UWB(Ultra Wideband)

UWB(Ultra Wideband) is a carrierless communications technology, using femtosecond seconds to level on the sine wave narrow pulses transmitted data. Some called it a revolutionary for radio spectrum, thinks it will become the progress of short-range wireless communication future mainstream technology.

UWB (the mk-ultra - Wideband) ultra-wideband, starting with using pulse radio technology, the technology can be traced back to the 19th century. Then by big companies such as Intel paper presents the application of the UWB technology program MB a - OFDM because of the two schemes are entirely different, and each has powerful faction, UWB standards formulated support 802.15.3 a workgroup could not decide in both the standard solutions, and eventually to market its solution. UWB still debate so far. UWB pulse width modulation using level in ns fast rising and falling pulse, pulse from dc to cover the spectrum of GHz, do not need regular narrowband modulation of RF frequency conversion needed, pulse forming can directly send it to antenna launch. Pulse fengfeng time interval from 10 to 100 ps level. What shape can narrow spectrum through continuous monopulse shape and antenna load characteristics to adjust. WB signal in time axis is sparse distribution, the power spectral density quite low, RF can simultaneously launching multiple UWB signal. UWB signal is similar to baseband signal, can use OOK, mirror pulse keying, pulse amplitude modulation or pulse position modulation. UWB is different from the baseband signal is transformed into radio frequency (RF) of conventional wireless system, which can be regarded as the baseband spread in RF programs in building internal energy spectrum density with extremely low 100 Mb/s data rate.
To further improve the data rate, UWB application ultrashort baseband rich GHz spectrums, use safe level of Signaling Signaling Method (Intriguing. Based on the broad spectrum UWB in 2002, the FCC announced UWB can be used for accurate location, metal detector, a new generation of WLAN and wireless communications. To protect the GPS, navigation and military communication frequency UWB limit, in 3.1 - GHz and below 41 dB 10.6 transmission power.

UWB(ultra wide band)

UWB(ultra wide band)  technology is a new type of wireless communication technology. It has a very steep by rising and falling time direct modulation of impulse pulse signal GHz, with the scale of bandwidth. Ultra-wideband technology which has solved the traditional wireless technology years of relevant major problem of the spread of channel decline, it has not sensitive, transmitting power spectral density low, low intercept capability, system and complexity, provide a few centimeters low the positioning precision, etc.

1 ultra-wideband signal and its features beauty the federal communications commission (FCC) regulation, part of the bandwidth for UWB signal boasts. Among them, some bandwidth for signal power spectral density 10dB place in - the value of measurement. Figure 1 for UWB signal and narrow width signal power spectral density comparison; A kind of typical pulse position modulation (PPM) UWB signal form way of [1], [2] for:

Str (k) (t) said the launch of the first k a user signal, it has not also is the number of single periodic impulsive move sum. W (t) said the single cycle pulse waveform transmission for single cycle, or gaussian pulse first and second order differential pulse one from the transmitter clock zero moment (t (k) = 0) started. The first j a pulse starting time for. Careful analysis of each time move weight:

(1) the pulse sequence diam-eter move the pulse said: form Time step of Tf, its single periodic impulsive 390v is extremely low, frames long or pulse repetition Time Frame a) (Tf typical values of pulse width for single cycle a hundred to a thousand times. ALOHA systems, so similar to the pulse sequence extremely easy cause random collisions.