Ultra Wideband: an Emerging Wireless Technology

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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
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Topics

• Definition
• Advantageous
• CRITICALITIES
• Applications
• Prototypes
• UWB Coexistence Issues
• Multiple Access UWB Communication
• Research Areas in UWB Communication
• Research groups Companies

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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
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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)
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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
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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

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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
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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

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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 ?
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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

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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

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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.

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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

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Pulse Position Modulation
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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.

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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.

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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)

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Random/Pseudorandom Time-Hopping Waveform
0
2
3
0
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Spectrum of Random/Pseudorandom Time-Hopping
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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
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Acquired Signals

• The transmitted signal get differentiated before
  it is decoded
• Multiple reflection cannot be avoided

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Other Multipath Scenarios
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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
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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

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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