Slashdot Mirror
DARPA Wants Wireless Devices That Can Blast Through the Noise
coondoggie writes "What if your wireless communications just absolutely, positively have to be heard above the din of other users or in the face of massive interference? That is the question at the heart of a new $150,000 challenge that will be thrown down in January by the scientists at DARPA as the agency detailed its Spectrum Challenge — a competition that aims to find developers who can create software-defined radio protocols that best use communication channels in the presence of other users and interfering signals."
Don't do it!
http://en.wikipedia.org/wiki/Ultra-wideband
Mother-in-law.
years ago. It's called Morse Code.
When all else fails, Morse Code gets through.
Do they want their new devices to not interfere with normal domestic use of consumer wireless devices?
If so, then I can see that it might be tricky. The only probable solution would be to dedicate specific channels for their use and have rigidly enforced laws in place which forbid usage by consumer devices. If they don't care if it interferes with such devices, then isn't it just a matter of increasing the power output on their transmitter?
File under 'M' for 'Manic ranting'
You gotta use multi-phasic shifting!
Make it so.
The actual DARPA page, with rules/etc., is here.
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
I'm not an engineer.. but some random thoughts?
1) Can you use out of band communications to trigger a special mode of the router (assuming you control it)? (e.g., A special listening mode that gives certain devices priority)
2) Rather than use typical QAM type of modulation, can you use a more limited constellation but BOOST the power so you can punch it through the noise? (which would also allow you to make very good use of forward error correction (FEC); again assumes that you are able to program both the sender and the router.
Assuming you can't alter the Network Stack on either device than you have to look at the communications itself
3) Other than that, it would seem you would need to use a programmable antenna/software antenna, Etc. turning your own Antenna into a high directional Antenna with as much gain as possible. Basically find the WIFI router you want (geo locate it, perhaps triangulation with the help of friendly nearby devices) and the push all your signal towards (a dynamic Yagi antenna that auto-magically maintains it's "aim" at the router even as the sender and/or the receiver move about.
4) If you did have some control over the router and you were sure that you could depreciate other traffic then the router would also get the same auto-magical antenna system and the two devices would "focus" on each other.
http://www.hawknest.com/
Enough said :)
Never antropomorphize computers, they do not like that
The goal is to "engineer software-based radios that transmit data faster than a competitor using identical hardware".
The goal isn't to develop fancy new hardware, or to use an overwhelming amount of power. The goal is to develop fancy new software.
With frequency-hopping and time-hopping techniques, if you can intelligently adapt to the local interference, and transmit in the time and frequency gaps where the interference doesn't occur, then you can transmit more data for the same amount of power. That's the goal.
They want the BEST solution.
Seriously, as others have pointed out, there are obvious ways to solve the problem.
DARPA is challenging the community to come up with optimal or at least more-optimal-than-everyone-else ways.
The only "downside" I can see is that the competition is in a controlled environment. I say let's do the tests in an "uncontrolled" environment, much like an outdoor sporting event where neither the competitors nor the officials get to control the weather. Play the "game" several times in several "representative" environments such as large cities, small towns, rural areas, and during several different times of day or night, etc. Then use a pre-determined, pre-published scoring rule to determine not only the "overall winner" but the "winners" in various categories, e.g. "best in big cities," "best at night," etc.
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
If spectrum licensing is predicated on the basis of a need to prevent / minimise interference, if such a technology is developed, the requirement to license spectrum (and for governments to print money carrying out such licensing) would seem to fall away.
Yochai Benkler has already made a persuasive case (I don't know if this was officially published) around this and, if it was possible to deploy widely technology that worked irrespective of interference, we'd seem to be one step closer.
The cynic in me thinks it might fail as a result, since I doubt many governments would want to lose the money, or incumbent operators a means of excluding others from the market.
The rules aren't available on the site yet, but I assume they're interested in resistance to jamming. From a theoretical perspective, as long as the receiver isn't saturated, there should be some data rate at which transmission is possible. This follows from Shannon. Noise can be overcome with redundancy, at the cost of data rate.
You can usually do better than that by moving around the spectrum to quieter areas. That's what frequency-hopping systems do. Jammers can be agile too, but unless the jammer is in a direct line between sender and receiver, the jammer is always at a time disadvantage due to speed of light lag. Very fast frequency hopping can overcome agile jammers.
What DARPA wants, I suspect, are systems that package up all this into a system that takes care of any noise problems automatically and will get a message through if it is physically possible. DoD has had systems for that for decades, but the technology tended to assume that the opposition didn't know the details of how it worked. It may be possible to have jam-resistant systems that work even if the opposition knows the technology.
Just out-blast them using the maximum strength power on the biggest directional antennae you have.
Didn't this happen back in the old pirate radio days where governments tried jamming them, until the pirates learned they were being jammed and thus changed frequency?
This is a solution looking for a non-existent problem. First responders and the military all have handy-talkies and their own dedicated spectrum. If you have too many police and firefighters in an area saturating the bandwidth it won't do any good to give each one a "priority" device, the bandwidth will still end up being saturated if everybody insists on speaking at once.
I don't know about the radio spectrum interference, but if they want relative freedom from sound interference, all they have to do is use something like the old WWII-style throat microphones that pilots used. They work. And of course I assume that the technology has gotten better since... they'd probably work even better now.
PPM (pulse position modulation) seems to be pretty resilient. Picking up mode-S transponder signals from planes as far away as 200km with a stock DVB-T antenna and a really cheap SDR (rtlsdr), which has very poor dynamic range. Even when the signal barely gets above the noise threshold.
If I can place my order just a few milliseconds faster, I will be able to make a LOT of money. If I make it possible,. how much do you think banks will be willing to pay me? 150.000USD will be pocket change.
I am sure I can at some zeroes when I offer it to the banks.
Don't fight for your country, if your country does not fight for you.
Frequency Modulation has a phenomenon known as capture. Whichever is the loudest is what you pick up in your car. So if you broadcast it with enough energy, it will break through all sorts of interfering signals on the same frequency.
Chewbacon
The Bible is like Wikipedia: written by a bunch of people and verifiable by questionable sources.
Re: The actual DARPA page, with rules/etc., is here.
.
Except for the fact that right now (~1pm PST 2012-12-22) that page has grayed out tabs for
1 -- Rules
2 -- Register
3 -- Q&A
;>)
The only tab that is live currently is the "Home" tab at that direct link http://www.darpa.mil/spectrumchallenge/. I don't think the other tabs go live until January 2013, so the rules and such are not available yet.
Like most DARPA competitions, this is not for novel research into techniques. The solution is usually selected from available technologies. I'm assuming that the most likely candidate is MIMO and null steering.
I was wondering how the terrorists were going to trigger their IEDs when the growlers were flying over head. DARPA to the rescue.
I have a feeling that people might use this research to blast their data packet on the existing crowded frequencies.
So, DARPA wants to override FCC rules of "any device must accept unintended interference"? ...
isn't it ironic ... that many DARPA projects, initially ARPA inspired originally at any rate are the main cause of interference as it stands at present. ...
Seems that the biggest visible tech, er, the internet, or rather its hardware leads the cause of electrical pollution
ADSL, along huge aerials, i mean wires, BPL switch mode power supplies etc can all trace ancestry to such.
Pedants may well (correctly) argue that its not so much the actual spec, as much as the implementation, ignorance and cost cutting in practical
areas such as screening, poor maintenance, insufficient filtering (like cheap far eastern electronics) and pure bloody mindedness..
I've been shouting about electronic pollution for years, but they'll only take notice when they are affected. dont Ya think ?
The stuff about "disaster relief" is entirely bogus. They are asking people to work on an entirely military application for very little gain...
This is a problem for me, since my neighborhood has really cluttered wifi channels. In my case the best solution I've found is to just bypass the door safety switches on my microwave and sweep it back and forth out the window for a few minutes.
I then have channel 9 to myself for the next couple months.
Jamming only works if the receiver can't tell the difference between the signal and the jammer. If your receiver can look around and see where different signals are coming from then it can check each one for validity and ignore the signals that have the wrong code. It's like if someone puts a high intensity flashing light on a billboard, you can just look away and still see stuff.