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What is Li-Fi?

This lightspeed wireless communications technology could power the Internet of Things - but how does it work?



Regular Wi-Fi uses radio waves to connect your devices to the internet. However, in much the same way as an old-fashioned analogue radio will crackle with static or lose its connection due to atmospheric interference, Wi-Fi can sometimes drop out. Bluetooth devices, baby monitors, microwave ovens and everyone else’s Wi-Fi can all interfere with yours.

Li-Fi is different. Rather than using radio frequencies, it uses visible light to transmit data. It’s not a new or novel idea: in 1880 Alexander Graham Bell designed what he called a photophone (later known as a radiophone) that could transmit audio using light. He considered it his greatest invention – “greater than the telephone,” he said – and the technology itself was the starting point for the fibre-optic networks we’re familiar with today, which send pulses of light down optical fibres to transmit data.

Li-Fi takes the same principle – transmitting data via light – but (the clue’s in the name) it does it wirelessly. It does this by using light from LEDs. The lights are switched on and off at nanosecond speeds, which are far too fast for the human eye to see and it’s this that carries the data – this is in a similar way to the infrared in your TV remote control. Thanks to the fact that LEDs can be switched on and off millions of times a second, Li-Fi can offer much higher bandwidth than traditional Wi-Fi. A 2015 test by Oxford University recorded data barrelling along at an incredible 224 gigabits per second.

So what would Li-Fi mean for the Android user? Well, it could leverage fibre-to-door providers like Alphabet Access (aka Google Fiber) to provide high-speed wireless internet at the flick of a light switch. It could bring fast, reliable internet access outdoors as it beams down from street lamps – for while the light has to be on to carry data, LEDs themselves can be dimmed to such a degree that we’re barely aware they’re on. But perhaps the biggest implication is for the Internet of Things.

The idea of always-on electronics that constantly interface with each other, the web and ourselves is a long-held dream that may be slowly becoming a reality, but one thing that holds it back is still the relative instability of Wi-Fi. With more Wi-Fi devices clamouring for bandwidth, their signal-to-noise ratio decreases, slowing them down and sometimes even booting  devices off the network altogether. This slows the very functions that the Internet of Things is designed for down to a crawl. However, with Li-Fi, the idea of multiple Android-powered devices talking to each other all of the time gets one step closer to reality.

Want to find out more about how Li-Fi works? Check out issue 59 of Android Magazine, available for instant download now.