Art et cognition (2000)

Ce texte est un bilan de l'appel à proposition dissu de l'ACI cognitique.Bilan de l'appel à proposition "Art et Cognition

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

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

Method for encoding data in bursts

The invention relates to a method for encoding data in a sequence of bursts (..., Bi-2, Bi-1, Bi, Bi+1,...), wherein each burst includes a block of data symbols and a block of redundancy symbols. The block of redundancy symbols (Ri) of the current burst (Bi) of the sequence is generated by the calculating the sum of a series of encoding values relating to a series of bursts (Bi-2, Bi-1), each encoding value from the series of encoding values being obtained by a respective encoding function applied to the block of data symbols of the burst corresponding to the series of bursts

The control of walking movements in the leg of the rock lobster

Cruse H, Clarac F, Chasserat C. The control of walking movements in the leg of the rock lobster. Biological Cybernetics. 1983;47(2):87-94

Un arboretum à Sophia-Antipolis.

International audienc

Enhancing satellite system throughput using adaptive HARQ for delay tolerant services in mobile communications

In this paper we propose the introduction of adaptive hybrid automatic repeat request (HARQ) in the context of mobile satellite communications. HARQ schemes which are commonly used in terrestrial links, can be adapted to improve the throughput for delay tolerant services. The proposed method uses the estimation of the mutual information between the received and the sent symbols, in order to estimate the number of bits necessary to decode the message at next transmission. We evaluate the performance of our method by simulating a land mobile satellite (LMS) channel. We compare our results with the static HARQ scheme, showing that our adaptive retransmission technique has better efficiency while keeping an acceptable delay for services

Enhanced HARQ for Delay Tolerant Services in Mobile Satellite Communications

The objective of our paper is to improve efficiency (in terms of throughput or system capacity) for mobile satellite communications. In this context, we propose an enhanced Hybrid Automatic Repeat reQuest (HARQ) for delay tolerant services. Our proposal uses the estimation of the mutual information. We evaluate the performance of the proposed method for a land mobile satellite channel by means of simulations. Results are compared with those obtained with a classical incremental redundancy (IR) HARQ scheme. The technique we propose, shows a better performance in terms of efficiency while maintaining an acceptable delay for services

Quand le comportement découvrit les neurones…

Dans les années 1960, Pierre Drach, alors directeur adjoint du CNRS pour les sciences exactes, préconise, dans le cadre du 3e plan, la création d’un institut de psychophysiologie. François Clarac et Jean Massion reviennent sur la genèse d’un institut qui profitait de la décentralisation et de la présence d’un pôle fort en neurologie à Marseille.François Clarac and Jean Massion recount the creation of an institute dedicated to psychophysiology and neurophysiology in the 1960s in Marseille