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Design considerations for Low Data Rate Ultra Low Power Radios

This submission discusses the design considerations for low data rate ultra-low power radios, focusing on operational life time, power consumption, communication, computation, sensor data processing, and power management. The advantages of UWB-IR technology and the need for a new communication system are also highlighted.

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Design considerations for Low Data Rate Ultra Low Power Radios

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  1. 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}@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

  2. Wireless Body-Area Networksfor health monitoring

  3. Design Considerations forLow Data Rate Ultra Low Power Radios Bart Van Poucke IMEC

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

  5. Technology challenges Operational life time: 1 week (band aid) to 10 years (implant) Total average power consumption < 100mW • Communication < 50mW • Computation < 40mW • Sensor < 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

  6. New communication system needed Pcons Low-power WPAN • Reducing baseline consumption • Extreme scaling of duty cycle Traditional systems Traditional solutions more efficient Pout (range)

  7. UWB-IR allows double duty cycling

  8. -41dBm/MHz 3.1Ghz 10.6Ghz 3.1Ghz 10.6Ghz -41dBm/MHz  Avoid strong interferers  More multiple-access freedom Multi-Band approach has advantages

  9. 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

  10. Advantages have been proofed Technology: 0.18m CMOS Center Frequency Range: 3-5GHz Bandwidth Range: 500MHz – 2GHz Power Consumption: 65 pJ/pulse @ 500MHz, 30 @ 1GHz Note: 90nm version shows Center Frequency Range: 3-10GHz

  11. 0.64 0.94 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

  12. 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

  13. 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)

  14. 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 T*B 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 <> -41.3 dBm/MHz Can be optimized up to 56 MHz PRR Higher PRR become energy inefficient

  15. 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

  16. 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

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