Network capacity appears to be the theme of the week.
First off, I spent a couple of days at IIR's conference on LTE - how will it fit against a background of WiMAX & UMB, when will it appear, what speeds can it deliver, what are the applications & services? Lots of slides mentioning 100Mbit/s and similar numbers, plus a tacit recognition that, give or take some IPR issues, LTE = WiMAX = UMB in terms of much of the underpinning technology.
There's still plenty of unanswered questions though - especially whether LTE has any real use if operators can't get hold of enough spectrum to run it in 2x10MHz or 2x20MHz channel widths, which is the only way to approach the peak bandwidths that are being mentioned. If they're stuck with the current UMTS networks' 2x5MHz channels, operators might just be better of sticking with HSPA.
Another theme which emerged was around applications - realistically, are there actually any mobile/handset applications that could exploit 100Mbit/s? Can screens or browsers actually exploit that much data? (I'll leave as a separate question whether anything running at 100Mbit/s without a fan could be held by hand without asbestos gloves).
So, what does need that much bandwidth?
...on mobile, anyway. But in terms of fixed networks, I've just heard a presentation that really raises the bar on bandwidth requirements and makes you realise just how many zeros we can use if we get the opportunity. I'm now at NetEvents in Malta, and the keynote speaker was the Network & Comms chief supremo from the CERN particle physics accelerator in Geneva. I was blown away to find out that the new Large Hadron Collider (LHC), when it finally comes online, will generate peak 'raw data' outputs of about 1 Petabyte per second. Not MB, not GB, not TB, that's PB. He bemoaned the fact that this had to be filtered down in realtime electronics to 'a few hundred GBit/s' of the most useful data, with the rest just discarded as it couldn't all be networked or stored even by their state-of-the art private optical network. (As a sidenote about backhaul/transmission capacity, these guys also have dedicated 10Gbit/s links to international research labs). They'd love to upgrade to full speed if they get a chance & network technology catches up.
Now the awkwardness of carrying around 1000+ 30-ton superconducting magnets means that we won't all be detecting Higgs Bosons or leptoquarks on our phones any time soon. But it's also worth pointing out that when I asked him whether they any wireless tech anywhere at all at CERN, I got a shrug and a comment that there's a bit of WiFi in the labs and experimental chambers, but nothing in 'the critical data path'.
OK, this is probably the most extreme example.... but it's also an ultimate reality check for those that suggest we can ever get too much capacity - wireless or wireline.