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Ultra Wideband: an Emerging Wireless Technology

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Title: Ultra Wideband: an Emerging Wireless Technology


1

forward-looking and higher-risks research
  • Ultra Wideband an Emerging Wireless Technology

By Dr. Ali Hussein Muqaibel
King Fahd University of Petroleum
Minerals Electrical Engineering
Department EE571-Digital Communications I
2
Topics
  • Definition
  • Advantageous
  • CRITICALITIES
  • Applications
  • Prototypes
  • UWB Coexistence Issues
  • Multiple Access UWB Communication
  • Research Areas in UWB Communication
  • Research groups Companies

3
What is UWB ?
  • UWB the use of extremely short pulses instead
    of continuous waves to transmit information.
  • The pulse directly generates a very wide
    instantaneous bandwidth signal according to the
    time-scaling properties of the Fourier transform
    relationship between time and frequency.

UWB is an old technology with the potential
to significantly impact the traditional way of
managing the spectrum
4
UWB/NARROWBAND DISCRIMINATION
  • rule of thumb RF bandwidth/centre frequency 25
  • far from/near to sinusoidal signal type
  • considerable/negligible difference in link
    attenuation



    at lower/upper frequency
  • transient nature

25 to gt100
SIGNAL STRENGTH AT DISTANCE R
lt 1
1/F
Density
Power Spectral
FREQUENCY (F)
5
Wireless Bandwidth in the Making
An intriguing alternative which may eventually
become practical, and even legal, for short-range
communication between static terminals is
ultra-wideband impulse radio. In fact, the
principle of impulse radio is firmly grounded in
information theory maximum power efficiency is
achieved by pulse-position modulation in an
infinite bandwidth channel although the whole
band occupied by the transmission, say, from DC
to a few gigahertz is owned by other systems,
much of it is unused at any given time. Thus,
reasonable receiver sensitivity can indeed be
achieved with very low transmitted power
Sergio Verdu
6
Historical Perspective on Ultra-Wideband (UWB)
  • Todays Environment
  • Scarcity of available spectrum for new
    applications
  • Proliferation of digital consumer electronics
    devices
  • Advances in microprocessor power
  • Numerous improvements in process technology (such
    as SiGe, CMOS and GaAs)
  • UWB Revolution
  • By 2000 Large companies had applied UWB to
    networking applications
  • UWB meets requirements for high throughput
    applications
  • Recycles scarce spectrum
  • History
  • lt1900 Hertz generated pulsed spark discharge
  • In 1940s used for radar
  • In 1970s matured as solution for covert military
    communications
  • In 1990s developed for location and positioning
    applications

7
Comparison between NB UWB
Advantages for
  • SUMMARY
  • spectrum efficiency (bits/Hz/s)
  • (system feature)
  • flexible resource allocation
    (user, geographically, spectrally)
  • versatility
  • (comms, sensing, positioning...)
  • wide area/global coverage
  • service integration
  • Less coding/diversity requirements

Narrowband UWB UWB Narrowband UWB UWB
8
Promised! UWB System Advantages
  • New technology considerable development
    potential.
  • Nearly "all-digital", with minimal RF
    electronics.
  • An LPD signature produces minimal interference
    to proximity systems , minimal RF health hazards
    and is hardly interceptible.
  • Extremely high data rate performance in
    multi-user network applications.
  • Can provide very fine range resolution and
    precision distance and/or positioning measurement
    capabilities.
  • Relativity immune to multipath cancellation
    effects as observed in mobile and in-building
    environments.
  • Low Power Consumption

9
UWB CRITICALITIES
  • Coexistence (FCC)
  • Multi-user capability
  • Real world performance
  • Implementation complexity
  • Cost and competitiveness
  • Connectivity with narrowband systems

Do many UWB devices operating within a small area
cause serious interference to existing licensed
services ?
10
Co-existence Issue Reply Comments
  • Wide agreement that this technology is very
    promising, there is a very broad applications
    range
  • Strong concern to allow the UWB devices operate
    below 2 GHz or even below 3 GHz.
  • they should be licensed !
  • This technology should not use (re-use the paid
    spectrum by others) the spectrum for free !
  • This technology is still immature and we dont
    know what the interference problems may rise
  • Extend the period of time to complete the
    interference tests

11
Some UWB Applications
  • Digital Video Networks
  • Short range radios
  • High Speed (tens Mb/s) WLANs, microphones, etc.
  • Precision Geo-location Systems
  • Industrial RF Monitoring Systems
  • Collision Avoidance Sensors
  • Motion and Intrusion Detection Radar
  • Automobile and aircraft proximity radar,
    including precision automatic landing
  • Subsurface in-ground penetration radar

12
Prototypes
  • Time Domain has built several prototypes
    including the following
  • A full duplex 1.3 GHz system with an average
    output power of 250 microWatts, and a variable
    data rate of either 39 kbps or 156 kbps.  The
    radio has been tested to beyond 16 kilometers (10
    miles).
  • A full duplex 1.7 GHz walkie-talkie with an
    average output power of 2 milliWatts, a data rate
    of 32 kbps and a range of 900 meters.   The unit
    was also capable of measuring the distance
    between radios with an accuracy of 3 cm (0.1 ft).
  • A simplex 2.0 GHz data link with an effective
    average output power of 50 microWatts, a data
    rate of 5 Mbps at bit error rate (BER) of 0 with
    no forward error correction (FEC) and a range of
    10 meters (32 ft) through two walls inside an
    office building.

13
Received Signal
  • Multiple Access, when the physical layer is UWB,
    is achieved by using time hopping codes
  • When the number of users is Nu , the received
    signal is

14
Pulse Position Modulation
15
Gaussian, Monocycle and Doublet Waveforms
  • 2GHz (gt1Mhz) , noise like.
  • fc typically 650 MHz 5MHz.
  • Tightly controlled pulse-to-pulse interval.
  • Pulse width 0.2 1.5 nanoseconds.
  • Pulse-to-Pulse interval 100-1000 nano-seconds.

16
Frame Delay
  • The quantity represents the
    transmitted monocycle waveform that nominally
    begins at time zero on the kth transmitters
    clock.
  • The quantity represents the
    transmitted monocycle in the j frame.

17
Uniform Pulse Train
  • Uniform Pulse train the frame time (Tf) may by
    100 to 1000 times the monocycle width, resulting
    in a signal with very low duty cycle.
  • Multiple Access signals composed of uniformly
    spaced pulses are vulnerable to occasional
    Catastrophic Collisions.
  • In frequency domain (Normalized)

18
Random/Pseudorandom Time-Hopping Waveform
0
2
3
0
19
Spectrum of Random/Pseudorandom Time-Hopping
20
Time Domain (TD) Measurement Setup
Tektronics 11801/HP 54120A Digitizing
Oscilloscope
Running LabView 6.0i
LN Amplifiers
Data Acquisition Unit
trigger input
Balun and wideband transmitting antenna
Balun and wideband receiving antenna
pretrigger
trigger
Pulse Generator Pico-second Pulse Labs model
4050A/4100
Step Generator Driver
21
Acquired Signals
  • The transmitted signal get differentiated before
    it is decoded
  • Multiple reflection cannot be avoided

22
Other Multipath Scenarios
23
Areas in UWB Research Communication
Measurements
  • Interference Measurements
  • Antenna Design
  • Spread Spectrum Techniques
  • Multiple Access Techniques
  • Multi-user detection
  • Time Hopping Codes
  • System Performance Evaluation under different
    channel conditions (Gaussian, Raleigh)
  • Coding and Diversity Applications
  • Pulse Shaping and Modulation

Models
Signal Processing Receiver Design
24
Research Groups
  • Ultra Wideband Working Group (UWBWG) www.uwb.org
  • Ultra Lab Web ultra.usc.edu/ulab/
  • University of Texas, Center of Ultra Wideband
    Research and Engineering sgl.arlut.utexas.edu/asd/
    Cure/impulse.html
  • Time Domain Laboratory (VT) tdl.ece.vt.edu
  • Time Domain www.time-domain.com
  • Bibliography Of Ultra-wideband Technology
    www.aetherwire.com/CDROM/General/biblio.html
  • Presentations from the 1st European Ultra
    Wideband Workshop www.cordis.lu/ist/ka4/mobile/uwb
    _workshop.htm
  • Ultra Wideband (UWB) Frequently Asked Questions
    (FAQ) www.multispectral.com/UWBFAQ.html

25
Working Towards UWB Wireless Communication
Dr. Ali Hussein Muqaibel muqaibel_at_kfupm.edu.sa Kin
g Fahd University of Petroleum
Minerals Electrical Engineering Department Time
Domain and RF Measurements Laboratory
http//tdl.ece.vt.edu/ali MPRG http//www.mprg.o
rg
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