400 research outputs found
Channel code division multiple access and its multilevel structured LDPC based instantiation
No full textIn this paper, we introduce and outline the concept of Channel Code Division Multiple Access (CCDMA) using a design example based on the recently proposed Multilevel Structured (MLS) LDPC codes. We succeeded in making the memory requirements of the multi-user transceiver to become practically independent of the total number of users supported by the system as well as ascertain that each user benefits from the same Quality of Service (QoS). Finally, we will demonstrate that despite their beneficial compact structure, the proposed MLS LDPC codes do not suffer from any Bit Error Ratio (BER) or Block Error Ratio (BLER) performance degradation, when compared to an otherwise identical benchmarker scheme using significantly more complex LDPC codes having pseudo-random parity-check matrices
Generalized MIMO transmit preprocessing using pilot symbol assisted rateless codes
No full textIn this paper, we propose a generalized multiple-input multiple-output (MIMO) transmit preprocessing system, where both the channel coding and the linear MIMO transmit precoding components exploit the knowledge of the channel. Moreover, we also propose a novel technique, hereby referred to as pilot symbol assisted rateless (PSAR) coding, where a predetermined fraction of binary pilot symbols is interspersed with the channel-coded bits at the channel coding stage, instead of multiplexing the pilots with the data symbols at the modulation stage, as in classic pilot symbol assisted modulation (PSAM). We will subsequently demonstrate that the PSAR code-aided transmit preprocessing scheme succeeds in gleaning more beneficial knowledge from the inserted pilots, because the pilot bits are not only useful for estimating the channel at the receiver, but they are also beneficial in terms of significantly reducing the computational complexity of the rateless channel decoder
Multilevel structured low-density parity-check codes for AWGN and Rayleigh channels
No full textWe propose a novel class of protograph low-density parity-check (LDPC) codes having a combinatorial rather than a random structure, which are termed multilevel-structured (MLS) LDPC codes. It is demonstrated that they posses a strikingly simple structure and, thus, benefit from reduced storage requirements, hardware-friendly implementations, and low-complexity encoding. Our simulation results provided for both additive white Gaussian noise (AWGN) and uncorrelated Rayleigh (UR) channels demonstrate that these advantages accrue without compromising the attainable bit error ratio (BER) and block error ratio (BLER) performance, when compared with their previously proposed more complex random-construction-based counterparts, as well as with other structured codes of the same length
Saving a Tree Genus: Researchers Are Working Toward an Ash Hybrid Resistant to Emerald Ash Borer
No full textAuthor Institution (Herms): Department of Entomology, The Ohio State University; Author Institution (Bonello): Department of Plant Pathology, The Ohio State Universit
Myths and Realities of Rateless Coding
No full textFixed-rate and rateless channel codes are generally treated separately in the related research literature and so, a novice in the field inevitably gets the impression that these channel codes are unrelated. By contrast, in this treatise, we endeavor to further develop a link between the traditional fixed-rate codes and the recently developed rateless codes by delving into their underlying attributes. This joint treatment is beneficial for two principal reasons. First, it facilitates the task of researchers and practitioners, who might be familiar with fixed-rate codes and would like to jump-start their understanding of the recently developed concepts in the rateless reality. Second, it provides grounds for extending the use of the well-understood code design tools — originally contrived for fixed-rate codes — to the realm of rateless codes. Indeed, these versatile tools proved to be vital in the design of diverse fixed-rate-coded communications systems, and thus our hope is that they will further elucidate the associated performance ramifications of the rateless coded schemes
Design of low-density parity-check codes: An overview
No full textThis article provides an overview of the conflicting design tradeoffs of low-density parity-check (LDPC) codes and thus advocates a more holistic approach to their design for wireless channels. We reveal some of the intricate interdependencies of the LDPC code parameters and hence recommend designing codes that strike an attractive tradeoff concerning a number of desirable attributes, rather than simply designing codes that closely approach capacity but possess less-attractive hardware implementations
Older men learning through religious and political affiliations : case studies from Malta
No full textThis article examines two case studies from Malta that focus on older men learning through informal channels. The first case study investigated the role of a community-based organisation – namely, a religious confraternity dedicated to ‘Our Lady of Immaculate Conception’ of the village of Mqabba – as an avenue for informal learning activities for older men. The second case study investigated the connection between affiliation in the Labour Party Veterans’ branch of the Labour Party (Malta) and informal learning. The case studies were carried out by employing a qualitative-methodological framework whereby data was collected through semi-structured interviews. The intent was to reveal the perceived interests and expectations regarding what would be considered a satisfying lifestyle in the context of membership of older men in both organisations. Findings reveal the benefits that older men enjoy through participation in such organisations, including increased levels of independence, improved social participation, and positive effects on participants’ self-esteem and personal confidence. Informants report that membership also contributed to their mental and physical health and to increased activity. Many underlined how participation aided them in escaping boredom and keeping in touch with the outside world. Findings also reveal that only a few informants were simultaneously involved in organisations and activities not related to their religious and political affiliations, which highlights the importance of both informal learning channels in helping older men lead successful and active livespeer-reviewe
Metapopulation structure of a benthic harpacticoid copepod and environmental factors
No full textTigriopus fulvus (Fischer, 1860) is a benthic harpacticoid copepod of the supralittoral environment, the study subject population is
currently resident in Genova Nervi rockpools (Ligurian Sea, 44°22'52.561 N; 9°2'12.570 E).
Main environmental rockpools parameters were studied from March To September 2014. Salinity, temperature, pH, density,
copepod abundance and rockpools trophism (Seston and Chlorophyll "a") were assessed, these parameters were chosen as more
relevant for copepod population development.
Populations trends and occasional extinction events suggest, together with appropriate statistic treatment, a metapopulation
structure for T.fulvus, even though a genetic evidence is required
Charmaine Bonello, Boys, early literacy and children’s rights in a postcolonial context [book review]
No full textIt is high time that we beat the boredom and unease some
boys equate with reading and writing. The author,
Charmaine Bonello, is a mother of two boys, an educator
with many years of experience with boys in the early years,
an advocate of children’s rights, a researcher and lecturer
within the Faculty of Education of the University of Malta.
Through this publication, she invites readers to listen to
the unheard voices of the boys in her study. She firmly
believes that all children deserve, and have a right, to an
excellent and meaningful reading experience so they may
become passionate about reading and writing. To capture
these voices Bonello held focus group interviews with 14
boys, aged 5 to 6 years (Year 1 in Primary School) old
within three State Schools in Malta.
In Chapter 1, Bonello presents the historical,
cultural, social and economic context for the study. The
researcher’s values, beliefs, attitudes and work experience
guided her to conduct a mixed method case study which
explores boys’ underachievement in literacy in early years
education in Malta. Although the participants were young
boys, elements of the context in which they live can be
traced much further back in time. [excerpt]peer-reviewe
Risk analysis in the evaluation of plant investments: the contribution of a non-deterministic approach
No full text- …
