Connecting the human body - Models, Connections and Competition

Abstract: Capacitive communication using human body as a electrical channel has attracted much attention in the area of personal area networks (PANs) since its introduction by Zimmerman in 1995. The reason being that the personal information and communication appliances are becoming an integral part of our daily lives. The advancement in technology is also helping a great deal in making them interesting,useful and very much affordable. If we interconnect these body-based devices with capacitive communication approach in a manner appropriate to the power, size, cost and functionality, it lessens the burden of supporting a communication channel by existing wired and wireless technologies. More than that, using body as physical communication channel for a PAN device compared to traditional radio transmission seems to have a lot of inherent advantages in terms of power and security etc. But still a lot of feasibility and reliability issues have to be addressed before it is ready for prime time. This promising technology is recently sub-classified into body area networks (BAN) and is currently under discussion in the IEEE 802.15.6 Task Group for addressing the technical requirements to unleash its full potential for BANs. This could play a part in Ericsson's envision of  50 billion connections by 2020. This thesis work is part of the main project to investigate the models, interface and derive requirements on the analog-front-end (AFE) required for the system. Also to suggest a first order model of the AFE that suits this communication system.In this thesis work the human body is modeled along with interfaces and transceiver to reflect the true condition of the system functioning. Various requirements like sensitivity, dynamic range, noise figure and signal-to-noise ratio (SNR) requirements are derived based on the system model. An AFE model based on discrete components is simulated, which was later used for proof of concept. Also a first order AFE model is developed based on the requirements derived. The AFE model is simulated under the assumed interference and noise conditions. The first order requirements for the submodules of the AFE are also derived. Future work and challenges are discussed.