WBAN Channel Characteristics Between Capsule Endoscope and Receiving Directive UWB On-Body Antennas

Abstract

This paper presents a study on the ultra wideband (UWB) radio channel characteristics between a capsule endoscope and a directive on-body antenna in different parts of the small intestine. The study is conducted using a finite integration technique (FIT) based electromagnetic simulation software CST Studio Suite and four of its anatomical voxel models. The capsule endoscope model is set inside different areas of the small intestine of the voxel models. A recently published directive on-body antenna designed for in-body communications is used in the evaluations. The obtained frequency and time domain channel characteristics are compared with previously published results with another directive on-body antenna designed for capsule endoscopy communications. Power flow presentations are used to understand differences obtained with two on-body antennas. Different rotation angles of the capsule are also considered in this study. It is found that channel characteristics vary remarkably depending on the antenna location in the small intestine and location of the on-body antenna. Thus, the on-body antennas should be located carefully to ensure coverage over the whole intestine area. Path loss does not only depend on the distance between a capsule and the on-body antenna but also on the tissues between the capsule and on-body antennas. Obviously, the antenna patterns have clear impact on the received signal's strength. Furthermore, orientation of the capsule affects also strongly impact when linearly polarized antennas are used. INDEX TERMS Abdominal monitoring, capsule endoscopy, directive antenna, ultrawide band, wireless body area networks.

Wireless Body Sensor Communication Systems Based on UWB and IBC Technologies: State-of-the-Art and Open Challenges

“…The second type is in-body (IB) sensors, implanted inside a human body, such as wireless capsule endoscopy, pacemakers, etc. [ 30 , 44 ]. Finally, the third type is off-body (OFF) sensors, placed in the vicinity of the human body.…”

“…During the measurement the transmitted signal power and relative position of transmitter and receiver units do not change over time. Furthermore, the UWB communications are also used for implantable sensors, for example, wireless capsule endoscopy [ 29 , 30 , 31 , 88 , 89 ].…”

“…The most frequent application of UWB technology is vital signs monitoring, i.e., respiration rate (RR) and heart rate (HR) [ 12 , 19 , 25 , 78 , 79 , 82 , 101 ]. The most recent research focus on wireless in-body to on-body UWB communication, i.e., capsule endoscopy and tumor detection [ 28 , 29 , 30 , 31 , 88 , 89 ]. However, there is an increasing tendency that UWB technology, in addition to the sensing part, could be also used as a communication interface, thus meaning that only one sensor node is necessary for providing information about the human health status and for communication with an external base station.…”

“…Recent research on UWB technology as a communication interface in WBAN systems, with an emphasis on in-body to on-body systems, is shown in Table 2 . As presented in Table 2 , there is an increasing number of studies of UWB applications in wireless capsule endoscopy [ 9 , 30 , 88 , 105 , 106 ] and implanted devices in general [ 3 , 107 ]. Due to its characteristics, UWB is suitable for implanted applications since it enables low power transmission and small physical dimension.…”

“…Such characteristics make them available in the market for commercial applications at low price. Lately, there has been a growing interest in research of applications of UWB systems in the health sector, e.g., for vital signs monitoring [ 11 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ], breast tumor detection [ 10 , 26 , 27 , 28 ], and for the wireless capsule endoscopy [ 9 , 18 , 29 , 30 , 31 ]. Besides the communication interface, UWB can be used as a radar in remote sensing and imaging techniques [ 19 , 32 , 33 , 34 ].…”