Transferring Bitcoin through radio signals?

[Lethn]

Say the worst case scenario happens and while governments might not be able to get the Bitcoin network itself down they managed to shut down many parts of the internet, do you think it would be possible to send Bitcoins through short range wireless radio signals? I'm talking walkie-talkie distances, I was wondering as well if maybe this could be a solution for anyone who doesn't really use the internet or have access to it. You could receive the Bitcoins from the network still left on the internet where there is a connection and then people could communicate through radio signals.

I'm wondering if I'm thinking of the right thing, it may well be there's a much simpler wireless option that we could use but I'm thinking in terms that wouldn't require any supporting infrastructure or outside help.

[rarkenin]

The first obvious possibility is for TCP/UDP connections over some protocol such as 802.11(commonly known as WiFi). This can be secured with simple to complex crypto so only users authorized to connect on a network can connect, so the network can't be compromised in that area.

Then, of course, there's sending the blockchain and transactions over radio without internet surrounding it. This would generally use encoding(the bitcoin protocol), error-checking(CRC32 or crypto-based MAC), and modulation. For short distances, we could get away with something like 64-QAM, falling back to simpler constellation patterns due to signal loss. In severe cases, or where it is not necessary to have high bandwidth(nodes once theyhave the blockchain), PSK can be used as it is a bit more resilient. While most PSK is at "normal" bandwidths at least in the tens of kilobits per second, PSK31 used in amateur radio is more resilient but offers bandwidth comparable to typing speed, around 10 bytes per second.  Securing it would be another challenge as there would need to be some sort of handshaking and authentication on the link. Anyone could easily interfere with this link, though, by using jammers, or badly soldered high school electronics projects that spark a bit.

This may be alleviated using highly directional antennas. With the correct set of reflectors and good aim, one can reduce the signal spread to a few degrees off center. Satellite links can also be used if one can find a satellite which will relay the data to the correct location or at least into the general internet.

So, you would save a lot of time, worry, and eyestrain(from technical documents) by using (relatively)high-distance wi-fi, or encapsulating internet protocols carrying Bitcoin packets on other radio links. Except in extreme cases, encoding the blockchain and other communication over radio is overkill, except in possibly a specialized miner setting where miners(ASICs or FPGAs) use their own radio signals to connect to a master machine. Still, it would be easier to use ethernet, USB, or WiFi.

[gollum]

Good idea!
Mesh-networking is otherwise a good solution, there are devices that can communicate with other nodes up to miles away.

[rarkenin]

Yes! There are already systems in place in the protocol to mesh well. All we need is for the nodes to do simple probes on their radio networks. I'm thinking running a hybrid between WiFI for high bandwidth+FCC/euro communication compliance, and a different frequency for longer distances with low power(as transactions don't need THAT much bandwidth), and lower detection/interference by existing annoyance methods. The problem is that if a mesh network were to disconnect, there would need to be checks in place(block rate, hash rate) to prevent a blockchain split as miners on one network work on their own blocks. All the equipment is provided by mesh nodes, some of which are able to also connect to the internet to keep the mesh from chain-splitting. No central towers, carriers, or anything like that is needed.

Anyway, as a compsci/telecommunications student, I'd love to collaborate this if anyone wants to. I understand C++ pretty well, and can program well in Java and PHP.

[Elwar]

I worked on such radio mesh networks for the military. It is certainly possible.

Even easier if you have nodes that are not mobile, but certainly do-able.

I would like to see a time when people buy solar mining rigs that also act as a bridge  on the mesh network which they can just mount on telephone poles or tall trees all over their town and anywhere else they can find to stick them.

There is even a solar spray paint now so you could just spray paint the top of the telephone pole and if you make the device small enough to go un-noticed (or make it look like part of the pole) it would probably stay there for years.

[gollum]

Assume that in a post-world war world internet is unreliable, some part of the network might be disconnected from the rest for a day. That would result in forking.
Can bitcoin protocol be changed so it dont becomed forked during such conditions?

[rarkenin]

As per https://en.bitcoin.it/wiki/Weaknesses#Segmentation, the fork won't happen with at least a trickle of data. Any nodes that CAN try to bridge the gap with a higher signal(200 watts or so) should try to do so, but if only a few devices can do this there is a signal of trust. Very-low-frequency systems can try to bridge this gap, as they are not necessarily restricted to full line-of-sight.

[rarkenin]

bump

I hope that sometime in the near future, we see a radio-based Bitcoin node setup, with possibly ethernet connections to the network at large... WaveCoin or something like that...

[gollum]

bump

I hope that sometime in the near future, we see a radio-based Bitcoin node setup, with possibly ethernet connections to the network at large... WaveCoin or something like that...

What we actually need is not a bitcoin-specific backup network, but a mesh-internet that is not hosted by governments or corporations, but in a true p2p manner by individuals. This net cannot be controlled or censored by governments.

Example of how such net can be set up around the world:
-100s of small and cheap satellites in orbit around the earth containing mesh networking routers and small servers running bitcoin, namecoin dns and decentralized websites. Sites such as piratebay that are banned on earth can be hosted in space instead.
-Several gateways in each city relaying signals between the satellites and the mesh network in that city
-Public mesh routers around each city on public places, some of them on walls and trees, and some on drones (sunpowered 24-7 in air).

This network won't have a high bandwidth or good ping but it will work when the regular internet is not working or is censored.

[rarkenin]

I'll gladly take part assuming I have the money to get a node. The best I can do is 1 watt WiFi at the moment. But it would need to be more distributed as DNS is quite centralized at the moment. Maybe some distributed table, or even the blockchain could be used for this.