The following text is copyright 2002 by Network World, permission is hearby given for reproduction, as long as attribution is given and this notice is included.


What are they so worried about?


By Scott Bradner


Earlier this year the U.S. Federal Communications Commission (FCC) gave very limited approval to the initial commercial development of ultrawideband wireless technology.  This was over the vehement objections on a number of fronts.  The objections have not gone away.  Just a few weeks ago a scare story popped up in the news from England where, the claim was, authorities were thinking of banning all lap top computers from airplane carry on luggage because they could not tell if a particular lap top might have an ultawideband card in it.  The doom stories are very well developed: planes falling from the sky, cars running into each other, cell phone service devastated, and much more. One would think that the ultrawideband proponents were building tools for terrorists.  Just  why is a chirping radio such a threat, and to what?


Ultrawideband (UWB) is hardly a new thing.  It was first developed more than 30 years ago, but has quite suddenly become all the rage well beyond the military research labs where is been quietly been being worked on.  Google gets 5270 hits, including a quite good article in the September 2002 issue of the magazine "Technology Review."


UWB works by sending out extremely short, broad spectrum, chirps of radio waves.  Originally designed to be able to penetrate physical objects like trees, the concept turns out to be quite flexible and can be used for a wide range of applications from radars that can "see" through buildings to short range high speed data network connections.


According to its critics, the very problem with UWB is the fact that it does use broad spectrum chirps.  The frequencies in these pulses overlap the frequencies used for other applications such as the global positioning satellite (GPS) system, the satellite system that supplies some of the input data to weather prediction systems and some cell phone systems.   Because they are using overlapping frequencies, there will be some interference with existing systems but there is significant disagreement over how important that interference will be.


UWB proponents claim that the interference will be minimal at worst while the opponents say it will significant at best.  The FCC has decided to try things out, much to the annoyance of the opponents who have even managed to get the scientific geniuses in Congress to hold a hearing on the topic.  (In case it's not clear, the above is sarcasm.)


I have two problems with the arguments of the UWB opponents: first, they are far too strident, it has been my observation that whenever there is a scientific disagreement, the side that brings out the scariest scenarios is the side with the fewest facts on its side, second, far too many of them have an economic reason to thwart the development of UWB.


By definition, UWB will cause some level of interference but if the interference from these very low power transmitters will significantly disrupt major infrastructure systems then we have a far more significant issue with the fragility of these systems to deliberate attack.


disclaimer:  One of Harvard's jobs is to develop graduates that will produce some level of interference with the status quo, but I know of no University policy on UWB.