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1
S C I E N C E P A S S I O N T E C H N O L O G Y
u www.tugraz.at
High-accuracy Positioning in Multipath Channels:
Location-Awareness for 5G Networks and Beyond
29-5-2018, COST IRACON, Cartagena,
Spain
Klaus Witrisal
Joint work with my PhD students / Post Docs:
Paul Meissner, Erik Leitinger, Stefan Grebien, Josef Kulmer, Thomas Wilding,
Anh Hong Nguyen, Michael Rath
2 2 High-accuracy Positioning: Applications
Introduction
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
Manufacturing Retail
Logistics Smart Labeling Assisted Living
Autonomous Driving
Requirements:
Accuracy (5 – 20 cm);
Reliability (90 – 100%)
Challenges:
Heterogeneity: scenarios and
technologies; multipath
Objectives:
Positioning and navigation;
activity recognition; control
Fotos: Ubisense, SES-magotag GmbH, brighamyen.com, Witrisal, Jungheinrich, slashgear.com
3 3 Location-aware Communications: many system parameters depend on the position
Introduction
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Di Taranto et al., “Location-Aware Communications for 5G Networks”, IEEE Signal Proc. Mag., Nov. 2014]
4 4 Outline
Introduction
Ranging and positioning in dense multipath
Bandwidth scaling (1) and MIMO gain (2)
Multipath-assisted indoor positioning (3)
Theory and modeling
Algorithms
Cognitive positioning and location awareness (4)
Conclusions
High-accuracy Positioning in Dense Multipath Channels
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
Four ingredients for high-accuracy positioning
and location awareness
5 5 An experiment: transmission of a (UWB) pulse in an indoor environment
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
6 6 Time-of-flight Ranging
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
7 7 Time-of-flight Ranging: Problem: Multipath Radio Propagation
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
8 8
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
Time-of-flight Ranging: Problem: Multipath Radio Propagation
9 9
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
Time-of-flight Ranging: Problem: Multipath Radio Propagation
10 10 Signal Processing for Robust Ranging (& Pos.)
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
Experiment
Modelling
Performance limits
Algorithms
Improvements
11 11 Modeling the dense multipath to derive the theoretical limit (CRLB)
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
Received signal from anchor j located at p(j): (s(t): TX signal)
[Witrisal et al. "Bandwidth Scaling and Diversity Gain for Ranging and Positioning
in Dense Multipath Channels," IEEE Wireless Commun. Lett., 2016.]
12 12 CRLB for ranging (in dense multipath (DM)) AWGN only
CRLB
mean-squared bandwidth
signal-to-noise ratio
CRLB scales with squared
bandwidth and SNR
AWGN + dense multipath
CRLB whitening
BW gain
reduced SNR due to DM
cost for nuissance estim.
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Witrisal et al. "Bandwidth Scaling and Diversity Gain for Ranging and Positioning
in Dense Multipath Channels," IEEE Wireless Commun. Lett., 2016.]
13 13 Ranging error bound and SINR shows the bandwidth scaling
Parameters
SNR = 30 dB
KLOS = 1 … LOS-to-DM-power
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Witrisal et al. "Bandwidth Scaling and Diversity Gain for Ranging and Positioning
in Dense Multipath Channels," IEEE Wireless Commun. Lett., 2016.]
bandwidth
detectability:
ML estimator
CRLB in
multipath
CRLB
in AWGN
14 14
anchor 3
anchor 1
agent: p anchor 2
Position error bound Fisher information
Position error variance (CRLB):
J independent measurements:
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
ranging direction matrix
geometry of nodes
[Y. Shen and M. Win, "Fundamental Limits of Wideband Localization; Part I: A General Framework,"
IEEE Trans. Inform. Theory, vol. 56, no. 10, pp. 4956-4980, October 2010. ]
15 15
anchor 1
agent: p anchor 2
(2) Diversity (MIMO) gain Fisher information
J independent measurements:
Diversity combining (SIMO,
MISO, MIMO):
approx. equal geometries
effective SINRs are added up:
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Witrisal et al. "Bandwidth Scaling and Diversity Gain for Ranging and Positioning
in Dense Multipath Channels," IEEE Wireless Commun. Lett., 2016.]
SINR gain
2 x 2 MIMO
gain = 4-fold;
STDV halved
16 16 Multi-antenna configurations – diversity (MIMO) gain for ranging
4 x 4 MIMO vs. SISO (1 x 1)
16 independent measm.
16-fold SINR (LOS-to-
multipath-power-ratio):
theoretical limit reduced by
factor 4
detection probability
strongly improved
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Witrisal et al. "Bandwidth Scaling and Diversity Gain for Ranging and Positioning
in Dense Multipath Channels," IEEE Wireless Commun. Lett., 2016.]
SISO ~ 1/100
1m
10cm
1cm 1/4
100MHz
17 17 CRLB for angle estimation (phased array) AWGN only
CRLB for AoA
squared effective aperture
signal-to-noise ratio
CRLB scales with fc (carrier),
squared aperture and SNR
AWGN + dense multipath
CRLB in DM
reduced SNR due to DM
multipath interference
limits the performance
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [T. Wilding, et al., "AoA and ToA accuracy for antenna arrays
in dense multipath channels," in ICL-GNSS, June 2018.]
18 18
2 antenna elements
16 antenna elements
Multi-antenna configurations – diversity gain for angle estimation in dense multipath
CRLB for AoA
uniform linear array (ULA)
bandwidth scales SINR
matched filter diverges
from CRLB
minimum SINR needed
for maximum likelihood
16-element array
> 20-fold aperture
16-fold SINR
detectability strongly
improved
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [T. Wilding, et al., "AoA and ToA accuracy for antenna arrays
in dense multipath channels," in ICL-GNSS, June 2018.]
19 19 Application to RFID – experimental validation
Wideband/UWB RFID Readers:
UWB for ranging
DSSS signal (@ 50 MHz) for ranging (TU Vienna, Arthaber)
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Arthaber, Faseth, Galler, Communications Letters 2015]
[Arnitz, Muehlmann, Witrisal; Electronics Letters 2010]
[Hinteregger et al., IEEE RFID 2016]
20 20 Position error bound and MIMO gain: applied to multistatic RFID positioning
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
1 range 1 range
1 TRX 1 TRX 1 TRX 1 TRX
1 bi
1 TX; 1 RX 1 TX; 1 RX
2 bistatic 1 range 1 range 4 range 4 range
2 TX, 2 RX 2 TX, 2 RX
8 bistatic
Three configurations are compared:
1. Each reader has:
1 antenna for TX and RX (1 TRX)
yielding 2 range measurements
2. Each reader has:
separated TX/RX antennas
yielding 2 range + 2 bistatic meas.
3. Each reader has
2 pairs of separated TX/RX ant.
yielding 8 independent range plus
8 independent bistatic measurem.
[Hinteregger, Witrisal, et al., "MIMO Gain and Bandwidth Scaling for RFID Positioning in
Dense Multipath Channels," in 2016 IEEE Intern. Conf. on RFID, 2016. ]
21 21 Position error bound and MIMO gain: applied to multistatic RFID positioning
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
Three configurations are compared:
1. Each reader has:
1 antenna for TX and RX (1 TRX)
yielding 2 range measurements
2. Each reader has:
separated TX/RX antennas
yielding 2 range + 2 bistatic m.
3. Each reader has
2 pairs of separated TX/RX ant.
yielding 8 independent range plus
8 independent bistatic measurem.
[Hinteregger, Witrisal, et al., "MIMO Gain and Bandwidth Scaling for RFID Positioning in
Dense Multipath Channels," in 2016 IEEE Intern. Conf. on RFID, 2016. ]
22 22 Integration Measurement Campaign
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
3 Campaigns
•TU Graz Demoroom
•Detego – Semi-industrial hall
•TU Wien Laboratory
23 23 Integration Measurement Campaign - Results
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
TU Graz – Maximum Likelihood
24 24 Integration Measurement Campaign - Results
Ranging and positioning in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
TU Graz – Positioning Accuracy
25 25 Conclusion (1)
High-accuracy positioning in dense multipath requires large
bandwidth and/or multi-antenna systems
5G systems to employ mm-wave and massive MIMO!
Ranging and positioining in dense multipath
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
26 26 Outline
Introduction
Ranging and positioning in dense multipath
Bandwidth scaling (1) and MIMO gain (2)
Multipath-assisted indoor positioning (3)
Theory and modeling
Algorithms
Cognitive positioning and location awareness (4)
Conclusions
High-accuracy Positioning in Dense Multipath Channels
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
27 27 Multipath-assisted Indoor Navigation and Tracking
(MINT) – concept and geometric model
Idea:
exploit range/position
information from reflected
multipath
Benefits:
less anchor nodes;
more redundancy, i.e.
robustness in NLOS;
higher accuracy
Geometric model (GPEM):
virtual anchors (VAs) (mirror
sources)
Multipath-assisted indoor positioning – theory and modeling
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Meissner, Steiner, Witrisal, "UWB Positioning with Virtual Anchors
and Floor Plan Information," in WPNC, Dresden, March 2010.]
28 28 Signal Model (Geometry-based stochastic channel model - GSCM)
Received signal: (s(t): TX signal)
K deterministic multipath components
Anchor (LOS), virtual anchors (NLOS), deterministic scatterers
Diffuse multipath v(t)
PDP
MPCs characterized by
Multipath-assisted indoor positioning – theory and modeling
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
29 29
Position error variance is bounded by
If no “path-overlap” occurs (orthogonal signals from VAs)
effective SINRk determines ranging information intensity
for MPC from k-th virtual anchor
Ranging direction matrix accounts for geometry
Position error bound for MINT (Cramér-Rao lower bound derived from LHF)
Multipath-assisted indoor positioning – theory and modeling
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Leitinger, et al., "Evaluation of Position-related Information in Multipath
Components for Indoor Positioning," IEEE JSAC, 2015.]
30 30 Validation of the signal model – and prediction of the position error bound
Multipath-assisted indoor positioning – theory and modeling
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Meissner, Witrisal, "Analysis of Position-Related Information in Measured UWB Indoor Channels," EUCAP 2012.]
[Meissner, "Multipath-Assisted Indoor Positioning," Ph.D. Thesis, Graz University of Technology, 2014.]
31 31 Tracking algorithms exploiting multipath • (1) data association of multipath ranges and state-space tracking
• (2) ranging uncertainty is estimated from multipath amplitudes
• (3) a SLAM-style algorithm is used to discover new VAs
Multipath-assisted indoor positioning – algorithms
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
GSCM update
GPEM update [Meissner, Witrisal, et al., "UWB for Robust Indoor Tracking: […],” IEEE Wireless Commun. Lett., 2014.]
[Leitinger, Witrisal, et al., "Multipath-assisted Indoor Simultaneous Localization and Mapping,“ ICC Workshops, 2015.]
[Witrisal, et al., "High-Accuracy Localization for Assisted Living,“ IEEE Signal Processing Mag., March 2016.]
data assoc.
32 32 Experimentation employing a lab-grade UWB channel sounder
Validation steps:
GSCM/GPEM-based simulation model measurement-based
analysis channel-sounder-based real-time implementation (2 anchors) (1 anchor)
Multipath-assisted indoor positioning – algorithms
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Meissner, et al, "Real-Time Demonstration System for Multipath-Assisted
Indoor Navigation and Tracking (MINT)," IEEE ICC Workshops 2014. ]
33 33 Online model updates GPEM – environment model
• position and cov. of VAs
GSCM – channel model
• SINR-values of MPCs
Multipath-assisted indoor positioning – algorithms
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
blackboard, anchor 1
left windows, anchor 2
[Leitinger, Witrisal, et al., "Multipath-assisted Indoor Simultaneous Localization and Mapping,“ ICC Workshops, 2015.]
34 34 Tracking performance
Analysis of accuracy and robustness (non-diverging runs)
Channel/environment model awareness yields robustness
Multipath-assisted indoor positioning – algorithms
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Meissner, Witrisal, et al., "UWB for Robust Indoor Tracking: Weighting of Multipath Components
for Efficient Estimation,“ IEEE Wireless Commun. Lett., 2014.]
35 35 Experimentation
Lab-grade UWB channel sounder (IlmSense; > 40 kEUR)
Can it be replaced by low-cost hardware?
DecaWave DW1000 based radio nodes
Multipath-assisted indoor positioning - experimentation
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
Decawave
EVK1000 Sequitur: DW1000 +
Raspberry Pi
Pozyx: DW1000 +
Arduino
[J. Kulmer, et al., "Using DecaWave UWB Transceivers for High-accuracy
Multipath-assisted Indoor Positioning," in IEEE ICC Workshops, May 2017.]
36 36 DecaWave DW1000 – RX Pulse shape obtained from DW1000 chip
Channel 2 (500 MHz) (top); Channel 4 (900 MHz) (bottom) sampled at 1.016 GHz (oversampled for time-domain fig.)
unknown time alignment
Raised-cosine pulse;
duration ~2.4ns
Raised-cosine pulse;
duration ~1.5ns
Multipath-assisted indoor positioning - experimentation
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [J. Kulmer, et al., "Using DecaWave UWB Transceivers for High-accuracy
Multipath-assisted Indoor Positioning," in IEEE ICC Workshops, May 2017.]
37 37 Analysis of Multipath-Components SINR-values in dB; two alignment methods
DW1000 and channel sounder reach similar levels
(difference ~ 1 – 2 dB, consistently)
SINRs: “LOS” is best; “white board” and “window”
still promising for positioning
Multipath-assisted indoor positioning - experimentation
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
DecaWave DW1000 Channel Sounder
[J. Kulmer, et al., "Using DecaWave UWB Transceivers for High-accuracy
Multipath-assisted Indoor Positioning," in IEEE ICC Workshops, May 2017.]
38 38 Approximate ML Positioning
AWGN model (neglect DM)
approximate log likelihood
Monte Carlo sampling
Multipath-assisted indoor positioning - experimentation
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [J. Kulmer, et al., "Using DecaWave UWB Transceivers for High-accuracy
Multipath-assisted Indoor Positioning," in IEEE ICC Workshops, May 2017.]
39 39 Positioning performance at 100 measurement positions; DW 1000
Ch. 4 (900 MHz)
beats Ch. 2 (500
MHz)
Select (virtual)
anchors based on
SINR values
improves
robustness
Multipath-assisted indoor positioning - experimentation
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [J. Kulmer, et al., "Using DecaWave UWB Transceivers for High-accuracy
Multipath-assisted Indoor Positioning," in IEEE ICC Workshops, May 2017.]
40 40 Low-cost dependable UWB positioning: Using adaptable directive antenna
Single-anchor positioning:
Multipath components are
exploited
Challenge:
Very large bandwidth needed
(~ 2 GHz) to separate
multipath components
Solution:
directive antenna; separation
of multipath components in
angular domain
Multipath-assisted indoor positioning - experimentation
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [M. Rath, et al., "Multipath-assisted Indoor Positioning Enabled by
Directional UWB Sector Antennas," in IEEE SPAWC, 2017.]
41 41 Sectorized Antenna: Performance Results
Experiments based on measured signals
One fixed anchor at a1
Agent positon p to be estimated
Bandwidth is 500 MHz
Likelihood function:
Probability of p given the measurement
Sectorized antenna yields clear
solution
CDF of position error:
Accuracy (60 cm 25 cm @ 90 %)
Robustness (55 % 90 % @ 25 cm)
Outliers (10 % > 0.6 m 0 %)
Multipath-assisted indoor positioning - experimentation
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
conventional antenna sectorized antenna
[M. Rath, et al., "Multipath-assisted Indoor Positioning Enabled by
Directional UWB Sector Antennas," in IEEE SPAWC, 2017.]
42 42 Maximum-Likelihood Positioning – using a single mm-wave access point
accurate estimation of multipath delays high position accuracy
7 x 7 array at the anchor (massive MIMO)
AoA resolution: multimodality is reduced
Multipath-assisted indoor positioning – algorithms
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal [Witrisal, et al., "High-Accuracy Localization for Assisted Living,“ IEEE Signal Processing Mag., March 2016.]
43 43 Conclusions (2)
A multipath-assisted indoor positioning system relies on models
of geometry and channel characteristics (environment model)
benefits from location awareness, raising robustness
yields location awareness to the underlying communications
system (predictability of PHY-layer performance indicators)
A single access point can support high-accuracy positioning in
UWB, 5G networks, etc.
large bandwidth and smart antenna yield delay and angle
resolution of MPCs
Multipath-assisted indoor positioning
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
44 44 Outline
Introduction
Ranging and positioning in dense multipath
Bandwidth scaling (1) and MIMO gain (2)
Multipath-assisted indoor positioning (3)
Theory and modeling
Algorithms
Cognitive positioning and location awareness (4)
Conclusions
High-accuracy Positioning in Dense Multipath Channels
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
45 45 Cognitive dynamic system – an engineering view inspired by cognitive neuroscience
Perception-action cycle (PAC)
sensed environment in a closed
loop control of sensing
Cognitive perceptor
extracts and separates relevant
information (memory, attention)
Cognitive controller
act on the environment to
maximize information gain
Probabilistic reasoning
mediates reciprocal coupling
Hierarchical structure
different abstraction layers
Cognitive positioning and location awareness
26-4-2018
Klaus Witrisal [Haykin and Fuster, Proceedings of the IEEE, 2014.]
[Leitinger, “Cognitive Indoor Positioning and Tracking using Multipath Channel Information,“ Ph.D. Thesis, TU Graz, 2016.]
46 46 Conclusions Large bandwidth / multiple
antennas
yields high accuracy
Exploiting multipath
yields high robustness
Cognitive positioning
to yield high efficiency, low
latency, etc.
foreseen evolution of wireless
networks
5G: mm-wave, massive MIMO
is becoming available (e.g.) with
5G mm-wave systems
environment model
mission critical positioning
massive RFID tag populations
full location awareness
High-accuracy Positioning in Dense Multipath Channels
29-5-2018, COST IRACON, Cartagena, Spain
Klaus Witrisal
Time has come for high-accuracy positioning, given current
technology trends
Location awareness is a way of the future for communications
and positioning in 5G and beyond