Technology Explained

Passive Wi-Fi Could Double the Battery Life of Mobile Devices

Joel Lee 27-04-2016

Wi-Fi has been around for almost 20 years now, so it’s exciting to hear that breakthroughs are still happening. Not long ago, we learned about a discovery that could lead to wireless Internet that’s 100x faster than Wi-Fi Li-Fi Is 100x Faster Than Wi-Fi, But What's the Catch? Everyone's going crazy over Li-Fi and its groundbreaking speeds, but is it really as good as they say? What are the drawbacks? Read More , but in this post, we’re going to explore the “energy efficiency” side of things.


Note that this new technology — dubbed “Passive Wi-Fi” — has nothing to do with delivering power over Wi-Fi 5 Reasons Why You'll Love "Power Over Wi-Fi" Technology With Power Over Wi-Fi, you'll be able to charge devices using leaked energy from wireless routers, but is it as exciting as it sounds? Read More or with charging devices over Wi-Fi What Is Wireless Charging & How Exactly Does It Work? [MakeUseOf Explains] We live in a wireless world. Except we don’t. Sure, we can send huge amounts of information across the airwaves, but the devices capable of sending and receiving it are tied down to power cords.... Read More . It’s a different kind of Wi-Fi hardware that solves a notable issue in modern Wi-Fi receivers.

Wi-Fi Uses a Lot of Energy

Some studies have shown that Wi-Fi use can account for up to 60 percent of a phone’s total energy consumption. That’s pretty significant if you ask me, so anything that can reduce that number would be a great development. But the question is, why so much energy?

For three main reasons:

This constant need to seek access points, maintain connections, and boost signals can result in fast battery loss on smartphones 10 Proven and Tested Tips to Extend Battery Life on Android Suffering from poor battery life on Android? Follow these tips to get more juice out of your Android device's battery. Read More , and that’s why enabling Airplane Mode when possible 7 Ways To Improve Battery Life on Windows 8 Tablets & Laptops In Windows 8.1 battery-saving features moved! Otherwise they are similar to options seen in previous Windows versions. Learn more to make your tablet or laptop battery last as long as possible. Read More can provide a significant boost to battery life. (Airplane Mode turns off Wi-Fi along with cellular service, mobile data, and GPS.)



And now that no-contract Wi-Fi-based mobile plans The Best US Cellular Data Plans for Your Smartphone Though mobile phones have improved over the years, cellular plans have either stayed the same or gotten worse. Luckily, we've found the best deals for US smartphone users. Read More are becoming more and more popular, along with the growing prevalence of the cloud, we’re all starting to feel the impact of Wi-Fi power drain. A solution is needed.

As an aside, Wi-Fi routers also draw power just to stay active Is Your Home Energy Efficient? 7 Things You've Overlooked The true cost of a smart home is far cheaper than you think. In fact, there are many home automation devices that everyone can afford, and many of them will feature in this article. Read More and maintain connections with devices — think about how many devices are connected to your router — but ultimately it’s not enough to worry about. It probably costs between $10 and $20 per year in electricity.

How Passive Wi-Fi Works

Here’s the news that’s got everyone excited: a group of engineering students at the University of Washington discovered a new energy-efficient method for transmitting Wi-Fi data. They’re calling it “Passive Wi-Fi”.

Modern low-power Wi-Fi transmissions require about 100 milliwatts of energy, whereas the new Passive Wi-Fi technology requires about 10 microwatts. That’s a difference of about 10,000 times.


Normally, every Wi-Fi-capable device needs a radio antenna (to receive incoming transmissions and separate the signal from other radio noise) and a radio transmitter (to encode data and send the transmission out). This means energy is used for both receiving and sending data.


With Passive Wi-Fi, most devices no longer need transmitters. Transmitting devices, like routers, will still need them, but other devices — like smartphones and tablets — will only need passive sensors.

These passive sensors allow a device to create new outgoing Wi-Fi packets just by reflecting incoming Wi-Fi waves. This technique, called “backscatter,” requires very little energy because it isn’t generating new transmissions from scratch.


But there are two big downsides:

  • Slower speed. As of now, Passive Wi-Fi can transmit at speeds up to 11 megabits per second (Mbps), which is slower than modern Wi-Fi which can reach speeds anywhere from 54 Mbps to 600 Mbps.
  • Less range. As with any kind of reflective action, you always lose something in the reflection. For Passive Wi-Fi, the backscatter waves travel less distance than actively-generated waves.

How Passive Wi-Fi Benefits You

Despite the technology’s drawbacks, Passive Wi-Fi has the potential to be a revolutionary step forward in wireless internet — not just in our homes, but for business and public use as well. But how exactly will it benefit you and what can you look forward to?

According to one of the co-developers, Passive Wi-Fi could drastically improve the battery life of any Wi-Fi-capable device — to the point where it would save as much energy as if Wi-Fi was disabled altogether.

Fortunately, Passive Wi-Fi doesn’t need any large or complicated components to work, so there won’t be any problem integrating it into smartphones and tablets.



Another potential benefit is that devices would charge faster 4 Tips To Increase Smartphone Charging Speeds Faced with a low battery warning right before you need to leave? These neat tricks can help you charge your smartphone faster than usual so you aren't left with a brick in your hand. Read More because there would be less energy being used during the charge. But more importantly, said devices would need to be charged half as frequently as they are now, which would require less charging overall, thus saving on your energy bill.

But perhaps the biggest benefit involves another cutting-edge bit of technology: the Internet of Things.

For those who aren’t familiar, the Internet of Things is the growing phenomenon of Internet-capable devices that can share data and communicate with one another What Is the Internet of Things? What is the Internet of Things? Here's everything you need to know about it, why it's so exciting, and some of the risks. Read More . For example, think of most smart home devices 9 Reputable Smart Home Brands With Products You Can Trust The modern world is moving toward all kinds of smart home automation, and the longer you hold out, the more difficult it's going to be when your day of conversion finally comes. Read More like the Nest thermostat or the Philips Hue lighting system, which can interact with other devices by Wi-Fi.


One reason the Internet of Things hasn’t caught on? Always-on power costs. But with Passive Wi-Fi, such devices would be able to constantly send data back and forth without much energy needed, and some plugged-in devices could even switch to being battery powered, thus paving the way for a better and cheaper Internet of Things.

Not sold on the idea? Check out these amazing Internet of Things products The Internet of Things: 10 Useful Products You Must Try in 2016 The Internet of Things is ramping up in 2016, but what does that mean exactly? How do you personally benefit from the Internet of Things? Here are a few useful products to illustrate. Read More that will surely change your mind.

It’s still early to make a definitive judgment on how impactful Passive Wi-Fi will be and how many companies will actually adopt it, but it’s interesting news indeed — and for now, it’s looking quite awesome.

Will Passive Wi-Fi catch on? Do you suffer from battery issues? How do you feel about the potential benefits, especially the point regarding the Internet of Things? Share your thoughts with us in the comments below!

Image Credits: Airplane Mode via Shutterstock, Wireless Router via Shutterstock, Charging Mobile via Shutterstock, Internet of Things via Shutterstock.

Related topics: Computer Networks, Internet of Things, Technology, Wi-Fi.

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  1. Jeremy Ward
    April 28, 2016 at 1:14 pm

    A couple of inaccuracies in the article:

    WiFi hasn't been around for 20 years; the WiFi Alliance was formed in 1999, while IEEE 802.11 was ratified in 1997 -- but was not known as WiFi until after the formation of the WiFi Alliance (a trade group that amoung other things provides interoperability testing).

    Also, a home WiFi router doesn't use anywhere near $10-$20 of power consumption in a month. A 100W light bulb uses about $8 of power a month (11¢ per kilowatt-hour) if left on continuously, while the most hungy enterprise-class access points barely scrape 30 Watts of power consumption.

    • Anonymous
      April 29, 2016 at 3:43 am

      He said $20 a year......

    • Namanati
      April 30, 2016 at 12:32 pm

      In 1999, pioneers of a new, higher speed variant, endorsed the IEEE 802.11b specification to form the Wireless Ethernet Compatibility Alliance (WECA) and branded the new technology Wi-Fi. Multiple sources can be found at

      Further the article does not state it's been around for 20 years, it states "Wi-Fi has been around for almost 20 years now", note the word 'almost'. 17 years certainly fits with the term of 'almost'.

      Finally, this article states $10 - $20 per year not month. That's about 83¢ to $1.67 per month. That's a huge difference. So your statement of "inaccuracies in the article" is the actual inaccuracy.