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The Military Communications Wireless Networking

DARPA Wants Extreme Wireless Interference Buster 105

coondoggie writes "This month the Defense Advanced Research Projects Agency will begin looking for technology that will let wireless communications work through the most extreme interference. From the article: 'The CommEx program will assess next generation and beyond jamming threats and then develop advanced interference suppression and avoidance technologies to successfully communicate in the presence of severe, traditional, and novel types of interference that are orders-of-magnitude more severe than what are currently addressed by the most advanced systems, DARPA stated.'"
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DARPA Wants Extreme Wireless Interference Buster

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  • by advocate_one ( 662832 ) on Thursday September 09, 2010 @02:55AM (#33517786)
    in the article... anyone got a better link?
  • by bugs2squash ( 1132591 ) on Thursday September 09, 2010 @03:00AM (#33517810)
    LDPC, spread spectrum and more EIRP. Or are they hoping to overturn Shannon ?
    Really, the state of the art is fractions of a dB away from theory. There are no further breakthroughs to be found. Unless you count social engineering the bad guys to block the wrong signals.
    • Re: (Score:3, Informative)

      by russ1337 ( 938915 )
      exactly. I'd speculate that these techniques have been combined and in use for some time.

      Just look at how long GPS has been around. For those not aware, it uses spread spectrum CDMA, with a signal is well below the noise level. I've speculated (in my mind) that you could easily combine the techniques to transmit and receive reasonable data at a level 'below the noise threshold' for some time. Just like GPS, you just need some reasonable clocks (hand held GPS quality), some decent processing (like an FPG
      • Re: (Score:3, Insightful)

        As a former ELINT / EW drone, I'd like to make a correction good sir. I can tell you that the GPS spread spectrum transmissions (actually, all spread spectrum transmissions) are not below the 'noise level' - or noise floor. They are quite distinctive on a spectrum analyzer and the link you posted does show this. I say this sitting at the back end of several 20+ meter satellite dishes and do acknowledge that for some receive systems, the transmissions may indeed be below their noise floor - but, to qualify t

        • by rcw-home ( 122017 ) on Thursday September 09, 2010 @07:53AM (#33519184)

          if something is below the noise floor, by extension this means it simply cannot be received. Including spread spectrum.

          No, it doesn't mean that at all. It does mean that your error-free bitrate will be limited to less than the bandwidth (how much less depends on how much more noise than signal you have). GPS uses 1.023MHz of bandwidth (for the civilian signal - 10.23MHz for the military one) and has a bitrate of 50 bits/sec. Typical noise levels are -110dBm and typical signal levels are -130dBm.

    • by tempmpi ( 233132 ) on Thursday September 09, 2010 @03:55AM (#33518036)

      They are looking at intentional jamming, not at white noise. Your solution would be almost perfect for white noise channels but not for channels with jamming.
      E.g.: No jammer will be able to distribute its noise evenly in both time and space. You should be able add a nice bit of performance if you are able to predict the behaviour of the jammer to some extend. So spread spectrum with non-uniform frequency distribution of the signal energy could be a topic. Some jammers might not even send real noise but pseudo random noise. Then you could try to subtract the jammer from your received signal.

      • by Aceticon ( 140883 ) on Thursday September 09, 2010 @07:10AM (#33518944)

        And then let's not forget the spatial dimensions in addition to the frequency dimension - jamming signals originate from one or more sources at specific locations so this could also be used in eliminating interference from jammers.

        I remebers from reading a bit of the GSM spec that mobile phones includes adaptative antenna and algorithms that allow retrieving a usefull signal not just from the direct line of sight transmission (from the mobile tower) but also from multiple reflections with different path lengths. Could not the same techniques be used to, instead of boosting a signal, offset that signal?

        • by TheLink ( 130905 )
          What you could do is have the sender have two or more antennas and the receiver too. Then put the antennas in different physical locations.

          If you know where exactly they are, it'll be much harder to jam, you can use all sorts of tricks to deal with the jamming.

          It's just like someone trying to jam your eyes by shining a randomly flickering bright light in your general direction. Assuming what they are sending is not bright enough to destroy your receivers (in which case why bother jamming), you could just ha
        • Situations where a single transmitter and single receiver are the norm are almost never the case anymore (at least in the wireless domain). A favorite paper on the subject is: http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1624625 [ieee.org] Cooperative MIMO, Spread Spectrum, and Cognitive networks potentially allow EM jamming to be avoided and more easily predicted. Perhaps DARPA suspects that the channel is, in reality, a non-zero-sum game. That would overturn Shannon alright!
      • by Skapare ( 16644 )

        Even a single carrier looks like white noise to a true spread spectrum receiver. Of course, a strong enough single carrier can look like strong enough white noise to obscure the information. Spreading wider reduces that effect. Smarter would be to have a system that detects such signals and applies active filtering, including modifying the transmission to not use frequencies around the interference (but maybe keep noise in there, anyway, to not let the interference operator know he was evaded). I'm sure

      • by Idbar ( 1034346 )
        If your signal is bandlimited, you could assume the noise is white in your band of interest.But I get your point if you put for example high powered tones

        I would be also interested on the distribution of the noise, more than its spectral characteristics. Many times it's easier to remove frequency shaped noise than distribution shaped noise.
    • Re: (Score:3, Interesting)

      by Trepidity ( 597 )

      I think that's probably true for algorithms, but it might not be for deployed systems. Current communications devices can't use all the available theoretical techniques over all possible frequencies in all possible configurations, so there might be some significant gains on that front with new transmitters/receivers/etc. For example, most spread-spectrum systems operate over relatively narrow portions of the spectrum, at least compared to the whole electromagnetic spectrum--- nobody is spreading over everyt

    • Re: (Score:2, Informative)

      by mattj452 ( 838570 )
      I'd imagine that not only will they look at those techniques (FEC, spread spectrum etc), but also techniques related to intelligent channel switching when a channel is jammed. Also, there are other methods than noise to interfere with the reception. For example, sending out false signals, repeated signals etc which also needs to be considered.
    • Re: (Score:3, Interesting)

      by AK Marc ( 707885 )
      You need signal/noise of some level. Jamming acts like noise. You can't add power past some point, so that means you must subtract noise. How? Well, you can try MIMO techniques that try to essentially lock on to the jamming signal and subtract it out. Or lock on to the generated signal with rejection of the jamming signal. Right there are two possibilities that don't violate the theory and should be able to get real gains. Maybe not the best possible, as moving jammers or moving desired signals would
    • Re: (Score:3, Insightful)

      by HungryHobo ( 1314109 )

      they could come up with some kind of missile designed to go after transmitters broadcasting interference, they'd be pretty loud and easy to spot.

      of course this is probably for drone tech so if you armed a drones as such and programmed them to attack the transmitters if their command channel was blocked the first thing any amoral adversary would do would be to stick an interference transmitter in a preschool with a camera crew nearby.

      • And then the taliban uses their favorite tactic : place the jammers in a kindergarten with journalists in the next building, camera's ready. Obviously the cameras won't flash when the journalists help the muslims kick a few more children directly into the weaponized zone, but they will flash after a rocket strikes.

        So avoiding the issue altogether, if you can, is probably a better idea.

      • by mcgrew ( 92797 ) *

        of course this is probably for drone tech so if you armed a drones as such and programmed them to attack the transmitters if their command channel was blocked the first thing any amoral adversary would do would be to stick an interference transmitter in a preschool with a camera crew nearby.

        Not all bombs are munitions. You could kill the transmitter with an EMP burst. Nobody gets hurt except the electronics.

        I think I need to start buying old vaccuum tubes -- EMP is ineffective against non-solid state gear.

      • They already have a weapon similar to this. It's called a HARM (High Speed Anti Radiation Missile). They were developed/used to take out radar sites. Similarly, they can be used to take out radar jammers (at least theoretically, I don't know if they ever have) since they operate on the same frequencies. So if you could tune the antenna/software to the right frequencies, then you can now go after communications jammers (and assuming some sort of IFF).

  • But... (Score:1, Funny)

    by Anonymous Coward

    How long after they develop the extreme wireless interference buster that someone develops the supreme wireless interference generator?

    • Sort of like VG-2 and Spectre speed radar. There's a huge list of technologies in a cat-and-mouse game between these radar guns and the detectors. Here's an idea of how it goes:

      1. Police invent new speed radar
      2. New detector comes out that can detect it
      3. Police update technology to evade detection and detect detector (they detect some radiation the detector emits in operation from what I understand)
      4. New detector comes out that can detect the updated radar gun and avoid detection
      5. Steps 3-4 may repeat a

  • by jd ( 1658 ) <{moc.oohay} {ta} {kapimi}> on Thursday September 09, 2010 @03:04AM (#33517830) Homepage Journal

    The conventional approach by NASA is to use Turbo Codes to handle burst errors and Reed-Solomon to handle randomly-distributed errors. You'd need to increase the error correction bits to handle really significant errors, but that seems like a good starting point. If you were to imagine the data as a cube, then produce the error-correction codes for each and every line you could draw through that cube, then each unit within that cube is represented by three sets of error-correction codes.

    • Re: (Score:3, Funny)

      I remember way back being taught about trellis code modulation - 8am - squeaky white board marker - "Right, today we'll cover a very simple 2 bit trellis code modulation scheme' - I thought I was a frigging rocket scientist back then, 2 bits, heh, some kind of noob joke?! I have to say after 2 minutes I'd actually glazed over, just like everybody else... : )

      Who dreams this stuff up! Seriously! These guys and girls don't actually think like the rest of us.

  • by nacturation ( 646836 ) * <nacturation@@@gmail...com> on Thursday September 09, 2010 @03:05AM (#33517836) Journal

    This is so easy. All you need to do is roll out a point to point Faraday cage between the two parties that wish to communicate. To build the Faraday cage, go to your local hardware store and purchase all the rolls of chicken wire they have in stock. Now take the chicken wire and form a loop about 5 meters in diameter. Keep on doing this and stitch the loops together until you have a big enough tunnel to reach from your source to the destination. Remember! There must be line of sight for your wireless to properly function. I recommend getting wooden pallets to smooth out any hills and valleys so that you can see clear through.

    Now the fun part. To make a proper Faraday cage you need to run current through the chicken wire. Experiment with the right voltage, but I find that running a chainsaw through a local wooden power pole will score you a big fat power cable capable of delivering the right amount of juice. Strip the power cable and attach the positive and negative wires to the chicken wire. CAREFUL!!! Make sure you're wearing latex gloves to protect your hands against the current. If you don't have latex gloves, fashion your own gloves out of banana peels.

    Once the power is hooked up, you have now created an impenetrable electromagnetically shielded tunnel through which your wireless transmissions can propagate. Place the transmitter at one end and the receiver at the other and enjoy your interruption free communications!

  • by HRbnjR ( 12398 ) <chris@hubick.com> on Thursday September 09, 2010 @03:30AM (#33517926) Homepage
    Just make sure the CommEx program doesn't contract the electrical engineers behind the iPhone 4 antenna - I hear they are looking for work :P
  • 'The CommEx program will assess next generation and beyond jamming threats and then develop advanced interference suppression...

    This is the only suppression I'm familiar with:
      http://en.wikipedia.org/wiki/Wild_Weasel [wikipedia.org]

  • Sounds more like when you're trying to bust someone busting you.

  • by Dutchmaan ( 442553 ) on Thursday September 09, 2010 @03:50AM (#33518018) Homepage
    This has drone research written all over it! Take out a signal to a drone and it's as good as shooting it down. It's probably easier to mess with a drone signal than shooting it down as well, but that's just pure speculation on my part.
    • by Jahava ( 946858 )

      This has drone research written all over it! Take out a signal to a drone and it's as good as shooting it down. It's probably easier to mess with a drone signal than shooting it down as well, but that's just pure speculation on my part.

      I wouldn't be surprised if the drone has enough wherewithal to at least attempt to make it home when command-and-control and/or GPS signals fail. Even assuming whatever radio channels it uses are jammed, it still shouldn't have too much trouble using magnetic / visual orientation to return to base. Seems unlikely that there aren't quite a few layers of redundancy in there.

      • by sjames ( 1099 )

        True, but even so, whatever the drone's mission, it's no longer accomplishing it at that point.

    • by Ksevio ( 865461 )
      Actually, being a drone it'll just fly around in circles or to somewhere that it can get signal. Shooting it down would be better for an adversary as there wouldn't a drone anymore.
  • Use neutrinos.
  • by syousef ( 465911 ) on Thursday September 09, 2010 @04:14AM (#33518108) Journal

    It's called cat5e.

  • by Kaptain Kruton ( 854928 ) on Thursday September 09, 2010 @04:31AM (#33518196)
    IP over Avian Carriers. (IPoAC). With the pigeons, you don't have to worry about EM radiation interrupting the signal. http://en.wikipedia.org/wiki/IP_over_Avian_Carriers [wikipedia.org]
    • Re: (Score:3, Funny)

      by L4t3r4lu5 ( 1216702 )
      They would indeed be impervious to the jamming effects of EM interference.

      However, unlike EM waves, they are totally at the mercy of buckshot.
      • > They would indeed be impervious to the jamming effects of EM interference.

        Not if there is enough of it.

        > However, unlike EM waves, they are totally at the mercy of buckshot.

        I think you mean birdshot.

        • I think you mean birdshot.

          This is DARPA we're talking about, we need to spend millions on improving the state of the art pigeons until they're bandwidth is greatly increased and you'll need buckshot to down them.

  • Seems like the best way to me...

    • Re: (Score:2, Informative)

      by f3rret ( 1776822 )

      I think there's a practical problem with running wires to Predator or Global Hawk drones...

  • by NouberNou ( 1105915 ) on Thursday September 09, 2010 @04:55AM (#33518314)
    Not really sure what they can advance on besides frequency hopping routines that are quicker and cover a larger spectrum. SINCGARS, HAVE QUICK I/II and SATURN are pretty good at counter-jamming already, as long as the sequence can not be easily predicted and the fills are updated regularly (every 24 hours or so) then jammers will have to invest quite a bit into the infrastructure of their broadcasting equipment. It certainly wouldn't be portable, and it'd be loud and easy enough to find and take out by more traditional means.

    The only thing, like I mentioned above, is moving to waveforms that are spread across larger frequency ranges (which can be problematic) and are faster so the jamming equipment can't keep up with the normal signal. Beyond that, digital data over RF can be reinforced by better packet correction and error handling.

    Of course you could always just overpower every other signal on your band, but I do not think battery tech has reached that level yet for portable radios, and well... Most soldiers prefer not to be cooked alive if they have a choice.
    • They may be hoping to promote communication techniques based on "new" theories such as concurrent codes. Early demonstrations of the BBC algorithm [usafa.edu], for example, are simply breathtaking. BBC allows jam-resistant spread spectrum without needing to coordinate a shared secret (such as a frequency hopping sequence) between the sender and receiver.
  • Seriously, doesn't everyone on slashdot want this as well? I'm surprised it doesn't have the 'want' tag yet. =)
  • Flag semaphore remains highly resistant to electromagnetic interference. http://en.wikipedia.org/wiki/Flag_semaphore [wikipedia.org] There is more to be done with interference cancellation techniques using active multiple-antenna systems, that can place a null toward the source of interference.
    • by Arimus ( 198136 )

      Might be safe against EM interference but interference from a sniper...

    • by dargaud ( 518470 )

      Flag semaphore remains highly resistant to electromagnetic interference. http://en.wikipedia.org/wiki/Flag_semaphore [wikipedia.org].

      You fail at both funny and informative: it's enough to block the electromagnetic spectrum from 390 to 750 nm to render those inoperative. It can happen with fog, or be done with smoke or any material placed in the line of sight. Guess why IR communications are hardly used for anything except TV remote controls even though they've been around for decades...

      • by sjames ( 1099 )

        You're forgetting, this is the U.S. dod. They're not the Boy Scouts. By the time the military-industrial complex gets done with this, the semaphore flags will be made of new cutting edge materials that reflect x-rays and can withstand anything short of a nuclear weapon. They'll be handled by an armor plated remotely operated computer controlled boy-scout mark 2. The reciever will use a combination of visible light, soft x-rays, and infrared.

  • Almost any sort of wireless interference can be used to break the security of connections. Almost any method of breaking a secure connection can be used as interference as well.
  • All I need to do to block those devices is to use a lot of those devices. The definition of "lot" depends on frequency spread, distance, power used, algorithmic magic etc, but...

  • If they really wanted to go scifi, they could develop neutrino communication. A beam of neutrinos can go through a light-year thick wall of lead with only a 50% loss!
    • Good luck modulating it unless you have a very electrically charged big-bang tiny black hole that you convinced not to evaporate.
  • 1) spatial domain: beamforming: make sure that the receiver, the transmitter, and the interferer are not aligned in a line. 3D: assume the interferer is on the ground. as long as one of the transmitter or the receiver is in the air/space, there is a good chance to use beamforming to improve reception.

    2) narrow band or long code: Effectively, this is slowing down the data rate. In this way, the SINR for a message can be good enough.

  • Antiphase? Have a receiver transmitter pair that receives the interference and then transmits the 180 degree out of phase equivalent - hopefully cancelling it out. For extra points deploy multiple stations, and for a bonus credit, don't evern transmit your signal, just modulate your antiphase to leave your signal as a remanant. Physics Problems: Can you near instaneously send the anti phase (those radio waves travel quite quickly)... What happens for moving receivers.....
  • They can take advantage of multiple antennas, directional antenntas, or both to lock onto the interference sources as well as the intended signal and use DSP to subtract out the noise and recover the original signal. Others have posted about how cellphones can take advantage of multipath interference to actually improve the received signal rather than degrade it. As long as the enemy is using a small number of stationary or slow-moving transmitters for their interference, you can locate them all and use DSP
    • Even if it's a very directional antenna, the bad guy on the ground can throw 10's of KW of RF at your receiver from 'closer' with the way less path-loss relative to your satellite. I was thinking of using satellite's too but there's no reason to assume the bad guys can't orbit one with jammers on-board too. If you say 'shoot them down' using SDI or something similar, then they could use the same to shoot down your satellites and you are back at square one. Besides there are cheaper things than satellites

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