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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
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Università degli Studi di Napoli Federico II
Master’s Degree in Electronics Engineering
Multipath channel characterization aboardAnsaldoBreda ETR 212 Train
Supervisors CandidateProf. Nicola Pasquino Giuseppe PapaIng. Attilio Marrese M61/27
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• Objective: Evaluation of multipath channel influence on indoor signal
propagation aboard train
• Context: Wireless network planning
• Measurements: Channel impulse response capture through Vector
Network Analyzer
Multipath channel characterization aboard SFSM ETR 212
AnsaldoBreda – Firema (WiFi band)
• Data extrapolation from .dat and .csv files, impulse response function and
frequency response function evaluation through MATLAB code
• Multipath channel parameters evaluation: Path Loss, RMS Delay
Spread, Coherence Bandwidth, Rician K-Factor
Data analysis and Multipath Channel parameters
Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
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Multipath Channel
• Multiple Paths
• LOS Propagation (Line Of Sight)
• NLOS Propagation (No Line of Sight)
Impulse response
• Signal repetition
• Random amplitude and phase
• Impulse response dependence on time and
receiver position
Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
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Relative Path Loss
PL is the reduction in power density (attenuation) of an electromagnetic wave as itpropagates through space, expressed in dB. Relative PL as a mean value is [1]:
Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
[1] Rappaport, S. T., “Wireless communications – principles and practice”, Prentice-Hall, 2002
RMS Delay Spread
Delay Spread is defined as the difference between the time of arrival of the earliestsignificant multipath component (typically the LOS component) and the time of arrivalof the latest multipath component. In terms of root mean square:
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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
Coherence Bandwidth
Coherence bandwidth is a statistical measurement representing the approximate
maximum frequency interval over which two frequencies of a signal are likely to
experience comparable or correlated amplitude fading. Heuristically [2]:
Rician K Factor
Rician K Factor is defined as the ratio between the power in the direct path and the
power in scattered paths [1]:
[1] Rappaport, S. T., “Wireless communications – principles and practice”, Prentice-Hall, 2002[2] John G. Proakis, "Digital Communications", McGraw-Hill Book Co., New York, (1989)
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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
Measurement Setup
Train Ansaldo Breda – Firema SFSM ETR 212
Tx Antenna Schwarzbeck BBHA 9120D (Horn)
Rx Antenna Electrometrics EM6865 (Biconical)
VNA #1 Agilent FieldFox N9918A
VNA #2 Rohde&Schwarz ZVL13
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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
Measurement Setup
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Tx Antenna Rx Antenna POL VNA Distance Points
Fixed (0 m) Mobile (1 m – 20 m) VER FieldFox Variable (1 m – 20 m) 171/151
Mobile (0 m – 10 m) Mobile (5 m – 15 m) VER/HOR ZVL13 Fixed(5 m) 89/85
Mobile (0 m – 10 m) Mobile (10 m – 20 m) VER/HOR FieldFox Fixed (10 m) 77/76
Mobile (0 m – 10 m) Mobile (15 m – 25 m) VER/HOR ZVL13 Fixed (15 m) 82/75
Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
Path Loss Exponent
Mean Middle DX Side
95%
Confidence
Interval
[1.61; 1.81] [1.58; 1.88] [1.59; 1.89]
Path Loss
Exponent1.74 1.72 1.77
Buildings(LOS)
Free Space
UrbanContext
Buildings(NLOS)
1.6 ~ 1.8 2 2.7 ~ 3.5 4 ~ 6
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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
Experimental distribution – Rician K Factor
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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
Experimental distribution - RMS Delay Spread
As expected, CDF fit a Normal distribution [3]
[3] P. A. Bello, “Characterization of randomly time-variant linear channels,” IEEE Trans. Commun. Syst., (1963)
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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
Experimental distribution – Coherence Bandwidth B09
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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
[4] Howard, S. and Pahlavan, K., "Autoregressive Modeling of Wide-Band Indoor Radio Propagation,“ IEEE Transactions on Communications, (1992)
Coherence Bandwidth VS RMS Delay Spread [4]
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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
0 1 2 3 4 5 6 7 8
5 m
10 m
15 m
τ [ns]
V
H
Delay Spread VS distance and polarization
• Delay increase as length increases
• Vertical Polarization is more
affected
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Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
Rician K FactorVS distance and polarization
• Rician K Factor increase as length increases
• Vertical Polarization is less affected
Coherence BandwidthVS distance and polarization
0 5 10 15 20 25
5 m
10 m
15 m
BC[MHz]
V
H
8.5 9 9.5 10 10.5
5 m
10 m
15 m
Rician K-Factor [dB]
V
H
• BC decrease as length increases
• Vertical Polarization is less affected
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• Path Loss Exponent suggests a space free propagation law
• Delay Spread and Coherence Bandwidth behaviour depends on distance and
polarization
• Rician K Factor analisys shows a less strong dependence
Conclusions
• Additional measurement campaigns (more points, alternative configurations)
• Mathematical model creation from IRF (parametric – non parametric)
Further developments
Multipath channel characterization aboard AnsaldoBreda ETR 212 Train
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