Design considerations for LDR ULPR

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Project IEEE P802.15 Working Group for Wireless
Personal Area Networks (WPANs) Submission Title
Design considerations for Low Data Rate Ultra Low
Power Radios Date Submitted March 12th,
2005 Source Bart Van Poucke, Julien Ryckaert,
Claude Desset Companie IMEC Voice 32 16 28
12 11 E-Mail Bart.VanPoucke,
Julien.Ryckaert,Claude.Desset_at_imec.be Abstract
Link system design options to implementation
limitations Purpose Technical contribution 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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Wireless Body-Area Networksfor health monitoring
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Design Considerations forLow Data Rate Ultra Low
Power Radios

• Bart Van Poucke
• IMEC

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Outline

• Ultra Low Power Radios Requirements
• UWB-IR is good candidate
• Spectrum issues
• Modulation issues
• Pulse Repetition Rate issues

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Technology challenges

• Operational life time 1 week (band aid) to 10
  years (implant)
• Total average power consumption lt 100mW
• Communication lt 50mW
• Computation lt 40mW
• Sensor lt 10mW

Sensor
Data
Processing
Commu-

nication
Control
Actuator
Power Management
Thick, hard Swallow Implant Mechanical energy 3D
integration 1cm3
Thin, flexible Stick to skin Integrate in
clothing Solar cell, Thermo-Electric
conversion 2D integration 5cm2
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New communication system needed
Pcons
Traditional systems
Traditional solutions more efficient
Pout (range)

• Low-power WPAN
• Reducing baseline consumption
• Extreme scaling of duty cycle

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UWB-IR allows double duty cycling
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Multi-Band approach has advantages
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A Carrier based system brings the required
flexibility at low cost

• Pulse Processing in baseband
• ?Flexible tuning of the bandwidth
• ?Reuse of traditional blocks
• ?Lower speed of signals
• Up and down conversion
• ?Flexible Selection of center frequency

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Advantages have been proofed

• Technology 0.18 ?m CMOS
• Center Frequency Range 3-5GHz
• Bandwidth Range 500MHz 2GHz
• Power Consumption
• 65 pJ/pulse _at_ 500MHz, 30 _at_ 1GHz
• Note 90nm version shows Center Frequency Range
  3-10GHz

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Triangular shape low spectral side-lobes, can be
matched with rectangle at receiver
Time
Correlation with rectangle only 0.5 dB loss wrt
ideal matched filter
26.5 dB
Frequency
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PPM versus BPSK

• Coherent BPSK versus non-coherent PPM
• () 4 dB gain
• OOK versus PPM for same performance?
• (-) need for accurate signal and noise power
  estimation
• () same pulse repetition rate achievable as in
  BPSK

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Coherent detection accurate timing!

• Autocorrelation
• PPM envelope only
• BPSK RF carrier

• Factor 40 difference!
• PPM 1.2 ns
• BPSK 33 ps
• (2/3 of maximum)

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Where communication theory and implementation
practice meet

• Theory Limit Inter Pulse Interference
• Practical Limit .090 CMOS 283 mVpp
• ?Ppeak -7 dBm
• ?Epulse 0.297 pJ (using TB of triangular
  pulse)
• ?Pactive Epulse PRR 11.9 uW (40 MHz PRR)
• ?PSD Pactive / BW 0.0237 pW/Hz
• 23.7e-6 mW/MHz -46.2 dBm/MHz
• ?PSDcomp -42.8 dBm/MHz ltgt -41.3 dBm/MHz
• ?Can be optimized up to 56 MHz PRR
• ?Higher PRR become energy inefficient

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ULPR Radio design needs close link between
algorithms and implementation

• Carrier based UWB-IR shows implementation
  advantages
• Full CMOS implementation (3-10GHz for 90nm)
• Flexible towards use of spectrum (carrier and
  bandwidth)
• Coherent detection pays an energy consumption
  price
• Factor 40 more accurate synchronization required
• PRR are bounded by technology
• 40 MHz seems good practical value for 90nm
• Antenna efficiency and spectral spikes not
  discussed yet

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Ultra Low Power Radios will improve the quality
of life

• Meanwhile the old rules apply
• Eat balanced
• Sleep rest relax
• Exercise
• Have a rich social life
• Think you live healthy
• Enjoy life