Low complexity partial selected mapping for PAPR reduction of OFDM system

International audienceWe present partial blind selected mapping method (P-BSLM) as a probabilistic OFDM-PAPR reduction method. The P-BSLM method generates more candidates than the classical SLM (C-SLM) method while using the same number of IFFT computations. Moreover, common stage computation in an IFFT process can reduce the computational complexity. More candidates increase the PAPR reduction capability, and give a better error performance in the presence of non-linear amplifier. This method has the maximum spectral efficiency without side information, and the phase sequence can be correctly detected using partial blind phase sequence detection

Performance of Turbo Product Codes on the Multiple-Access Relay Channel with Relatively Poor Source-Relay Links

International audienceIn this paper, we study a cooperative coding scheme based on turbo product codes where a number of sensors transmit to a same destination with the help of a relay. This network can be modeled by a multiple-access relay channel (MARC). In the proposed scheme, the relay applies algebraic systematic Network Coding to the source codewords and forwards only the additional redundancy to the destination where an overall product codeword is observed. Based on the single-relay scenario that has been studied in a previous paper, we analyze the error probabilities at the relay input and output for different relay strategies. Taking into account the residual errors at the relay, an appropriate loglikelihood ratio is used at the destination by the turbo decoder. The error performance under the degraded source-relay channel condition is shown on the Rayleigh fading channel. Besides that, we analyze the error correlation in the relay-generated redundancy and investigate the benefits of using multi-relay cooperation. Different cooperation schemes are compared in terms of performance, complexity and energy consumption

Overview of evolved Multimedia Broadcast Multicast Services (eMBMS)

MBMS was introduced as a service to optimize the dissemination of common interest multimedia content. Recently, it evolved to eMBMS based on LTE-centered flexibilities. However, launch of eMBMS over LTE may support new services e.g. pushed content for M2M services and delivery of premium content to the users enjoying secured QoS. This document primarily focusses on the rules, procedures and architecture supporting MBMS based data exchanges, which have not seen any major changes since Release 9

New architecture for high data rate turbo decoding of product codes

International audienceThis paper presents a new circuit architecture for turbo decoding, which achieves very high data rates when using product codes as error correcting codes. Although this architecture is independent of the elementary code (convolutional or block) used and of the corresponding decoding algorithms, we focus here on the case of product codes. This innovative circuit architecture stores several data at the same adress and performs parallel decoding to increase the data rate. It is able to process several date simultaneously with one memory (classical designs require m memories); its latency decreases when the amont of data processed simultaneously is large. We present results on block turbo decoder designs of 2-data, 4-date and 8-data decoders (where 2, 4 and 8 are the number of data symbos processed simultaneously). For each decoder circuit, the latency is decreased, the area of the processing unit is inscreased by a factor m and the critical path and memory size are constant (the data rate is increased by m2 if we have m paralel decoders)

Reed-Solomon turbo product codes for optical communications: from code optimization to decoder design

International audienceTurbo product codes (TPCs) are an attractive solution to improve link budgets and reduce systems costs by relaxing the requirements on expensive optical devices in high capacity optical transport systems. In this paper, we investigate the use of Reed-Solomon (RS) turbo product codes for 40 Gbps transmission over optical transport networks and 10 Gbps transmission over passive optical networks. An algorithmic study is first performed in order to design RS TPCs that are compatible with the performance requirements imposed by the two applications. Then, a novel ultrahigh-speed parallel architecture for turbo decoding of product codes is described. A comparison with binary Bose-Chaudhuri-Hocquenghem (BCH) TPCs is performed. The results show that high-rate RS TPCs offer a better complexity/performance tradeoff than BCH TPCs for low-cost Gbps fiber optic communications

Interference alignment: improved design via precoding vectors

International audienceThe degree of freedom of the Single Input Single Output (SISO) fading interference channel is asymptotically upperbounded by K/2. This upperbound can be achieved using the Interference Alignment approach (IA), proposed by Cadambe et al.. In this work, a new optimized design of the IA scheme is presented. It involves introducing, for each user, a combination matrix so as to maximize the sum rate of the network. The optimal design is obtained via an iterative algorithm proposed in the K-user IA network, and a convergence to a local optimum is achieved. Numerical results enable us to evaluate the performance of the new algorithm and to compare it with other designs

Interference alignment for a multi-user SISO interference channel

International audienceOur work addresses the single-input single-output interference channel. The goal is to show that although interference alignment is suboptimal in the finite power region, it is able to achieve a significant overall throughput. We investigate the interference alignment scheme proposed by Choi et al. (IEEE Commun. Lett. 13(11): 847-849, 2009), which achieves a higher multiplexing gain at any given signal dimension than the scheme proposed by Cadambe and Jafar (IEEE Trans. Inform. Theory 54(8), 2008). Then, we try to modify the IA design in order to achieve enhanced sum-rate performance in the practical signal-to-noise ratio (SNR) region. Firstly, we introduce a way to optimize the precoding subspaces at all transmitters, exploiting the fact that channel matrices in the interference model of a single-input single-output channel are diagonal. Secondly, we propose to optimize jointly the set of precoder bases within their associated precoding subspaces. To this end, we combine each precoder with a new combination precoder, and this latter seeks the optimal basis that maximizes the network sum rate. We also introduce an improved closed-form interference alignment scheme that performs close to the other proposed schemes

Etude des parties codantes de l'ADN en fonction du sens lecture

Dans les séquences ADN, certaines portions dites codantes contiennent l'information nécessaire à l'élaboration des protéines. Le code génétique utilise des règles de correspondance entre les séquences de nucléotides et les acides aminés, constituants élémentaires de protéines. Ce code génétique est dit dégénéré, c'est-à-dire qu'un même acide aminé peut-être représenté par un ensemble de groupe de nucléotides ou codons. Une manière d'étudier les séquences ADN est de s'intéresser aux fréquences d'apparition des mots. Dans cet article nous étudions les fréquences d'apparition des mots suivant les différents sens de lecture de l'ADN et suivant le brin. Nous montrons en particulier que ces fréquences d'apparition des mots dans la séquence ADN présentent des propriétés qui ne peuvent être reproduite à l'aide de modèles statistiques simple

Formation de voie pour la maximisation du débit dans les schémas d’alignement d’interférence

National audienceDans ce papier, nous traitons le problème de la maximisation du débit d'un système multi-utilisateurs, utilisant un schéma d'alignement d'interférence sur un canal à interférence, pour des valeurs de rapport signal à bruit finies. Nous définissons des matrices de changement de base des précodeurs élémentaires qui préservent l'alignement d'interférence et maximisent le débit global en fonction du récepteur utilisé. Ensuite, nous proposons une méthode itérative de résolution du problème d'optimisation. Les résultats de simulation montrent un gain de débit global par rapport aux schéma de référence

Precoding and Decoding in the MIMO Interference Channel for Discrete Constellation

International audienceThis paper addresses the problem of decoding and precoding in the K-user MIMO interference channels. At the receiver side, a joint decoding of the interference and the desired signal is able to improve the receive diversity order. At the transmitter side, we introduce a joint linear precoding design that maximizes the joint cut-off rate, known as a tight lower bound on the joint mutual information for high signal-to-noise ratio (SNR). We also derive a closed-form solution of the precoding matrices that maximizes the mutual information when the SNR is close to zero. This solution is characterized by its low computational complexity, and only requires a local channel state information knowledge at the transmitters. Our simulation results show that decoding interference jointly with the desired signal results in a significant improvement of the receive diversity order. Also a substantial bit error rate and sum-rate improvements are illustrated using the proposed precoding designs