Communication reliability and energy efficiency are important issues that have to be carefully considered in WBAN design. Due to the large path loss variation of the WBAN channel, transmission power control, which adaptively adjusts the radio transmit power to suit the channel condition, is considered in this paper. Human motion is one of the dominant factors that affect the channel characteristics in WBAN. Therefore, this paper introduces motion-aware temporal correlation model-based transmission power control that combines human motion classification and transmission power control to provide an effective approach to realizing reliable and energy-efficient WBAN communication. The human motion classification adopted in this study uses only the received signal strength to identify the human motion; no additional tool is required. The knowledge of human motion is then used to accurately estimate the channel condition and suitably select the transmit power. A performance evaluation shows that the proposed method works well both in the low and high WBAN network loads. Compared to using the fixed Tx power of -5dBm, the proposed method had similar packet loss rate but 20-28 and 27-33 percent lower average energy consumption for the low network traffic and high network traffic cases, respectively.

An implantable WBAN path-loss model for a capsule endoscopy which is used for examining digestive organs, is developed by conducting simulations and experiments. First, we performed FDTD simulations on implant WBAN propagation by using a numerical human model. Second, we performed FDTD simulations on a vessel that represents the human body. Third, we performed experiments using a vessel of the same dimensions as that used in the simulations. On the basis of the results of these simulations and experiments, we proposed the gradient and intercept parameters of the simple path-loss in-body propagation model.

This letter presents a performance evaluation of wireless communications applicable into a capsule endoscope. A numerical model to describe the received signal strength (RSS) radiated from a capsule-sized signal generator is derived through measurements in which a liquid phantom is used that has electrical constants equivalent to human tissue specified by IEC 62209-1. By introducing this model and taking into account the characteristics of its direction pattern of the capsule and propagation distance between the implanted capsule and on-body antenna, a cumulative distribution function (CDF) of the received SNR is evaluated. Then, simulation results related to the error ratio in the wireless channel are obtained. These results show that the frequencies of 611 MHz or lesser would be useful for the capsule endoscope applications from the view point of error rate performance. Further, we show that the use of antenna diversity brings additional gain to this application.

The wave absorber which is formed by arranging cylindrical bars periodically composed of magnetic loss material and metallic bars is proposed for improving ETC environment, and characteristics of reflection loss and shielding effect are analyzed and measured. As a result, the change of various characteristics can be confirmed quantitatively by changing the thickness of magnetic loss material covering around a metallic bar and the pitch interval between bars. Furthermore, it is clarified that reflection loss of -9 dB and shielding effect of -25 dB are obtained at 5.8 GHz when the covering thickness of material is 1.5 mm and the pitch interval is 16.0 mm. Therefore, the wave absorber formed by arranging cylindrical bars that satisfies various characteristics required for the improvement of ETC environment can be realized.

Body Area Network (BAN) is considered as a promising technology in supporting medical and healthcare services by combining with various biological sensors. In this paper, we look at wearable BAN, which provides communication links among sensors on body surface. In order to design a BAN that manages biological information with high efficiency and high reliability, the propagation characteristics of BAN must be thoroughly investigated. As a preliminary effort, we measured the propagation characteristics of BAN at frequency bands of 400 MHz, 600 MHz, 900 MHz and 2400 MHz respectively. Channel models for wearable BAN based on the measurement were derived. Our results show that the channel model can be described by using a path loss model for all frequency bands investigated.

In this paper, a novel approach of a human motion classification system in wireless body area network (WBAN) using received radio signal strength was developed. This method enables us to classify human motions in WBAN using only the radio signal strength during communication without additional tools such as an accelerometer. The proposed human motion classification system has a potential to be used for improving communication quality in WBAN as well as recording daily-life activities for self-awareness tool. To construct the classification system, a numerical simulation was used to generate WBAN propagation channel in various motions at frequency band of 403.5MHz and 2.45GHz. In the classification system, a feature vector representing a characteristic of human motions was computed from time-series received signal levels. The proposed human motion classification using the radio signal strength based on WBAN simulation can classify 3-5 human motions with the accuracy rate of 63.8-95.7 percent, and it can classify the human motions regardless of frequency band. In order to confirm that the human motion classification using radio signal strength can be used in practice, the applicability of the classification system was evaluated by WBAN measurement data.

The wave absorber composed of cylindrical bars arranged periodically and metallic mesh for improving visibility is proposed for ETC, and characteristics of reflectivity and shielding effect are evaluated analytically and experimentally. As a result, reflectivity of -10 dB and shielding effect of -25 dB are obtained for circularly polarized wave when the gap between cylindrical bars is 30 mm. Therefore, realization of proposed wave absorber for installing between ETC lanes can be clarified.

In this paper, we performed six human movement simulation by a commercial software (Poser7). We performed FDTD simulations for body area network propagation with one transmitter and six receivers. Received amplitudes were calculated for every time frame of 1/30 s interval. We also demonstrated a polarization diversity effectiveness for dynamic wearable body area network propagation.