project: ieee p802.15 working group for wireless...
TRANSCRIPT
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
Jan. 2005
CWC/AETHERWIRE/CEA-LETI/STM
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
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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
Jan. 2005
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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
Jan. 2005
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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
Jan. 2005
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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
Jan. 2005
CWC/AETHERWIRE/CEA-LETI/STM
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
Jan. 2005
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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
Jan. 2005
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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
Jan. 2005
CWC/AETHERWIRE/CEA-LETI/STM
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
Jan. 2005
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doc.: IEEE 802. 15-05-0011-00-004a
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
Jan. 2005
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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
Jan. 2005
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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
Jan. 2005
CWC/AETHERWIRE/CEA-LETI/STM
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)
Jan. 2005
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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
Jan. 2005
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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
Jan. 2005
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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
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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
SynchroSynchroTrackingTracking
Thresholds Thresholds settingsetting
Jan. 2005
CWC/AETHERWIRE/CEA-LETI/STM
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
SynchroSynchroTrackingTracking
Thresholds Thresholds settingsetting
D2
DelayD2
DelayDelayDD22
Jan. 2005
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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
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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
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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
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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)
+
Jan. 2005
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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
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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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Slide 32
ThroughputData Frame (32 bytes PSDU) ACK Frame (5 bytes PSDU)
Preamble SFD PSDU = MPDUPHY layer
PPDU (PHY Protocol Data Unit)
PSDU (PHY Service Data Unit)SHR
Bytes 324 1
Frame length
PHR
1
Preamble SFD PSDUPHY layer
PPDU (PHY Protocol Data Unit)
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
Jan. 2005
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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
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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)
Jan. 2005
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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
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CWC/AETHERWIRE/CEA-LETI/STM
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…)
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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
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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
Jan. 2005
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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
Jan. 2005
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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
CWC/AETHERWIRE/CEA-LETI/STM
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
CWC/AETHERWIRE/CEA-LETI/STM
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
Time-IntegratingCorrelator
Time-IntegratingCorrelator
Real TimeClock
Real TimeClock
Processorand MemoryProcessor
and Memory
CrystalOscillatorCrystal
Oscillator
RFAmplifier
RFAmplifier
ReceiveAntenna
TransmitAntenna
Jan. 2005
CWC/AETHERWIRE/CEA-LETI/STM
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
CWC/AETHERWIRE/CEA-LETI/STM
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
CWC/AETHERWIRE/CEA-LETI/STM
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
CWC/AETHERWIRE/CEA-LETI/STM
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
CWC/AETHERWIRE/CEA-LETI/STM
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
CWC/AETHERWIRE/CEA-LETI/STM
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
CWC/AETHERWIRE/CEA-LETI/STM
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
CWC/AETHERWIRE/CEA-LETI/STM
doc.: IEEE 802. 15-05-0011-00-004a
Slide 50
Backup Slides
Jan. 2005
CWC/AETHERWIRE/CEA-LETI/STM
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
SynchroSynchroTrackingTracking
Thresholds Thresholds settingsetting
I&DI&DI&D
I&DI&DI&D
I&DI&DI&D
Tapped Delay Line
d1
d2
d3
Jan. 2005
CWC/AETHERWIRE/CEA-LETI/STM
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
SynchroSynchroTrackingTracking
Thresholds Thresholds settingsetting
NCD1NCDNCD11
NCD2NCDNCD22
NCD3NCDNCD33
Tapped Delay Line
r1
-
-
-
r2
r3
Jan. 2005
CWC/AETHERWIRE/CEA-LETI/STM
doc.: IEEE 802. 15-05-0011-00-004a
Slide 53
Non-Coherent Detector (NCD)
d(t)( )2⋅ LPFLPFLPF ThresholdThresholdThreshold
s(t)
Jan. 2005
CWC/AETHERWIRE/CEA-LETI/STM
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
CWC/AETHERWIRE/CEA-LETI/STM
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
CWC/AETHERWIRE/CEA-LETI/STM
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)