Ultra wide band

ELITEX 2007 Seminar on 1Oth January 2007
Ultra Wide Band (UWB)
Technology & Its Applications
by
Dr.A.T.Kalghatgi
Chief Scientist
Central Research Laboratory
Bharat Electronics Limited.,
Bangalore

Overview
• Trends that drive short range wireless
• Definition of UWB
• Advantages of UWB
• Applications of UWB
• UWB Challenges

• The growing demand for wireless data capability
in portable devices at higher bandwidth
• Crowding in the spectrum that is segmented and
licensed by regulatory authorities in traditional
ways.
• The growth of high-speed wired access to the
Internet in enterprises, homes, and public
spaces.
• Shrinking semiconductor cost and power
consumption for signal processing.
Trends that are driving short-range wireless

Communication using Pulse
A pulse is narrow in time and wideband in frequency
Sinusoidal signals are narrow in frequency and "wide" over
time

Narrow band Problems
Narrowband 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

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

Comparison of UWB vs Spread
Spectrum and Narrow Band

Definition of UWB
Conventional Definition- Short Pulse
• “Carrier Free”,”Baseband” or “Impulse
based”
• Typically only a Free RF Cycles
- Large fractional bandwidth (BW/f)
• Very low duty cycles resulting in low
average energy densities
• Typically generated by impulse or step
excited antennas and filters

UWB Pulse Waveforms

UWB Fractional Bandwidth
As per FCC guidelines UWB fractional
bandwidth is defined by,
Where:
fu
= upper –10 dB point
fl
= lower –10 dB point

Either 25% fractional bandwidth
criteria should be met or the
instantaneous bandwidth of 500 MHz.

Multi Band OFDM

FCC Emission Requirements

Comparison of occupied bandwidths
by UWB and other wireless
technologies

Comparison of Spatial Capacity

Comparison of Spatial Capacity of
Various Indoor Wireless System
System Maximum
Data Rate
[Mbps]
Transmissio
n Distance
[m]
Spatial Capacity
[kbps/m2]
Spectral
Capacity
[bps/Hz]
UWB 100 10 318.3 0.013
IEEE
802.11a
54 50 6.90 2.7
Bluetooth 1 10 3.2 0.012
802.11b 11 100 0.35 0.1317

Comparison of UWB bit rate with
other wired and wireless standards
Speed
(Mbit s/
second)
St andard
480 UWB,USB2.0
200 UWB(4m minimum),1394a (4.5m)
110 UWB(10m minimum)
90 Fast Et hernet
54 802.11a
20 802.11g
11 802.11b
10 Et hernet
1 Bluet oot h

UWB Major Application Areas
a) Communications
–Wireless Audio, Data & Video Distribution
–RF Tagging & Identification
b) Radar
–Collision/Obstacle Avoidance
–Precision Altimetry
–Intrusion Detection (“see through wall”)
–Ground Penetrating Radar
c) Precision Geolocation
–Asset Tracking
–Personnel localization

Some of Military & Commercial
Applications of UWB

Source:MSSI

Voice and Data Communications
•With increasing congestion in the radio spectrum
from communications appliances of all forms,
new schemes for allowing more users in a given
area are always sought.
•UWB allows users to simultaneously share the
spectrum with no interference to one another and
to apply it in UWB devices, such as high-speed
home and business networking devices as well as
storage tank measurement.

Ground and Ice Penetrating
RADAR
• A system used to detect objects buried in the
ground.
•A special directional antenna to transmit the
stimulus signal into the ground and receive the
reflected waves.
•Depth of penetration is typically between 0.5
and 10 m, very short pulses are needed to
resolve typical buried targets.

Wall Imaging Radar System
•To detect the location of objects contained within
a "wall," such as a concrete structure, the side of a
bridge, or the wall of a mine.
•Operation is restricted by FCC to law enforcement,
fire and rescue organizations, to scientific research
institutions, to commercial mining companies, and
to construction companies.

Through Wall Radar
System•Uses very short pulses to provide
detection of objects on the opposite side of
a non-metallic wall.
•The stimulus signal is transmitted into the
wall. A portion of the signal incident on the
wall is transmitted through the wall and
into the space on the far side.
•Objects in the field then reflect the signal back to the wall
where part of the signal is transmitted through the wall to
the receiver.
•Freq of Operation: below 960 MHz or 3.1-10.6 GHz band.

Surveillance Systems
•UWB based Surveillance
systems operate as "security
fences" by establishing a
stationary RF perimeter field
("bubble") and detecting the
intrusion of persons or objects in
that field.
•"Bubble" can be established to cover either
certain area or certain object, such as aircraft,
vehicle etc.
•Frequency band 1.99-10.6 GHz.

Vehicular Radar Systems
Potential applications include
• collision avoidance,
• proximity aids,
•intelligent cruise control systems,
•improved airbag activation
•& suspension systems that better respond to road
conditions.
•FCC limits operation of vehicular radar to the 22-29
GHz band using directional antennas on terrestrial
transportation vehicles provided the center frequency
of the emission and the frequency at which the highest
radiated emission occurs are greater than 24.075 GHz.

Fluid Level Measurements
UWB distance measuring hardware can
be used as an electronic dipstick, to
determine the level of a fluid in a tank by
measuring the distance between the top of
the tank and the interface with the surface of
the fluid.

Asset Location
• Another form of data communications.
• Up-to-date inventory of assets in a given
location.
• A coded transmitter can be attached to each
asset for instantaneous inventory control.
• Not only can determine the presence of a
particular object, but also provides
information as to its exact location.

ID Tags
•Similar to asset tracking, ID tags can be used to
wirelessly identify individuals with issued ID
tags.
•Other applications are Intelligent Transportation
Systems, Electronic Signs and Smart Appliances

UWB can enable a wide variety of
WPAN applications.
• Replacing IEEE1394 cables between portable
multimedia CE devices, such as camcorders, digital
cameras, and portable MP3 players, with wireless
connectivity
• Enabling high-speed wireless universal serial
bus (WUSB) connectivity for PCs and PC peripherals,
including printers,scanners, and external storage
devices
• Replacing cables in next-generation Bluetooth
Technology devices, such as 3G cell phones, as well
as IP/UPnP-based connectivity for the next generation
of IP-based PC/CE/mobile devices
• Creating ad-hoc high-bit-rate wireless
connectivity for CE,PC, and mobile devices

PC Clusters interconnected thru
UWB enabled Wireless USB

UWB Key Design Challenges
• Co-existence with other services Strong narrow band
interference
• Shaping of spectrum of the TX signal (impulse radio, multi-band
OFDM based UWB etc.)
• Practical and Simple Receiver Design (Synchronisation/Coherent
or non coherent receiver design)
• Wideband RF components (antenna,LNA etc.)
• Time Domain response of antenna is important since the
antenna shapes the pulse
•Antennas for impulse radio can no longer be optimized at the
carrier frequency
•Flat group delay so that high and low frequency signals arrive
simultaneously
• High Sampling rate ADCs for digital implementations

For UWB technology to become a widely adopted radio
solution, a few key areas need to be resolved:
•Performance (including over-the-air data rate performance,
power consumption, co-existence with other wireless devices,
immunity to interference, and link robustness)
•Interoperability
•Time-to-market considerations
•Ease of product integration and certification
•Overall solution cost (to the OEM)
•Fulfillment and support
•Quality of service
•Global spectrum allocation
Other Challenges for UWB

Thank You

Ultra wide band

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