In this article, we propose an all-optical bidirectional wireless communication system for off-body sensor communication. Optical technology uses infrared (IR) for uplinks and visible light communication (VLC) for downlinks. From numerical simulations, we discuss the impact of body sensor positions on IR and VLC channels. Our goal is to evaluate the possibilities of using optical technology to transmit sensor data for extreme positions such as the ankle, for which the presence of the body creates blockages. In addition, we also consider the variations in orientation of transceivers due to random mobility of body parts during normal movement. Based on a statistical approach, we evaluate performance in terms of outage probability using channel impulse response sets corresponding to the studied scenario, which is health monitoring. Considering a given quality of service, we address trade-offs related to emitting power and data rate. We discuss the results regarding sensor node position and body reflectivity specifically for ankle sensors, corresponding to an extreme but realistic position in the health-monitoring context.

Communications inside an aircraft cockpit are currently based on wired connections especially for the audio headsets used by the pilots. A wireless headset would be an advantage in terms of comfort and flexibility but the use of classical radio frequencies is limited by interference and security issues. Optical wireless communication technology is an option for headset connectivity. Indeed, as optical beams are confined, this technology provides robustness against the risk of hacking, thus increasing security. In addition, the use of optical waves ensures the absence of radio-frequency disturbances. Using simulation, this paper presents a thorough study of the optical wireless channel behavior inside the cockpit of an aircraft by considering a headset worn by a pilot possibly in motion and an access point at the ceiling. The impact of the characteristics of the environment model, such as the level of geometric description, the reflectivity of materials and for the first time, the ambient noise induced by the sun, is highlighted. System performance is evaluated in terms of optimal half-power angles and the necessary average optical power of the light sources.

The growing aging of the world population is leading to an aggravation of diseases, which affect the autonomy of the elderly. Wireless body sensor networks (WBSN) are part of the solutions studied for several years to monitor and prevent loss of autonomy. The use of optical wireless communications (OWC) is seen as an alternative to radio frequencies, relevant when electromagnetic interference and data security considerations are important. One of the main challenges in this context is optical channel modeling for efficiently designing high-reliability systems. We propose here a suitable optical WBSN channel model for tracking the elderly during a walk. We discuss the specificities related to the model of the body, to movements, and to the walking speed by comparing elderly and young models, taking into account the walk temporal evolution using the sliding windowing technique. We point out that, when considering a young body model, performance is either overestimated or underestimated, depending on which windowing parameter is fixed. It is, therefore, important to consider the body model of the elderly in the design of the system. To illustrate this result, we then evaluate the minimal power according to the maximal bandwidth for a given quality of service.

The massive deployment of IoT connected devices brings up different modern problems, such as radiofrequency spectrum saturation and energetic requirements. Organic photovoltaics are good candidates for indoor energy harvesting and data reception in a simultaneous lightwave information and power transfer scenario applied for IoT, at which the non-directive channel significantly contributes to the optical system performance. However, achieving the channel impulse response of diffuse links requires complex numerical approaches. This article presents the first ever OPV model used in a Monte-Carlo ray-tracing simulation, associated to theoretical and experimental validation. Finally, for the first time, an optical simulation with an OPV receiver is realized in a cubic environment, from which the received optical power and generated current distributions were obtained. Results show that the employed OPV is suited for indoor energy harvesting to supply low power IoT nodes, and with proper dedicated front-end, could manage to receive optical data in a SLIPT scenario.

In this article, we explore the performance of optical wireless technology for ensuring audio communications inside an aircraft cockpit. One advantage is that, unlike radio frequencies, opaque objects block optical signals and, therefore, signals cannot pass through walls. This can reduce security risks against eavesdropping and hacking of the physical layer, which is one of the main concerns in the aviation environment. However, optical wireless technology faces some issues, including range limitation and sensitivity to blockages. To study the achievable performances, we propose a modeling of the channels for the uplink and the downlink between the headsets of the four pilots of an Airbus A350 and the access point at the cockpit ceiling. A ray-tracing approach associated with a Monte-Carlo method takes into account the 3D geometric model of the cockpit, the presence of the pilots and their movements. We show that using spatial diversity for headset transceivers can improve performance. Using IEEE 802.11 medium access control mechanism to ensure multi-user communication, the approach highlights the trade-offs between power and delay for a successful communication, linked to the maximum achievable data rate for a given performance level.