Optimization of energy efficient relay position for galvanic coupled intra-body communication

Implanted medical sensors and actuators within the human body will enable remote data gathering, diagnosis, and the ability to directly control drug delivery actuators. To establish the communication links through the body tissues, we adopt galvanic coupling that uses low frequency electrical signals of weak amplitude. In this paper, we propose a topology management strategy using Weiszfeld algorithm that attempts to minimize the transmission power of the body nodes by reducing the distance from the source nodes to pick-up points or relays that gather and forward the received information. It takes into account the unique propagation model of the electrical signals within the body at various tissue layers, which is completely different from over the air RF. Our algorithm considers separately the constraints of on-skin nodes and the implanted nodes, especially in terms of minimizing the energy for the latter, which cannot be easily retrieved and re-charged. It also considers the difference in specific bandwidth requirements for the applications running within the nodes, by moving relays closer towards the high data rate demanding regions. We show that by optimizing the position of the relay node, the energy consumption can be significantly improved to extend the lifetime of the intra-body network up to several years.