master's degree - giuseppe papa

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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


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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]:


[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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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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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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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


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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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Experimental distribution – Rician K Factor

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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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Experimental distribution – Coherence Bandwidth B09

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[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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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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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


master's degree - giuseppe papa

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