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Wireless Networking Power Technology

Researchers Make Low-Power Wi-Fi Breakthrough (networkworld.com) 99

alphadogg writes: The biggest downside of Wi-Fi for most users might be that it can really drain your smartphone or tablet battery, but a research team at the University of Washington has come up with a way to make using the nearly ubiquitous wireless technology in a less taxing way. They have demonstrated a technique for using 10,000 times less power than typical Wi-Fi (well, at up to 11Mbps anyway) and next month will present a paper titled "Passive Wi-Fi: Bringing Low Power to Wi-Fi Transmissions" at the USENIX Symposium on Networked Systems Design in Santa Clara. The main trick involves decoupling digital and analog components of a typical Wi-Fi router.
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Researchers Make Low-Power Wi-Fi Breakthrough

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  • by RogueWarrior65 ( 678876 ) on Wednesday February 24, 2016 @11:09AM (#51574769)

    Blazing speed and low power are less important to me than long range. And these router manufacturers are getting rather annoying with their "specs." Oh, it covers 14,000 square feet. That's a square less than 120 feet on a side. So what? That's what you get for 600 mW of output power?

    • by Pseudonymous Powers ( 4097097 ) on Wednesday February 24, 2016 @11:14AM (#51574791)

      These router manufacturers are getting rather annoying with their "specs." Oh, it covers 14,000 square feet. That's a square less than 120 feet on a side.

      Never mind the rest of the specs. The real story here is, how'd they get their radio antenna to cover a square instead of a circle?

      • by Jason Levine ( 196982 ) on Wednesday February 24, 2016 @12:25PM (#51575161)

        I'd be highly concerned if a router only covered a two dimensional area. You definitely want to pay extra for the router that can cover a cube or a sphere.

        • by hawk ( 1151 )

          Ehh.

          For most settings, a hemisphere is fine . . . basements are rare around here . . .

          hawk

        • With the antennas of a router (with external antennas) in the usual configuration (all pointing up), the radiation pattern of a router will be more like a torus (shaped like a doughnut). It will radiate equally well in all directions on the router's plane, with reduced signal off-axis up or down. There will be very little signal directly above or below the router. The weak radiation up and down is one reason that multistory houses often need more than one access point. If the router has more than one antenn

      • It's digital, duh!

      • by wwalker ( 159341 )

        Same way you drill a square hole!

      • Never mind the rest of the specs. The real story here is, how'd they get their radio antenna to cover a square instead of a circle?

        They must have used a Squarial https://en.wikipedia.org/wiki/... [wikipedia.org]

      • Sure, there are times that longer range is what you need, but there are a lot of applications for which Really Low Power is a real enabler, and 11 Mbps is plenty (while Bluetooth/BLE/Zigbee speeds may not be), plus being able to use one software stack instead of having to keep a Bluetooth one and a Wifi one or needing some badly designed hopelessly insecure IoT gateway box is a big win. 1kbps is enough to drive your lightbulbs, but if your refrigerator needs a software update or whatever, the higher speeds

    • by swb ( 14022 ) on Wednesday February 24, 2016 @11:30AM (#51574871)

      Besides the power requirements, the problem with long range is that there's limited spectrum allocation so your extended range ends up being someone else's interference and you both end up with reduced throughput due to competition for the spectrum.

      Then there's the security implication of excess range -- your network being reachable where you might not want it reachable. Sure, you're relying on security to prevent malicious access, but that works better when there's no access at all.

      The question I would have is if they only have the data rate is only 11 Mbps, it seems to cover a lot of the use cases already covered by Bluetooth.

    • by Eloking ( 877834 ) on Wednesday February 24, 2016 @11:32AM (#51574883)

      Blazing speed and low power are less important to me than long range. And these router manufacturers are getting rather annoying with their "specs." Oh, it covers 14,000 square feet. That's a square less than 120 feet on a side. So what? That's what you get for 600 mW of output power?

      Why not both?

      I didn't read TFA, but if that passive antenna is slower and have less range, it won't replace the wifi of our smartphone anytime soon.

      But I don't think it'll be impossible to implement that passive technology to actual antenna. So if you're not using a lot of data (sleep mode) and a good wifi signal is available, the phone could turn off the "active" antenna and activate the "passive" low power one.

      Just an idea.

      • by Bengie ( 1121981 )
        Sounds useful for something like Bluetooth
        • Or perhaps (please don't shoot me for this) IOT devices.
        • by Eloking ( 877834 )

          Sounds useful for something like Bluetooth

          As I said, I didn't read TFA but, for what little I know, that passive technology need a powerful source. So, basically, the host use a lot more power so the devise use less.

          And for most Bluetooth application in my head, both use batteries.

        • Bluetooth is the first thing I thought about when I read this. Bluetooth actually has three modes. Low/Med/High just for this reason.
      • by goombah99 ( 560566 ) on Wednesday February 24, 2016 @12:43PM (#51575293)

        from the article "This translates to 10000x lower power than existing Wi-Fi chipsets and 1000x lower power than Bluetooth LE and ZigBee."

        The system works by remodulating the poweful carrier from a transmitter to shift it's frequency. Thus it doesn't need much power itself, it is just reflecting the power from a powerful source. The set the powerful source frequency just outside wifi channel frequncy and the reflected modulated signal is shiften inband. this lets an existing wi-fi receiver pick up the signal. Thus it works with conventional wiFi systems without them having to be aware they are communicating with a low power device. I believe it will require the addition of the high power transmitter of the carrier that is being passively reflected.

        • from the article "This translates to 10000x lower power than existing Wi-Fi chipsets and 1000x lower power than Bluetooth LE and ZigBee."

          That may be true for the actual transmission, but I wonder if it will equate to a real world difference in low-power long battery life systems where 802.15.4 is currently king. The problem being not so much the power used to transmit but the length of time needed on the protocol itself to do the work. Current low-power WiFi transmitters don't consume unreasonable amounts of power, but waking them from sleep, connecting, sending a packet and returning to sleep is something that can take several seconds. Comp

      • Occasionally it might be nice to have longer range, but 30-foot through-wall and 100-foot free-space is usually enough for most wifi environments I'm in, and having a phone wifi that didn't burn battery so fast would be extremely useful, and would more than justify having to put a few extra wifi repeaters in my office space.

    • Meh, I'd prefer shorter range, but some way to create multiple access points in a user friendly way to make the range work the way you want. Needless to say, those APs should be cheap.

      I want to elminate blackspots in my own home. What I don't want to do is give the neighbors free internet access.

      • You don't have to give your neighbors free internet access. Haven't you heard of WPA2? It's not hard to use.

        The problem with multiple APs is that then you have to figure out a way to wire them all up to your router. Depending on how your house is laid out, that may not be that easy to do.

        You do have a good point, however, about setting up multiple APs being a pain in the ass; generally, you need enterprise-level equipment, RADIUS authentication, etc. to do that.

      • by rsborg ( 111459 )

        Meh, I'd prefer shorter range, but some way to create multiple access points in a user friendly way to make the range work the way you want. Needless to say, those APs should be cheap.

        I want to elminate blackspots in my own home. What I don't want to do is give the neighbors free internet access.

        Neighbors are one thing - how about interlopers in cars parked in front of your house? My house has a small curb setback - so we had to rip out our xfinitywifi router because it was delivering service (outside our firewall) to strangers - which I really don't mind - but they stayed parked in front of my house with their engines running. Annoying to say the least.

    • Yeah, I hear you.

      As a radio hobbyist, one of the things that really irritates me is all of the consumer-grade two-way radios that make increasingly bold claims about the distance you supposedly can reach with them. This is an extension of that same behaviour. Any claim, at any power level, of an ability to reach a particular distance, without defining the terrain, is speculation at best, and marketing bullshit more oft than not.

      • by enwewn ( 910842 )
        They always use free space (perfect space) to make these claims. They are math not real world.
        • Exactly. Let me offer some anecdotal examples.

          My real world experience is that in my relatively flat residential neighbourhood, 400m is about the limit between handheld UHF radios (tried on both 450ish and 915ish MHz frequencies), ranging from 500mW to 7W. VHF (around 140-155 MHz) goes a little further under those circumstances (there are lots of trees in my neighbourhood, and trees have a larger negative impact on UHF than VHF).

          At the same time, put one end on top of a hill, mountain, tower, building, or

    • The limited range is what allows these open frequencies to remain open. Because the power is limited, your neighbor's wifi isn't able to overwhelm your wifi, and the two can reasonably co-exist.

      If you want greater range, you need to move to a directional antenna. Currently, this means something like a Yagi [wikipedia.org]. But there's hope on the horizon. Newer wifi chipsets are using multiple receivers (the math for a receiver is the same as for a transmitter, so they are interchangeable). Right now it's only used
    • Range is limited by the FCC requirements for the spectrum allocated, not so much the technology which is already doing borderline black magic to achieve what is does given the form factor limitations.

    • by antdude ( 79039 )

      Even if it is slow like dial-up modem connections? [grin]

    • Blazing speed and low power are less important to me than long range.

      Long range is important, because in a dorm, tall office building, apartment, or crowded library it backs up my traffic behind all the competing signals in the region. I'll get my faster service from a wired connection (about half a millimeter range of the little plastic connector body). For a host of minor tasks, like TV remote control, thermostat setting, smoke alarm, and zombie attack warning (it sounds better than home intrusion

  • So many people use Wi-Fi on their phones for Internet and VoIP phone calls (plus Whatsapp..etc). Would be cool not to have to worry about my phone battery going dead within a few hours after using the Wi-fi for Internet.
    • So many people use Wi-Fi on their phones for Internet and VoIP phone calls (plus Whatsapp..etc). Would be cool not to have to worry about my phone battery going dead within a few hours after using the Wi-fi for Internet.

      Even cooler if the wifi signal could charge my phone.

      • by Shatrat ( 855151 )

        I think it would be pretty warm actually if you were pushing that much 2.4ghz into the room...

        • Heat your room during the winter AND charge your devices at the same time!

          (Of course, during the summer this won't be very pleasant.)

  • Wi-Fi is a registered trademark which indicates certified compliance and interoperability with an industry trade group's requirements. This ain't that.
    • And never xerox a paper or take an aspirin. Don't cool your food with dry ice or store it in a thermos. Don't ride an escalator. Put down your flip phone.

      • by msauve ( 701917 )
        I make photocopies on occasion. Aspirin, dry ice, thermos, escalator and flip phone are not trademarks in the US.
        • Not anymore, but they all were.

          • by msauve ( 701917 )
            So your point is, what? Wi-Fi is still a trademark.

            Someone pitching a technical academic paper who doesn't know the correct terminology for that technology is demonstrating ignorance, not knowledge.
            • Yeah, well,... I used the term "wi-fi" long before some genius trademarked it. Guess all of us techies never thought of doing that (trademarking an obvious adapted slang term).

            • It's not an academic, it's an industry rag pointing to some interesting research. The article itself gives almost no useful information other than to show that it exists. Diluting a trademark is hardly a cardinal sin in this case. I'm not even sure what the generic term is that they should use, but I am sure that it would be liable to confuse their target demographic.

              • by msauve ( 701917 )
                You quite obviously haven't even looked at the paper,which was conveniently linked in the summary. Buh-bye, I see no point in further discussion with someone so deliberately ignorant.
            • Ah, I take it back. Didn't RTFA (the other one). I agree the academics should probably say "WLAN" or something. Whatever the standard is.

              • by skids ( 119237 )

                802.11b in this case. Considering the phase this research is at it is not surprising compliance tests have not been engaged.

                Assuming they aren't polluting outside their band, given the range they demonstrated they've got something viable here -- WiFi is headed towards a microcell architecture (consumer gear has yet to realize it, but the enterprise is already moving that way) and APs could easily embed side-stream transmitters, and maybe even wedge it into the channel plan in one of the 802.14.5 troughs (o

  • by Anonymous Coward

    SNR level is going to suck with other higher powered 2.4Ghz being that it's already unlicensed spectrum.

  • A WiFi system that generates 9.999 watts of free energy per milliwatt of transmit power is going to rewrite ALL of the physics books!

    Oh, wait, never mind. The author just meant that it uses one ten-thousandth as much power as standard methods, but was apparently too dumb to write it properly.

    • I don't get what's problematic with anything that's been written.

    • "n times less than x" is very common speech. It means, as you say, one x divided by n. It is unambiguous, because the only other interpretation (x minus n times x) provides a value which - as you point out yourself - makes absolutely no sense at all. This is not a good example of someone being "dumb".

    • That is called language. When the locution is used the other way around, it fails the literal interpration too. When you say something is "50 times more expensive", the intended meaning is that the price or cost is 50x that of the other item, and not 51x. Thus "times more" is a straight multiplication not a multiplication and addition. "Times less" is the reciprocal, thus it is a division not a multiplication followed by a negative addition*.

      * Tought experiment : k is the factor. Literal "times more" means

  • > next month will present a paper titled "Passive Wi-Fi: Bringing Low Power to Wi-Fi Transmissions" at the USENIX Symposium on Networked Systems Design in Santa Clara

    lol looks like UNISEX.

  • by davidwr ( 791652 ) on Wednesday February 24, 2016 @12:26PM (#51575167) Homepage Journal

    It's not that it takes orders of magnitude less power, it's that they move the power-consuming-part to a device that isn't relying on a battery.

    Here's a comparison:

    Back in my grandfather's day, two kids who live on adjacent farms might use flashlights to "talk" to each other at night using Morse Code over distances of several hundred meters. But the flashlight batteries only had so much juice. But what if, instead of using flashlights, they used lenses and mirrors so they light source was a lamp that was plugged into the electrical outlet? They could talk all night and not use up any batteries at all.

    Well, that's the gist of these devices. The "low power battery-operated devices" still need batteries to do the equivalent of "manipulating the lenses and mirrors" and operating an RF receiver, as well as whatever other task they are supposed to be doing (say, monitoring for pollution, or whatever).

    They key is that they don't need to waste energy operating an RF transmitter - that work is done by a nearby device that has a reliable energy source.

    That, and several "low power" devices can "share" the same transmitter.

    Something not noted in the summary: Depending on the scenario, this may result in a net increase in power consumption if the "shared transmitter" is in a naive, "always on" mode compared to a conventional system where the transmitter(s) would only be on when needed. I'm not saying you can't design such a system that isn't "naive," just that if you do, your total power usage may be higher than a conventional system. But since you are "plugged in" and not on battery, it the "cost" may be negligible.

    Bottom line: It's a neat and useful trick and if "mains power" is "many times cheaper than battery power" for your application, this is a big win. On the other hand, if "overall power used" is the controlling factor, it's not such a big win and if you aren't careful, it could be a big loss.

    • by Mirar ( 264502 )

      (That needs to be modded up.)

      I find it very interesting. It basically means I can have a wifi device powered by a CR2032 battery for years;
      something a BLE device can do, but a z-wave device needs a CR123 battery.

      Wifi is a much more complicated protocol, but I think the point is that it works, as opposed to z-wave (xor checksum? really?) or BLE (good standard, but noone can implement it so it works).

  • Or we could unleash a holograph Moriarty come to life! http://memory-alpha.wikia.com/... [wikia.com]
  • by Applehu Akbar ( 2968043 ) on Wednesday February 24, 2016 @01:01PM (#51575441)

    Let's hope for a wireless mouse that no longer needs batteries every time you pick it up.

    • There are plenty. I have a Logitech M510 at work and haven't replaced the batteries for 3 years. Logitech also has a wireless gaming mouse that will last 250 hours.
    • Huh? As someone who spends a lot of times playing games, and the rest of my time moving my mouse continuously (I move the mouse cursor around the screen while reading), I get between 6 months and a year out of my mouse. Off the shelf Microsoft mouse with a blue laser. My previous Logitech lasted just as long.

  • ...as "10,000 times less."
    • No such thing as "10,000 times less."

      Well, there is, but that's not how most people use it. That phrase only makes sense when you're saying something like (for proper context), "The old batteries were large, at 10cm wide. The newer batteries were smaller, at 5cm. But these latest batteries are more than twice as small, at only just over 1cm." But even that construction is awkward. It's a lot easier to say, "The newest batteries are less than a quarter the size of the originals." The "X time smaller" construct only makes sense when you're comparing the size to something that's already considered small compared to something else ... because it's the "er" that counts.

      • But even that construction is awkward.

        Not as awkward as your use of quoting.

        The problem I think comes in when fractions or percentages below 1% try to be expressed.

        The newer batteries at 5cm are half as big. The newest batters are a fifth the size at 1cm. The bleeding edge batteries are 0.5% the size at 50 Micrometers.

        • Percentages and fractions (depending on what's trying to be visualized) are BOTH a better bet than "500 smaller than..." unless the entire point of the expression is to say "A is big, B is smaller by some amount, and C is five times smaller than that." Because in that context, A>B>C, it's the fact that C is even smaller than something else that was already small (compared to something else) that is the point of what's being said. But that's almost NEVER what the "500 smaller than" people are trying to
      • No, it never makes sense.

        It's just bad grammar. Just because "most people do it that way" is merely proof that most people are idiots. It does not justify doing something the wrong way.

        The fact that the same usage is seen in modern advertising does not help the situation. The people creating that advertising are probably coddled 20-somethings who were never told they were wrong because their feelings might get hurt.
  • Practically every mobile app has analytics of some sort. This provides no value whatsoever to the user and wastes power sending data to the server. There are some firewall apps that can do this.

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