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