshTNC) to (AFAICT) bridge LoRa (or some specific LoRa L2 protocol — Meshtastic, probably?) to packet radio, i.e. digital packet-switched signalling over amateur (HAM) radio bands.
In that context, the tradeoff of high throughput for low propagation makes sense. Insofar as you're working with LoRa, and want to build and experiment with a bunch of site-local devices that mesh between themselves and interoperate with LoRa data-link protocols, you'd likely be speaking something like LoRA over 2.4GHz (LoRa itself doesn't spec a way to do that, but you could make it happen within the closed ecosystem of your own home/office.)
And in that context, you could use a MeshTNC device as something like "LoRaLAN" router. It'd be something you'd keep somewhere central in your house (like a wi-fi router), plugged into power + an antenna (internal to your house, like a wi-fi router) and plugged into a packet-radio transceiver with its own even-bigger antenna, outside your house. (Like a wi-fi router being plugged into a gateway modem on its upstream WAN port.)
This MeshTNC device would then pick up signals from:
- regular LoRaWAN IoT devices and Meshtastic handsets in your building
- more custom devices in your building†, that you've built yourself, that use another MeshTNC module; where these other devices do their part of the meshing only on the 2.4GHz band, which means they don't need big fiddly external antennas like LoRa devices do, but can be quite compact
- and possibly, a separate bidirectional LoRa repeater (made from any existing "high-gain" LoRa module, i.e. the kind used in mains-powered LoRaWAN base stations) — which brings in LoRa mesh traffic from outside your building, and picks up and carries away "destined for elsewhere in this area" LoRa mesh traffic that your "LoRaLAN" device has emitted (either due to forwarding it from your 2.4GHz-only mesh handsets/devices, or due to forwarding it after receiving it from packet radio.)
Though keep in mind you only need that complexity for the 2.4GHz-only mesh devices, since there isn't an existing mesh to forward those packets. But this whole setup is still also a regular LoRa mesh, and so you can still use regular LoRa (e.g. meshtastic) handsets, and put out packets that make their way through your regional mesh, back to the packet-radio bridge in your building; and from there to who-knows-where.
† To be clear, the 2.4GHz mesh handsets would only work reliably inside your building (if the 2.4GHz antenna is inside your building); but knowing HAMs, half the point would be seeing how far away you could get from your house/office and have your 2.4GHz mesh handsets keep working. (You'd probably want to have a second MeshTNC "base station" with a building-external antenna to try that. Pleasantly, that doesn't complicate the topology; it's all still just mesh, so you can just drop that in.)
Mesh radio is a fun way to chat with radio nerds in your area. Not a serious infrastructure.
Meshtastic should be the obvious answer for this but in my limited experience the app(s) and code are buggy on even the most typical hardware. Wish it wasn’t the case but it is.
If you're talking about a few miles/KMs between nodes, plain old LoRaWAN might be more than sufficient, esp. for the sensor use case. The nice thing about using LoRaWAN is that's it's literally providing an IPv6 overlay so you can run e.g. MQTT or a text-based messaging protocol designed for regular TCP/IP use. UDP is preferable to avoid frequent session resets and keepalive traffic chewing up your available bandwidth.
Meshtastic and MeshCore can theoretically provide "infinite" range so long as there are peers between the nodes you want to connect. Theoretically, mobile peers can also serve as store-and-forward nodes so that reachability doesn't need to be constant, just frequent enough to handle the messaging you want to do.
I would absolutely not rely on either for a safety-critical application, though. If you want emergency comms in case something happens while you're out on the mountain, use a satellite communicator. There are a ton of these marketed for outdoor/portable use, and they have much more robust "SOS" capabilities (up to and including direct dispatch of search-and-rescue).
I think people need to think more about what the actual scenario they have in mind is because it seems most people think of mesh radio as some backup for the government shutting the internet down. When in reality it’s almost useless for that since it’s so easy to jam or flood mesh radio.
The mesh networks are dealing with, by definition, a sparse and widely distributed set of devices which are independently configured and controlled, and in their current widely available form are only dealing with terrestrial communication. Without that point of centralisation you would need to focus on targetted regional jamming, as from a practical standpoint you cannot perform wideband RF jamming over an entire country - signal jammers don't scale that well, and geographic features come into play. As an example you might effectively block mesh networks from operating reliably in a given city, but if people were to move outside of that area then the mesh would operate again. Geography is both a strength and a weakness here: a mountain range will impede direct communication with someone on the other side, but it will also have the same effect on jammers which will vastly increase the cost to deploy them in a ubiquitous fashion.
The protocol-aware class of attack you describe does require some knowledge of the radio parameters being used, since LoRa runs on very narrow bands and uses both time and frequency-hopping to avoid congestion on any one virtual channel. They even apply (very basic) encryption to messages to prevent unknown senders from flooding the channel.
Unfortunately, both systems come preconfigured out of the box to use a default configuration which most users never override. So like cheap FRS/GMRS walkie talkies, all it takes is a few jerks who don't care about common use to overwhelm everyone with bogus messages. If you fire up a new device running the default Meshtastic firmware in any kind of dense urban environment, odds are it will more or less immediately get inundated with spam: "ping", "test", "hello from <neighborhood>", etc.
And since MT + MC both flood the shared channels to push messages across intermediary nodes, they pretty much self-DDoS by doing...nothing.
Jamming is done in military scenarios too, but in that case it’s limited by the fact that a jammer is a big transmitter painting itself with a big sign that says “fire missile here.” Civilian mesh doesn’t have that fallback.
I've been tinkering with the tech to make city-wide flrc meshes joined together over the internet, my estimates are that it should be at least able to support thousands of users per region.
If IP were designed today the packets would have 500+ bytes of plain text JSON as headers and the spec would support hundreds of extensions.
The official Android app (blessed by the "community") still has in-app purchases up. It gates the remote repeater management, afair one of the things Andy's MeshOS app for TDeck is gating.
The underlying protocol is open source, but the companion app isn't.
Yes, in the current version of Meshcore app it's possible to manage the repeater without the key, after a wait period, but that changed recently and they still nudge towards in-app purchase.
Similarly Andy's firmware* can be used for free, without purchasing a key, unless the user wants the full functionality.
*is it even his, considering it's been AI-generated?
A big mess. Also the network is a big mess, now I understand why.
E.g. drones geographically organize themselves into a chain with each of them serving as a mesh-network node, then each of them, including the tip of a chain, can be controlled by operators, and the whole setup is a closed network which works without requiring Internet access
Meshing two digit number of drones on a military grade reliability is a real uphill battle with chirp based protocols, as the high ToA reaches congestion fast.
> each of them serving as a mesh-network node
might have worked for a bit in the past, but is easily disrupted by jammers, and forced a switch to fiber-optic in-theater. People have learned from that and don't bother with radio anymore, even in new theaters.
Fiber optic tethers limit range and target conditions. You can't go into a forest or even an urban canyon, you basically need to run the drone along roads and fields. And you have to drag it with you, which reduces what you can carry. The fiber itself is very light weight and has a habit of getting sucked up into the props on quadcopters.
There's a lot of frequency hopping and chirp systems being used now, with a mix between analog radios mostly for FPV and digital radios or Starlink for larger ISR drones or larger gliders. Digital still gets used a lot for FPV because of how readily available it is, but good drone FPV pilots want the lower latency of analog and will take it if they can get it.
the flip side of that is that your operator can be miles away, and using repeaters, hundreds of miles away. As the operator is the difficult to replace part, its a fair tradeoff.
Frequency hopping is nice, as is spread spectrum but its still easily detectable, as is the operator.
https://trellisware.wpengine.com/waveforms/tsm-waveform/
Nodes can cooperate to beamform and reach greater distances.
And giving away their location. Radio is prettymuch dead for drones.
Depends on the context, I guess. Distance, jamming probability, availability of relays, etc.
Fiber-optics are close-range.
I'm trying to envision the application of a mesh like this. These could be examples?
- interconnected nodes need to share data (like images)
- interconnected nodes are acting as a collective array of sensors (eg. geolocation)
- interconnected mesh nodes provide redundant pathways back to the central node
- interconnected mesh nodes provide spatial diversity in case of interference or jamming
- nodes are mobile (eg. drone or vehicle) and mesh provides alternative connectivity based on node location and RF attenuation (also provides longer range with mesh connectivity)
not really, the reason why Wifi is useful is that its reasonably efficient and high bandwidth. Unless you need to cover hectares of land without any buildings, its easier just to use decent wifi (ie unfi)
Mesh networking with multi-path is really hard to tune for bandwidth efficiency, throughput and power efficiency at the same time
HN has a lot of us that have ~0 idea what you'd use this for, even when we steelman, all we can do is vaguely handwave about easier to setup wireless internet on a vast compound we own.
Would be really cool if someone could hop in and just give a couple one off examples, i guess? Only other one handwave I can think of is IOT x assembly line stuff for businesses, but I'm real curious why individuals are so into it -- or maybe they're not, and that's why the codebase quality is so poor? Idk.
In the end: LoRa is only good for very short text messages at somewhat long distance (up to 10km without special setup) and without bad conditions (obstacles on line of sight, rain/fog). There is an ongoing fight between each of the two frequencies to be used as default and this publication adds another frequency into the battle.
There is WiFi HaLow, a relatively new WiFi protocol which seems to solve the low bandwidth issues with LoRa on relatively confortable distance (likely up to 8km, same as with LoRa in regards to Line of Sight), albeit slightly less affected by weather conditions. The advantage here is permitting to send images and binary data in general, but think about something being sent at the speed levels from 2005 (which in any case is good speed for most usable things).
Then there are other relevant mesh protocols yet to mention here like ESPnow which is my personal favorite. Whereas the other two options above are exotic and with transceivers around the 50 EUR and above. With ESPnow you just need any cheap ESP32 embedded device with an optional antenna to increase range for about 3 EUR (antenna included). With that you get similar returns to WiFi HaLow with less range (about 3 kilometers max on my experiments) but cheap like heck.
To setup internet on a vast compound, WiFi HaLow might be a good investment. If you are with a constrained budget, then ESP32 is your friend. To remember, long distance is limited so if you are considering more than 8 devices exchanging heavy data, you should just go for proper WiFi long range transmitters.
- emergency communication
- low power data transfer for sensors
- low data rate data transfer for mobile groups. Air softers use it to transmit information to each other while playing.
HaLow:
- "high" data rate over shorter range, though much higher range than 2.4 wifi - data sharing between mobile groups like above, but high enough bandwidth for low quality video
- large area wifi deployments
By using a long distance communication device this eliminates the proximity strike problem. This could easily be extended to say like distributing the voting rights to different generals at different regions, and given that the device is genuine and not modified, can be a hardware voting key to say like launch the nuke in secrecy or not.
Whether adversarials can use the radio signals that it emits to triangulate you and thus track you is another story, though.
https://www.nordicsemi.com/Products/Wireless/DECT-NR
https://en.wikipedia.org/wiki/DECT-2020
Doesn’t change my excitement about it a bit though. Eager to get this onto my workbench!
[0] https://en.wikipedia.org/wiki/LoRA_(machine_learning)
Network doesn't usually care much about the apps running on top of it.
Say I start the node and then what?
I’m struggling to see the value here. At $50, this seems hard to justify given the availability of cheaper, well-supported options like MuziWorks Duo, Ebyte, and other newer LR1121/LR2021-based designs. Those chips offer both 2.4 GHz and sub-GHz support in a single modern package, often at roughly half the price, which makes the SX1281 feel fairly outdated.
I mean 2.4gig is unlicensed as is 433 and 939 in the EU, so unless its not conforming with regs, no it wont be.
AFAICT, this just combined two chips on a board. And the 100x bandwidth is due to using a higher frequency chip. Nothing revolutionary.