A CDE Definition
WiMedia Alliance
(WiMedia Alliance, Inc., San Ramon, CA, www.wimedia.org) A membership organization founded in 2002 devoted to the development of short-range, ultra-wideband (UWB) transmission. In 2005, the Multiband OFDM Alliance merged with WiMedia Alliance to promote a single standard based on multiband OFDM (MB-OFDM). ECMA has also standardized this technology under ECMA-368 and ECMA-369. See UWB.
UWB
(Ultra-WideBand) A wireless technology that uses less power and provides higher speed than Wi-Fi and first-generation Bluetooth products. Governed by the WiMedia Alliance, UWB is geared for home theater video, auto safety and navigation, medical imaging and security surveillance.
Pulse Radio
Unlike other radio transmission, UWB does not use a continuous carrier frequency. It transmits extremely short pulses, and the durations between pulses use no power. One method transmits the pulses in continuously varying time slots based on a pseudo-random number sequence like CDMA. The other divides the spectrum into smaller frequency bands that can be added and dropped as necessary.
UWB Sees Through Walls
Because UWB can transmit through materials that would bounce other radio signals, it is also used to pinpoint objects behind barriers or buried underground. First invented by Gerald Ross at Sperry Rand Corporation in the late 1960s, UWB has been used by the military for various radar systems. In 1998, the FCC allowed UWB for police work and fire fighting. In 2002, it sanctioned the technology at considerably lower power for commercial use. See WiMedia Alliance, 802.15 and GPR.
Max. Freq. Indoor
Wireless Speed Range Range
Type (Mbps) (GHz) (ft.)
UWB 480 3.1-10.6 33
Bluetooth
BT 1.2 1 2.4 330
BT 2.0 3 2.4 330
Wi-Fi
802.11b 11 2.4 150
802.11g 54 2.4 170
802.11a 54 5 95
802.11n 600 2.4/5 230
802.11ac 6770 5 230

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