1,721,008 research outputs found
Implementation issues of diffusion-based molecular communications receivers based on transcriptional elements
No full textThe recent research activities on molecular communications systems highlighted impressive potentials for realizing new services in many fields. They include biomedical systems, nanotechnologies, food production and many others. Since the nature of such areas may be extremely different, in terms of geometrical scale, information delivery media, and related technologies, the proposed molecular communication systems include different reception techniques, adapted to the operating environment. In this survey, we focus on systems based on diffusion of signaling molecules, and analyze the main components running in a receiver, namely the reception process and the information decoding mechanism. For each of them, we review the most popular techniques proposed in literature, and discuss the feasibility of using these models to realize receivers based on living cells. In more detail, for the reception process, we discuss the matching between literature models and real reception mechanism. As for the information decoding mechanism, we review and critically discuss its possible implementation through transcriptional elements, which is the main way of implementing processing elements in living cells, highlighting feasibility in term of complexity and decoding time
Enhancing java call control with media server control functions
No full textIn this article, we propose a novel abstraction layer for application service implementation compliant with the Java Call Control (JCC) specifications. It simplifies creation of multimedia services using SIP and the Media Gateway Control Protocol. In order to show its effectiveness, we have implemented a JCC resource adaptor for a JAIN service logic execution environment (JSLEE), using the Mobicents application server, which is the only existing open source JSLEE implementation. Experimental results obtained by implementing a complex VoIP service show both a significant simplification of service implementation and improved performance over legacy solutions
A Migration Path to provide End-to-End QoS over Stateless Networks by Means of a Probing-driven Admission Control
No full textThis document proposes a new admission control paradigm, called GRIP
(Gauge&Gate Reservation with Independent Probing), devised to
transparently operate over DiffServ domains. GRIP relies the
decision to admit a new flow upon the successful and timely
delivery, through the Internet, of probe packets independently
generated by the end points.
The key idea is to use failed receptions of probes to discover, at
the end points, that a congestion condition occurs in the network,
and to reject the new admission request. This idea is extremely
close to what TCP congestion control technique does, but it is used
in the novel context of admission control. Similarly to TCP, GRIP is
a pure end-to-end distributed protocol operation, whose intelligence
is kept at the edge of the network and whose operation (i) does not
require any specific protocol implementation in the core routers,
which are stateless and remain oblivious to individual flows, and
(ii) does not require any specific peer and router agreement on the
probes payload information. GRIP is coherent with the architectural
assumptions of RFCs [1,2] and attempts answering to a number of
issues raised in these documents.
While GRIP can be seamlessly applied to DiffServ (and even legacy)
Internet, a marginal increase in QoS is envisioned in these existing
scenarios. The performance of GRIP are in fact related to the
capability of routers to locally take decisions about the degree of
congestion in the network, and suitably drop probe packets when
congestion conditions are detected. However, such decisions are
localized and do not involve any coordination among routers and
between routers and end points. Thus, GRIP opens up a future smooth
migration path toward gradually improved QoS, as routers in
different domain will be enhanced (e.g., with measurement-based
admission decision criteria) without losing inter-operability with
installed devices. Strict end-to-end QoS guarantees are eventually
provided when all the crossed routers are equipped with GRIP
capabilities
A simulation tool for nanoscale biological communication systems
No full textBiological nanonetworks is a novel interdisciplinary research area including nanotechnology, biotechnology, and ICT. In this abstract, we briefly illustrate a simulation tool designed for modeling communications at nanoscales. This tool is fully adaptable to all nano-scale bearers, used to transport information, which may range from electromagnetic waves to calcium ions. In addition, it can be easily adapted to the interested environment. In this abstract, we illustrate an example of the simulator functions by modeling a portion of a lymph node, and simulating the information transfer during the humoral immune response by antibody molecules
Per-flow QoS support over a stateless Differentiated Services IP domain
No full textThis paper consists of two parts. In the first part, we propose an admission control paradigm, called Gauge & Gate Reservation with Independent Probing (GRIP), devised to operate over a stateless Differentiated Services IP domain. GRIP admits a new flow upon the successful and timely delivery, through the domain, of probing packets independently generated by the end-points. Failed reception of probing packets is interpreted as congestion in the network. Our solution is fully distributed and scalable, as admission control decisions are taken at the edge nodes, and requires no coordination between routers, which are stateless and remain oblivious to individual flows. An interesting feature of the GRIP operation is its backward compatibility (at the expense of experienced performance) with existing routers. The performance of GRIP is related to the capability of routers to locally take decisions about the degree of congestion, and suitably block probing packets when congestion conditions are detected. In the second part of the paper we describe a specific GRIP implementation, characterized by the capability of providing strict Quality of Service guarantees, thanks to suitable assumptions made on the supported traffic and on the traffic control mechanisms, in a specific domain
Optimal Deployment of Open-Source Application Servers providing Multimedia Services
No full textThis article shows the usage and the experimental analysis of open source software packages for designing and implementing carrier-grade multimedia services. The shown implementation is based on the use of Java Call Control APIs for managing SIP sessions and MGCP connections. This JCC implementation has been integrated within an open source platform, Mobicents JSLEE. Mobicents is a runtime environment suitable for deploying services integrating voice, video, and messaging over different networks. An extensive experimental campaign has allowed suitable deployment strategies to be identified, depending on the service features. The main contribution of this article is to present these strategies, consisting of resource allocation and configuration in a virtualized environment. The results of our experiments are aimed at providing general guidance on configuring servers in a virtualized environment such as a cloud. They can also be helpful to address the server placement problem, which is beyond the scope of this article. An additional contribution of this article consists of a simple and effective model to predict the achievable server throughput, expressed in calls per second. For this purpose, we have measured the CPU time for processing SIP and MGCP messages, and estimated the maximum sustainable load of each virtual machine. In this way, we can preliminarily estimate the number of virtualized instances of the platform needed for handling a given workload with the desired quality of service
Dimensioning of dual leaky bucket parameters for regulating voice sources
No full textAn analytical approach to set the parameters of a dual leaky bucket for the purposes of regulating a voice over IP call at the network ingress is presented. The analytical model is used to determine the theoretical packet loss as a function of the dual leaky bucket parameters for traffic generated by a G.726 codec, then the theoretical packet loss is compared with that measured using a real voice conversation taking place over a Linux system and using an implementation of the G.726. The results are found to be in excellent agreement
Consistency analysis of sensor data distribution
No full textIn this paper we analyze the probability of consistency of sensor data distribution systems (SDDS), and determine suitable evaluation models. This problem is typically difficult, since a reliable model taking into account all parameters and processes which affect the system consistency is unavoidably very complex. The simplest candidate approach consists of modeling the state sojourn time, or holding time, as memoryless, and resorting to the well known solutions of Markovian processes. Nevertheless, it may happen that this approach does not fit with some working conditions. In particular, the correct modeling of the SDDS dynamics requires the introduction of a number of parameters, such as the packet transfer time or the packet loss probability, the value of which may determine the suitability of unsuitability of the Markovian model. Candidate alternative solutions include the Erlang phase-type approximation of nearly constant state holding time and a more refined model to account for overlapping events in semi-Markov processes
An Experimental System for Continuous Users Tracking in Emergency Scenarios
No full textIn emergency scenarios, like those following a earthquake, road accident in tunnel, large fire and so on, the possibility to track personnel engaged in providing first aid and rescue services is of paramount importance, also in order to promptly manage unexpected and potentially hazardous situations. While in open areas the precision, accuracy and availability of GPS service is enough in most cases, in partially obstructed environments, such as urban canyon, or indoor, GPS service is not available or the quality of provided estimates could be quite coarse. While the literature reports a lot of solutions able to overcome these limitations of the GPS system in standard settings, in emergency scenarios these solutions could be partially or completely unavailable, raising serious concerns about their suitability in these situations. In this paper, we propose a localization and tracking system based on the usage of IEEE 802.11 technology for augmenting the GPS coverage where it is scarce, and to completely substitute it where it is missing, e.g. indoor. The system is characterized by ease of deployment and usage by non-technical personnel, such as that engaged in rescue services in emergency scenarios. In order to assess the feasibility of the proposed solution, we implemented a proof-of-concepts prototype made up of low-cost commercial off-the-shelf components. The preliminary performance tests we performed confirm the effectiveness of proposed system
Simulating an in vitro experiment on nanoscale communications by using BiNS2
No full textNanoscale communications is an emergent research topic with potential applications in many fields. In order to design nanomachines able to exploit the communication potentials of nanoscale environments, it is necessary to identify the basic communication mechanisms and the relevant parameters. In this paper, we show how system parameters can be derived by suitably matching the results of in vitro experiments with those obtained via simulations by using the BiNS2 simulator. In order to scale the simulation from micrometric settings, with timescale in the order of seconds, to real experiments lasting tens of minutes with millimetric size, we enhanced the BiNS2 simulator by introducing a space partition algorithm based on the octree. In this way, the simulator can exploit the high level of parallelism of modern multicore computer architectures. We have used this technique for simulating an experiment focused on the communication between platelets and endothelium through the diffusion of nanoparticles. Simulation results match experimental data, thus allowing us to infer useful information on the receiver operation
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