On Ultra Wideband Channel Modeling for In-Body Communications A. Khaleghi 1,3 , R.Chávez-Santiago 1,2,3 , X. Liang 1,3 , I. Balasingham 1,2,3 , V. C. M. Leung 4 and T. A. Ramstad 2 1 The Interventional Centre, Oslo University Hospital, Norway 2 Dept. of Electronics and Telecommun., Norwegian University of Science and Technol. (NTNU), Norway 3 Institute of Clinical Medicine, University of Oslo, Norway 4 Dept. of Electrical and Computer Engineering, University of British Columbia (UBC), Canada [Ali.Khaleghi; Raul.Chavez-Santiago]@rr-research.no Abstract—Innovative medical applications such as implant wireless sensors for health monitoring, automatic drug deliverance, etc. can be realized with the use of ultra wideband (UWB) radio technology. Nevertheless, for efficient design of wireless systems operating inside the human body a radio communication channel model is essential. Although a lot of research effort has recently been devoted to the characterization of the on-body UWB radio communication channel, just a few works describing the radio propagation inside the human body have been reported. To address this problem, a computational study of the propagation of UWB signals through human tissues in the 0.1–1 GHz and 1–6 GHz frequency bands is presented in this paper. This is based on numerical simulations using a heterogeneous anatomical model of the human body with frequency dependent tissue material properties. Subsequently, a statistical channel model is introduced for UWB in-body communications in the 1–6 GHz frequency band. The model is provided for two typical depths inside the human chest. This work contributes to the practical design of UWB medical implant communication systems. Keywords-channel model; implant devices; in-body communication; ultra wideband; wave propagation I. INTRODUCTION In modern telemedicine systems the physiological data of patients can be measured with the aid of electronic sensors located on and inside the human body [1]. In most in-body medical applications, the data collected by the implant sensors are transmitted wirelessly to an external unit for processing thereby enhancing the health monitoring, diagnosis, and therapy of the patients. Ultra wideband (UWB) technology can greatly improve the communication between medical implants and external units owing to its inherent low power consumption, high transmission speed, and simple electronics [2]. However, accurate characterization of the propagation channel is necessary for the efficient design of UWB implant wireless communication systems. Considerable research effort has been devoted to characterizing the propagation of radio waves from medical sensor devices; in most cases, however, the proposed path loss models in the literature correspond to narrowband telemedicine applications [3]–[7]. The IEEE 802.15.6 standardization group has issued several propagation models for medical and nonmedical devices [8], both in-body and on-body, for wireless body area networks (WBANs). Nevertheless, the IEEE 802.15.6 in-body channel models characterize narrowband applications whereas the UWB models are valid for on-body communication channels only. To the best of our knowledge, the sole UWB channel model for implant sensor communications that has been reported so far can be found in [9], [10]. In that work, the characterization of an UWB link in the 3.4–4.8 GHz frequency band is presented. The model was developed assuming 20 arbitrary locations of a transmitting implant device inside the human chest between 6– 18 mm depth. This paper aims at furthering the current understanding of the UWB in-body radio communication channel. For that sake, several characteristics of the UWB in-body channel in the 0.1– 1 GHz and 1–6 GHz frequency bands are obtained through numerical simulations. The lower frequencies are attractive for microwave imaging and microwave hyperthermia applications, in which less signal attenuation by living tissues are required to achieve deeper penetration into the body. The higher frequencies are currently being considered for high data rate communications with low power consumption and compact- size devices. In fact, due to international regulations the 3.4–4.8 GHz frequency band has been suggested for implementing UWB implant communication systems in Japan [9] and possibly Europe. Additionally, in this paper the UWB channel characteristics are studied for higher depth inside the human chest well above 100 mm. Finally, a statistical model is introduced for reproducing the channel characteristics without relying on time-consuming numerical simulations. Two typical depths, 20 mm and 80 mm, are modeled. This work was funded by the SAMPOS, WISENET, and MELODY Projects, which are sponsored by the Research Council of Norway. 2010 5th International Symposium on Wireless Pervasive Computing (ISWPC) 978-1-4244-6857-7/10/$26.00 ©2010 IEEE 140