On the Importance of Accurate Utilization of Pathloss Model for Real-Time UWB-based Wireless Capsule Endoscopy Localization and Communication in Individual

Wireless Capsule Endoscopy (WCE) is an advanced medical technology for in-vivo examination of the human body's gastrointestinal tract (GI). The current WCE system comprises an ingestible capsule and an on-body receiver belt in the Medical Implant Communication Services (MICS) band (402-406 MHz). Due to the low power consumption and lesser tissue damage, the Ultra-Wide Band (UWB) is a desirable candidate for positioning and communication in the WCE system. However, the heterogeneous nature of the human body damages the UWB pulses to a greater extent. Hence, the pathloss between the in-body transmitter and the on-body receiver depends on the direct distance between the transmitter and receiver and the tissues between them. This paper studies the signal propagation characteristics of five phantoms: a homogenous muscle, a homogenous fat tissue, a 2-layer heterogenous model of combined fat and muscle tissue, a homogenous colon, and a homogenous small intestine tissue. It supports the fact that the pathloss exponent varies for different tissue types. Hence, the paper insists on the importance of calculating the pathloss exponent, which could vary according to individuals based on factors like Body Mass Index (BMI) or body type, whichever will be appropriate while estimating the position of the capsule endoscope.