project: ieee p802.15 working group for wireless...

Jan. 2005

CWC/AETHERWIRE/CEA-LETI/STM

doc.: IEEE 802. 15-05-0011-00-004a

Slide 1

Project: IEEE P802.15 Working Group for Wireless Personal Area NProject: IEEE P802.15 Working Group for Wireless Personal Area Networks (etworks (WPANsWPANs))

Submission Title: STM_CEA-LETI_CWC_AETHERWIRE 15.4aCFP responseDate Submitted: January 4th, 2005Source: Ian Oppermann (1), Mark Jamtgaard (2), Laurent Ouvry (3), Philippe Rouzet (4)Companies:

(1) CWC-University of Oulu, Tutkijantie 2 E, 90570 Oulu, FINLAND(2) Æther Wire & Location, Inc., 520 E. Weddell Drive, Suite 5, Sunnyvale, CA 94089, USA(3) CEA-LETI, 17 rue des Martyrs 38054, Grenoble Cedex, FRANCE (4) STMicroelectronics, CH-1228, Geneva, Plan-les-Ouates, SWITZERLAND

Voice: (1) +358 407 076 344, (2) 408 400 0785 (3) +33 4 38 78 93 88, (4) +41 22 929 58 66 E-Mail: (1) [email protected], (2) [email protected](3) [email protected], (4) [email protected], Abstract: UWB proposal for 802.15.4a alt-PHY

Purpose: Proposal based on UWB impulse radio for the IEEE 802.15.4a CFPNotice: 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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doc.: IEEE 802. 15-05-0011-00-004a

Slide 2

List of Authors

• CWC – Ian Oppermann, Alberto Rabbachin (1)• AetherWire – Mark Jamtgaard, Patrick Houghton (2)• CEA-LETI – Laurent Ouvry, Samuel Dubouloz,

Sébastien de Rivaz, Benoit Denis, Michael Pelissier, Manuel Pezzin et al. (3)

• STMicroelectronics – Gian Mario Maggio, ChiaraCattaneo, Philippe Rouzet & al. (43)

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 3

Outline• Introduction• Transmitter• Receiver architectures• System performances• Link budget• Framing, throughput• Power Saving • Ranging• Proof of concept• Conclusions

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 4

Introduction (1/2)

• Proposal main features:1. Impulse-radio based (pulse-shape independent)2. Pulse duration optimized to available spectrum3. Enables accurate ranging/positioning4. Robustness against SOP interference5 Robustness against other in-band interference6 Ad-hoc dynamic network organization7 Modulation format general enough to support

different receiver architectures (coherent/non-coherent) Trade-off complexity/performance

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 5

Introduction (2/2)• Motivation for (7):

• Typical scenario: Self-organizing ad-hoc wireless network, where sensors send information towards a “concentrator” node (G)

• Different classes of nodes, with different reliability requirements (and $) must interwork, while sharing the same modulation format

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 6

Preliminaries (1/4)• Modulation:

• TH code (PN sequence) and/or polarity flipping for channelization and spectral smoothing purposes

• Coherent integration (n pulses/symbol): Energy collection, proportional to TH code length, results in processing gain

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 7

Preliminaries (2/4)

• Definitions:– Coherent RX: The phase of the received carrier

waveform is known, and utilized for demodulation– Differentially-coherent RX: The carrier phase of

the previous signaling interval is used as phase reference for demodulation

– Non-coherent RX: The phase information (e.g. pulse polarity) is unknown at the receiver, that operates as an energy collector

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 8

Preliminaries (3/4)

• Pros (+) and cons (-) of RX architectures:– Coherent

• + : Sensitivity• + : Use of polarity to carry data or to perform multiple access• + : Optimal processing gain possible• - : Complexity of channel estimation and RAKE receiver• - : Longer acquisition time

– Differential (or using Transmitted Reference)• +/- : Trade-off!• + : Gives a reference for faster channel estimation (coherent approach)• + : No channel estimation (non-coherent approach)• - : Asymptotic loss of 3dB for transmitted reference (not for DPSK)

– Non-coherent• + : Low complexity• + : Acquisition speed• - : Sensitivity, robustness to SOP and interferers

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 9

Preliminaries (4/4)Traditional Narrowband, Sinusoidal

Time Frequency• UWB trades off bandwidth (> 1 GHz)

for Radiated Power (< Part 15)• UWB transmits pulses; there is no

carrier frequency• UWB requires high resolution in Time

as opposed to high resolution in Frequency

• UWB design challenge is to provide accurate timing resolution without high-frequency clocks

UltraWideband, Pulse

FrequencyTime

Spread Energy Over Existing Noise Floor

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 10

Transmitter• Modulation, rate and spectrum

– Modulation:• Symbol to pulse mapping: multiple schemes possible (TR, PPM, etc.)

– Rate:• Bit to symbol mapping (modulation efficiency)

– Spectrum:• Single pulse of duration Tp ~ 1/BW shape • Time hopping or polarity codes (smoothing)

Bit to symbol mapping

Symbol to pulse mapping

Pulse shapingPPDU Antenna

Tp

½ PRP ½ PRPPRP : pulse repetition period

Example

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 11

TX: Modulation Formats

½ PRP ½ PRP

« 1 »

« 0 » TR-BPSK

D

« 1 »

« 0 »

« 1 »

« 0 »OOK

DBPSK (one pulse per PRP )

« 1 »

« 0 » BPPM

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 12

Transmitted Reference (TR)

• TR schemes simplify the channel estimation phase• Reference waveform available for synch. purposes• Potentially more robust (than non-coherent) under SOP

operation• Amenable of both coherent/non-coherent demodulation

(see for instance TR-BPSK OOK)• For LDR systems, ISI can be avoided• Energy efficiency can be improved (see next slides)• Reference waveform averaging (non-coherent integration); see

also GLRT [Franz, Mitra; Globecom’03, pp. 744-748, Dec 2003]• Implementation challenges:

– Analogue: Delay line (<10ns), delay mismatch, jitter– Digital: OK

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 13

TR Schemes (1/3)• GTR (Generalized Transmitted Reference) BPSK

Extension to N-ary TR

• Concept: Multi-level version of the TR scheme, where the energy associated with the reference pulse is «shared» to improve efficiency

« A »

« B »

« C »

D D

« D »

PRP

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 14

TR Schemes (2/3)• TR-BPPM (with/without BPAM)

D1

D2

Extension to N-ary TR« A »

« B »

« C »

« D »

CoherentDetection

PRP

• Concept: Transmitted-reference version of BPPM, with BPAM [Zasowski, Althaus and Wittneben, Proc. IWUWBS/UWBST’04, Kyoto, Japan]• TR-BPPM (non-coherent): Binary symbols restricted to “A” and “B”

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 15

TR Schemes (3/3)

• TR-PCTH (pseudo-chaotic time hopping)[Maggio, Reggiani, Rulkov; IEEE Trans. CAS-I, v. 48, no. 12, p. 1424, Dec 2001]

½ PRP ½ PRP

« 0 »

« 1 »

Random inter-pulse interval Extension to N-ary TR

D

• Concept: Random TH Smoothes spectral lines in the PSD • Modulation: Pulses in the first ½ PRP correspond to « 0 » and vice versa for « 1 »• Demodulation: Similar to PPM, but more flexible (threshold or Viterbi detector)

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 16

Transmission

• Advantages of Episodic Transmission– Very low power operation achievable with low

duty-cycle• Typical 1% duty cycle with 1ms cycle time• Network precise timing (~1ppb) allows extended sleep

mode (~40s)

– Back-and-forth Ranging exchange spans ≈20µs• Better than 1cm absolute accuracy with 2ppm timebase

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Slide 17

TX: Design Parameters (1/2) • Motivation:

– Flexible waveform – Still simple– Compatible with multiple coherent/non-coherent receiver schemes

• Preferred limitations (compliant with FCC)– Bandwidth for:

• (+) High transmit power• (+) High time resolution• (-) Low power, low complexity• (-) Less stringent requirements on blockers filtering

Signal BW of 1-2 GHz in 3-5 GHz bandSignal BW of 700 MHz in 0 to 960 MHz band (low band)

– Pulse Repetition Period for:• (+) High « single pulse » detectability at the receiver• (+) No inter-channel interference due to channel delay spread• (-) Transmitter peak power compatible with technology• (-) Shorter acquisition time

PRP Between 125ns and 2 µs

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 18

TX: Design Parameters (2/2)

•Nominal scenario - low-band (X0=250 Kbps):– PRP = 125 ns, 2-level modulation, code length of 31chips per bit: – PHY-SAP payload bit rate (Xo) is 250 kbps

• Preferred limitations (cont’)– Simple modulations:

• Transmitted Reference⇒ At least 1-2 bits/symbol (more for GTR)

– Channelization (« nearly orthogonal » channels):• Coherent schemes: Use of TH codes and/or polarity codes• Non-coherent schemes: Use of TH codes (polarity codes for spectrum smoothing

only)

– TH code length:• (-) Faster acquisition, shorter frame size (synch. phase)• (+) Lower bit-rate, high processing gain ⇒ TH code length from 1 to 16

• Nominal scenario - high-band (X0=250 Kbps):– PRP = 500 ns, 2-level modulation, TH code of length 8:

PHY-SAP payload bit rate (Xo) is 250 kbps

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 19

0 1 2 3 4 5 6 7 8 9 10 11-60

-55

-50

-45

-40m

ean

PS

D [d

Bm

/MH

z]

frequency [GHz]

Max amplitude vs PRP vs Bandwidth - R = 50 Ohms

B = 0.8GHz, Low BandB = 0.5GHzB = 1GHzB = 2 GHzB = 7.5GHz

102 1030

2.5

5

7.5

10

Max

am

plitu

de [V

]

102 103-30

-20

-10

0

10

Pow

er p

eak

[dB

m]

PRP [ns]

Pulse Amplitude and Peak Power vs. PRP

FCC limit : 0 dBm(upper band only)

Example :CMOS 0.13 µm limits

~ 3.3 V

Con

stan

t mea

n po

wer

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 20

Receiver • Optimal Receiver:

Filter matched to channel and pulse waveform for Maximum Ratio CFilter matched to channel and pulse waveform for Maximum Ratio Combining (MRC)ombining (MRC)

2:

:

02 NNoise

EbSignal

=σEb∫

T

s(t)

Example of 2-ary modulation (Symbol duration: T)Matched filter input :

- Signal = r(t)- Noise = n(t), Gaussian, PSD = N0

Matched filter output :- Signal2 = Eb- Noise = Gaussian (µ = 0, σ2 = N0/2)

r(t) = s(t)+n(t)

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 21

«Bit Energy» Recovery

PRP

T = N x PRP

TimeN = TH/polarity code length

Example with N = 3Code is (1 1 -1)

Pulse matched filter : Eb = Ereceived_pulse x N : collects bit energy on a single path

Compound Response matched filter : Eb = Eresponse x N : collects all bit energy

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 22

Coherent Receiver Architecture

LNALNALNA BPFBPF ADCADC BufferBuffer

Pulse MatchedPulse Matched

Estimated CIR

Estimated CIR

∑ Integration / Decision

Integration / Decision

SynchronizationClock Tracking

Thresholds settingChannel Estimation

SynchronizationSynchronizationClock TrackingClock Tracking

Thresholds settingThresholds settingChannel EstimationChannel Estimation

Coefficients

Trig

Threshold

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 23

Pulse MatchedPulse Matched

LNALNALNA

OOK / PPMOOK / PPM

DelayDelayDelay

TRTR

BPFBPF

Modulation Option

SynchroTracking

Thresholds setting

SynchroSynchroTrackingTracking

Thresholds Thresholds settingsetting

DumpLatchDumpDumpLatchLatch

RA

ZR

AZ

DUMPDUMP

ControlledControlledIntegratorIntegrator

ADCADC

Demodulation Demodulation branchbranch

RAZRAZ

TriggerTrigger

Time baseTime baseTime base

THRESHOLDTHRESHOLD

ADCADC

ComparatorComparatorComparator

IntegratorIntegrator

Localization Localization branchbranch

Differentially-Coherent/Non-Coherent Receiver Architecture

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 24

TR-BPSK Non-Coherent Detection• Concept: Transmitted-reference BPSK symbol can be decoded

by a non-coherent detector (like OOK symbol)• Advantages: Differential and non-coherent receiver may coexist;

reference can be used for synch. and threshold estimation• Concept can be generalized to N-ary TR-BPSK

Pulse MatchedPulse Matchedf(t) s(t)

r(t)“0”

“1”“1”

“0”

LNALNALNA

DelayD

DelayDelayDD

BPFBPF

D

NonNon--Coherent DetectorCoherent Detector(Energy Collection)(Energy Collection)

-SynchroTracking

Thresholds setting



Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 25

TR-BPPM Non-Coherent Detection• Concept: Transmitted-reference BPPM symbol can be decoded

by a non-coherent receiver (like OOK symbol)• Advantages: Different receiver schemes may coexist; Reference

pulse can be used for synch. and threshold estimation• Concept can be generalized to N-ary TR-BPPM

Pulse MatchedPulse Matchedf(t) s(t)

r(t)“0”

“1”“1”

“0”

LNALNALNA

Delay(D2 -D1)DelayDelay(D(D22 -DD11))

BPFBPF

D1

NonNon--Coherent DetectorCoherent Detector(Energy Collection)(Energy Collection)

-SynchroTracking

Thresholds setting



D2

DelayD2

DelayDelayDD22

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 26

BER Performance (1/2)

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 2010-5

10-4

10-3

10-2

10-1

Eb/N0

BER

MRC Solution (coherent)Differential SolutionEnergy Collection solution in OOKTransmitted Reference solution

AWGN channel

-3 dB : the « reference » is not in the same PRP !

( )Nerrorbiterrorpacketp −−≥ 11PER = 1% with 32 bytes PSDU BER ~ 10-5 with no channel coding

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 27

BER Performance (2/2)• Comparison of receiver schemes : non coherent for 2PPM and OOK, differentially coherent for TR

0 2 4 6 8 10 12 14 16 18 20 22 24 26

10-6

10-5

10-4

10-3

10-2

10-1

100

Eb / N0

Pe

Analytical Performance Comparison - Ti = 70ns - CM4

OOK (Optimal Treshold)PPM (Disjoint)TR (Delay > CIR length)

Integration Time

CM.15.3a-4

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 28

Integration Time Range impact on BER (for non coherent receiver on PPM)

15 16 17 18 19 20 21 22 23 24 250

10

20

30

40

50

60

70

80

90

100

110

120

130

140PPM - Integration Time Range for Pe = 10-5

Inte

grat

ion

Tim

e Ra

nge

[ns]

Eb/N0 [dB]

single pathCM1CM2CM3CM4

15.3a

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 29

Comparison Matrix for non coherent receivers

OOKOOK PPMPPM TR (and variations)TR (and variations)

Energy EfficiencyEnergy Efficiency½ pulse per bit

+1 pulse per bit

+/-2 pulses per bit (or less)

- (+/-)

Euclidean Euclidean DistanceDistance

1

-sqrt(2)

+/-2

+Required ERequired Ebb/N/N0 0

[dB][dB] 18.9 20.1 22.9

Max Range @ 10 Max Range @ 10 kbps [m] kbps [m] –– α = 3 30 31 29

Synchronization & Synchronization & trackingtracking - +/- +

-SOP robustnessSOP robustness - +

Implementation Implementation challengeschallenges

« Multiplier / quadrator »

+Delay multiplier (or adder)

+/-

Threshold Threshold estimationestimation

Yes

-No

+No (easy for TR OOK)

+

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 30

Link BudgetParameter Mandatory Value Optional Value

Peak Payload bit rate (Rb) 250 kb/s 250 kb/s

Average Tx Power Gain (PT) -10.64 dBm -10.64 dBm

Tx antenna gain (GT) 0 dBi 0 dBi

f’c: (geometric frequency) 3.873 GHz 3.873 GHz

Path Loss @ 1m: L1 = 20log10(4.π.f’c / c) 44.20 dB 44.20 dB

Path Loss @ d m: L2 = 20log10(d) 29.54 dB @ d = 30 m 12.04 dB @ d = 4 m

Rx Antenna Gain (GR) 0 dBi 0 dBi

Rx Power (PR = PT + GT + GR – L1 – L2) -84.38 dBm -66.88 dBm

Average noise power per bit: N = -174 + 10log10(Rb) -120.02 dBm -123.02 dBm

Rx noise figure (NF) 7 dB 7 dB

Average noise power per bit (PN = N + NF) -113.02 dBm -113.02 dBm

Minimum Eb/N0 (S) in 15.3a CM4 22.9 dB 22.9 dB

Implementation Loss (I) 5 dB 5 dB

Link Margin (M = PR - PN – S – I) 0.74 dB 18.24 dB

Proposed Min. Rx Sensitivity Level -85.12 dBm -85.12 dBm

Required Eb/N0 for diff-coherent receiveron TR-BPSK using PRP = 4us, and no channel coding.Remove X dB for coherent receiver, plus 3dB for DBPSK

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 31

Framing

CAP CFP IPBP

Beacon Interval

BP : Beacon PeriodCAP : Contention Access PeriodCFP : Contention Free PeriodIP : Inactive Period (optional)

Superframe Duration

Beacon slot CAP slot CFP slot

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Preamble SFD PSDU = MPDUPHY layer

PPDU (PHY Protocol Data Unit)

PSDU (PHY Service Data Unit)SHR

Bytes 254 1

Frame length

PHR

1

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 32

ThroughputData Frame (32 bytes PSDU) ACK Frame (5 bytes PSDU)

Preamble SFD PSDU = MPDUPHY layer


PSDU (PHY Service Data Unit)SHR

Bytes 324 1

Frame length

PHR

1

Preamble SFD PSDUPHY layer


PSDUSHR

Bytes 54 1

Frame length

PHR

1

Tdata T_ACK Tack IFS

• Numerical example (high-band)• Preamble + SFD + PHR = 6 bytes• Tdata = 1.216 ms• T_ACK = 50 µs (> turn around time requested by 15.4 is 192µs)• Tack = 0.352 ms• IFS = 100µs

⇒ Throughput = 32 bytes/1.718 ms = 149 kb/s⇒ Average data-rate at receiver PHY-SAP in excess of 250 kb/s

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 33

Saving Power• Numerous Power Saving techniques can be achieved by combining advantages

offered at 3 levels:– technology (best if CMOS)– Architecture (flexible schemes provided by the TH pulse modulation)– System level (framing, protocol usage)

• Here are selected techniques used in one of the current realizations (see proof of concept slides)

– Low-duty cycle Episodic transmission/reception• Scheduled wake-up• 80µs RTOS tick

– Ad-hoc networking using multi-hop• Special rapid acquisition codes / algorithm• Matchmaking further deduces acquisition time

– Multi-stage time-of-day clock• Synchronous counter / current mode logic for highest speed stages• Ripple counter / static CMOS for lowest speed stages

– Compute-intensive correlation done in hardware

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 34

Ranging• Motivation :

– Benefit from high time resolution (thanks to signal bandwidth):

• Theoretically: 2GHz provides less than 20cm resolution• Practically: Impairments, low cost/complexity devices should lead

to ~50cm accuracy with simple detection strategies (could bebetter with high resolution techniques)

• Approach :– Use Two Way Ranging between 2 devices with no network

constraint (preferred); no need for time synchronization among nodes

– Use One Way Ranging and TDOA under some network constraints (if supported)

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 35

Two Way Ranging (TWR)To T1

Terminal A TX/RX

Terminal B RX/TX

Terminal B

Request

Prescribed Protocol

Delay and/or Processing

Time

TReplyTOF TOF

Terminal A

( )[ ]cTd

TTTT

AOFAB

AOF

.~~21~

Reply01

=

−−=

TOF Estimation

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 36

Two Way Ranging (TWR)

( ) ( )( )B

BAAAOFAOF

TTT

∆+

∆−∆+∆+=

121~ Reply

Main Limitations / Impact of Clock Drift on Perceived Time

0f0. f∆ Is the frequency offset relative to the nominal ideal frequency

Range estimation is affected by :• Relative clock drift between A and B

• Prescribed response delay

• Clock accuracy in A and B

• Channel response (weak direct path)

∆f/f \ Treply(max error) 192 µs 10 µs

4 ppm 0.23 m 0.01 m

40 ppm 2.30 m 0.12 m

Example using Imm-ACK SIFS of 15.4 and 15.3

Relaxing constraints on clock accuracy is possible by

• Performing fine drift estimation/compensation

• Benefiting from cooperative transactions (estimated clock ratios …)

• Adjusting protocol durations (time stamp…)

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 37

Cooperative Networking• Position location using inexpensive timebases

– Quartz crystal or MEMS oscillator• 2 ppm (10-6) with on-chip software-mediated temperature compensation• Nodes can track each other’s clock frequencies for ppb (10-9) matching

– Absolute position accuracy of entire network is raised to the absolute accuracy of the best oscillator or known distance

– Digital post-correction of actual versus expected arrival time

• Potential for Code & Time Division channelization for a million Localizers per km2

• Multi-hop communication– Defeats 1/Rn received power reduction (n ≥ 3)– Reduces probability of interference

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 38

Time Difference Of Arrival (TDOA) & One Way Ranging (OWR)

To

Anchor 1 RX

Mobile TX

TOF,1

T1

Anchor 2 RX

TOF,2

T2

Anchor 3 RX

TOF,3

T3

Anchor 1

Anchor 2Anchor 3

Mobile

Isochronous

Info T2

Info T3

Info T2

Info T3

TOA EstimationTDOA Estimation

Passive Location

cTdTTT

cTdTTT

.~~~.~~~

23232323

21212121

=⇒−=

=⇒−=

TDOA Estimation

321 ,, TTTTOA Estimation

Isochronous

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 39

Mobile (xm,ym)

Anchor 1 (xA1,yA1)

Anchor 2 (xA2,yA2)

Anchor 3 (xA3,yA3)

Positioning from TDOA

( )

3 anchors with known positions (at least) are

required to find a 2D-position from a couple of TDOAs

( ) ( ) ( )( ) ( ) ( ) ( )2222

31

222232

1133

2233

MAMAMAMA

MAMAMAMA

yyxxyyxxd

yyxxyyxxd

−+−−−+−=

−+−−−+−=

3132~,~ dd

Measurements Estimated Position

MM yx ~,~Specific Positioning Algorithms

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doc.: IEEE 802. 15-05-0011-00-004a

Slide 40

Antenna Practicality• Bandwidth: 3 GHz-10 GHz• Form factor • Omni-directional

y

x

z

7 mm

ground planeØ 80 mm

antenna hatØ 24 mm θ

ϕ

-26

-24

-22

-20

-18

-16

-14

-12

-10

-8

-6

-4

-2

0

2 3 4 5 6 7 8 9 10 11 12

|S11

| (dB

)

frequency (GHz)

M.S.measured

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 41

“Proof of concept” (1)

5 Mbps BPPM 350 ps pulse train

with long scrambling code

UWBANTENNA

DLLCM

Oscilator Generator

x16528 MHz

Flagrst8....

Flagrst1

RX

Controlline

Energycollection

DIGITALCONTROL

LOGIC

DLLPG

-DIGITALLOGIC UWB

PG

TX

Fref33 MHz

BASEBANDDSP

(decision logic)

DETECTIONBIT

DECISION

(digital)

2

( )LNAVGA

GAIN SELECTION

A/DConverter

SWITCH

/2

Non-coherent, Energy Collection Receiver

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 42

Proof of concept (2)• Low-Band Coherent Transceiver Architecture

TransmitterAntennaDriver

TransmitterAntennaDriver

CodeSequenceGenerator

CodeSequenceGenerator

Time-IntegratingCorrelator

A/DConverter

A/DConverter



Real TimeClock

Real TimeClock

Processorand MemoryProcessor

and Memory

CrystalOscillatorCrystal

Oscillator

RFAmplifier

RFAmplifier

ReceiveAntenna

TransmitAntenna

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 43

Proof of Concept (2):Receiver

32 T

ime

32 T

ime --

Inte

grat

ing

Inte

grat

ing

Cor

rela

tors

Cor

rela

tors

PLL

Loo

p Fi

lter

PLL

Loo

p Fi

lter

VG

C A

mp

VG

C A

mp

CodeCodeSequenceSequenceGeneratorsGenerators

LF RTCLF RTC

DA

Cs

DA

Cs

““ Rai

ls” f

or te

stin

g R

ails

” for

test

ing

anal

og c

ircui

tsan

alog

circ

uitsDA

Cs

DA

Cs

Hig

hH

igh --

Freq

uenc

yFr

eque

ncy

Rea

l Tim

e C

lock

Rea

l Tim

e C

lock

Coherent UWB Receiver withmultiple time integrating correlators

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 44

Proof of Concept (2): Transmitter

Del

ayD

elay

Buf

fers

Buf

fers

N-CNN--Channel DriversChannel Drivers

PP--Channel DriversChannel Drivers

UWB Transmitter chip for generating impulse doublets

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 45

Proof of Concept(2) AntennaBaseband impulses (<1GHz) can be effectively radiated from small

(<4 cm) Large Current Radiator (LCR) antenna (FDTD simulation)4cm LCR Source Waveform

-1

0

1

2

3

4

5

6

0 1 2 3 4 5 6 7 8 9 10

ns

Volts

4cm LCR Far-Zone Electric Field

-0.15

-0.10

-0.05

0.00

0.05

0.10

0.15

0 1 2 3 4 5 6 7 8 9 10

ns

Volts

/met

er

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 46

Proof of Concept (2): Antenna• Large Current Radiator

– Preserves impulse shape– Frequency response varies <6dB from

<100MHz to >2.5GHz– Requires low (1Ω) source impedance

• Direct drive from chip• No transmission line

• 6 cm Electric Dipole– 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 (> 1 meter)

Far-Zone Electric Field from 5 v / 1 Ω Gaussian Edge Stimulus

-0.12

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0 1 2 3 4 5ns

Volts

/met

er

4cm Large Current Radiator 6cm Electric Dipole

Relative Antenna Gain with Gaussian Edge Stimulus

-60

-50

-40

-30

-20

-10

0

10

20

0.0 0.5 1.0 1.5 2.0 2.5GHz

dB G

ain

4cm Large Current Radiator 6cm Electric Dipole

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 47

“Proof of concept” (3)

UWB Transmitter400 µm x 400 µm 0.35 µm CMOS

UWB Transceiver<10 mm2

0.35 µm SiGe Bi-CMOS

UWB-IR BPPM Non-Coherent Transceiver Implementation

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 48

“Proof of concept” (4)RF front end chipset in CMOS 0.13µm, 1.2V

20 GHz digitizer for UWB

20 GHz DLL for UWB

3-5 GHz LNAChip and layout

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 49

Conclusions• Proposal based upon UWB impulse radio

– High time resolution suitable for precise ranging using TOA– Modulation:

• Pulse-shape independent• Robust under SOP operation• Facilitates synchronization/tracking• Supports multiple coherent/non-coherent RX architectures

• System tradeoffs– Modulation optimized for several aspects (requirements, performances, flexibility,

technology)– Trade-off complexity/performance RX

• Flexible implementation of the receiver– Coherent, differential, non-coherent (energy collection)– Analogue, digital

• Fits with multiple technologies– Easy implementation in CMOS– Very low power solution (technology, architecture, system level)

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 50

Backup Slides

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 51

GTR-BPSK Differentially-Coherent Receiver

DelayD1

DelayDelayDD11

FilterFilter DelayD2

DelayDelayDD22

DelayD3

DelayDelayDD33

SynchroTracking

Thresholds setting



I&DI&DI&D

I&DI&DI&D

I&DI&DI&D

Tapped Delay Line

d1

d2

d3

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 52

GTR-BPSK Non-Coherent Detection

DelayD1

DelayDelayDD11

FilterFilter DelayD2

DelayDelayDD22

DelayD3

DelayDelayDD33

SynchroTracking

Thresholds setting



NCD1NCDNCD11

NCD2NCDNCD22

NCD3NCDNCD33

Tapped Delay Line

r1

-

-

-

r2

r3

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 53

Non-Coherent Detector (NCD)

d(t)( )2⋅ LPFLPFLPF ThresholdThresholdThreshold

s(t)

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 54

Delay Estimation With Energy Collection (1/2)

• Uses banks of integrators to locate symbol within confined window• Integrators provide course synchronisation• Two approaches have been considered to delay estimation:

– Approach #1 - TOA estimation is based on threshold technique. • First integrator output that crosses the threshold is used for TOA estimation.

– Approach #2 - the TOA is estimated by taking the peak value between the integrator outputs

• Improvements on basic performance possible

• Approach #1 trade-off is false alarm probability versus missed signal• Approach #2 reduces the false alarm probability but increases the

probability of a positive TOA error due to the channel characteristics

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 55

Delay Estimation With Energy Collection (2/2)

• TOA estimation error (normalised)

(1) (2)

• Example: 20 integrators spanning 100 ns symbol period (Tacc 5 ns) in CM1 (1) without and (2) with peak method

Jan. 2005


doc.: IEEE 802. 15-05-0011-00-004a

Slide 56

Ranging Performance for Non-Coherent Receiver

0 038

9

953

0 0

962

0 040 24

511

415

10

950

0 023 30

440 424

83

894

10 0

6444

259

439

184

742

0

100

200

300

400

500

600

700

800

900

1000

packet error rangingfailure

error < -1m -1m < error <-0.15m

-0.15m <error < 0.15m

0.15m < error< 1m

1m < error |error| < 1m

CM 0CM 1CM 2CM 3

One way ranging "error"15.3a channel modelsSNR = sensitivity in CM1 and CM2 + 3dBResolution = 1ns = 30 cm1000 channel realisations per modelNon coherent receiver on PPM modulation

(CM 0 is AWGN channel)

project: ieee p802.15 working group for wireless...

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