60 GHz networking, the story so far

Some faffery is going on over IBM's announcement of a deal with MediaTek to produce 60 GHz wireless chips that can squeeze out data at 2.5 Gbs sometime in the next two to three years.

But that's all it is - a co-development deal. There's no new technology mentioned here over and above that which IBM talked about more than eighteen months ago, and nothing substantial on power requirements, range or modulation techniques.

60 GHz is extremely short range: it's never going to be a direct competitor for any of the 802.11 wi-fi standards - a fact reflected by the IEEE's standardisation group devoted to the new standard, 802.15.3c. That's in the same family as Bluetooth, Zigbee and ultrawideband... and it's funny that nobody's mentioning UWB, which is far further advanced and has pretty well identical speed and range potential. It should, moreover, be lower power.

It's noticable that IBM is referencing Wi-Fi in its announcement, when that isn't a competitor, and not UWB, which is. That's usually a sign that a company is hoping to keep the debate going on its terms - which, so far, seems to be happening.

Nevertheless, there's a lot of work going on in 60 GHz - and unsurprisingly so. There's 7GHz of bandwidth available between 57 and 64 GHz for unlicenced devices, and companies such as SiBeam are gearing up to get there first. SiBeam's schtick is that it can make its chips out of ordinary silicon using reasonably normal CMOS techniques (guess who's hoping to be snapped up by Intel), while IBM is working with silicon-germanium. There are other companies doing far whackier things.

But even with the mainstream engineering, expect the unexpected. One radio engineer i talked to pointed out that, at these extremely high frequencies, you can counter the much greater loss of signal by making very small yet very high gain antennas. One an inch across could easily add 25dB of oomph, and beam the resultant very tightly focussed signal in just the right direction to hit the distant receiver -- or bounce it off a wall to get past an obstacle.

Which sounds like good news, until you do the sums. If you put a mere 500 milliwatts into a 25dB gain antenna, you get an effective radiated power of nearly 160 watts. That's quite a lot of microwave to have zooming around your front room, chasing the cat.