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Bluetooth to go UWB

Ultra-wideband is to networking what the integrated circuit was to computing. …

The Bluetooth SIG announced today that they plan to base a future version of Bluetooth—probably the next version—on ultrawideband technology. The SIG is teaming up with the WiMedia alliance, which Microsoft recently joined, and the UWB Forum to iron out the details of how to bring the benefits of UWB to Bluetooth.

The groups have already defined a suggested architecture that would merge Bluetooth and UWB requirements. Work on defining the key convergence layer specification is underway. "We want this to emerge as the next Bluetooth spec," said Foley, adding that a key consideration would be backwards compatibility with existing Bluetooth devices. Foley said higher-level Bluetooth spec would quell concerns of device makers about adopting Bluetooth, while speeding time-to-market for devices incorporating a UWB capability.

UWB has been "on the horizon" since at least 2002, but regulatory issues at home and abroad have held it back. (Specifically, wireless providers are deathly afraid of it, but more on that in a moment.) The technology has a number of advantages, like a combination of very high bandwidth (as in "wireless Firewire") and low power, that makes it perfect for Bluetooth. In fact, the two are such an obvious match that there has been some speculation that Bluetooth would go UWB for a few years now.

The basic idea behind UWB is to take advantage of modern digital signal processors to do away with the old idea of using narrow slices of spectrum to transmit data by modulating a constantly transmitted carrier signal. Instead, UWB transmits data by sending a series of power spikes across a relatively broad range of frequencies, and these power spikes are then picked up and decoded by the receiving hardware. Decoding these power spikes takes a little bit of DSP horsepower, which is why UWB wasn't even concievable in before the rise of modern semiconductors.

UWB's power spikes sound like noise to regular radio hardware, so they don't interfere with existing radio equipment (unless you're operating a radio telescope, in which case the proliferation of UWB spells doom for your astronomy research). Even more important, though, is the fact that UWB devices don't interfere with each other, so multiple UWB wireless networks can exist in the same physical space without any kind of crosstalk that might lower amount of available bandwidth. In fact, depending on how many UWB devices you can gang together, the amount of bandwidth per unit volume of space that UWB can provide is theoretically infinite.

Here's a great page that defines UWB in greater detail. I'll quote two paragraphs that describe the benefits of UWB, and then I'll tell you why this could be a really important "disruptive technology."

The end result is a technology that provides potentially unlicensed operation, simplicity, very low transmit power, multipath and interference immunity, and the capability to deliver data rates in excess of 100 Mbits/second-all the while consuming very little battery power and relatively small amounts of silicon area, translating to low cost.

Thanks to its low spectral density, unlicensed UWB radio emissions do not add up to cause harmful interference to other radio systems operating in dedicated bands... That means UWB devices can be co-located with GPS and PCS equipment.

Moreover, ultrawideband's low power, wide spectrum and coded waveform make it difficult for eavesdroppers to detect. A further security benefit lies in a UWB device's ability to detect the distance to another ultrawideband device based on round-trip delay information. The high precision of this range information allows a device to reject communications with another device unless it is at or within an authorized range. The corollary is that ultrawideband receivers can use range information to reduce their level of interference even further (using transmit power control) and optimize network configuration and traffic flow.

So let's see: there's no technical reason why UWB products would require a license to operate; the only limitation on the technology's range is political (the FCC approved a neutered, short-range version of it); and the tecnology is low-power, high-bandwidth, and difficult to eavesdrop on. If you think the current Internet is giving Hollywood and law enforcement heartburn, wait until it morphs into an ad hoc, peer-to-peer mesh of high-bandwidth UWB devices. At that point, you can also say goodbye to wireless providers, because who needs Sprint if you've got UWB and VoIP.

Every libertarian and Randite who's on an "abolish the FCC" crusade should take up the cause of UWB evanglism with a vengance. Since there's no need to let anyone monopolize a slice of the spectrum with UWB, the fantastically idiotic libertarian proposal that the government should permanently sell off chunks of spectrum to private industry could die the quick death it deserves.

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