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Energy is scarce in mobile computing devices including wearable and implantable devices in a wireless body area network. In this paper, an adaptive routing protocol is developed and analyzed which minimizes the energy cost per bit of information by using the channel information to choose the best strategy to route data. In this approach, the source node will switch between direct and relayed communication based on the quality of the link and will use the relay only if the channel quality is below a certain threshold. The mathematical model is then validated through simulations which shows that the adaptive routing strategy can improve energy efficiency significantly compared with existing methods. [ABSTRACT FROM PUBLISHER]

In this paper, a new method for measuring and monitoring human body joint angles, which uses wearable ultrawideband (UWB) transceivers mounted on body segments, is proposed and investigated. The model is based on providing a high ranging accuracy (intersensor distance) between a pair of transceivers placed on the adjacent segments of the joint center of rotation. The measured distance is then used to compute the joint angles based on the law of cosines. The performance of the method was compared with a flexible goniometer by simultaneously measuring joint flexion-extension angles at different angular velocities, ranging between \8 and \90^\circ \/s. The measurement errors were evaluated by the average differences between two sets of data (ranging from \0.8^\circ for slow movement to \2.8^\circ for fast movement), by standard deviation (ranging from \1.2^\circ to \4.2^\circ for various movement speeds) and by the Pearson correlation coefficient (greater than 0.99) which demonstrates the very good performance of the UWB-based approach. The experimental results have shown that the system has sufficient accuracy for clinical applications, such as rehabilitation. [ABSTRACT FROM AUTHOR]

Reliable on-body wireless network design needs to incorporate the natural body movements. However, existing models are static or pseudo-dynamic models. In this work, the lack of a comprehensive channel model for a moving body is addressed. A dynamic radio channel around the human body is statistically analyzed and modeled. Important parameters of the channel are estimated from measured data and compared with the model prediction. Simulations show that the model can predict the parameters of a system working in a dynamic body area network with 92% accuracy. [ABSTRACT FROM PUBLISHER]

The simultaneous tracking of the chest respiratory rate and amplitude of human beings using a low-power ultrawideband (UWB) impulse radio signal is investigated for the application of sleep apnea monitoring. The measurement of respiratory amplitude, in addition to the breathing rate, is crucial for sleep apnea assessment which requires, among other things, the accurate estimation of tidal volume per minute. Backscattered UWB impulse radio signals from a human subject are detected in the time domain to calculate the chest displacements in this paper. Since the pulse disposition in time is linearly related to the chest movement, the amplitude of the chest movement can be extracted accurately without calculation approximations normally used in many of the existing methods. The multipeak detection of the pulse disposition method, instead of using only the single pulse peak detection, is also proposed to improve the accuracy of the calculation further. The experiments are carried out on four human subjects with different sizes and genders. The correlation of the chest movements' amplitude and breathing rate between the simultaneously measured results obtained by our method and by the respiratory chest band is very good. [ABSTRACT FROM AUTHOR]