Application de la logique floue aux techniques d'accès multiples par répartition des codes CDMA

· En CDMA (Code Division Multiple Access) les codes utilisés sont générés à l'aide des systèmes à registres. Toutefois ceux-ci présentent plusieurs inconvénients: la connaissance du nombre de registres ainsi que leurs connexions internes permet de produire la même séquence et l'utiliser ensuite pour écouter les conversations des autres ou bien les falsifier. On se propose d'implanter un modèle de génération de séquence qui serait purement aléatoire pour remplacer le générateur classique. Ceci est modélisé par un processus basé sur les principes de la logique floue moyennant certaines règles et certaines conditions initiales

Blind DFE based on NLMS algorithm with generalized normalized gradient descent regularization

International audienc

Distributed binary consensus algorithm in wireless sensor networks with faulty nodes

In sensor networks, consensus is a procedure to enhance the local measurements of the sensors with those of the surrounding nodes, and leads to a final agreement about a common value. The question here is how we can achieve the the consensus in a large network containing some faulty nodes. In this paper, we present distributed binary consensus algorithm (BCA) over the wireless sensor networks (WSN) in presence of faulty nodes. With binary consensus, each sensor node, observes one of two states TRUE and FALSE and the aim is to decide which one of the two states was held by the majority of the nodes. We details the implementation of the distributed BCA in WSN when the network contains P faulty nodes. The implementation was tested on sensor nodes using the TinyOSSimulator (TOSSIM) for a WSN with a large number of nodes. Here, TOSSIM guarantees that the code performs correctly when deployed on the physical nodes. In performance evaluation, we consider the analysis of the average convergence time over the simulated environment and considering the presence of P malicious nodes. These results are presented for a WSN with different topologies such as fully connected, path, ring, Erdos Reny random, and star-shaped.Scopu

Etudes de la capacité du canal ionosphérique et de la réception par turbo-égalisation adaptative

CERGY-ENSEA (951272302) / SudocPARIS-CNAM (751032301) / SudocSudocFranceF

GMRES Interference Canceler for doubly iterative MIMO system with a Large Number of Antennas

International audienceIn this paper, we propose a reduced complexity interference canceler for a Turbo Space-Time Codes (TSTC) receiver. Actually, the TSTC receiver is based on a linear Minimum Mean Squared Error (MMSE) filter inside an Interference Canceler (IC) loop. In this scheme, considering the matrix inversion cost, the overall complexity remains important for a large number of transmit and receive antennas. In the proposed receiver, we integrate the Generalized Minimum residual method (GMRES) for symbol detection to compute the MMSE filter without matrix inversion. A good tradeoff between performances and complexity is thus achieved for a system with a large number of transmit and receive antennas. The bit error ratio (BER) and the complexity are evaluated with respect to the number of iterations of the GMRES and the number of transmit/receive antennas. A comparison with the existent IC-MMSE is presented and discussed at the end of the paper

Iterative MMSE interference canceler for cooperative diversity MIMO relay network

International audienceIn multiple-input multiple-output (MIMO) relay network relaying at the relay nodes is performed during two phases: broadcasting phase and cooperative phase known as multiple access phase. The main question is, which is the best receiver able to increase the distributed diversity gain in MIMO relay network for spatial multiplexing (SM) scheme and time division multiple access (TDMA) or multi-carrier multiple access (MC MA). In this paper, we apply an iterative minimum mean squared error (MMSE) interference canceller (IC-MMSE) for MIMO relay network. This receiver detects the transmitted symbols from each antenna using iterative process including interference canceller, MMSE filter and maximum a posteriori (MAP) decoder. Under the assumption of the orthogonality of the forwarding channels, case of TDMA or MC MA, we derive a closed form expression of the instantaneous capacity of the MIMO relay network. We evaluate also the system performances in terms of bit error rate (BER) versus the number of relays K and the signal to noise ratio (SNR) measured at the destination

GMRES Interference Canceler for doubly iterative MIMO system with a Large Number of Antennas

International audienceIn this paper, we propose a reduced complexity interference canceler for a Turbo Space-Time Codes (TSTC) receiver. Actually, the TSTC receiver is based on a linear Minimum Mean Squared Error (MMSE) filter inside an Interference Canceler (IC) loop. In this scheme, considering the matrix inversion cost, the overall complexity remains important for a large number of transmit and receive antennas. In the proposed receiver, we integrate the Generalized Minimum residual method (GMRES) for symbol detection to compute the MMSE filter without matrix inversion. A good tradeoff between performances and complexity is thus achieved for a system with a large number of transmit and receive antennas. The bit error ratio (BER) and the complexity are evaluated with respect to the number of iterations of the GMRES and the number of transmit/receive antennas. A comparison with the existent IC-MMSE is presented and discussed at the end of the paper

Distributed binary consensus algorithm and wireless sensor network

We consider the design and implementation of the binary consensus algorithm in wireless sensor networks (WSN) under real life environment. This algorithm is applied for the evaluation of a consensus of a measured values in presence of a faulty/attacked node. As this algorithm has been tested theoretically, we deploy it for real-life environment including distributed and routing features. In this paper, we propose the development and the implementation of the distributed binary consensus algorithm in WSN under Tinyos environment. The implementation was tested on sensor nodes using the TinyOSSimulator for a WSN with a large number of nodes and a testbed with limited number of nodes. We evaluate the performances related to the average convergence time of nodes states to a consensus value. As in analytical results, in the simulations, we applied the distributed algorithm for fully connected, ring, cycle, Erdos Reny random, and star-shaped topologies.Scopu

Outage Analysis of Space Time Block Coding MIMO Cooperative System with Amplify-and-Forward Scheme

International audienc

Master-Slave TMR Inspired Technique for Fault Tolerance of SRAM-Based FPGA

International audienceIn order to increase reliability and availability of Static-RAM based field programmable gate arrays (SRAM-based FPGAs), several methods of tolerating defects and permanent faults have been developed and applied. These methods are not well adapted for handling high fault rates for SRAM based FPGAs. In this paper, both single and double faults affecting configurable logic blocks (CLBs) are addressed. We have developed a new fault-tolerance technique that capitalizes on the partial reconfiguration capabilities of SRAM-based FPGA. The proposed fault-tolerance method is based on triple modular redundancy (TMR) combined with master-slave technique, and exploiting partial reconfiguration to tolerate permanent faults. Simulation results on reliability improvement corroborate the efficiency of the proposed method and prove that it compares favorably to previous methods