International audienceThe first analytical model of Body Area Network channels is presented. The formulation includes the body morphology and the characteristics of the human tissues. The studied transmission paths are along curved parts like the waist or the head. The model is derived from the diffraction theory describing the attenuation of creeping waves along a circular path on a lossy dielectric surface. The model is validated by measurements performed with Planar Inverted-F Antennas on human subjects

The first results achieved in the French ANR (National Research Agency) project BANET (Body Area NEtwork and Technologies) are presented (Part I). This project mainly deals with the antenna design in the context of Body Area Networks applications and channel characterization. General conclusions are drawn on the body impact on the antenna performance for onon and in-on communications (Medical Implant Communication Systems). Narrow-band and ultra-wideband contexts are addressed both numerically and experimentally, and it is shown that design questions are significantly different for each case, leading to different constraints and guidelines. For narrow-band antennas, an alternative and original approach of desensitization using ferrite sheets is proposed and compared to classical techniques based on ground-plane screening. The characterization of numerical phantoms is also analyzed with narrow-band canonical antennas. For the specific on-on scenario, morphologies and electrical properties of the human tissues are also included in the topics of interest. For ultra-wideband antennas, focus is put on planar balanced designs, notably to reduce harmful "cable effects" occurring during the antenna characterization or the channel sounding. For both types of antennas, the main parameter under study is the distance to the body, which has a significant influence.

Reduction of specific absorption rate (SAR) has now become a buzz word because of the growing health concerns over microwave exposure. Ferrites are found to be effective in diminishing electromagnetic influence. In this reported work, flexible polymeric ferrite sheets are characterised on the basis of their shielding efficiencies. SAR measurements are carried out with a planar wearable antenna and polymeric ferrite shielding to confirm its competence.

The first results achieved in the French ANR (National Research Agency) project BANET (Body Area NEtwork and Technologies) concerning the channel characterization and modeling aspects of Body Area Networks (BANs) are presented (part II). A scenario-based approach is used to determine the BAN statistical behavior, trends, and eventually models, from numerous measurement campaigns. Measurement setups are carefully described in the UWB context. The numerous sources of variability of the channel are addressed. A particular focus is put on the timevariant channel, showing notably that it is the main cause of the slow fading variance. Issues related to the data processing and the measurement uncertainties are also described.

The goal of this paper is to study the feasibility of making intelligent antenna selection decision in IEEE 802.15.4 Wireless Sensor Networks (WSNs). This study provides us the basis to design and implement software defined intelligent antenna switching capability to wireless sensor nodes based on Received Signal Strength Indicator (RSSI) link quality metric. First, we discuss the results of our newly designed radio module (Inverted-F Antenna) for 2.4 GHz bandwidth (WSNs). Second, we propose an intelligent antenna selection strategy to exploit antenna diversity. Third, we propose the prototype of our diversity antenna for the TelosB mote and the intelligent switch design. Finally, we compare the performance of the built-in TelosB antenna with our proposed external antenna in both laboratory and realistic environments. Experimental results confirm the gain of 6 to 10 dB of the proposed radio module over the built-in radio module of the TelosB motes.