[Our cover story that was published in the July 2011 issue of PC & Tech Authority magazine was a must-read for Wi-Fi users. We've previously published a small excerpt. Below is an expanded excerpt, featuring a list of things that can get in your Wi-Fi's way.]
Wireless speakers and console controllers
Wireless speakers, console controllers and music players: it might seem like the living room of the future, but those devices can all interfere with Wi-Fi. “A major issue is any device can operate in the unlicensed band [used by Wi-Fi],” said Mathias. “There are a lot of devices in that band.” Cordless phones shouldn’t interfere with your Wi-Fi (unless you’ve bought them from abroad), as they don’t operate in the 2.4GHz band.
Microwave ovens were the very first household electronic devices to emit interference in the 2.4GHz band, so wait until the movie has downloaded before cooking your microwave popcorn. Research from the Farpoint Group suggests that data throughput can fall by 64% within 25ft of a microwave, and Farpoint analyst Craig Mathias said the firm had even “seen problems at 50m”. Unlike video senders, microwave interference should only occur when the oven is in use.
Video senders – typically used to beam satellite/cable pictures to another TV in the house – are commonly regarded as public enemy number one when it comes to Wi-Fi interference. Everyone, from carriers through to router manufacturers, points their finger at the senders and similar devices, such as baby monitors and wireless security cameras. “Analogue video senders have a different spectrum profile to Wi-Fi, to the point where they obliterate Wi-Fi. You can’t even see an SSID,” said BT’s Adrian Pote. Since the signal is always on, even when no video is being sent, video senders are often hard to diagnose as a source of interference, and their reach is wide enough to hurt neighbours’ wireless too.
Bluetooth devices can also interfere with Wi-Fi. New devices that use Bluetooth solve the problem by jumping to different frequencies, but older gadgets are “still a bit of a problem”, said ABI Research analyst Michael Morgan.
Every holiday season, ISPs receive a spike in complaints that internet connections aren’t working. The culprit: that festive, sparkly, lit-up tree in the living room. TalkTalk said Christmas tree lighting and other household lights can reduce Wi-Fi performance by 25%, and interference is at its worst when the lights are blinking. Fluorescent lighting can also degrade signal, but analysts stressed that the router would need to be placed very close to the light to cause a noticeable interference.
Sometimes it isn’t the gadgets in your home, but the house itself that’s blocking Wi-Fi. The worst culprit is chicken wire, which is used to help plaster stick to walls, especially in Victorian or Edwardian era homes. The gaps in the metal mesh are just the right size to block waves from the 2.4GHz range, turning the house into a Faraday cage.
Modern homes constructed largely of plaster board also use signal-bouncing foil coating in bathrooms and kitchens. Indeed, any metal in walls can cause signal to degrade, with corners and staircases wreaking the most havoc in the home.
Anything with metal running through it can degrade Wi-Fi signal, but cables add electricity to the mix, and the electromagnetic radiation given off can, in theory, create radio frequency noise that interferes, said Morgan. However, he stressed the effect is likely to be minimal.
Large mirrors can hurt signal by reflecting it back – essentially the opposite of covering the wall behind a Wi-Fi router with tin foil. “If you have a bathroom between your router and computer, the signal on the other side might not be good,” warned John Merrill, marketing director for Wi-Fi firm Xirrus.
It isn’t just new gadgets that generate interference: an ancient CRT television knocked wireless signal out for a whole neighbourhood. The ISP was forced to buy a new TV for one man after the power supply on his faulty television hit services in a 200m radius.
Stick your router next to your 5ft aquarium and you’ll be casting a massive Wi-Fi shadow for devices on the other side of the water.