Error Probability Bound Considering Beat Noise in 2-D OCDMA Systems

Considering a 2-Dimensional Optical Code Division Multiple Access (2-D OCDMA) system using spreading codes in both time and wavelength domains, we study in this paper the impact on the performance of one of the most predominant performance limitation which is beat noise due to the photo detection. The beat noise impact is correlated with the wellknown OCDMA limitation named Multiple Access Interference (MAI). Our contribution is to assess, through a theoretical analysis, an error probability bound of a system working in incoherent or partially coherent optical regime. Thanks to the theoretical error probability expression we have developed, the specifications and requirements needed to neglect beat noise effect in a 2-D OCDMA system with a conventional receiver are easily obtained. For a targeted Bit Error Rate (BER), and a given number of active users, one can determine from our results, the 2-D code family parameters, the available data rate and the optical source characteristics, required to be free of beat noise impact

Outage Probability Performance in Mobile Indoor Optical Wireless Communication Environment

3pagesInternational audienceIn this paper, we study an Optical Wireless Communication system for indoor healthcare monitoring application, taking into account the impact of indoor environment. We consider a diffuse link between an emitter placed on a mobile monitored patient and a base station located on the ceiling considering a one-bounce model. Thanks to Ray Propagation Simulator (RaPSor) developed at the Xlim-SIC laboratory, wall, floor and ceiling reflections are taken into account so that the system is more accurately designed, even for low data rates. This is of main concern for healthcare application because it is important to evaluate the required emitter power, related to the power autonomy of monitoring system

Autonomie et santé - Challenges et enjeux : Un exemple : Le projet SAPHIRALE

National audienc

Utilisation de la technologie optique sans fils pour la transmission de données médicales en milieu confiné et sous contraintes de mobilité

National audienc

Spectral and Temporal Optical CDMA for Access Networks.

International audienc

Optical wireless headset inside Aircraft cockpit: study of the integration of LiFi technology in the cockpit to ensure robust audio communication

International audienceToday, pilots of large aircrafts use wired headsets to communicate with cockpit crew, cabin crew or the Air Traffic Control. They could use wireless headsets, but so far all the available solutions rely on RF technologies such as Bluetooth, WiFi etc. The problem with those technologies is that they are known to be unsecure: signal can be jammed, or eavesdropped. On top of that, they are subject to electromagnetic interferences. Those drawbacks seriously limit the use of such conventional technologies in an environment such as cockpit where security and safety are paramount

Wireless Optical technology based Body Area Network for health monitoring application

International audienc

Codage de canal pour les communications optiques sans fil

Cette thèse aborde la performance du codage de canal pour les communications optiques sans fil indoor. L application visée concerne la télésurveillance des données physiologiques de patients mobiles en milieu hospitalier. Après avoir présenté les caractéristiques des liens optiques infrarouges en visibilité directe et en diffus, les techniques permettant de fiabiliser le canal optique non stationnaire à variations lentes notamment par l emploi de codes correcteurs d erreurs et de codes correcteurs d effacements, sont introduites. Les performances des codes de Reed Solomon et LDPC sont évaluées et comparées à la probabilité de blocage du canal optique mobile. L étude permet de montrer que l efficacité des codes augmente avec le rendement au prix d une probabilité de blocage élevée impactant directement les couches supérieures. La performance du codage correcteur d effacement (codage LT) est alors étudiée en termes de débits atteignables et comparée à la performance de l ARQ hybride ainsi qu à la capacité avec blocage. L étude met en évidence que le codage LT permet d augmenter le débit effectif et de réduire la puissance optique émise ce qui est important pour une application de télésurveillance médicale, embarquée sur le patient.This thesis deals with the performance of channel coding for wireless optical communications in an indoor environment in the context of mobile patient monitoring. After presenting the optical channel characteristics of LOS and diffuse links, error correcting codes and erasure correcting codes are introduced as a way to achieve reliable transmissions over the non stationary optical channel. The performance of Reed Solomon codes and LDPC codes is then determined and compared to the outage probability of the optical channel. The results show that the performance of LDPC codes increases with the code rate at the expense of an higher outage probability which is a typical parameter for the higher layers. The performance of erasure correcting codes (LT codes) is then studied in terms of achievable rate and compared to the performance of hybrid ARQ and outage capacity. The study shows that LT codes can increase the achievable rate and reduce the optical emitted power which is important for healthcare applications, embedded on the patient.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Channel Modeling of an Optical Wireless Body Sensor Network for Walk Monitoring of Elderly

International audienceThe 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

Optical Wireless Links as an Alternative to Radio-Frequency for Medical Body Area Networks

International audienceIt is now established that optical wireless communications (OWC) technology is a promising alternative or a complement to radio-frequencies for indoor transmissions. Considering that using OWC permits the reduction of electromagnetic pollution in human environment, this technology can be also a good candidate for wireless body area networks (WBANs) in particular for medical applications such as health monitoring. In this paper, we investigate the use of on-body OWC for mobile medical WBAN. Based on transmission scheme exploiting diffuse optical reflections over the patient environment, we investigate a star BAN topology using spreading codes for multiple access. We have developed a theoretical analysis to determine the performance of such network considering that the patient is moving in the room. The achievable quality of service for a typical health monitoring application is reported and discussed regarding the performance required by medical applications