Search results for "Computer Science::Networking and Internet Architecture"
showing 10 items of 137 documents
Aggregated Packet Transmission in Duty-Cycled WSNs: Modeling and Performance Evaluation
2017
[EN] Duty cycling (DC) is a popular technique for energy conservation in wireless sensor networks (WSNs) that allows nodes to wake up and sleep periodically. Typically, a single-packet transmission (SPT) occurs per cycle, leading to possibly long delay. With aggregated packet transmission (APT), nodes transmit a batch of packets in a single cycle. The potential benefits brought by an APT scheme include shorter delay, higher throughput, and higher energy efficiency. In the literature, different analytical models have been proposed to evaluate the performance of SPT schemes. However, no analytical models for the APT mode on synchronous DC medium access control (MAC) mechanisms exist. In this …
Fuzzy topology discovery protocol for SDN-based wireless sensor networks
2017
Abstract The growing trend in pervasive systems forces traditional wireless sensor networks to deal with new challenges, such as dynamic application requirements and heterogeneous networks. One of the latest paradigms in this area is software defined wireless sensor network. According to the paradigm, the networks take care of managing topological information and forwarding decisions using a bipartite architecture in which a control plane decides the forwarding policies and the data plane (i.e. ordinary sensor nodes) executes them. Unfortunately, in highly dynamic networks, this approach generates an overhead of control packet exchange between the ordinary nodes and the control plane, that …
Improving the efficiency of a standard compliant wireless battery charger
2012
In this paper, a wireless charger for portable electronics devices is presented. A power transmitter, also known as the magnetic pad, and a power receiver are magnetically coupled. A receiver architecture which improves the power conversion efficiency is proposed. All advantages brought by the proposed architecture are discussed and standard constraints are presented as well. The receiver is fully standard-compliant. A wireless station for mobile application is designed and tested. Simulation and experimental results are compared. As shown by experimental results, thanks to the proposed architecture the power conversion efficiency of the receiver section is really close to a unit value. Pow…
Decentralized Synchronization for Zigbee wireless sensor networks in Multi-Hop Topology
2010
Abstract The most effective solution for energy saving in low-rate wireless sensor networks is maintaining each node in a doze state as long as possible. In order to guarantee network connectivity, the intervals at which the network sensors are turned on and off have to be coordinated. We analyze the Zigbee MAC performance in sensor networks deployed in multi-hop topologies. For this networks, critical inefficiencies can arise due to transmissions performed by hidden nodes. We evaluate the impact of different synchronization schemes on the network performance, both in terms of network capacity and in terms of energy consumption. We show how the synchronization function can be opportunistica…
A unified radio control architecture for prototyping adaptive wireless protocols
2016
Experimental optimization of wireless protocols and validation of novel solutions is often problematic, due to limited configuration space present in commercial wireless interfaces as well as complexity of monolithic driver implementation on SDR-based experimentation platforms. To overcome these limitations a novel software architecture is proposed, called WiSHFUL, devised to allow: i) maximal exploitation of radio functionalities available in current radio chips, and ii) clean separation between the logic for optimizing the radio protocols (i.e. radio control) and the definition of these protocols.
Routing quantum information in spin chains
2013
Two different models for performing efficiently routing of a quantum state are presented. Both cases involve an XX spin chain working as data bus and additional spins that play the role of sender and receivers, one of which is selected to be the target of the quantum state transmission protocol via a coherent quantum coupling mechanism making use of local/global magnetic fields. Quantum routing is achieved, in the first of the models considered, by weakly coupling the sender and the receiver to the data bus. In the second model, strong magnetic fields acting on additional spins located between the sender/receiver and the data bus allow us to perform high fidelity routing.
A mathematical study on effective wavenumber, an operative computation procedure, and its use with radiance-temperature relationships
2003
In this paper we study the existence of effective wavenumber for any sensor by means of simple mathematics. We implement a numeric algorithm, based on the developed mathematical background, into a computer program named 'srf2radi', which is freely available via anonymous File Transfer Protocol (FTP) at ftp://ftp.uv.es/pub/src/. The number of effective wavenumbers for each temperature and their accuracy are also computed and studied for NOAA-16 Advanced Very High Resolution Radiometer Version 3 (AVHRR/3) channel 4. These effective wavenumbers can be used to obtain radiance-temperature relationships with physical meaning for any sensor in user-defined temperature intervals.
Measurement of vertical bar V-cs vertical bar using W decays at LEP2
1998
Decays of W± bosons, produced at LEP2, have been used to measure the |Vcs| element of the Cabibbo-Kobayashi-Maskawa matrix. Values for |Vcs| were extracted both from the measured hadronic branching ratio of W± decays and by tagging the flavour of hadronic jets produced in W± decays. Applying the two methods to the data collected during 1996 at energies of 161 and 172 GeV, DELPHI obtains |Vcs|=0.91+0.15−0.14(stat)±0.05(syst).
H2S: A Secure and Efficient Data Aggregative Retrieval Scheme in Unattended Wireless Sensor Networks
2009
In unattended wireless sensor networks, data are stored locally and retrieved on demand. To efficiently transmit the collector’s retrieval results, data are aggregated along being forwarded. The data confidentiality and integrity should be protected at the intermediate nodes. End-to-end encryption or hop-by-hop encryption based schemes are not efficient. Straightforward homomorphic encryption based scheme is not compromise resilient. To achieve all the desires, we propose a scheme - H2S by making use of both homomorphic secret sharing and homomorphic encryption. The security and efficiency of our scheme are justified by extensive analysis.
Analysis of the IEEE 802.11e EDCA Under Statistical Traffic
2006
Many models have been proposed to analyze the performance of the IEEE 802.11 distributed coordination function (DCF) and the IEEE 802.11e enhanced distributed coordination function (EDCA) under saturation condition. To analyze DCF under statistical traffic, Foh and Zukerman introduce a model that uses Markovian Framework to compute the throughput and delay performance. In this paper, we analyze the protocol service time of EDCA mechanism and introduce a model to analyze EDCA under statistical traffic using Markovian Framework. Using this model, we analyze the throughput and delay performance of EDCA mechanism under statistical traffic.