Researchers See Through Walls With Wi-Fi 

New technology recently engineered by scientists at UC Santa Barbara using Wi-Fi signals has enabled people to see objects and read letters through walls.

Your initial reaction to this is probably one of two things:

  1. Wow – Amazing! What a breakthrough
  2. Well this seems like a potential privacy issue further down the line

How have Wi-Fi systems been used to see through walls?

Researchers from UC Santa Barbara developed this system where the edges of solid objects on one side of a solid barrier ie. a wall, can be traced from the other side using WI-Fi signals. This includes letters of the alphabet. 

Imaging the letters individually, in one experiment this technology was used to work out the word ‘believe’ from the other side of a wall, deciphering the letters one by one. 

They did this using 3 standard Wi-Fi transmitters. Over a particular area, these Wi-Fi transmitters sent wireless waves. The imaging was based on measuring the signal power received by a Wi-Fi receiver grid via receivers mounted on a movable vehicle. 

3 transmitters you say – Would that not be triangulation? One of the researchers on this project states that triangulation is not being used. Instead, each transmitter is merely providing a different viewpoint, illuminating the area from different angles. This approach helps to reduce the chance that one of the edges they are detecting will not fall into a ‘blind region.’ To leave a signature on the receiver grid, they need to be ‘seen’. 

The key to the success of this tech system using Wi-Fi signals to see through walls is their edge-based approach. Triangulation in this instance would not perform well. 

How can objects be tracked using Wi-Fi signals?

This tech system is based on the principle of Keller’s Geometric Theory of Diffraction (aka The Keller Cone). 

Keller introduced his Geometrical Theory of Diffraction (GTD) in the 1950s. The development of this theory was revolutionary, as it explained the phenomena of wave diffraction entirely in terms of rays for the first time, via a systematic generalisation of Fermat’s principle. In simple terms, it explains the process of a wave bending around an object (or obstacle) and how it spreads out across a particular space. 

Using the principle of this theory, the system can interpret what could be on the other side of a wall. 

Why is seeing through walls with Wi-Fi something new?

Scientists have actually been attempting to do this for a while, years in fact. This particular team at UC Santa Barbara have been working on this since 2009. This latest engineering breakthrough is significant because it was previously thought that anything as complex as reading the English alphabet through walls using Wi-Fi signals would be too difficult due to the complexity of the lettering. 

Indeed, using Wi-Fi for imaging something still (like letters) has been a challenge due to the lack of motion. However, they seem to have overcome this issue by tracing the edges of the objects.

Back in July, we saw a similar tech engineered by researchers at Carnegie Mellon University where they tracked a 3D shape as well as human bodies moving in a room using Wi-Fi signals. 

Seeing Through Walls With Wi-Fi – What will it be used for?

Assuming that this tech system matures and is put to wider use, we might find it useful for a few different applications: 

  • Crowd analytics
  • Identifying individuals
  • Boosting smart spaces 

Is the resolution high enough? 

Resolution on imagery can be improved by increasing the signals to higher frequencies. However, this would also increase the propagation loss so there would be a trade-off on energy.

This is likely where future experimentation will lie, as researchers and scientists look to explore this energy trade-off as frequencies and propagation loss increase.  

Is it just edges of objects that can be detected? If this tech system of looking through walls with Wi-Fi signals is going to be widely adopted then depth sensing would also be useful. This can be achieved by using a wideband signal for transmission. 

The experiment spoken about in this article was designed to showcase the performance of everyday radio signals, using 802.11n Wi-Fi which is narrowband. However, the framework could easily be expanded to utilise wideband signals too. 

What challenges could ‘seeing through walls’ with Wi-Fi face?

As we stated at the start of this article, some potential issues that could arise from using Wi-Fi signals to see through walls relate to privacy and security. 

Thus, this could have an effect on how successful this new tech system could be. 

Could cyber criminals use this technology in part of an attack? Could law enforcement officials abuse this technology in some contexts?

We wrote on this topic of Wi-Fi seeing through walls back in January, about a similar piece of research that used ‘dense pose’ from Wi-Fi, using Wi-Fi signals as a human sensor and a way to map the position of human bodies using AI. You can read it here.

What are your thoughts on this – We’d love to know! Which camp do you sit in – Amazing Breakthrough or Privacy Nightmare? Get in touch on Facebook, X or Instagram

Is an Everyday Household Item Slowing Down Your Wi-Fi?

Whether you rely on your Wi-Fi to work, stream Netflix or game, one thing we can all agree on is that there is nothing more frustrating than slow, buffering Wi-Fi or internet blackouts. Frozen zoom calls, ‘Something’s gone wrong’ error messages in the middle of binge-watching your favourite series or letting the team down mid-battle could have you tearing your hair out in frustration.

These days, having a strong, reliable, fast broadband connection is vital. And often, we don’t realise quite how much we need something until it’s not working effectively or completely gone. 

But what if one of your everyday household items was the cause of your Wi-Fi woes? Here are some commonplace things that you likely have around your house that could be causing your internet issues – And things you can do to help overcome them. 

Can concrete cause Wi-Fi problems? 

Obviously, there’s nothing much you can do about the actual structure of your home, but if it’s full of thick concrete walls then you may experience problems getting Wi-Fi throughout your property. It’s a tough material that’s difficult to penetrate, meaning your network coverage could struggle. 

This could result in a lag in signal or some rooms being in a deadspot. 

We’re not suggesting taking a sledgehammer to your walls – But you can carefully consider where you are placing your router for optimum coverage. You could also look at whether extenders could help your signal reach parts of the house that the signal can’t get to. 

Can metal interfere with my Wi-Fi?

Metal is another dense material that can negatively affect your Wi-Fi speed. Using metal structurally could inhibit the strength of the signal you are transmitting. Likewise, too many metal household items (like blinds) or decorative items (e.g. wall art) could cause issues with signal reaching your devices. 

As above, thinking carefully about where you place your router can imrpove things, and extenders can be used to access those hard to reach places. 

Can plaster and drywall affect my Wi-Fi? 

Most if not all houses will have elements of plaster and drywall. Thankfully, it doesn’t interfere with signal as much as concrete does so there should be less signal lost. 

Could the ceramic tiles in my house cause internet issues?

Ceramic tiles are a popular choice in our kitchens and bathrooms. Unfortunately, this material can disrupt Wi-Fi signals in your home. Ceramic tiles also tend to be coupled with other disruptive material like plaster and drywall mentioned above, which can cause even more interference to your Wi-Fi.  

Placing your router somewhere central in an elevated position can help to combat some of this Wi-Fi interference. 

Are my Low-E windows causing Wi-Fi problems?

Every house has windows – But a certain type can cause problems with your Wi-Fi. Those conscious of their energy consumption and trying to reduce how much energy is lost by installing Low-E (low emissivity) windows could unfortunately result in problems with their Wi-Fi instead. 

Low-E windows have a metallic film on them to help reduce energy consumption, which also means they can absorb or interfere with Wi-Fi signals. So they could be great for your energy bills but not so great for your internet connection. 

Do mirrors interfere with Wi-Fi signal? 

Mirrors have a thin coating of metal behind the glass which together can cause enough electromagnetic interference to disrupt your Wi-Fi signal. Especially if your house is adorned with lots of mirrors! 

The level of disruption depends on how big the mirrors are and how many you have. 

Is water the reason my Wi-Fi is slow?

Water can hinder the passage of Wi-Fi signal, so things like fish tanks and even people can make your connection weaker by the time it reaches your device. 

This can have a big impact on how well your devices connect to your Wi-Fi and thus how effective they work. 

Can my furniture cause internet problems? 

Do you have pieces of large furniture in your home? A house full of big, thick furniture could struggle with less stable internet. 

Experiencing signal disruption is more likely if you place your router too close to any large items of furniture – Try to choose a an area that is unobstructed and in as open a space as possible.

Could my household appliances be disrupting my Wi-Fi?

Houses are full of white goods, and unfortunately these can cause a weak Wi-Fi connection. Appliances like microwaves and dishwashers emit their own radio waves, so it’s a good idea to place your router well away from them. 

You might even be able to salvage a weak Wi-Fi connection by moving your router away from appliances like this. 

Got Wi-Fi Issues In Your Home?

If you are facing some Wi-Fi troubles in your home, then try these top tips to try and mitigate any interference from household items. 

  • Don’t tuck your router away in a cupboard, out of sight or surrounded by furniture. 
  • Find a central location for your router so that it stands the best chance of reaching every corner of your home
  • Deploy your router in an elevated position to help transmit that signal 
  • Avoid installing your router close to bulky furniture
  • Thick concrete walls are not your router’s friend – Try not to place your router near them 
  • Water (think fish tanks, water tanks, even people) absorb the signal and can interfere with how effectively your device can connect so deploy your router away from these things
  • Kitchens are full of white goods (microwaves, dishwashers etc) which emit their own electromagnetic waves, so don’t put your router in this room if you want it to work at it’s optimum  
  • Try to avoid placing your router near large mirrors or windows. If you are considering Low-E windows, think carefully about whether this could affect how effective your Wi-Fi is