Today, it’s almost impossible to remember the world before wireless technologies like Wi-Fi and Bluetooth, which are now so ubiquitous even our hairbrushes, juicers and coffee pod machines come internet-connected.
Wi-Fi is, famously, an Australian invention that dates to the 1990s. It was developed by Dr John O’Sullivan and colleagues at the CSIRO who created the wireless local area network (or, wireless LAN) technology from mathematics developed for recording nanosecond pulses of radio waves from exploding black holes.
The catchy title we know it by today – Wi-Fi – was actually the work of branding agency Interbrand, which also designed its familiar symbol of waves expanding from a point.
Meanwhile Bluetooth was developed by telecommunications company Ericsson, and named after a 10thcentury Danish king Harald Blatand (or, Bluetooth).
This historical figure is most famous for uniting Norway and Denmark in 958, which lasted until 1814 – a metaphor chosen by its developers in hopes of uniting the warring industries of PC and mobile via a short-range wireless link.
The logo even reflects the story – its overlapping Nordic runes H and a B – the Viking king’s initials.
How do Wi-Fi and Bluetooth actually work?
Wi-Fi and Bluetooth both operate over radio waves – similar to walkie-talkies, mobile phones, televisions and radios.
But while AM and FM radio transmits in the kilohertz or megahertz radio frequencies, Wi-Fi and Bluetooth operate in the higher gigahertz range (along with your household microwave).
Most computers and devices now come with WiFi adapters built in, which translate information (like a word document or image) into a radio signal that can be transmitted.
A wireless router receives the signal and decodes it, sending the information to the internet via a physical connection. The same happens in reverse.
Bluetooth is most commonly used to communicate between a primary device – say a desktop computer – and secondary or peripheral ones, like a wireless keyboard, mouse or earbuds, forming a small network called a piconet.
Bluetooth works in a similar way to Wi-Fi but at closer range. Bluetooth-enabled devices have a microchip with a small antenna and software to process the signals. When they are close enough, paired devices can exchange data via radio waves instead of cables, a system which uses very little power.
There’s a lot of overlap between the two technologies, but there are also differences. Wi-Fi is generally open to more devices, users, and has larger range and speed. Bluetooth is closer range, connects up to eight devices but is far less power-hungry.
How far can the signal go?
Wi-Fi was designed for local area networks, and most regular Wi-Fi routers can reach around 50m indoors or 90m outdoors.
Researchers have demonstrated the ability to extend Wi-Fi hundreds of kilometres. For example, the Italian Centre for Radio Activities achieved an unamplified link of 304 km stretching from Tuscany to Sardinia.
Bluetooth technology is intended for shorter range connections, but can stretch as far as a few hundred metres.
Do these technologies pose any health risks?
Radiofrequency electromagnetic radiation is the name given to the transfer of energy by radio waves, which can result from natural sources like the Sun, or artificial sources like communications technologies.
Australia’s radiation safety agency, ARPANSA, along with international authorities like the World Health Organisation, say there’s no scientific evidence suggesting exposure to the low level electromagnetic energy associated with wireless technology leads to adverse health effects.
In theory, very high levels the radiation could heat human tissue, causing damage. But in practice the levels in the normal environment are way below safe exposure limits.
Wi-Fi and Bluetooth are the biggest contributors in terms of exposure to this kind of radiation, and levels are increasing over time. But a study in the British Medical Journal involving 13 countries including Australia found exposure levels remain orders of magnitude lower than regulated limits in all countries investigated.
ARPANSA even undertook a comprehensive study of Wi-Fi in schools in Victoria and New South Wales, measuring exposure levels inside school buildings, the library and outside in the schoolyard.
It found typical exposure to all types of radio frequencies – Wi-Fi, radio, mobile phone, television – were hundreds of thousands or millions of times below the exposure limits.
What about security risks?
Like many digital technologies, both Wi-Fi and Bluetooth can be used for spying and surveillance.
In a 2019 study, University of Chicago and California researchers showed it was possible to turn ambient Wi-Fi signals transmitted inside a person’s home, into spy signals giving people the ability to ‘see through walls’, even without knowing the location of devices.
When a person is standing or moving inside a room, their presence and location can be accurately determined by analysing the strength of the signal, or the way its deformed or degraded as it moves and refracts around human obstacles.
The researchers call this a silent surveillance attack, conducted with the help of small, accurate and unobtrusive devices called Wi-Fi sniffers.
Protection could be provided, the researchers say, by insulating buildings against Wi-Fi leaks, or by emitting a cover signal to confuse the data by making it look like there’s always people around.
Bluetooth technology comes with a list of possible wireless hacks with names like ‘blue-snarfing’ and ‘blue-bugging’.
‘Blue-jacking’ – for example – is a way of sending unsolicited or unwelcome messages to Bluetooth enabled devices.
Unsurprisingly advertisers have shown interest in using the technique to send unsolicited messages to people’s mobile phones, as a shopper walks in the door. And apparently hotels are using Bluetooth enabled technology to allow guests to walk in and be automatically checked in.
The problem, according to a professor of cyber security at Edith Cowan University is that devices which use Bluetooth weren’t and aren’t designed with privacy or security in mind.
To be safe, only leave your Bluetooth devices in discoverable mode when you pair and maybe avoid divulging national security secrets when you’re wearing earbuds.
Originally published by Cosmos as Explainer: Answering the why in Wi-Fi (and Bluetooth)
Petra Stock
Petra Stock is a journalist and engineer. She has previously worked in climate change, renewable energy, environmental planning and Aboriginal heritage policy.
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