Low-rate coding using incremental redundancy for GLDPC codes

In this paper we propose a low-rate coding method, suited for application-layer forward error correction. Depending on channel conditions, the coding scheme we propose can switch from a fixed-rate LDPC code to various low-rate GLDPC codes. The source symbols are first encoded by using a staircase or triangular LDPC code. If additional symbols are needed, the encoder is then switched to the GLDPC mode and extra-repair symbols are produced, on demand. In order to ensure small overheads, we consider irregular distributions of extra-repair symbols optimized by density evolution techniques. We also show that increasing the number of extra-repair symbols improves the successful decoding probability, which becomes very close to 1 for sufficiently many extra-repair symbols

Pêche et paramètres de reproduction de Pellonula leonensis Boulenger 1916, dans le lac de Taabo (Fleuve Bandama, Côte d’Ivoire): implications pour une exploitation durable du stock

La pêche et la reproduction de Pellonula leonensis provenant du lac de barrage de Taabo, ont été étudiées de novembre 2008 à octobre 2009, en vue d’une meilleure gestion du stock de l’espèce. L’engin de pêche utilisé pour la capture de P. leonensis est la senne de plage de maille variant entre 6 et 8 mm. L’effort de pêche fourni est de 3547 sorties de pêche par an. La prise par unité d’effort est de 59,52 kg/sortie de pêche. La production totale de P. leonensis à Taabo-village, a été estimée à 211,860 tonnes. Au total, 621 spécimens de P. leonensis (de longueur standard comprise entre 27 et 65 mm pour une moyenne de 40,33 ± 6,08 mm et de masse variant de 0,078 à 5,54 g avec une moyenne de 1,19 ± 0,63 g) ont été examinés pour l’étude de la reproduction. Le sex-ratio de 1 : 0,68 est en faveur des mâles. La taille de première maturité sexuelle est de 27,45 mm et de 27,48 mm respectivement chez les femelles et les mâles. Les évolutions du rapport gonadosomatique et des fréquences des stades matures ont révélé que la période de reproduction de P. leonensis s’étend principalement de décembre à avril et accessoirement en juin et août.Mots-clés : Effort de pêche, production annuelle, taille de première maturité, période de reproduction, Côte d’Ivoir

Data journalism beyond majority world countries:Challenges and opportunities

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. This commentary reflects on the state of research on data journalism and discusses future directions for this line of work. Drawing on theory in international development and postcolonial studies, we discuss three critical pitfalls that we encourage future scholarship in this area to avoid. These include using a linear model of progress, in which journalists in Majority World nations struggle to ‘catch up’ to their Minority World counterparts because of the ‘obstacles’ they face; reproducing a simplistic split between the ‘West and the Rest’, thus missing the complex interaction of structures operating at different levels; and failing to examine journalistic agency due to an overemphasis on the technical structuring of the ‘tools’ used in data journalism. We also encourage scholars to engage in more comparative work rather than single case studies; increase dialogic communication between scholarship produced in, or about, different parts of the world; and incorporate more diverse methodologies with the aim of building theory. More broadly, we advocate for greater critical reflection upon—if not the challenging of—our dominant modes of thought in order to build more nuanced frameworks for explaining the complex causes, and potentially mixed effects, of data journalism around the world

Novel precoded relay-assisted algorithm for cellular systems

Cooperative schemes are promising solutions for cellular wireless systems to improve system fairness, extend coverage and increase capacity. The use of relays is of significant interest to allow radio access in situations where a direct path is not available or has poor quality. A data precoded relay-assisted scheme is proposed for a system cooperating with 2 relays, each equipped with either a single antenna or 2-antenna array. However, because of the half-duplex constraint at the relays, relaying-assisted transmission would require the use of a higher order constellation than in the case when a continuous link is available from the BS to the UT. This would imply a penalty in the power efficiency. The simple precoding scheme proposed exploits the relation between QPSK and 16-QAM, by alternately transmitting through the 2 relays, achieving full diversity, while significantly reducing power penalty. Analysis of the pairwise error probability of the proposed algorithm with a single antenna in each relay is derived and confirmed with numerical results. We show the performance improvements of the precoded scheme, relatively to equivalent distributed SFBC scheme employing 16-QAM, for several channel quality scenarios. Copyright © 2010 Sara Teodoro, et al.European project CODIVPortuguese project CADWINPortuguese project AGILEFC

Novel precoded relay-assisted algorithm for cellular systems

Cooperative schemes are promising solutions for cellular wireless systems to improve system fairness, extend coverage and increase capacity. The use of relays is of significant interest to allow radio access in situations where a direct path is not available or has poor quality. A data precoded relay-assisted scheme is proposed for a system cooperating with 2 relays, each equipped with either a single antenna or 2-antenna array. However, because of the half-duplex constraint at the relays, relaying-assisted transmission would require the use of a higher order constellation than in the case when a continuous link is available from the BS to the UT. This would imply a penalty in the power efficiency. The simple precoding scheme proposed exploits the relation between QPSK and 16-QAM, by alternately transmitting through the 2 relays, achieving full diversity, while significantly reducing power penalty. Analysis of the pairwise error probability of the proposed algorithm with a single antenna in each relay is derived and confirmed with numerical results. We show the performance improvements of the precoded scheme, relatively to equivalent distributed SFBC scheme employing 16-QAM, for several channel quality scenarios. Copyright © 2010 Sara Teodoro, et al.European project CODIVPortuguese project CADWINPortuguese project AGILEFC

Novel precoded relay-assisted algorithm for cellular systems

Cooperative schemes are promising solutions for cellular wireless systems to improve system fairness, extend coverage and increase capacity. The use of relays is of significant interest to allow radio access in situations where a direct path is not available or has poor quality. A data precoded relay-assisted scheme is proposed for a system cooperating with 2 relays, each equipped with either a single antenna or 2-antenna array. However, because of the half-duplex constraint at the relays, relaying-assisted transmission would require the use of a higher order constellation than in the case when a continuous link is available from the BS to the UT. This would imply a penalty in the power efficiency. The simple precoding scheme proposed exploits the relation between QPSK and 16-QAM, by alternately transmitting through the 2 relays, achieving full diversity, while significantly reducing power penalty. Analysis of the pairwise error probability of the proposed algorithm with a single antenna in each relay is derived and confirmed with numerical results. We show the performance improvements of the precoded scheme, relatively to equivalent distributed SFBC scheme employing 16-QAM, for several channel quality scenarios. Copyright © 2010 Sara Teodoro, et al.European project CODIVPortuguese project CADWINPortuguese project AGILEFC

Data-precoded algorithm for multiple-relay-assisted systems

A data-precoded relay-assisted (RA) scheme is proposed for a system cooperating with multiple relay nodes (RNs), each equipped with either a single-antenna or a two-antenna array. The classical RA systems using distributed space-time/frequency coding algorithms, because of the half-duplex constraint at the relays, require the use of a higher order constellation than in the case of a continuous link transmission from the base station to the user terminal. This implies a penalty in the power efficiency. The proposed precoding algorithm exploits the relation between QPSK and 4 L -QAM, by alternately transmitting through L relays, achieving full diversity, while significantly reducing power penalty. This algorithm explores the situations where a direct path (DP) is not available or has poor quality, and it is a promising solution to extend coverage or increase system capacity. We present the analytical derivation of the gain obtained with the data-precoded algorithm in comparison with distributed space-frequency block code (SFBC) ones. Furthermore, analysis of the pairwise error probability of the proposed algorithm is derived and confirmed with numerical results. We evaluate the performance of the proposed scheme and compare it relatively to the equivalent distributed SFBC scheme employing 16-QAM and non-cooperative schemes, for several link quality scenarios and scheme configurations, highlighting the advantages of the proposed scheme

Exploring perceptions of advertising ethics: an informant-derived approach

Whilst considerable research exists on determining consumer responses to pre-determined statements within numerous ad ethics contexts, our understanding of consumer thoughts regarding ad ethics in general remains lacking. The purpose of our study therefore is to provide a first illustration of an emic and informant-based derivation of perceived ad ethics. The authors use multi-dimensional scaling as an approach enabling the emic, or locally derived deconstruction of perceived ad ethics. Given recent calls to develop our understanding of ad ethics in different cultural contexts, and in particular within the Middle East and North Africa (MENA) region, we use Lebanon—the most ethically charged advertising environment within MENA—as an illustrative context for our study. Results confirm the multi-faceted and pluralistic nature of ad ethics as comprising a number of dimensional themes already salient in the existing literature but in addition, we also find evidence for a bipolar relationship between individual themes. The specific pattern of inductively derived relationships is culturally bound. Implications of the findings are discussed, followed by limitations of the study and recommendations for further research