109,409 research outputs found

    A novel multipath-transmission supported software defined wireless network architecture

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    The inflexible management and operation of today\u27s wireless access networks cannot meet the increasingly growing specific requirements, such as high mobility and throughput, service differentiation, and high-level programmability. In this paper, we put forward a novel multipath-transmission supported software-defined wireless network architecture (MP-SDWN), with the aim of achieving seamless handover, throughput enhancement, and flow-level wireless transmission control as well as programmable interfaces. In particular, this research addresses the following issues: 1) for high mobility and throughput, multi-connection virtual access point is proposed to enable multiple transmission paths simultaneously over a set of access points for users and 2) wireless flow transmission rules and programmable interfaces are implemented into mac80211 subsystem to enable service differentiation and flow-level wireless transmission control. Moreover, the efficiency and flexibility of MP-SDWN are demonstrated in the performance evaluations conducted on a 802.11 based-testbed, and the experimental results show that compared to regular WiFi, our proposed MP-SDWN architecture achieves seamless handover and multifold throughput improvement, and supports flow-level wireless transmission control for different applications

    Exploiting programmable architectures for WiFi/ZigBee inter-technology cooperation

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    The increasing complexity of wireless standards has shown that protocols cannot be designed once for all possible deployments, especially when unpredictable and mutating interference situations are present due to the coexistence of heterogeneous technologies. As such, flexibility and (re)programmability of wireless devices is crucial in the emerging scenarios of technology proliferation and unpredictable interference conditions. In this paper, we focus on the possibility to improve coexistence performance of WiFi and ZigBee networks by exploiting novel programmable architectures of wireless devices able to support run-time modifications of medium access operations. Differently from software-defined radio (SDR) platforms, in which every function is programmed from scratch, our programmable architectures are based on a clear decoupling between elementary commands (hard-coded into the devices) and programmable protocol logic (injected into the devices) according to which the commands execution is scheduled. Our contribution is two-fold: first, we designed and implemented a cross-technology time division multiple access (TDMA) scheme devised to provide a global synchronization signal and allocate alternating channel intervals to WiFi and ZigBee programmable nodes; second, we used the OMF control framework to define an interference detection and adaptation strategy that in principle could work in independent and autonomous networks. Experimental results prove the benefits of the envisioned solution

    Single-particle levitation system for automated study of homogeneous solute nucleation

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    We present an instrument that addresses two critical requirements for quantitative measurements of the homogeneous crystal nucleation rate in supersaturated aqueous solution. First, the need to perform repeated measurements of nucleation incubation times is met by automating experiments to enable programmable cycling of thermodynamic conditions. Second, the need for precise and robust control of the chemical potential in supersaturated aqueous solution is met by implementing a novel technique for regulating relative humidity. The apparatus levitates and weighs micron-sized samples in an electric field, providing access to highly supersaturated states. We report repeated observations of the crystal nucleation incubation time in a supersaturated aqueous sodium chloride droplet, from which we infer the nucleation rate

    ACE 16k based stand-alone system for real-time pre-processing tasks

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    This paper describes the design of a programmable stand-alone system for real time vision pre-processing tasks. The system's architecture has been implemented and tested using an ACE16k chip and a Xilinx xc4028xl FPGA. The ACE16k chip consists basically of an array of 128×128 identical mixed-signal processing units, locally interacting, which operate in accordance with single instruction multiple data (SIMD) computing architectures and has been designed for high speed image pre-processing tasks requiring moderate accuracy levels (7 bits). The input images are acquired using the optical input capabilities of the ACE16k chip, and after being processed according to a programmed algorithm, the images are represented at real time on a TFT screen. The system is designed to store and run different algorithms and to allow changes and improvements. Its main board includes a digital core, implemented on a Xilinx 4028 Series FPGA, which comprises a custom programmable Control Unit, a digital monochrome PAL video generator and an image memory selector. Video SRAM chips are included to store and access images processed by the ACE16k. Two daughter boards hold the program SRAM and a video DAC-mixer card is used to generate composite analog video signal.European Commission IST2001 – 38097Ministerio de Ciencia y Tecnología TIC2003 – 09817- C02 – 01Office of Naval Research (USA) N00014021088

    Agents in Network Management

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    The ubiquity and complexity of modern networks require automated management and control. With increases in scale, automated solutions based on simple data access models such as SNMP will give way to more distributed and algorithmic techniques. This article outlines present and near-term solutions based on the ideas of active networks and mobile agents, which permit sophisticated programmable control and management of ultra large scale networks

    Applying Lessons from Cyber Attacks on Ukrainian Infrastructures to Secure Gateways onto the Industrial Internet of Things

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    Previous generations of safety-related industrial control systems were ‘air gapped’. In other words, process control components including Programmable Logic Controllers (PLCs) and smart sensor/actuators were disconnected and isolated from local or wide area networks. This provided a degree of protection; attackers needed physical access to compromise control systems components. Over time this ‘air gap’ has gradually been eroded. Switches and gateways have subsequently interfaced industrial protocols, including Profibus and Modbus, so that data can be drawn from safety-related Operational Technology into enterprise information systems using TCP/IP. Senior management uses these links to monitor production processes and inform strategic planning. The Industrial Internet of Things represents another step in this evolution – enabling the coordination of physically distributed resources from a centralized location. The growing range and sophistication of these interconnections create additional security concerns for the operation and management of safety-critical systems. This paper uses lessons learned from recent attacks on Ukrainian critical infrastructures to guide a forensic analysis of an IIoT switch. The intention is to identify and mitigate vulnerabilities that would enable similar attacks to be replicated across Europe and North America
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