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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) Submission Title: France Telecom / CEA / Thales final proposal Date Submitted: March 10th, 2009 Source: Jean Schwoerer (1), Laurent Ouvry (2), Arnaud Tonnerre(3) Companies:

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Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs)

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  1. Project: IEEE P802.15 Working Group for Wireless Personal Area Networks (WPANs) • Submission Title: France Telecom / CEA / Thales final proposal • Date Submitted: March 10th, 2009 • Source: Jean Schwoerer (1), Laurent Ouvry (2), Arnaud Tonnerre(3) • Companies: • (1) France Telecom R&d, 28 chemin du vieux chênes, 38240 Meylan, Cedex, FRANCE • (2) CEA-LETI, 17 rue des Martyrs 38054, Grenoble Cedex, FRANCE • (3) THALES, 146 boulevard de Valmy, 92704 Colombes, France • Voice: (1) +33 4 76 76 44 83, (2) +33 4 38 78 93 88, (3) +33 1 46 13 28 50 • E-Mail: (1) jean.schwoerer@orange-ftgroup.com, (2) laurent.ouvry@cea.fr, (3) arnaud.tonnerre@fr.thalesgroup.com, • Abstract: Response to IEEE 802.15.6 call for proposals • Purpose: Proposal based on UWB impulse radio for the IEEE 802.15.6 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. List of Authors • France Telecom – Jean Schwoerer, Benoit Miscopein, Stephane Mebaley-Ekome (1) • CEA-LETI – Laurent Ouvry, Raffaele D’Errico, François Dehmas, Mickael Maman, Benoit Denis, Manuel Pezzin (2) • THALES – Arnaud Tonnerre (3)

  3. Outline • Introduction • Band Plan • Pulse Repetition Frequency • Preamble • Modulation • Variable bit rate & throughput • Link Budget • Performances • Feasability examples • Conclusions & References

  4. Introduction • Proposal main features: • Based on IEEE802.15.4a-2007 where a very reduced set of mode is selected for the BAN context • UWB Impulse-radio based • Support for different receiver architectures (coherent/non-coherent) • Flexible modulation format • Support for multiple rates • Support for multiple SOP

  5. Advantages of UWB Low radiated power Low PSD, low interference, low SAR High co-existence with existing 802.x standards Real potential for low power consumption Large bandwidth worldwide Spectrum is worldwide available Robust to multipath and fast varying channels Flexible, scalable (e.g. data rates, users) Low complexity HW/SW solutions in advanced development (eg 802.15.4a)

  6. Complexity vs. data rate & coverage Complexity / Power Coherent Rake IR-UWB EQ IR-UWB Non coherentIR-UWB Coherent IR-UWB FM-UWB Non coherentIR-UWB LDR Long range MDR Medium Range HDR Short Range Coverage

  7. Band plan (selection from 15.4a) • Comparison with 15.4a : • Only 500 MHz bandwidth channels • No sub-GHz band

  8. Band plan versus regulation for UWB

  9. PLL Reference Diagram Oscillator Phase Detector LPF VCO fcomp fc XTAL fX ÷ N ÷ M fs = 499.2 MHz For channels 5,6,8,9,10,12,13,14 (high band), the factor N becomes respectively 13,14,15,16,17,18,19,20

  10. Pulse Repetition Frequency • Selected value • 15.6 MHz PRF (64.10 ns of pulse repetition period PRP) • Use of binary codes, No bursts => mean PRF = peak PRF • Rationale • Typical channel delay spread for indoor applications below 25 ns in 90% of channel realizations => very limited ISI (or IPI) • Integer relationship with base frequency of the bandplan (499.2 MHz / 32) => no fractional PLL • Maximized Pulse amplitude • => better for transmitter power consumption (between-pulses duty cycling) • => better for pulse detectability in the receiver • => better for threshold crossing receivers • => compatible with low voltage CMOS technologies without I/O « tricks » (around 780 mVp-p) • A single value => simplicity • Compatible with bit rate scalability with short spreading factors • No high speed clock / long FIRs filters to generate or correlate with bursts of pulses

  11. Preamble • PRF is the same as one of the mean PRF in 15.4a • Sp code duration: • Example with N=31 : Tpsym = 31 * PRP = 1.9871 us • To be checked if enough for a correct (Pd,Pfa) versus complexity (=> May meeting) • Number of Sp codes in the preamble • Example with Nsp = 16 : Tsync = 16 * Tpsym = 31.7936 us • This is probably a maximum value • To be checked if enough for a correct (Pd,Pfa) versus overhead (=> May meeting) Sp code : binary. Length TBD. Unique. PRP = 64.10 ns Sp code duration N*PRP

  12. Modulation Sd = +1 +1 +1 −1 −1 +1 −1 Symbol : +1 PRP = 64.10 ns Symbol : -1 • PRF is ~ the same as one of the mean PRF in 15.4a • Spreading code length Sd • Example with N=7 (BARKER CODE) : Symbol duration Ts = 7 * PRP = 0.4488 us • Modulation : 1 bit per symbol + second bit used for redundancy OR non coherent demod • DBPSK : BPSK with differential encoding (at symbol level) • Sub-optimal but easier to implement and less sensitive to clock drift • Same + PPM : the whole S code can be shifted within the PRP with ½ the PRP value • Does not affect the mean PRF value and the spectrum shape • Is simple to implement (though a little more complex than pure DPBSK) • Is compatible with non coherent / threshold crossing detectors • Is ISI compatible in the BAN context Symbol duration = 7 pulses ~ 448.8 ns

  13. Modulation : Bit-DBPSK + 2-PPM(an orthogonal keying modulation)

  14. Variable bit rates • Bit rates • Bit rate is adjusted with the number of pulses per symbol keeping a constant mean PRF • 2.22 Mbit/s is the default data rate • 5.2 and 15.6 Mbit/s are mandatory => No additional complexity & allows to reduce channel use • 31.2 Mbit/s is proposed optionally for coherent receiver (uses both PPM & DPBSK) • Proposed FEC : systematic RS (63,55) as in 15.4a (maximum efficiency ~0.87)

  15. Performances analysis methodology and channel models • Goal: • Get/discuss performances at a link budget / outage probability level with the different channel models at the default 2.2 Mbps rate before digging into the design level performances • Methodology: • Perform extra measurements at CEA-Leti (for UWB 3-5GHz but also for 2.4 GHz) • Complement the IEEE802.15.6 CM3 UWB channel model with extra measurements and models • Compare channel models with each other • Move towards a scenario based approach • Scenario = [at least] given (Tx,Rx) couple + given generic environment + given generic movement • Justified by the huge dispersion of the BAN radio channel • Calculate outage probabilities given the path loss and shadowing statistics

  16. Performances: channel path loss models • Available CM3 UWB channel models as in TG6 document : • A (source NICT) • Indoor and anechoic • B (source IMEC) • Anechoic • C (source Samsung) • Indoor and anechoic • Conclusion • Huge dispersion (tens of dBs) between models • Distance is not a relevant parameter to get a path loss model • Coming back to the scenario based channel characterization is proposed • Reference • Roblin C.; D'Errico R.; Gorce J.M.; Laheurte J.M ; Ouvry L., « Propagation channel models for BANs: an overview », COST 2100, 16/02/2009 - 18/02/2009, Braunschweig , Allemagne

  17. Performances: extra channel measurements • 2-5 GHz, indoor and anechoic, 7 subjects, standing/walking/running • Scenarios as depicted below • Log normal path loss model. Shadowing and small scale fading modeled separately. • Measurement set up details available on request

  18. Performances : outage probability • Starting from: • The link budget • PTx + antenna = -20.5 dB • Sensitivity = -90.5 dB • Includes 6dB NF, 5dB I.L. and 9dB min required EbN0 • 70dB total link margin • The different scenario based path loss models • CM3 UWB A back to the scenarios • CM3 UWB C back to the scenarios • CEA-Leti’s measurements • Get the outage probability performance for an EbN0 • from 9dB (10dB => PER=1e-2 with optimal DBPSK in AWGN) • to 18dB (to account for higher rate and multi path conditions) • (Note that the 5dB I.L. in the link budget already account for some inability of the receiver to collect all the multi-path energy : early simulations showed 13dB required EbN0 for a 3-finger RAKE for pure DBPSK on the CM3 BAN channel)

  19. Performances : scenario based outage probability • Tentative consolidation of • CM3 A (NICT) • CM3 C (Samsung) • CEA-Leti’s measurements for four indoor scenarios : • Hip-chest • Hip-right wrist • Hip-thigh • Hip-chest • (others available as well, including anechoic chamber cases)

  20. Conclusions on performances • The proposed link budget and system specification makes the UWB proposal feasible for most of the scenarios (outage of 1e-2 ~ PER of 1e-2 in first approximation) • However, large variations between the different models (CM3 A is optimistic, CM3 C is pessimistic, CM3 B and CEA-Leti’s measurement are median) • Further analysis in the 7.25-8.5 GHz band is necessary • The low transmit power is a very attractive feature for system adoption

  21. Transmitter 4.5 GHz Receiver 4.5 GHz Max amplitude Min Mean PRF Modulations Power consumption : 700mVpp : 3.9MHz : OOK, PPM, BPSK : 0.7mW S11 IIP3 Input BW Max sensitivity Power consumption (analogue + digital RF) : <-15dB : -15dBm : 850MHz : -78dBm : 17mW Feasibility example (see references) • RF part only • Total Power consumption: 34mW (Rx:17 + Tx:0.7 + I/O:16.3) • Max data rate: 31Mb/s • RF receiver energy efficiency : 1.1nJ/b @ 31Mb/s • RF transmitter energy efficiency : 23pJ/b @ 31Mb/s • Overall transceiver • DBPSK Digital BB: 347 kbps - 1 Mbps • Total power consumption: • 45mW peak in synchronization mode(Rx=17 + Tx=0.7 + BB=27.3) • 26mW in demodulation mode(Rx=17 + Tx=0.7 + BB=8)

  22. Conclusions • Proposal based upon UWB impulse radio alt-PHY of 15.4a • Advantage • Early implementations exist: experienced proposal • Selection of the most relevant modes and their adaptation to the BAN context (note: 15.4a mandatory mode is NOT the selected option for 15.6) • A standard exists which will speed up the 15.6 standard drafting steps • Modulation: • DBPSK provide robustness for a limited complexity & 2PPM allow several receiver implementations • RS FEC help to improve link budgets and parity bit will improve robustness of the DBPSK receiver • System tradeoffs • Variable bit rates allow to accommodate all applications envisaged in TG6 • Minimizing talk time improve energy consumption, SOP performances, and regulatory compliance • Flexible implementation of the receiver • Compatible with almost all kind of UWB detectors (coherent, differential, energy, threshold crossing) • FEC decoder is optional • Fits with multiple technologies • Compatible with implementation in low voltage CMOS • Very low power integrated solutions already proven Will permit good compromises between cost, performances and energy consumption

  23. References • M. Pezzin, D. Lachartre, « A Fully Integrated LDR IR-UWB CMOS Transceiver Based on "1.5-bit" Direct Sampling », ICUWB 2007, Singapore, September 2007 • D.Lachartre, B. Denis, D. Morche, L. Ouvry, M. Pezzin, B.Piaget, J. Prouvée, P. Vincent, « A 1.1nJ/b 802.15.4a-Compliant Fully Integrated UWB Transceiver in 0.13μm CMOS», ISSCC 2009, San Francisco, February 2009 • European ICT PULSERS II and ICT EUWB projects deliverables • French ANR "BANET" project

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