Making light of 2.4 GHz overload

01 Feb 2010

The more Wi-Fi-enabled consumer electronics we see, the more some people start to worry about just how far we can stretch the unlicensed 2.4 GHz band before we have to give up and go back to cables to connect our home networks.

For example, I was recently forwarded a post on Slashdot from someone who pointed out that at this year’s CES event in Vegas, Intel and Connectify announced software than can turn Windows-powered laptops into access points, while Push2TV promises to enable wireless video streams of your PC display to your television.

“Isn't this going to kill lower powered 2.4 GHz devices, like Bluetooth mice and headsets? When does the 2.4 GHz band collapse completely? Why can't we push all this short-range, high-bandwidth stuff onto 5 GHz?"

It’s an old question, and the answers aren’t all that new, either. For a start, using 5 GHz shortens your range. Also, while it’s true that the home networking sector is a busy one, with a number of technologies vying for space in the 2.4-GHz band (802.11b/g/n, Bluetooth, ZigBee, etc), they all use spectrum differently and at different ranges, and are basically designed to keep interference down to a minimum. That doesn’t mean there won’t be interference problems, but for the most part they should be fairly manageable ones.

The other thing is that other technologies are on tap to offload bandwidth-intensive home networking traffic onto other frequencies. 60 GHz technologies like WirelessHD and WiGig are being touted as wireless video transmission solutions, as is WHDI, which operates in the unlicensed 5-GHz band. And then of course there are femtocells running on 3G frequencies (though those are more likely to be used for web surfing, not linking your Blu-Ray player to a TV monitor in the next room – at least not until LTE goes mainstream).

If that’s not enough spectrum for you, one day you’ll be able to use your lighting system as a data network.

A couple of weeks ago, researchers at Siemens announced they had broken the world record for wireless data transmission by achieving speeds of 500 Mbps using white LEDs instead of radio waves.

Siemens used Ostar LEDs, which are modulated at a frequency that allows for high-speed data transfers, to transmit data to a photodetector that converts light signals to electrical pulses.

Siemens says that this so-called VLC (Visible Light Communication) technique isn't necessarily a competitor to Wi-Fi, and could in fact augment existing Wi-Fi networks by mitigating interference issues. For example, if neighboring Wi-Fi networks are causing interference problems, a VLC option could serve as a workaround, according to Network World.

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