Towards implantable body sensor networks - Performance of MICS band radio communication in animal tissue

Reliable wireless communication inside the human body is crucial for the design of implantable body sensor networks (IBSN). The tissues in human body are heterogeneous and have dierent conductivity and permitivity, which make the modeling of the wireless channel challenging. The design of upper layers of the network stack requires the physical layer characteristics including the channel model. Currently, there is no unique channel model available for implant communication inside body. Various measurement campaigns of channel characteristics are underway. The channel model characteristics depends on the hardware components used such as antenna and matching circuit as well as the operating frequency, which are not taken into account by the existing channel models for implant communication. Moreover, hardware losses and dierent tissue characteristics have not been taken into account in the link budget of the existing channel models. The approach used in this paper pays special attention to the losses introduced by hardware components of the implant itself and the physical medium. This paper presents characteristics of radio channel using animal tissue. A comparison is made between these measured characteristics and the existing channel characteristics provided by the IEEE 802.15.6 standard. The empirical measurements are used to validate the simulations of the IEEE 802.15.6 model

Implantable body sensor network MAC protocols using wake-up radio - Evaluation in animal tissue

Applications of implantable sensor networks in the health-care industry have increased tremendously over the last decade. There are different types of medium access control (MAC) protocols that are designed for implantable body sensor networks, using different physical layer technologies such as narrow band, ultra wide-band, human body communication, and ultrasound with an innovative low power access technology called wake-up radio (WuR). The WuR operates alongside the main radio either in the same frequency or different frequency, with much lower power and reduced hardware components than main radio. In this article we analyze the impact of WuR on commonly used MAC protocols and evaluate three MAC protocols with WuR using real hardware implanted in animal tissue and compare them with three other MAC protocols without WuR. The hardware implantable board is embedded with a micro-processor, wireless communication unit and is subcutaneously implanted under the skin of the animal tissue. Five nodes with one of them being the central controller connected in star topology are used for evaluation. Energy efficiency, reliability in terms of packet loss ratio, and end-to-end delay for each node are considered as the evaluation criteria