UWB is a disruptive short-range radio-frequency wireless technology that could provide a potential solution to many problems in the WPAN communication and computing domain, such as low data rate and insufficient frequency. Despite the standardization controversy with regard to UWB, commercial UWB products were demonstrated at the Consumer Electronics Show in early 2005. Prototypes of UWB-enabled cell phones, HDTVs, DVD players, and music players are expected to hit the market very soon. One example of such an effort is the wireless USB technology, a short-range wireless connectivity technology resembling the wired USB standard. UWB was initially developed in the 1960s for high-resolution radar communication. The primary inventor of UWB was Gerald Ross, who held several patents for this technology. UWB was originally referred to as “ baseband, ” “ carrier-free, ” or “ impulse. ” In 1978, Bennett and Ross published a seminal paper on UWB titled Time-Domain Electromagnetics and Its Applications . The year 1986 saw the birth of the first UWB system, and the FCC approved the marketing and operation of UWB in 2002.

The FCC’s First Report and Order [6] defi nes a UWB device as any device-emitting signals over a bandwidth that is 20% greater than the center frequency or a bandwidth of at least 500 MHz at all times of transmission within a frequency band between 3.1 and 10.6 GHz. UWB devices operate by emitting a large number of very short pulses (often of a duration of only nanoseconds or less) of signals over a wide bandwidth within a range of 10 m, resulting in an unprecedented data rate on the level of several hundred megabits per second. UWB does not require any dedicated frequency allocation. Instead, it is designed to operate in frequency spectrum occupied by existing radio technologies. The channel capacity of UWB is linearly proportional to the bandwidth occupied for signal transmission. The advantages of UWB include:

» High data capacity: Due to the use of wide bandwidth, UWB offers very high data capacity, up to several gigabits per second.

» Use of a license-exempt frequency band: As a short-range wireless technology, UWB does not require any licensed frequencies to operate.

» Low power: The output power of UWB is at the level of less than 1 mW, compared with tens to a few hundred milliwatts of wireless LAN APs; typically 3 mW is allowed for a cell phone.

» Resilient to multipath fading and distortions: Because the signal is transmitted over a wide bandwidth with sufficient redundancy, fading and distortion are significantly reduced.

» Security: UWB is inherently secure. Like other spread spectrum technologies, the signal appears to be random noise to outsiders.

Source of Information : Elsevier Wireless Networking Complete 2010


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