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

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.

Comments

They "cheat" but it's still very useful

[davidwr]

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.