Sparse graph-based coding schemes for continuous phase modulations

The use of the continuous phase modulation (CPM) is interesting when the channel represents a strong non-linearity and in the case of limited spectral support; particularly for the uplink, where the satellite holds an amplifier per carrier, and for downlinks where the terminal equipment works very close to the saturation region. Numerous studies have been conducted on this issue but the proposed solutions use iterative CPM demodulation/decoding concatenated with convolutional or block error correcting codes. The use of LDPC codes has not yet been introduced. Particularly, no works, to our knowledge, have been done on the optimization of sparse graph-based codes adapted for the context described here. In this study, we propose to perform the asymptotic analysis and the design of turbo-CPM systems based on the optimization of sparse graph-based codes. Moreover, an analysis on the corresponding receiver will be done

On the feasibility of a secondary service transmission over an existent satellite infrastructure: design and analysis

International audience; In this paper, we present a realistic use case in order to investigate the feasibility of a secondary service transmission over an existent satellite infrastructure. By introducing the overlay cognitive radio paradigm towards satellite communications, we compute a theoretical achievable data rate greater than 16 kbps for the secondary service, which is suitable for most M2M applications. Using simulation results, we show that this can be achieved while preserving the primary service performance. In addition, a system design framework is discussed in order to dimension such systems

Asymptotic Analysis and Design of LDPC Codes for Laurent-based Optimal and Suboptimal CPM Receivers

International audienceIn this paper, we derive an asymptotic analysis for a capacity approaching design of serially concatenated turbo schemes with low density parity check (LDPC) codes and continuous phase modulation (CPM) based on Laurent decomposition. The proposed design is based on extrinsic mutual information evolution and Gaussian approximation. By inserting partial interleavers between LDPC and CPM and allowing degree-1 variable nodes under a certain constraint we show that designed rates are very close to the maximum achievable rates. Furthermore, we discuss the selection of low complexity receivers that works with the same optimized profiles

Design of Unstructured and Protograph-Based LDPC Coded Continuous Phase Modulation

In this paper, we derive an asymptotic analysis and optimization of coded CPM systems using both unstructured and protograph-based LDPC codes ensembles. First, we present a simple yet effective approach to design unstructured LDPC codes : by inserting partial interleavers between LDPC and CPM, and allowing degree-1 and degree-2 variable nodes in a controlled pattern, we show that designed codes perform that can operate very close to the maximum achievable rates. Finally, the extension to protograph based codes is discussed. We provide some simple rules to design good protograph codes with good threshold properties

Schémas codés pour modulation de phase continue à l'aide de codes définis sur des graphes creux

L'utilisation de la modulation à phase continue (CPM) est particulièrement intéressante lorsque le canal de communication comporte une forte non-linéarité et un support spectral limité, en particulier pour la voie aller, lorsque l'on dispose d'un amplificateur par porteuse à bord du satellite, et pour la voie retour où le terminal d'émission travaille à saturation. De nombreuses études ont été effectuées sur le sujet mais les solutions proposées reposent sur la démodulation/décodage itératif des CPM couplées à un code correcteur d'erreur de type convolutif ou bloc. L'utilisation de codes LDPC n'a pas été à ce jour abordée de façon précise. En particulier, il n'existe pas à notre connaissance de travaux sur l'optimisation des codes basés sur des graphes creux adaptés à ce type de schémas. Dans cette étude, nous proposons d'effectuer l'analyse asymptotique et le design d'un schéma Turbo-CPM basé sur des graphes creux. Une étude du récepteur associé comportant les fonctions de démodulation sera également effectuée.The use of the continuous phase modulation (CPM) is interesting when the channel represents a strong non-linearity and in the case of limited spectral support; particularly for the uplink, where the satellite holds an amplifier per carrier, and for downlinks where the terminal equipment works very close to the saturation region. Numerous studies have been conducted on this issue but the proposed solutions use iterative CPM demodulation/decoding concatenated with convolutional or block error correcting codes. The use of LDPC codes has not yet been introduced. Particularly, no works, to our knowledge, have been done on the optimization of sparse graph-based codes adapted for the context described here. In this study, we propose to perform the asymptotic analysis and the design of turbo-CPM systems based on the optimization of sparse graph-based codes. Moreover, an analysis on the corresponding receiver will be done

Modulation GMSK codée spatialement couplée

International audienceWe propose a method to spatially couple a concatenated serial scheme composed of an external convolutional code and a GMSK modulation respecting the phase continuity. Through asymptotic analysis, we show that this scheme shows very competitive thresholds compared to carefully optimized codes such as LDPC codes. Finally, in view of the obtained results, we observe that the threshold of our scheme saturate to a value very close to the threshold given by the area under the EXIT curve theoremNous proposons une méthode pour coupler spatialement une modulation GMSK concaténée en série avec un code convolutif en assurant la continuité de la phase. Nous montrons ensuite que ce schéma démontre des seuils asymptotiques très compétitifs par rapport à des codes LDPC optimisés. Ensuite, au vu des résultats obtenus, nous observons que le seuil du schéma obtenu saturent vers une valeur très proche du seuil donné par le théorème de l'aire sous la courbe EXIT

Une Approche Générale pour l'Optimisation des Concaténations en Série Spatialement Couplées

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A General Framework and Optimization for Spatially-Coupled Serially Concatenated Systems

International audienceIn this paper, we provide a general framework for spatially-coupled concatenated systems. We explicit the analogy with spatially-coupled protographs and provide an adapted EXIT chart analysis. By proposing a continuous-valued coupling matrix, we propose a code design procedure for faster convergence. When considering general bit- interleaved coded-modulation scheme, we also conjecture that the spatially-coupled scheme of general detectors saturates to a value very close (lower bound) to the threshold given by the Area theorem

Delay Optimization of Conventional Non-Coherent Differential CPM Detection

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