528 research outputs found
Random Access in DVB-RCS2: Design and Dynamic Control for Congestion Avoidance
In the current DVB generation, satellite terminals are expected to be
interactive and capable of transmission in the return channel with satisfying
quality. Considering the bursty nature of their traffic and the long
propagation delay, the use of a random access technique is a viable solution
for such a Medium Access Control (MAC) scenario. In this paper, random access
communication design in DVB-RCS2 is considered with particular regard to the
recently introduced Contention Resolution Diversity Slotted Aloha (CRDSA)
technique. This paper presents a model for design and tackles some issues on
performance evaluation of the system by giving intuitive and effective tools.
Moreover, dynamic control procedures that are able to avoid congestion at the
gateway are introduced. Results show the advantages brought by CRDSA to
DVB-RCS2 with regard to the previous state of the art.Comment: Accepted for publication: IEEE Transactions on Broadcasting; IEEE
Transactions on Broadcasting, 201
On the genetic optimization of APSK constellations for satellite broadcasting
Both satellite transmissions and DVB applications over satellite present
peculiar characteristics that could be taken into consideration in order to
further exploit the optimality of the transmission. In this paper, starting
from the state-of-the-art, the optimization of the APSK constellation through
asymmetric symbols arrangement is investigated for its use in satellite
communications. In particular, the optimization problem is tackled by means of
Genetic Algorithms that have already been demonstrated to work nicely with
complex non-linear optimization problems like the one presented hereinafter.
This work aims at studying the various parameters involved in the optimization
routine in order to establish those that best fit this case, thus further
enhancing the constellation.Comment: IEEE International Symposium on Broadband Multimedia Systems and
Broadcasting (BMSB), 2014; IEEE proceedings, 201
Interference Calculation in Asynchronous Random Access Protocols using Diversity
The use of Aloha-based Random Access protocols is interesting when channel
sensing is either not possible or not convenient and the traffic from terminals
is unpredictable and sporadic. In this paper an analytic model for packet
interference calculation in asynchronous Random Access protocols using
diversity is presented. The aim is to provide a tool that avoids time-consuming
simulations to evaluate packet loss and throughput in case decodability is
still possible when a certain interference threshold is not exceeded. Moreover
the same model represents the groundbase for further studies in which iterative
Interference Cancellation is applied to received frames.Comment: This paper has been accepted for publication in the Springer's
Telecommunication Systems journal. The final publication will be made
available at Springer. Please refer to that version when citing this paper;
Springer Telecommunication Systems, 201
Impressionable Biologies: From the Archaeology of Plasticity to the Sociology of Epigenetics
Chapter 1st of the book.
This chapter explores the fundamental ambiguity of the concept of plasticity – between openness and determination, change and stabilization of forms. This pluralism of meanings is used to unpack different instantiations of corporeal plasticity across various epochs, starting from ancient and early modern medicine, particularly humouralism. A genealogical approach displaces the notion that plasticity is a unitary phenomenon, coming in the abstract, and illuminates the unequal distribution of different forms of plasticities across social, gender, and ethnic groups. Taking a longer view of the plastic body as a ubiquitous belief in traditions predating and coexisting with modern medicine will help contextualize the seeming radicalism of today’s turn to permeability and the exceptionalism of Western findings. By highlighting the complex biopolitical usages of plasticity in the past, the chapter warns against simplistic appropriations of the term in contemporary body/world configurations driven by findings in neuroscience, epigenetics and microbiomics
Thinking embodiment with genetics: epigenetics and postgenomic biology in embodied cognition and enactivism
The role of the body in cognition is acknowledged across a variety of disciplines, even if the precise nature and scope of that contribution remain contentious. As a result, most philosophers working on embodiment – e.g. those in embodied cognition, enactivism, and ‘4e’ cognition – interact with the life sciences as part of their interdisciplinary agenda. Despite this, a detailed engagement with recent findings in epigenetics and post-genomic biology has been missing from proponents of this embodied turn. Surveying this research
provides an opportunity to rethink the relationship between embodiment and genetics, and we argue that the balance of current epigenetic research favours the extension of an enactivist approach to mind and life, rather than the extended functionalist view of embodied cognition associated with Andy Clark and Mike Wheeler, which is more substrate neutral
- …