Wifi Through Walls

Posted By admin On 18/01/22

Are you curious why a part of your home, or even an area just outside the house, has poor Wi-Fi reception? It could be due to the material used for the wall, or other physical barriers that block or weaken Wi-Fi signals.


Worst Signal Loss: Concrete

Concrete, with and without metal reinforcement, is one of the worst building materials for wireless signals to pass through, but masonry block and bricks can also be serious barriers for Wi-Fi. Plywood and drywall come close to zero signal loss in tests.

  1. Use regular wired (always works, but you need a cable). Use regular wired via existing wall sockets (powerline). Use either of the two above and connect to a second wireless access point in the cellar (still using wired/powerline to get the data to the cellar). Be very lucky and play with the antenna's.
  2. RF-Pose provides accurate human pose estimation through walls and occlusions. It leverages the fact that wireless signals in the WiFi frequencies traverse walls and reflect off the human body. It uses a deep neural network approach that parses such radio signals to estimate 2D poses.

Signal Loss by the Numbers

Wi-Vi is a new technology that enables seeing through walls using Wi-Fi signals. It allows us to track moving humans through walls and behind closed doors. Wi-Vi relies on capturing the reflections of its own transmitted signals off moving objects behind a wall in order to track them.

Wifi Through WallsWall

The numbers in the graphic above and the table below are based on the findings in extensive experiments performed by the US National Institute of Standards and Technology.

Wifi Signal Through Walls

These figures are taken from the report 'Electromagnetic Signal Attenuation in Construction Materials', NIST Construction Automation Program Report No. 3 from the National Institute of Standards and Technology.

Geek's Corner


You can read the full research report here: http://fire.nist.gov/bfrlpubs/build97/art123.html

Article by Jorunn D. Newth

Young woman using mobile phone and laptop in coffee shop, smiling

Most computer users know little about how Wi-Fi works. In fact, one of the only things many do know is that sometimes it doesn’t. But even a little bit of background knowledge can go a long way towards making your Internet connection zip along.

Initially developed as a way to replace your ethernet cable — the cord that used to connect computers to the web after we ditched dial-up — Wi-Fi is a popular technology that provides interconnectivity between devices.

“People are probably most familiar with using Wi-Fi as a way to connect to the Internet, since for most people it’s the network they use at home or at work,” says Wi-Fi Alliance CEO Edgar Figueroa. “However, Wi-Fi has evolved and now it’s a replacement for many different cables such as video cables, audio cables, USB cables.”

But most importantly, Wi-Fi currently carries more than 60% of the world’s Internet traffic. Interestingly enough, this great achievement is basically done with radio waves, though it’s a little more complicated than your car stereo. Unlike the FM receiver in your car, Wi-Fi is essentially two radios communicating back and forth that use lower power and broadcast over a much shorter distance. These two radios let web users download data from the Internet as well as upload information — even just submitting addresses via your browser counts in this two-way communication.

Another way Wi-Fi is more sophisticated than terrestrial radio is that it uses the Internet Protocol to communicate. This language of the Internet makes Wi-Fi very resilient and very structured. “Every single transmission that we send and receive has that requirement for confirmation,” says Figueroa. “It takes a lot of investment and orchestration.” Imagine instead of sending data, you’re shipping a package across the world with request for delivery confirmation, says Figueroa. That’s what the Internet Protocol is like, only it applies to every single byte transmitted.

And once that data is flying through the air in radio waves, it’s subject to interference, victimized by everything from other Wi-Fi signals to radio waves emitted by microwave ovens to cement walls. That’s where Wi-Fi’s two frequencies, 2.4 gigahertz and 5 gigahertz, come in. Wi-Fi can broadcast on both frequencies, a benefit that helps its signal cut through all the noise and deliver a fast, strong signal from your wireless router to your computer.

“Essentially these frequencies are like two different FM radio stations,” says Figueroa. According to physics, the lower the frequency, the farther a transmission can go. With Wi-Fi, 2.4 gigahertz is the lower frequency, so it can reach computers located farther away than than the 5 gigahertz band can. But 5 gigahertz offers the capacity to carry more transmissions. “Imagine if you had a highway that went very far but it was only a one lane highway,” says Figueroa describing 2.4 gigahertz Wi-Fi. By comparison, 5 gigahertz Wi-Fi is a highway that doesn’t go as far, but it offers 6 lanes, so it can make traffic move faster.
“Five gigahertz Wi-Fi offers enough coverage in terms of area that it can cover the whole home,” he says. “So for most people, the distance is not really as much of an issue as the speed.”

Wifi Signal Through Cement Walls

But ever since the age of cordless phones, people have had problems with radio signals crossing. The issue continues today with neighbors and their Wi-Fi networks. One way to get around this is by setting your frequency to broadcast on a certain channel. While that sounds technical, it’s really not. Most routers are good at automatically detecting the best channel to use. And 5 gigahertz networks have many more channels than networks broadcast on the 2.4 gigahertz frequency, another reason to use the new standard, if you can.

For people who have patchy Wi-Fi, fine-tuning their network is a better idea than simply installing a network extender. “Network extenders are becoming more popular,” says Figueroa. “They’re repeaters, so they take what might be a faint signal coming from upstairs into the downstairs environment and then, essentially, they’re repeating that signal.” But the problem with these extenders is that they propel an already weak signal. So, if your wireless Internet is only transmitting at half the speed it should, the extender will repeat that signal, pushing out an even weaker signal itself. You could be standing next to the extender and have full bars on your phone or laptop because, technically, you’ve got a strong wireless signal, but your Internet speed and performance will be degraded and poor.

Wi-Fi also has a number of security features. To access the network, users must have a password for WPA2, also known as Wi-Fi Protected Access (the 2 represents the fact that this feature is in its second generation). This is where you put in your password to get onto the Wi-Fi network. There’s another security feature called Advanced Encryption Standard (better known as AES) that was developed by the U.S. government to keep data safe as it transmits from one device to the other. “Every instance of every communication that goes over Wi-Fi is exclusive in that it’s encrypted and only the two parties involved understand it,” says Figueroa.

But perhaps the most important feature of Wi-Fi is that it’s backwards compatible. This is how all your old computers are able to connect with your new, super-fast routers. “If you go buy a Wi-Fi (router) today, it works for that device you may have bought back in 2000,” says Figueroa. “There’s not too many technologies that you can say that about.”

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