Enabling Realistic Cross-Layer Analysis based on Satellite Physical Layer Traces

We present a solution to evaluate the performance of transport protocols as a function of link layer reliability schemes (i.e. ARQ, FEC and Hybrid ARQ) applied to satellite physical layer traces. As modelling such traces is complex and may require approximations, the use of real traces will minimise the potential for erroneous performance evaluations resulting from imperfect models. Our Trace Manager Tool (TMT) produces the corresponding link layer output, which is then used within the ns-2 network simulator via the additionally developed ns-2 interface module. We first present the analytical models for the link layer with bursty erasure packets and for the link layer reliability mechanisms with bursty erasures. Then, we present details of the TMT tool and our validation methodology, demonstrating that the selected performance metrics (recovery delay and throughput efficiency) exhibit a good match between the theoretical results and those obtained with TMT. Finally, we present results showing the impact of different link layer reliability mechanisms on the performance of TCP Cubic transport layer protocol.Comment: 6 pages, 5 figures and 1 table. Submitted at PIMRC 201

Conception d'un système laser de mesures de déplacements par interférométrie à rétroinjection optique dans le cas de feedbacks faible et modéré

L'utilisation des lasers est répandue dans le domaine de l'instrumentation. Cependant, le fonctionnement de tels dispositifs peut être perturbé par le phénomène de rétroinjection optique (ou self-mixing) auquel est soumis la diode laser. Cette sensibilité du laser au faisceau optique de retour offre de nombreux avantages, notamment pour la mesure de déplacements. Les capteurs basés sur ce principe présentent l'avantage d'être compact, sans contact, et autoalignés. Après une analyse théorique, un modèle comportemental complet du self-mixing est présenté. Un capteur a été conçu afin de pouvoir fonctionner dans les cas les plus répandus expérimentalement, à savoir un feedback faible puis modéré. Deux algorithmes ont ensuite été développés de manière à traiter le signal pour ces différents feedbacks. Ce nouveau capteur permet également de reconstruire des déplacements aléatoires de cibles. Il a de plus, été testé sur un montage mécanique utilisé pour l'analyse de revêtements amortissants.Optical feedback interferometry, also known as the self-mixing effect, is similar to conventional two-beam interferometry but without any auxiliary bulk. When a small fraction of the backscattered laser beam from diffusely-reflecting surfaces re-enters the laser cavity, its spectral properties are affected. This generates a variation in the laser optical power, resulting in self-mixing which has been demonstrated to be suitable for sensing applications. A high-level behavioural model has been proposed to represent this phenomenon. A displacement sensor based on this principle has thus been designed to operate under weak and moderate feedback regimes. Two algorithms have also been developed in order to process the resulting signals, rendering the sensor capable of reconstructing random displacements. This have been verified on damped anti-vibration coatings via modal analysis.TOULOUSE-ENSEEIHT (315552331) / SudocSudocFranceF

Mesure de déplacements par interférométrie à rétro-injection optique: cas des rétro-injections faibles et modérés

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Mesures de Déplacements Par Interférométrie À Rétro-Injection Optique

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Self-Mixing Sensors

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Extending satellite service availability through energy efficient cooperation

International audienceIn this paper, we address the design of a cooperative protocol for a hybrid satellite/terrestrial emergency system. We want to perform energy savings compared to the case where all the terrestrial relay nodes are forwarding satellite messages to ground receivers. This is done via the selection of relevant relay nodes. The parameterization of the protocol phases has been done through simulations and takes into account the duration of the selection process, the number of selected nodes, and the signaling overhead. The selection process based on a node identifier (ID) appears to provide greater energy savings compared to the selection process based on the signal to interference and noise ratio (SINR). The solutions have been implemented in the real case scenario of forest fire that has been thoroughly documented by the US administration. According to the scenario parameters, 100% of the masked nodes are reached after cooperation

Characterization of a self-mixing displacement sensor under moderate feedback

International audienceA displacement sensor enabling us to perform measurements under moderate feedback has been designed with a resolution up to 40 nm. Its performance can be optimized by using the wavelet transform when the signal is disturbed by electromagnetic fields, mechanical coupling, or speckle effect. By determining the repeatability and the reproducibility of this sensor, we have also demonstrated that this measuring device is suitable for statistical process control when an interval of tolerance of ±300 nm is require

Auto Adaptive Signal Processing of a Laser Diode Self-Mixing Displacement Sensor

International audienceA semiconductor laser subject to optical moderate feedback can be used to design an interferometric displacement sensor. The auto adaptive signal processing presented in this paper has been computed in order to ameliorate the accuracy of such a sensor. This set-up has been successfully tested for both harmonic and aleatory displacements of a remote piezoelectric actuator. Measurements of displacements up to 10 mum has been achieved with an accuracy of plusmn80 n

Rule-based Packet Scheduling for DVB-S2 Through Generic Stream Encapsulation

International audienceIn this paper, we consider the problem of IP packet scheduling over a GSE/DVB-S2 satellite link. Scheduling flows with QoS requirements has been widely addressed in the mobile field, especially in LTE and WiMAX, with emphasis on fairness, efficiency and dynamic adaptation to transmission conditions. We focus on the well-known empirical scheduling rules known as PF, M-LWDF and EXP-PF for both QoS and MODCOD scheduling, and present how they were adapted to GSE/DVB-S2 encapsulation. Some of the challenging issues yielded by DVB-S2 are tackled, such as joint scheduling of both QoS and MODCODs, concatenation of numerous user packets into one BBFrame and fairness issues introduced by the scheduling algorithm, especially when dealing with various transmission scenarios. We show the potential of our scheduling algorithm using several simulations