Position Estimation Method of Medical Implanted Devices Using Estimation of Propagation Velocity inside Human Body

Makoto KAWASAKI  Ryuji KOHNO  

IEICE TRANSACTIONS on Communications   Vol.E92-B   No.2   pp.403-409
Publication Date: 2009/02/01
Online ISSN: 1745-1345
DOI: 10.1587/transcom.E92.B.403
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Section on Medical Information and Communications Technologies)
medical implanted device,  position estimation,  inside human body,  ultra wideband,  propagation velocity,  

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Wireless communication devices in the field of medical implant, such as cardiac pacemakers and capsule endoscopes, have been studied and developed to improve healthcare systems. Especially it is very important to know the range and position of each device because it will contribute to an optimization of the transmission power. We adopt the time-based approach of position estimation using ultra wideband signals. However, the propagation velocity inside the human body differs in each tissue and each frequency. Furthermore, the human body is formed of various tissues with complex structures. For this reason, propagation velocity is different at a different point inside human body and the received signal so distorted through the channel inside human body. In this paper, we apply an adaptive template synthesis method in multipath channel for calculate the propagation time accurately based on the output of the correlator between the transmitter and the receiver. Furthermore, we propose a position estimation method using an estimation of the propagation velocity inside the human body. In addition, we show by computer simulation that the proposal method can perform accurate positioning with a size of medical implanted devices such as a medicine capsule.