Simplified Human Body Models for Interference Analysis in the Cognitive Radio
for Medical Body Area Networks
Łukasz Januszkiewicz
Lodz University of Technology, Institute of Electronics, Poland
Outline:
• Motivation
• Human Body Models
• Simplified body model
• Interference scenario for CR in WBAN
• Computer simulations
• Conclusions
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Motivation for the resarch on human body models
Measurements and simulation of:
• Wearable antenna
• Wireless Body Area Network
• Wearable wireless sensors
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Human Body Models
Numerical heterogeneous models
• Represent human body tissues which are „sampled” to allow finite difference / finite elements calculation
• Differ with number of tissues and size of elementary cell
• Remcom NMR Hershey
• CST HUGO
• Virtual Population
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Human Body Models
Homogenous models used for measurements
• The shape of body is preserved
• Tissues are simulated with a liquid
• SAM – Specific Anthropomorphic Mannequin
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Simplified body model
Goals
• Simple physical model that can be easily manufactured (geometry and materials which make it easily to reproduce)
• Comparable values of simulated radio signal attenuation and antenna radiation pattern with heterogeneous model
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Simplified body model
• The simplified model consist of cylinders.
• Dimensions approximate NMR Hershey model with 6 standard PVC pipes
• Model geometry optimized with XFdtd®
• PCV pipes filled with tissue-simulant liquid
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Simplified body model
Simplified model was verified by measurements of wearable antenna radiation pattern in 2.4 GHz band
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Medical Body Area Networks
• The MWBAN structure:* – Intra- Wireless Body Area Network (Intra-WBAN)
– Inter- Wireless Body Area Network (Inter-WBAN).
*Chavez-Santiago, R.; Nolan, K.E.; Holland, O.; De Nardis, L.; Ferro, J.M.; Barroca, N.; Borges, L.M.; Velez, F.J.; Goncalves, V.; Balasingham, I., "Cognitive radio for medical body area networks using ultra wideband„, Wireless Communications, IEEE , vol.19, no.4, pp.74,81, August 2012
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Interference scenario for CR in WBAN
• Cognitive radio in Intra-WBAN, radio channel affected by radio wave attenuation in the body
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Interference scenario for CR in WBAN
• Cognitive radio in Inter-WBAN, radio channel affected by on-body antenna radiation pattern
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Computer simulations
• UWB antenna model used for simulations
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The results of the model validation for Intra-WBAN
• Signal attenuation between transmitter located on the front of the torso and the receiver located on the back
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The results of the model validation for Intra-WBAN
• Signal attenuation between transmitter located on the front of the torso and the receiver located on the left arm
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The results of the model validation for Intra-WBAN
• Signal attenuation between transmitter located on the right arm and the receiver located on the left arm
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The results of the model validation for Inter-WBAN
900 MHz 1500 MHz
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• On-body antenna radiation pattern simulated with NMR Hershey model and simplified model
The results of the model validation for Inter-WBAN
• On-body antenna radiation pattern simulated with NMR Hershey model and simplified model
2500 MHz 5000 MHz
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The results of the model validation for Inter-WBAN
• On-body antenna radiation pattern simulated with NMR Hershey model and simplified model
7500 MHz
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Conclusions
• Results obtained with the simplified and the reference model are similar for Intra-WBAN case.
• The signal attenuation simulated for the high attenuation case shows good agreement in several sub-bands (2000MHz ÷ 3000MHz, 4000MHz ÷ 5500MHz)
• In case when different antenna locations are used the results obtained with simplified and reference model are in good agreement.
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Conclusions
• The simplified model gives very similar results to the reference model for Inter-WBAN simulations.
• The radiation patterns of UWB antenna located on the body obtained with those models do not differ much in the frequency range from 900 MHz to 7500 MHz.
• The proposed simplified phantom can be suitable for further experimental investigation and testing of CR wireless body area networks.
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Thank you.
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