15-05-0390-00-004a

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Project IEEE P802.15 Working Group for Wireless
Personal Area Networks (WPANs) Submission Title
Sub-GHz_Overview Date Submitted July 7th,
2005 Source Mark Jamtgaard (1) Companies (1)
Æther Wire Location, Inc., 520 E. Weddell
Drive, Suite 5, Sunnyvale, CA 94089, USA
Voice (1) 408 400 0785 E-Mail (1)
mark_at_aetherwire.com Abstract UWB proposal for
802.15.4a alt-PHY Purpose Proposal based on UWB
impulse radio for the IEEE 802.15.4a CFP Notice
This document has been prepared to assist the
IEEE P802.15. It is offered as a basis for
discussion and is not binding on the contributing
individual(s) or organization(s). The material in
this document is subject to change in form and
content after further study. The contributor(s)
reserve(s) the right to add, amend or withdraw
material contained herein. Release The
contributors acknowledge and accept that this
contribution becomes the property of IEEE and may
be made publicly available by P802.15
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Advantages

• Propagation
• Low Frequencies Have Better Propagation
  Characteristics Than High Frequencies
• Low Frequencies Experience Less Shadowing
• Important for Ranging (first arrival detection)

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1.2cm Wallboard Attenuation

• Attenuation at 620 MHz 0.4 dB/m
• Attenuation at 4.12GHz 0.45 dB/m

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4.5cm Door Attenuation

• Attenuation at 1.01GHz 0.51 dB/m
• Attenuation at 3.81GHz 1.56 dB/m

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5.9cm Cloth Office Partition Attenuation

• Attenuation at 520 MHz 0 dB/m
• Attenuation at 4.02 GHz 1.91 dB/m

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• 5.8cm Brick Attenuation
• Attenuation at 1.01 GHz 2.06 dB/m
• Attenuation at 4.01 GHz 5.27 dB/m

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Suburban Home Propagation

• Link through 3 walls.
• 8xDrywall 2xBrick 4 6 10dB
• Sub-GHz band propagation advantage over 3-5 GHz
  band

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Office Building Propagation

• Link through 5 partitions.
• Sub-GHz band has a 10dB propagation advantage
  over 3-5 GHz band

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Regulator Status

• FCC In the frequency band below 960 MHz these
  devices are permitted to emit at or below the
  15.209 limits First order and report, 2002
• 15.209
• Measured With Quasi-Peak Detector (CISPR 16-1)
  with 120-kHz resolution filter
• Charge time is 1ms
• Discharge time is 550ms

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FCC Mask
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Disadvantages

• More Interference In The Sub-GHz Band
• Non-coherent detection not possible
• Longer code lengths
• Larger dynamic range

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Applications

• Numerous applications require 3D position
  tracking in buildings.
• These applications require 5 links per node to
  compute 3D position.
• To robustly maintain 5 links in real applications
  requires
• Penetration through multiple walls / objects
• 30 meter range

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Track Firefighter Status

• A network of locators determine their location
  relative to each other and transmit their
  location to a command center
• Can penetrate Buildings, Metal containers, Fire
  and smoke

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Military Operations in Urban Terrain
Penetrates Interior Walls
MOUT
1-meter accuracy
50-200m range
UWB Localizer
Wearable Computer
Low power
LPI/LPD
Lightweight
GPS Receiver
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Signal Spectrum Doublets

• Spectral Nulls chosen by Impulse Separation to
  notch out selected frequency bands for
  transmission reception (i.e. GPS, cellular)

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Link Budget
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System Block Diagram
Time-Integrating Correlator
Time- Integrating Correlator
RF Amplifier
A/D Converter
Large Current Radiator
Transmitter Antenna Driver
Code Sequence Generator
Real Time Clock
Crystal Oscillator
Processor and Memory
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Large Current Radiator

• Baseband impulses (lt1GHz) can be effectively
  radiated from small (lt4 cm) Large Current
  Radiator (LCR) antenna (FDTD simulation)

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Antennas

• Large Current Radiator
• Preserves impulse shape
• Frequency response varies lt6 dB from lt100 MHz to
  gt2.5 GHz
• Requires low (1W) source impedance
• Direct drive from chip
• No transmission line
• 6 cm Electric Dipole (for comparison, 4 cm LCR
  fits within 6cm sphere)
• Differentiates impulse shape
• Gain varies 40 dB from 100 MHz to 2.2 GHz
• Other UWB antennas with comparable low-frequency
  response (e.g. TEM horn) are physically large (gt
  1 meter)

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Reception

• Coherent Reception via Correlation
• Time Integrating Correlator is a Matched Filter
• Analog input signal is multiplied by Reference
  code integrated
• Each of 32 correlator phases represents a
  different time alignment of input signal
  reference code
• Tolerant of clock jitter and drift
• 30 dB Process Gain with families of orthogonal
  1023-chip codes
• Each reception starts with zero integrated noise
• Doppler shift insignificant for less than
  orbital velocity
• Time Domain Filtering to reduce noise
• Additional 7-10 dB increase in S/N ratio

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Real Sub-GHz UWB Signals At 10m
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Conclusion

• The Sub-GHz band propagation characteristics make
  it attractive for indoor, industrial applications.