Building Large-Scale Mesh Networks Using Ubiquitous Software-Defined Radios
from the distributed,-ad-hoc,-federated,-and-self-organizing dept
A couple of years ago, we noted that one lesson from Snowden's leaks was that the NSA and GCHQ were listening in to all the major pipes and nodes that go to make up the Internet. Mesh networks seemed one way to make things harder for the snoopers, but they have been slow to develop on a scale large enough to make a difference. A fascinating article on the Wireless Week site offers tantalizing glimpses of a new generation of wireless technologies that could make meshes easy to set up and hard to monitor. The basic technology is software-defined radio (SDR):
Thanks to inexpensive open source software-defined radios (SDRs), innovators will now be able to design their own wireless protocols. These protocols will be easy to use and effective in solving concrete problems instead of broad generalizations or focusing on exceptional use cases. The Github generation of wireless engineers will be born.
As their name suggests, the big breakthrough of SDRs is that many components that were previously implemented in hardware can be recreated in software. That means they can be easily changed, which allows wide-ranging and continuing experimentation. Couple that with plummeting costs, and we could be seeing SDRs built into practically everything:
Digital signage, smart light poles, vending machines, ATMs, home appliances, and many more devices can all have an SDR in them and provide mobile broadband or other wireless solutions with licensed spectrum, as well.
From that, it might seem that SDRs are just a superior, programmable form of the Internet of Things. But here's where things get interesting:
Any device will be able to be part of a distributed ad-hoc, federated, self-organizing broadband network. Running a mobile network will be less about installing large antennas and more about automating the management of distributed networks that get built on top of third-party owned equipment.
In other words, once SDRs are cheap and commonplace, and can be found in all kinds of everyday devices, they can then be turned into the ultimate mesh network simply by tweaking their software. That avoids the current problem with mesh networks, which is that they are often hard to set up -- a barrier to their widespread use.
These SDR-based networks would have another big advantage. Since they could potentially be on a huge scale, with multiple nodes in a single home, there is potential for obfuscatory routing of the kind used by Tor. Another interesting possibility is to build the ultra-cheap SDRs into drones, and use them as part of the ad-hoc mesh networks too. None of these approaches is guaranteed to stop the NSA and friends from spying on everyone, but they certainly offer the hope of making it considerably more difficult.
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Filed Under: ad hoc networks, mesh networks, sdrs, software defined radio
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Re: IP
(b) If it does run IP, it can have private addresses inside of it, with the correspondence between internal and external addresses known only to the mesh itself - NAT at the scale of the mesh
(c) You might as well build the thing using IPv6 and use self-assigned, rotating IP's - with, again, the addresses only known within the mesh. IPv6 addresses are large enough that you don't have to worry about collisions.
Keep in mind that you don't typically "own" an IP today. Rather, you ISP lends you one so that it can route packets to you. Thus, the ISP knows the correspondence between you as a customer and your IP address at any given time. In the case of a mesh network, it's the mesh itself that acts as your ISP. It, in turn, has to connect to the Internet somewhere - but it has its own address for the mesh as a whole; it doesn't externalize your address. A packet arrives at the mesh and then is somehow (details "TBD") routed through the mesh to you. Only the mesh need know who you are.
(Of course, you could build the mesh with IP "straight through", in which your IP would indeed identify "you". Some meshes will probably be built that way. But it's not the only alternative.)
-- Jerry
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Re: Re: IP
So when I stretch out on the couch and start surfing for pr0n^H^H^H^Heducational materials that I have a License from the copyright holders to access (ahem), there's only a small chance (or perhaps zero if that's how the mesh is configured) that my browsing session will go out my broadband connection. It's about 95% likely to jump from my mesh to my neighbours, and then to theirs, and use some random connection to the internet.
So any connection to the internet, on a per connection (I'm talking individual TCP/IP connections here, where a single page load in a browser could establish several score separate TCP connections) could either go out my link to the internet, or my next door neighbours, or a link half a city away, traversing a random local wireless mesh network before it finds a suitable (random within your configured QoS guidelines for latency, bandwidth and so on) link to the Internet backbone.
Therfore you won't be surfing with your ISP-provided IP address, each page you load will be using some random's v4 or a completely random v6 IP address, different every time you load a page (or whatever it is you are doing).
Of course, if the mesh is implemented badly, or even just poison meshes are involved, ala the Tor compromised exit nodes on so on, then it could still be possible to trace connections.
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Mesh with SDR
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Scratching the surface
We currently subdivide the frequency spectrum into bands and assign each band to an exclusive use and user within a geographical area. This way of dealing with the spectrum was introduced early in the 20th century to avoid interference: Given the modulation mechanisms available at the time, it was the only approach. Of course, it also lead to a whole visualization of spectrum as "real estate" that could be "owned" and had to be protected.
With SDR, this view of things is unnecessarily limiting - immensely so. Modulation techniques can share spectrum with minimal interference - spread spectrum effectively smears a narrow, tall signal at one "spot" in the spectrum over a much broader but but shorter signal. If two "tall" signals overlap, both are wiped out; if parts of two (or more) "shorter" signals partially overlap, each gets a tiny bit noisier but (up to a point) they both get through. USB (Ultra Wide Band) spread spectrum takes this idea to an extreme (and is used today).
On top of this, "cognitive radio" relies on protocols in which transmitters "skip themselves into the conversation" where they find silent spots. This is how WiFi works today - it's why you can have large numbers of WiFi devices using a pretty narrow piece of spectrum "simultaneously" without interfering (up to a point; everything has some limit).
In the old days, geographical areas were large - typically on the order of large cities - as the high power in on narrow, tall signal carried a long way at the frequencies in use, so transmitters had to be far from each other to avoid interference. Cellular phones are an example of how modern technologies can use much small geographical areas (WiFi and Bluetooth use even small ones). The fact that the same frequencies are assigned across much larger areas - hundreds, even many thousands, of cells - is a product of history and politics, not a necessity of the technology,
Finally, the move to ever-higher frequency bands - which can carry data at ever-higher rates, which implies the need for much lower power to carry the same amount of data (the power needed goes down as the square of the available bandwidth) opens up way more possibilities.
The "spectrum crunch" we face today is more a product of legacy technologies and regulations than of physics, as the Telco's want you to believe. Massive re-engineering will be needed - and the changes will be fought tooth and nail by the incumbents, who will see their "spectrum real estate", in which they've invested fortunes, dissolving away. But the time will come.
Another interesting point to consider: Spread spectrum techniques were originally developed by the military for two reasons: They are resistant to jamming, but they are also difficult to detect. A spread spectrum signal based on a cryptographic spreader, properly run, is visible only as slightly increased noise. If it's low power - all that's needed in a geographically limited piece of a mesh - you have to be very close to even notice that. So the traditional methods of finding and shutting down "rogue signals" don't work well against this kind of technology.
But the real control that the FCC (and analogous regulators the world over) have wielded over the spectrum in the last four decades or so is through regulation of the hardware. The old days of people throwing together radios from parts faded with the newer technologies and higher frequencies even by the 1980's. Stuff moved on chips - eventually, it became impossible for anything but chips to do the job. While it's possible to put together your own police scanner, say, very few people were in a position to do it. Regulate what the few hardware makes are allowed to build and you can keep the vast majority of people out of the police bands if you want.
We just saw a manifestation of this in the regulation of 5GHz WiFi radio controls. You can change some things - but power and frequency is locked down in the hardware, and it's impractical to build your own.
SDR changes all that. It allows you to use stock components - DtoA and AtoD converters - driven by software to implement all that stuff which used to be in easily-controlled hardware. "How are you going to keep them down on the farm after they've seen the big city."
The easy tight regulation of the electromagnetic spectrum that's defined the last hundred years is going to dissolve. There will be battles exactly like the copyright battles we see today. There will be huge technological winners - and losers. But the wireless world 20, 30 years from now will be very, very different.
-- Jerry
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Re: Scratching the surface
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Re: Re: Scratching the surface
I hear that the bandwidth is huge, however a few bitch about the latency!
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Re: Re: Scratching the surface
You might find the following article of interest:
http://www.nytimes.com/2016/08/09/technology/rural-electrical-cooperatives-turn-to-the-inte rnet.html
-- Jerry
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Re: Scratching the surface
all great stuff but as with most things in the radio world there is a catch to going to higher freqs. Range drops off dramatically due to the attenuation of the signal by walls, trees, buildings...and even the moisture in the air.
Also the backplane that defines the physical capabilities of the radio (available frequencies) is a pretty much physical thing. You can't make a backplane at the GHz range with wires that are on the order of the wavelength as those become antennas... interference, unwanted modulation,..... the list goes on and on.
Bet if you gave this problem to a Ham Radio operator he could have it figured out in a few minutes.
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Same with HTTP: it was just intended to link together documents for scientists. It was amazingly well designed for its time, but it was never designed as a framework to run applications or drive the series of tubes the internet has become.
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Re:
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Regulation
Take so-called software defined radios, for example. The FCC (government) generally requires that the software that controls the actual transmitting characteristics of such radios be locked down such that users have no access to it.
Another technology with great potential would be ultra wide band radio. Imagine if people had free access to communications that were highly secure, unmonitorable and virtually undetectable. No way. That would threatened both the government's ability to listen in and control the airwaves and the profits of the communications industry. That's why it's used by the military but mostly illegal for civilians.
The issues aren't so much technical as political/legal. And I don't see the those restraints getting any better anytime soon, if ever.
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Re: Regulation
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Re: Regulation
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The biggest step to reducing a governments ability to spy on people would be to give every device and endpoint a fixed IP address, which is possible with IP V6, and avoid centralized services wherever reasonable.
The Big weakness with present IOT is a dependency on a centralized server, which is not necessarily eliminated by use of mesh networks. Also, mesh networks based on low power radios can be established in densely populated, but will require high bandwidth connections through few nodes to provide the links between urban areas, countries and continents. The network links that governments tap into will not be eliminated by mesh networks, and nor will they make life more difficult for government so long as people rely Facebook, Twitter and YouTube etc. to keep in touch wit friends and hold conversation with like minded people around the world.
Interestingly however, mesh network will make it much harder for government to block communication in areas where protests are happening, where the issue is not so much government surveilance, but rather government censorship.
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potential but be careful
It's true that you will have new routes to move data around but who says that the individual nodes of each mesh are not compromised? The FBI (or was it NSA) that started de-anonymizing TOR?
Traffic will still be transmitted over wireless signals and require a standard communication protocol between each mesh unless you can get your own personal mesh to extend all the way from the physical start and end points of your data transmission.
I do admit that having a decentralized communication network will make it harder for the NSA and friends but they will still eventually get access to the data being transmitted.
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First, one must understand 'Mesh'
Now, if you diverge into 'meshing packets' (using multiple channels to send sporadic packets of data that are not complete to themselves) you can make the process of 're-meshing' far more difficult for the NSA, but then again, you can also put a CB in your car and instead of using your cell phone in-town, use your CB to chat and talk instead - far more likely ensuring anonymity than any cell phone will ever do again.
CB's - the ultimate anonymous party line, where you have to not only know the handles, but the voice, to even begin to guess at who you are talking to - and no idea of who is really listening. You ever notice how the more society pushes 'we must have no secrets' when selling NSA over-reach, no one ever brings up the idea of 'how great CB is as a communication device'? There is a very obvious reason they don't - because 'Big Brother' couldn't decipher half of the communication stream if it became popular again.
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Holes in the mesh are too big
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Can you say "internet of (insecure) things"?
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Re:
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Meanwhile in the 1950's...
And now try to find another node. Even with a 30 mile range or more, no dice.
Radio Shack, before their demise, sold PCMCIA Radio Cards (and the associated box with antenna) for under $30 that you could tune to any frequency you can imagine. Also used by exactly nobody (except some rare conspiracy theorists trying to figure out what those "numbers stations" were gabbing on about.)
Basically, this isn't new. Ok, it's software instead of hardware, fine. The problem is that it was never hard to do in hardware in the first place. Anyone who wanted to could've done so for $30.
Sorry to be the bubble-buster in the room but this is not an important development. Moving this to software will accomplish nothing because 99% of the public will still prefer good old 802.11 and PC makers won't spend another 50 cents on another radio in their boxes, much less $5-$10. The only way this ever becomes a thing is if the government mandates it.
Yeah, doesn't sound like something they'd mandate to me, either.
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Re: Meanwhile in the 1950's...
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It's complicated
Building the antennas and such is interesting because their scale is on the order of features on chips. So you actually build your antennas right on the chip with the electronics. I saw some samples which were cool: Some of the classic antenna designs, etched on a chip. But you can actually do much better by designing metamaterials.
Complicated stuff, but it was in the "engineering characterization" phase (i.e., we know that it works, now we need to figure out how to do it practically) 4 or 5 years ago. It's coming.
-- Jerry
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