Stéphane Van Roy

Dynamic Channel Modeling for Multi-Sensor Body Area Networks

A channel model for time-variant multi-link wireless body area networks (WBANs) is proposed in this paper, based on an extensive measurement campaign using a multi-port channel sounder. A total of 12 nodes were placed on the body to measure the multi-link channel within the created WBAN. The resulting empirical model takes into account the received power, the link fading statistics, and the link auto- and cross-correlations. The distance dependence of the received power is investigated, and the link fading is modeled by a log-normal distribution. The link autocorrelation function is divided into a decaying component and a sinusoidal component to account for the periodical movement of the limbs caused by walking. The cross-correlation between different links is also shown to be high for a number of specific on-body links. Finally, the model is validated by considering several extraction-independent validation metrics: multi-hop link capacity, level crossing rate (LCR) and average fade duration (AFD). The capacity aims at validating the path-loss and fading model, while the LCR and AFD aim at validating the temporal behavior. For all validation metrics, the model is shown to satisfactorily reproduce the measurements, whereas its limits are pointed out.

Impact of the environment and the topology on the performance of hierarchical body area networks

Personal area networks and, more specifically, body area networks (BANs) are key building blocks of future generation networks and of the Internet of Things as well. In this article, we present a novel analytical framework for network performance analysis of body sensor networks with hierarchical (tree) topologies. This framework takes into account the specificities of the on-body channel modeling and the impact of the surrounding environment. The obtained results clearly highlight the differences between indoor and outdoor scenarios, and provide several insights on BAN design and analysis. In particular, it will be shown that the BAN topology should be selected according to the foreseen medical application and the deployment environment.

Extracting specular-diffuse clusters from MIMO channel measurements

In previous work, it has been observed that the specular and the diffuse component are linked in the angular domain. The idea of adding a diffuse component to each specular cluster has been proposed to model the specular-diffuse channel. In this paper, an approach is proposed to treat the specular and the diffuse measurement data simultaneously, with a clustering algorithm that is applied jointly on the specular and the diffuse component. The output of the clustering algorithm gives clusters that are characterized by their specular and their diffuse component. Measurement results are presented based on double-directional measurements, and parameter values are extracted using the proposed methodology.

Propagation Modeling for UWB Body Area Networks: Power Decay and Multi-Sensor Correlations

Body area networks are now accepted as an important part of 4th generation mobile technology. These networks operating at very low consumption, efficient power radio communications have to be developed. A promising solution is using multi-sensor MIMO (MS-MIMO) ultra-wideband (UWB) systems : each sensor carries one antenna, while the central device uses an antenna array. Thereby, this paper proposes a new analytical channel model for the diffracted waves mechanism. This is derived from the existing IEEE 802.15.4 a standard channel model and innovates with space-time considerations.

Azimuth radiation pattern characterization of omnidirectional antennas near a human body

In this paper, measurements of radiation patterns for an antenna close to the human body at different frequencies are presented. An analytical channel model based on multiple cylinder scattering is proposed. Measurement results and simulations are compared and highlight the impact of body shadowing and arm scattering on the modification of the antenna azimuth radiation pattern.

An ultra-wideband SAGE algorithm for body area networks

Body Area Networks (BANs) consist of a set of bio-sensors placed on the human body and measuring some physiological or contextual information. The data are collected by some central devices located on the body or in the surrounding environment of the body, via single or multi-hop transmissions. Typical applications include the real-time monitoring of heart activity, blood pressure, breathing rate, or skin temperature, for the purpose of diagnostics or generating automatic calls for emergency.