Effect of Limb Joints and Limb Movement on Intrabody Communications for Body Area Network Applications

This study investigates the influence of human body movement on signal attenuation during intrabody communication (IBC) for body area network (BAN) applications. While recent studies have shown channel loss measurements for IBC caused by upper limb mobility, these attenuations have yet to be addressed with respect to both upper and lower body limbs in full-body implementations. In this paper, a number of in vivo experiments are conducted to determine the signal attenuation of the body during IBC. Since limb joints control human mobility, the impacts of the elbow and knee joints within the signal path as well as the effects of joint flexion and extension on signal attenuation are examined. The effects of various natural environments on human body signal transmission are taken into account within a high frequency band (0.3-200 MHz). Results show that the presence of limb joints causes high signal attenuation (up to 8.0 dB). Moreover, the signal attenuation decreases with decreasing joint angle; for example, flexion of the elbow joint resulted in 5.0 dB of signal attenuation at 10 MHz. The results indicate that IBC is most likely to be influenced by movement with frequencies below 50 MHz. Above this, signal attenuation is more influenced by the environment and is less dependent on human body composition, indicating that the signal is less coupled through the body.