2,801 research outputs found
The Road Ahead for Networking: A Survey on ICN-IP Coexistence Solutions
In recent years, the current Internet has experienced an unexpected paradigm
shift in the usage model, which has pushed researchers towards the design of
the Information-Centric Networking (ICN) paradigm as a possible replacement of
the existing architecture. Even though both Academia and Industry have
investigated the feasibility and effectiveness of ICN, achieving the complete
replacement of the Internet Protocol (IP) is a challenging task.
Some research groups have already addressed the coexistence by designing
their own architectures, but none of those is the final solution to move
towards the future Internet considering the unaltered state of the networking.
To design such architecture, the research community needs now a comprehensive
overview of the existing solutions that have so far addressed the coexistence.
The purpose of this paper is to reach this goal by providing the first
comprehensive survey and classification of the coexistence architectures
according to their features (i.e., deployment approach, deployment scenarios,
addressed coexistence requirements and architecture or technology used) and
evaluation parameters (i.e., challenges emerging during the deployment and the
runtime behaviour of an architecture). We believe that this paper will finally
fill the gap required for moving towards the design of the final coexistence
architecture.Comment: 23 pages, 16 figures, 3 table
Design issues in quality of service routing
The range of applications and services which can be successfully deployed in packet-switched networks such as the Internet is limited when the network does nor provide Quality of Service (QoS). This is the typical situation in today's Internet. A key aspect in providing QoS support is the requirement for an optimised and intelligent mapping of customer traffic flows onto a physical network topology. The problem of selecting such paths is the task of QoS routing QoS routing algorithms are intrinsically complex and need careful study before being implemented in real networks. Our aim is to address some of the challenges present m the deployment of QoS routing methods.
This thesis considers a number of practical limitations of existing QoS routing algorithms and presents solutions to the problems identified. Many QoS routing algorithms are inherently unstable and induce traffic fluctuations in the network. We describe two new routing algorithms which address this problem The first method - ALCFRA (Adaptive Link Cost Function Routing Algorithm) - can be used in networks with sparse connectivity, while the second algorithm - CAR (Connectivity Aware Routing) - is designed to work well in other network topologies. We also describe how to ensure co-operative interaction of the routing algorithms in multiple domains when hierarchial routing is used and also present a solution to the problems of how to provide QoS support m a network where not all nodes are QoS-aware.
Our solutions are supported by extensive simulations over a wide range of network topologies and their performance is compared to existing algorithms. It is shown that our solutions advance the state of the art in QoS routing and facilitate the deployment of QoS support in tomorrow's Internet
A critical analysis of research potential, challenges and future directives in industrial wireless sensor networks
In recent years, Industrial Wireless Sensor Networks (IWSNs) have emerged as an important research theme with applications spanning a wide range of industries including automation, monitoring, process control, feedback systems and automotive. Wide scope of IWSNs applications ranging from small production units, large oil and gas industries to nuclear fission control, enables a fast-paced research in this field. Though IWSNs offer advantages of low cost, flexibility, scalability, self-healing, easy deployment and reformation, yet they pose certain limitations on available potential and introduce challenges on multiple fronts due to their susceptibility to highly complex and uncertain industrial environments. In this paper a detailed discussion on design objectives, challenges and solutions, for IWSNs, are presented. A careful evaluation of industrial systems, deadlines and possible hazards in industrial atmosphere are discussed. The paper also presents a thorough review of the existing standards and industrial protocols and gives a critical evaluation of potential of these standards and protocols along with a detailed discussion on available hardware platforms, specific industrial energy harvesting techniques and their capabilities. The paper lists main service providers for IWSNs solutions and gives insight of future trends and research gaps in the field of IWSNs
Collective behavior of colloids due to critical Casimir interactions
If colloidal solute particles are suspended in a solvent close to its
critical point, they act as cavities in a fluctuating medium and thereby
restrict and modify the fluctuation spectrum in a way which depends on their
relative configuration. As a result effective, so-called critical Casimir
forces (CCFs) emerge between the colloids. The range and the amplitude of CCFs
depend sensitively on the temperature and the composition of the solvent as
well as on the boundary conditions of the order parameter of the solvent at the
particle surfaces. These remarkable, moreover universal features of the CCFs
provide the possibility for an active control over the assembly of colloids.
This has triggered a recent surge of experimental and theoretical interest in
these phenomena. We present an overview of current research activities in this
area. Various experiments demonstrate the occurrence of thermally reversible
self-assembly or aggregation or even equilibrium phase transitions of colloids
in the mixed phase below the lower consolute points of binary solvents. We
discuss the status of the theoretical description of these phenomena, in
particular the validity of a description in terms of effective, one-component
colloidal systems and the necessity of a full treatment of a ternary
solvent-colloid mixture. We suggest perspectives on the directions towards
which future research in this field might develop.Comment: review, 88 pages, 19 figure
Reconciling cooperation, biodiversity and stability in complex ecological communities
Empirical observations show that ecological communities can have a huge
number of coexisting species, also with few or limited number of resources.
These ecosystems are characterized by multiple type of interactions, in
particular displaying cooperative behaviors. However, standard modeling of
population dynamics based on Lotka-Volterra type of equations predicts that
ecosystem stability should decrease as the number of species in the community
increases and that cooperative systems are less stable than communities with
only competitive and/or exploitative interactions. Here we propose a stochastic
model of population dynamics, which includes exploitative interactions as well
as cooperative interactions induced by cross-feeding. The model is exactly
solved and we obtain results for relevant macro-ecological patterns, such as
species abundance distributions and correlation functions. In the large system
size limit, any number of species can coexist for a very general class of
interaction networks and stability increases as the number of species grows.
For pure mutualistic/commensalistic interactions we determine the topological
properties of the network that guarantee species coexistence. We also show that
the stationary state is globally stable and that inferring species interactions
through species abundance correlation analysis may be misleading. Our
theoretical approach thus show that appropriate models of cooperation naturally
leads to a solution of the long-standing question about complexity-stability
paradox and on how highly biodiverse communities can coexist.Comment: 25 pages, 10 figure
Community analysis in social networks
We present an empirical study of different social networks obtained from
digital repositories. Our analysis reveals the community structure and provides
a useful visualising technique. We investigate the scaling properties of the
community size distribution, and that find all the networks exhibit power law
scaling in the community size distributions with exponent either -0.5 or -1.
Finally we find that the networks' community structure is topologically
self-similar using the Horton-Strahler index.Comment: Submitted to European Physics Journal
Survey of Spectrum Sharing for Inter-Technology Coexistence
Increasing capacity demands in emerging wireless technologies are expected to
be met by network densification and spectrum bands open to multiple
technologies. These will, in turn, increase the level of interference and also
result in more complex inter-technology interactions, which will need to be
managed through spectrum sharing mechanisms. Consequently, novel spectrum
sharing mechanisms should be designed to allow spectrum access for multiple
technologies, while efficiently utilizing the spectrum resources overall.
Importantly, it is not trivial to design such efficient mechanisms, not only
due to technical aspects, but also due to regulatory and business model
constraints. In this survey we address spectrum sharing mechanisms for wireless
inter-technology coexistence by means of a technology circle that incorporates
in a unified, system-level view the technical and non-technical aspects. We
thus systematically explore the spectrum sharing design space consisting of
parameters at different layers. Using this framework, we present a literature
review on inter-technology coexistence with a focus on wireless technologies
with equal spectrum access rights, i.e. (i) primary/primary, (ii)
secondary/secondary, and (iii) technologies operating in a spectrum commons.
Moreover, we reflect on our literature review to identify possible spectrum
sharing design solutions and performance evaluation approaches useful for
future coexistence cases. Finally, we discuss spectrum sharing design
challenges and suggest future research directions
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