Peer to peer text message forwarding for disasters and other emergencies
A few years ago I was taking part in a meeting to brainstorm ideas on how we (our global society) should plan to survive a flu pandemic or other widespread disaster. One of the things that became very clear to me was the critical importance of information and communication: people need accurate information in a timely manner in order to help them decide what to do. Absent that, they either make bad decisions or panic.
During the meeting it also became clear that our communications infrastructure was basically fragile. Power outages or equipment failures can quickly cause radio, TV, and cell phone networks to fail. Natural disasters can either destroy communications systems directly, or overwhelm them as people try to call their loved ones.
Throughout these discussions, one thing kept nagging at me: we all have cell phones in our pockets. There are at least two billion cell phones throughout the world. Each one of these phones is a two-way radio: it broadcasts and receives, at a range of several miles at least. But each of these phones is completely useless if cell towers within its range fail. To me that seemed somehow basically wrong, and eminently frustrating in the case of a disaster where urgent broadcast communication could save lives or prevent panic, but where towers were blown down or not available.
So I had a pretty obvious idea, I thought: find a way to turn cell phones into an ad-hoc peer to peer communication network. There must be people working on this, and it would only be a matter of time before somebody figured it out. In fact, somebody did, and developed a product suite around mobile mesh networks. Seems interesting, but too complicated to implement on top of billions of cell phones.
So here's my proposal: a simple peer-to-peer emergency text messaging forwarding system. Here's how it would work. Cell phone handsets would be programmed to listen for a special, authenticated text message on whatever frequency they normally listen on. Receiving such a message, it would display it to the user, and then broadcast it over the same frequency for a short period of time. That's basically it. A simple solution in concept at least.
I've thought a little bit more about how you could implement this and safeguard it from abuse, and how you could possibly expand it. Here a some more detailed points:
- The primary objective of this system would be to allow authorities or officials to broadcast a text message to the public, even in the absence of electricity, radio transmitters, or cell phone towers. It's not designed for a member of the public to send a message to call for help, although I have some ideas about how you could implement that in a future phase.
- Authentication: you would probably want to use some form of public key cryptography, so that handsets could verify that the text message package was officially authenticated, and that eavesdroppers couldn't learn enough to spoof an official message. My limited understanding of PKC says that this is possible.
- Here's how a message would be sent. In an emergency, an official would use a specially-programmed handset (or one into which an authentication code could be entered) and would author and send a special emergency message. The message would be broadcast on the special "listen" frequency that cell phones use to receive messages from a cell network tower. The broadcast would be repeated something like every minute for 10 minutes (network engineers can figure out what a good rate would be).
- Ordinary handsets would be listening in to the tower frequency even if they aren't in range of a working tower. (I'm not sure how exactly handsets operate when towers are down or out of range, but presumably they are least hunting at regular intervals. Perhaps they would have to be programmed to be listening constantly for a special message, which might cause more battery drain; I'm not sure.) When the handset receives and authenticates the special text message, it displays it and then rebroadcasts it every minute for 10 minutes.
- You would probably use message IDs and a rate limiter to avoid overwhelming transmission or unnecessarily repeating a message.
- The net result is that if your handset is within a few miles of another handset, it should receive the emergency message within minutes, even if there is no power, no cell phone towers, etc.
I'm not a network engineer and I'm more of a software person than hardware, so I'm sure there are some technical issues with the above that I'm not seeing. On the surface, it seems like it's basically a software problem, telling phones to listen for a special message on existing frequencies. Here are some possible problems:
- Reduced battery life. It's critical in a power-loss disaster to preserve the existing battery charge of every cell phone, so you would want to make sure they weren't transmitting unnecessarily. I don't know if "listening" for emergency text messages would require pulling more battery power: perhaps an engineer could answer that question?
- Multiple frequency networks. GSM phones don't talk to CDMA phones, etc., and phones only listen to frequencies that are related to their carrier, obviously. Therefore, in order to reach the entire phone population, emergency messages would have to be sent on each network from separate handsets. Interoperability seems like it might be more trouble than it's worth. Just have the official key in the same message into three or four different handsets or however many to cover all the networks in the region.
- Interference caused by large numbers of handsets re-broadcasting the same message. Message IDs would prevent the same handset from displaying or rebroadcasting the same message, but there's probably some interference effect of having hundreds of handsets in a small region trying to send the same message on the same frequency. Again, I'm hopeful a network/radio engineer would know how to solve this problem. You could also use software tricks like rate limits and random broadcast intervals I suppose.
I've talked to several people about this idea over the past few years; more so recently. There haven't been any immediately-obvious stumbling blocks. It seems like a capability you could add to the next version of your handset's firmware. If you're in the cell phone network business or understand these technologies, I encourage you to critique this idea. If it seems sensible, I encourage you to implement it!
Recent disasters have shown again and again that official communication has a hard time reaching people in a time of urgent need. This system seems like it would offer a consistent and reliable way to reach people, without relying on expensive network infrastructure.
Comments
Pierre, this is exciting to read because it's so well thought out. When Andy Carvin made a sort of passing reference to the potential of Twitter as a first responder, I remember you mentioning the idea of cellphones then. The outages during Hurricane Katrina and other disasters did indeed render them essentially useless, but what you are suggesting makes a heap of sense, and I hope that in fact it does catch. In terms of a device where there is a critical mass, cellphones are clearly it.
Sad to say that the need for this kind of thing feels more urgent than ever. Hope your punting this into the ethos returns some sort of tangible response, because this seems like a very pragmatic, do-able thing.
Sue.
Seeing as how the nation is again sensitized to solutions for public safety, I thought that your idea should be promulgated and enriched. I can’t do anything about the promulgation, but here’s my contribution for enrichment:
Ideas -
Why not have all the cell towers broadcast an Emergency Network Test message at 11 am every Friday?
Why not offer cell phones that allow you to monitor “emergency band” text messages from the police, fire, and disaster departments? Something like CB scanners do now. This also works if said departments also have broadcasting portable units. Moreover, it resolves the problem of reduced battery life that results from transmitting. (Altho, as you point out, too many duplicate messages is a logistical problem. Perhaps a code could also be transmitted with a “message number” that tells the next receiving cell phone to disregard the message with this “number” if it has already been received. This would be part of the emergency channel’s protocol, whereupon 5 or 10 minute broadcast intervals would not tax the system nor the cell phone.)
Altho upgrading all the 2 billion cell phones on the planet is impractical, it IS practical to upgrade the communications equipment of “first responders” to the standard you suggest. I’m surprised that this has not already been done, what with the “terrorist prevention” mentality that has recently overtaken government.
You can bet that Early Adopters will want one of these “enhanced” cell phones. Why not finesse this desire into a civic duty, namely, licensing. Anyone who gets a souped-up cell phone must also agree to the protocols of emergencies, these being… well, I’ll let the experts create these.
Questions –
Don’t cell towers already have emergency battery back-ups in case of power failures?
It may seem silly, but isn’t there a hand-crank cell phone recharger on the market? Wouldn’t such a devise be invaluable in case of total power grid failure? I am speaking of particularly of the equipment carried by “first responders”.
Problems –
A broadcasting cell phone runs down much more quickly.
There needs to be “levels of emergency” factored in as well as local, regional, and national “rings” of affected areas. Also, “kinds of emergency” would be helpful, but this could be addressed by having different channels, much like fire and police scanners.
Observations –
It may be an oversimplification, but disasters come in 2 varieties: Communications Networks down and Communications Networks functioning. In the case of “down”, the proposals you make are completely reasonable, but again, I am wondering if local and state governments are not already gearing up for this since the advent of Homeland Security. In the case of “up”, the problem becomes much more complicated because the networks being overwhelmed with important and unimportant activity.
It seems to me that emergency text channels and priority broadcasting of same would go far to solve the dilemma. Because the cell network “knows” which phones are available, it would be a simple matter for a disaster command center to broadcast a message to all phones as needed. It could even be limited to small areas, such as a 10 block alert for a shooting suspect. It is scary, though, how by degrees we are creating a surveillance society.
Coincidence? I think not.
I just posted an eBay idea along with my raft of initial blogs, and YOU are eBay’s daddy. Would you do me the kindness of critiquing it?
http://news.bbc.co.uk/1/hi/technology/6577307.stm
I'm eager to see what can be done remotely in villages for secure access. The GATR technology seems mobile and deployable in a pinch for backup systems.
Thanks for your responses. There are definitely some exciting technologies for remote Internet access, and I don't know enough about the technical details to prefer one over the other. Clearly wireless in general is the way to go.
This particular SMS forwarding idea is really focused on the cases where cell phone networks cease to function because towers either run out of power or are physically damaged. Other than radio transmission -- which is also vulnerable to power-loss and physical damage during an emergency -- I haven't seen any communication plans that would enable large scale broadcast like this plan might.
Self-generating and self-replicating batteries are essential; long term we need power systems that are far more efficient in recharge. There's a group of friends at MIT working on solutions and an architect in our home working on heavy metals reclamation of the LA River as a potential new resource for battery systems for emergency preparedness.
Toyshoppe had light-based ideas that would allow for fine-tuned conversation over great distances. Sound is less efficient but useful; digital tools may fail quickly and power may not be easy to generate for most of the millions who go without power during major disasters.
Here in LA we're feeling the heat, very literally. I live sandwiched in four miles of neighborhood between two parks; one that's now halfburned and the other that has countless oil wells and storage facilities on site. There's nothing I've seen in LA that can handle the diverse needs of this city in a clear and direct way. The old emergency siren down the street is from the 50s.
I don't think such a system can ever fully work. What would you say in a situation like Virginia Tech? How do you word it to get people to safety when you don't have a handle of the situation? Additionally, if a serious event / crime is happening because of an individual, and that same individual is on the page system, then they know the actions of the authorities. Had this system existed at VT, and school officials were to say, go here or there, then the shooter would have known where to go to inflict maximum damage. I also think of the repercussions since people are lawsuit happy. I can see the lawsuits fly with parents suing the University because they told their kid to go somewhere and they died. If something like this were to be setup, there should be Federal Law to protect against liability in case the worst should happen.
For those interested in the technical details, data being sent from the cell tower (the so-called "forward link") is encoded using a mathematical technique called Walsh coding. This coding technique allows more data to be sent in a given amount of bandwidth. Basically, the cell tower is simultaneously transmitting to multiple cell phones, so the data can be encoded in a way where each individual tranmission does not interfere with the other simultaneous transmissions.
Because the cell phone isn't sending multiple simultaneous data streams, Walsh coding isn't possible from the cell phone (the so-called reverse link).
This is all a giant simplification, but I hope I conveyed the general problem.
This is a great idea, however the technology will fail in certain disasters (nuclear, gamma ray burst, etc).
The electrical circuitry (cellphones, computers, radios tvs) is very fragile, and will be destroyed by these events. There will not be enough time to be notified, even if the power grid does not go down.
There isn't a lot of good disaster management systems out there, but, a promising one is Sahana, http://www.sahana.lk/
It would seem that if a person gets the initial text message, they could message back that they would like to help, and then they could be integrated into Sahana for more details.
Maybe you should set-up a wiki page for this? Maybe do an IRC brainstorming session to bounce more ideas around, and we could invite more people who might want to jump on board and run with various aspects of these ideas. An evening of work to seed the wiki, perhaps? Feel free to email me if you want help setting something like that up.
-Josh