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Ultra-Wide Band And Bluetooth Working Together
judgecorp writes "This week the Bluetooth people adopted UWB as a future fast connection. What not many people have spotted is - the big winner in this could be UWB.. Sure, Bluetooth is a slow protocol for headsets, and UWB is, potentially, much much more. But Bluetooth is established. It's in phones and regulators understand it. If Bluetooth likes UWB, that could really be a major factor to convince the people that are blocking UWB - operators and regulators outside the US - that UWB is safe to use."
UWB has been the latest buzz for a while. Reminded me when I, Cringely was all over it making it out to be the next big thing. That was in 2002 though. Time will tell....
sure I'll have a sig.
The term "ultra wideband" is a relatively new term to describe a technology which had been known since the early 1960's as "carrier-free", "baseband" or "impulse" technology. The basic concept is to develop, transmit and receive an extremely short duration burst of radio frequency (RF) energy - typically a few tens of picoseconds (trillionths of a second) to a few nanoseconds (billionths of a second) in duration. These bursts represent from one to only a few cycles of an RF carrier wave. The resultant waveforms are extremely broadband, so much so that it is often difficult to determine an actual RF center frequency - thus, the term "carrier-free". Early methods of signal generation utilized "baseband" (i.e., non-RF), fast rise-time pulse excitation of a wideband microwave antenna to generate and radiate the antenna's effective "impulse" response. (More precisely, it is the antenna's "step" response that is actually produced.) More modern UWB systems, such as those developed by MSSI, no longer utilize direct impulse excitation of an antenna because of the inability of such an approach to adequately control emission bandwidths and apparent center frequencies.
What are the advantages of UWB technology?
Since UWB waveforms are of such short time duration, they have some rather unique properties. In communications, for example, UWB pulses can be used to provide extremely high data rate performance in multi-user network applications. For radar applications, these same pulses can provide very fine range resolution and precision distance and/or positioning measurement capabilities. In fact, multifunction architectures encompassing communications, radar and positioning applications have been developed. These short duration waveforms are relatively immune to multipath cancellation effects as observed in mobile and in-building environments. Multipath cancellation occurs when a strong reflected wave - e.g., off of a wall, ceiling, vehicle, building, etc. - arrives partially or totally out of phase with the direct path signal, causing a reduced amplitude response in the receiver. With very short pulses, the direct path has come and gone before the reflected path arrives and no cancellation occurs. As a consequence, UWB systems are particularly well suited for high-speed, mobile wireless applications. In addition, because of the extremely short duration waveforms, packet burst and time division multiple access (TDMA) protocols for multi-user communications are readily implemented. As bandwidth is inversely related to pulse duration, the spectral extent of these waveforms can be made quite large. With proper engineering design, the resultant energy densities (i.e., transmitted Watts of power per unit Hertz of bandwidth) can be quite low. This low energy density translates into a low probability of detection (LPD) RF signature. An LPD signature is of particular interest for military applications (e.g., for covert communications and radar); however, an LPD signature also produces minimal interference to proximity systems and minimal RF health hazards, significant for both military and commercial applications. Among the most important advantages of UWB technology, however, are those of low system complexity and low cost. UWB systems can be made nearly "all-digital", with minimal RF or microwave electronics. Because of the inherent RF simplicity of UWB designs, these systems are highly frequency adaptive, enabling them to be positioned anywhere within the RF spectrum. This feature avoids interference to existing services, while fully utilizing the available spectrum.
Except when they realise that that's a comparative, and discover BROADESTband: the band to end all broads.
Sorry folks, I forgot to put the source. I was editing and adding something and it got misplaced along with some other information. No intention of taking the credit or passing that text as my own. Multispectral solutions has a well written FAQ and needs no rewording. Thanks for pointing it out. :)
UWB's combination of broader spectrum and lower power improves speed and reduces interference with other wireless spectra. In the United States, the Federal Communications Commission (FCC) has mandated that UWB radio transmissions can legally operate in the range from 3.1 GHz up to 10.6 GHz, at a limited transmit power of -41dBm/MHz. Consequently, UWB provides dramatic channel capacity at short range that limits interference. When used as intended, the emerging short- and medium-range wireless standards vary widely in their implicit spatial capacities. For example: IEEE 802.11b has a rated operating range of 100 meters. In the 2.4GHz ISM band, there is about 80MHz of useable spectrum. Hence, in a circle with a radius of 100 meters, three 22MHz IEEE 802.11b systems can operate on a non-interfering basis, each offering a peak over-the-air speed of 11Mbps. The total aggregate speed of 33Mbps, divided by the area of the circle, yields a spatial capacity of approximately 1,000 bits/sec/square-meter. Bluetooth, in its low-power mode, has a rated 10-meter range and a peak over-the-air speed of 1Mbps. Studies have shown that approximately 10 Bluetooth "piconets" can operate simultaneously in the same 10-meter circle with minimal degradation yielding an aggregate speed of 10Mbps [3]. Dividing this speed by the area of the circle produces a spatial capacity of approximately 30,000 bits/sec/square-meter. IEEE 802.11a is projected to have an operating range of 50 meters and a peak speed of 54Mbps. Given the 200MHz of available spectrum within the lower part of the 5GHz U-NII band, 12 such systems can operate simultaneously within a 50-meter circle with minimal degradation, for an aggregate speed of 648Mbps. The projected spatial capacity of this system is therefore approximately 83,000 bits/sec/square-meter. UWB systems vary widely in their projected capabilities, but one UWB technology developer has measured peak speeds of over 50Mbps at a range of 10 meters and projects that six such systems could operate within the same 10-meter radius circle with only minimal degradation. Following the same procedure, the projected spatial capacity for this system would be over 1,000,000 bits/sec/square-meter.
UWB is the physically layer and has been designed to take multiple link layers- USB, IEEE1394 and IP. More information can be found at
http://www.multibandofdm.org/
http://www.usb.org/wusb/home
http://en.wikipedia.org/wiki/Ultra_wideband