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UWB:

ULTRA-WIDE BAND

Presented by:

ABHI KOTHARI

kthr_abhi@yahoo.com

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UWB: What is it?

Ultra-Wideband is defined by the FCC (Federal Communications

Commission) as a transmission whose bandwidth is either:

-20% of its center frequency-At least 500 MHz wide

Narrowband Bf < 1%

Wideband 1% < Bf < 20%

Ultra-Wideband Bf > 20%

Ultra wide band technology working can be applicable on the places

where the distance is shorter and needs transmission of higher

speed.

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So why UWB is interesting?

7.5 Ghz of free spectrum in the U.S.

FCC recently legalized UWB for commercial use

Spectrum allocation overlays existing users, but its allowed powerlevel is very low to minimize interference

Very high data rates possible

500 Mbps can be achieved at distances of 10 feet under current

regulations

The peak or instantaneous power of individual UWB pulses can berelatively large, but because they are transmitted for only a very short

time (Ton < 1nanosecond), the average power becomes

considerably lower.

.

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Narrow band Problems

Multipath fading

Destructive interference of CW signals causes signal loss

Insecure

Narrow Band signals are easily detected and jammed

Poor range resolution-Range resolution for tracking applications is a function of RF

bandwidth

Limited data rate

Narrow RF bandwidth means narrow data bandwidth

.

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The UWB solution

Ultimate in spectrum spreading

GHz of RF bandwidth

Has all the advantages of spread spectrum

But to a much larger extent

Immune to multipath fading

Virtually undetectable

Unprecedented range resolution

Potential for very high data rates

Simple to implement

High capacity

.

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UWB v/s NB: modulation

Frequency

Modulation

2.4 GHz

Narrowband

Communicatin

0 1 0 1

Time-domain behavior Frequency-domain behavior

Impulse

Modulation

3 10 GHzfrequency

Ultrawideband

Communication

time

1 0 1

(FCC Min=500Mhz)

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mpulse modulation Impulse Radio (IR): the use of extremely short duration pulses (sub-

nanosecond) instead of continuous waves to transmit information.

The pulse directly generates a very wide instantaneous bandwidth

signal according to is property. As frequency is inversely related to time, the short-duration UWB

pulses spreadtheir energy across a wide range of frequencies from

near DC to several Gigahertz (GHz)

Spread-spectrum techniques are methods by which a signal

generated in a particular bandwidth is deliberately spread in the

frequency domain, resulting in a signal with a wider bandwidth

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mpulse modulation (contd)

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COMPARISION

UWB is a form of extremely wide spread spectrum where RF energyis spread over gigahertz of spectrum

Wider than any narrowband system by orders of magnitude Power seen by a narrowband system is a fraction of the total

UWB signals can be designed to look like imperceptible random noise toconventional radios

Narrowband (30kHz)

Wideband CDMA (5 MHz)

UWB (Several GHz)

Frequency

Part 15 Limit

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UWB Signal Propagation

Generally follow a free space propagation law.

Millions of coded pulses transmitted per second.

Emissions below conventional receiver noise floor and across an

ultra wide bandwidth.

Low probability of detection and interception.

UWB systems reside below the noise level of a typical narrowband

receiver and enables UWB signals to coexist with current radio

services with minimal or no interference.

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Dells UWB Usage Models

Peripherals

Displays

Human Interface Devices

Mobilephones

Digital Home

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Applications Digital video camcorder (DVC)

Smartphone/PDS, Media player

Requirements Range is in view of display (