Real Human Body Measurements, Model, and Simulations of a 2.45 GHz Wireless Body Area Network Communication Channel E. Reusens, W. Joseph, Member, IEEE, G. Vermeeren, D. Kurup, and L. Martens, Member, IEEE Abstract—In this paper, the propagation channel between two half-wavelength dipoles at 2.45 GHz, placed near a human body is studied. Measurements are performed on a real human, considering different parts of the body separately. The measurement results are compared with FDTD simulations, using an anatomically correct model of the human body. Channel characteristics are extracted from the measurement and simulation data. A semi-empirical path loss model is proposed and lognormal behaviour is validated. I. INTRODUCTION Wireless Body Area Network (WBAN) consists of several small devices (e.g. sensors and actuators) close to, attached to or implanted into the human body, which communicate wirelessly and form a network that typically expands over the whole body of a person. A WBAN offers many promising, new applications in medicine, sports, and multimedia, all of which make advantage of the unconstrained freedom of movement a WBAN offers. The characterization of the physical network layer is an important step in the development of a WBAN. Propagation near flat, homogeneous and layered phantoms has been investigated in [1]-[2]. [3]-[6] characterize the wireless on- body channel for specific configurations of the transmitter and receiver. In this paper, measurements are performed on a real human using two half-wavelength dipoles, considering different parts of the human body separately. In total, 583 antenna positions are considered, enabling a statistical approach. The on-body channel is characterized for the arm, back, torso, and leg. Path loss models are determined and the lognormal behavior is validated. The measurement results are compared with FDTD (Finite-Difference Time- Domain) simulations in SEMCADX, using an anatomically correct model of the human body. This research can be used by manufacturers to validate the performance of WBAN systems using well specified setups. Another application of the models of this paper is cross-layer design. In order to investigate if single-hop networks are possible to realize or if multi-hop is required, higher-layer design (protocol level) can be performed using our physical-layer models. Manuscript received February 1, 2008. This research is partly funded by the Fund for Scientific Research - Flanders (FWO-V, Belgium) project G.0531.05. W. Joseph is a Post-Doctoral Fellow of the FWO-V (Research Foundation Flanders). The authors would like to thank Toon Depessemier for helping us during the measurement campaign. The authors are with Ghent University / IBBT, Dept. of Information Technology, G. Crommenlaan 8 box 201, B-9050 Ghent, Belgium (e-mail: Wout.Joseph@intec.ugent.be). The outline of this paper is as follows. Section II describes the measurement and simulation setup, and the configurations that are investigated. In Section III, the on- body channel characteristics are examined, and path loss models are derived from the measurements and simulations. Finally, Section IV summarizes the conclusions. II. MEASUREMENT AND SIMULATION SETUP A. Configuration Two identical half-wavelength dipoles at 2.45 GHz, with a length of 5.7 cm and a diameter of 1 mm, are placed at various positions on the human body (see Fig. 1 where Tx and Rx represent the transmitting and receiving antenna, respectively). The dipoles are placed parallel to each other and are lined up for maximal power transfer. The propagation channel characteristics depend strongly on the height of the antenna above the body [1]. In this paper the separation between body and antennas is 5 mm, because this is a realistic height for WBANs. We examine the wireless on-body channel along the arm, back, torso, and leg. Fig. 1 Configuration: antenna positions on the body. For the measurements along the arm, Tx is placed on the wrist and Rx is moved in steps of 1 cm towards the shoulder. The distance between the antennas varies from 5 cm up to 40 cm. A total of 214 measurements are performed on two persons: a man (height 1.73 m, weight 73 kg) and a woman (height 1.69 m, weight 61 kg), both 23 years old. The measurements on the back and the torso are performed on a male person lying on a table. Tx is placed at approximately shoulder height at one of three different positions (left, middle, or right, see Fig. 1). Rx is placed A