1,271 research outputs found

    Switching techniques for broadband ISDN

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    The properties of switching techniques suitable for use in broadband networks have been investigated. Methods for evaluating the performance of such switches have been reviewed. A notation has been introduced to describe a class of binary self-routing networks. Hence a technique has been developed for determining the nature of the equivalence between two networks drawn from this class. The necessary and sufficient condition for two packets not to collide in a binary self-routing network has been obtained. This has been used to prove the non-blocking property of the Batcher-banyan switch. A condition for a three-stage network with channel grouping and link speed-up to be nonblocking has been obtained, of which previous conditions are special cases. A new three-stage switch architecture has been proposed, based upon a novel cell-level algorithm for path allocation in the intermediate stage of the switch. The algorithm is suited to hardware implementation using parallelism to achieve a very short execution time. An array of processors is required to implement the algorithm The processor has been shown to be of simple design. It must be initialised with a count representing the number of cells requesting a given output module. A fast method has been described for performing the request counting using a non-blocking binary self-routing network. Hardware is also required to forward routing tags from the processors to the appropriate data cells, when they have been allocated a path through the intermediate stage. A method of distributing these routing tags by means of a non-blocking copy network has been presented. The performance of the new path allocation algorithm has been determined by simulation. The rate of cell loss can increase substantially in a three-stage switch when the output modules are non-uniformly loaded. It has been shown that the appropriate use of channel grouping in the intermediate stage of the switch can reduce the effect of non-uniform loading on performance

    Exploration and Design of Power-Efficient Networked Many-Core Systems

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    Multiprocessing is a promising solution to meet the requirements of near future applications. To get full benefit from parallel processing, a manycore system needs efficient, on-chip communication architecture. Networkon- Chip (NoC) is a general purpose communication concept that offers highthroughput, reduced power consumption, and keeps complexity in check by a regular composition of basic building blocks. This thesis presents power efficient communication approaches for networked many-core systems. We address a range of issues being important for designing power-efficient manycore systems at two different levels: the network-level and the router-level. From the network-level point of view, exploiting state-of-the-art concepts such as Globally Asynchronous Locally Synchronous (GALS), Voltage/ Frequency Island (VFI), and 3D Networks-on-Chip approaches may be a solution to the excessive power consumption demanded by today’s and future many-core systems. To this end, a low-cost 3D NoC architecture, based on high-speed GALS-based vertical channels, is proposed to mitigate high peak temperatures, power densities, and area footprints of vertical interconnects in 3D ICs. To further exploit the beneficial feature of a negligible inter-layer distance of 3D ICs, we propose a novel hybridization scheme for inter-layer communication. In addition, an efficient adaptive routing algorithm is presented which enables congestion-aware and reliable communication for the hybridized NoC architecture. An integrated monitoring and management platform on top of this architecture is also developed in order to implement more scalable power optimization techniques. From the router-level perspective, four design styles for implementing power-efficient reconfigurable interfaces in VFI-based NoC systems are proposed. To enhance the utilization of virtual channel buffers and to manage their power consumption, a partial virtual channel sharing method for NoC routers is devised and implemented. Extensive experiments with synthetic and real benchmarks show significant power savings and mitigated hotspots with similar performance compared to latest NoC architectures. The thesis concludes that careful codesigned elements from different network levels enable considerable power savings for many-core systems.Siirretty Doriast

    Integration Results

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    The H2020 What to do With the Wi-Fi Wild West (Wi-5) project combines research and innovation to propose a Software Defined Networking (SDN) architecture based on an integrated and coordinated set of smart Wi-Fi networking solutions. In this document, we present the integration methodologies and provide the integration test results of the developed functionalities of Wi-5. The integration of the functionalities is being developed within Work Package 5. First, the smart and cooperative solutions provided by the SDN based Wi-5 architecture will be briefly described. Next, we will define and explain the modular approach to be applied in Wi-5 APs and the Wi-5 controller. According to this approach, we will describe the functionalities of both the Wi-5 APs that are modelled as a combination of the monitoring and network configuration modules, and the Wi-5 controller which is composed of the monitoring, decision, and network configuration modules. Following this, we will define and explain the Wi-5 integration strategy that was utilized to integrate the smart and cooperative functionalities in terms of assembly of the modules utilized to model the Wi-5 AP and the Wi-5 controller. The integration approach and steps of the proposed functionalities are then given and the limitations that have been faced during the integration progress of the functionalities are clearly explained in each subsection. Moreover, the design criteria and possible evaluation approaches of such nonintegrated functionalities are explicitly provided. During the integration process, coordinated work between WP3 and WP4 was carried out and, after the feedback was shared for WP5-WP3 and WP5WP4, some novel innovations and contributions are introduced. The online integration approach for the channel assignment algorithm of the radio resource management solution is proposed, and integrated as a product of this mutual feedback. Also, the proactive handover application for seamless handover functionality is another product of this collaboration. After the integration process, the test definitions and evaluation results of the integrated functionalities are presented. Also, the available test metrics and network deployments for each of the functionality tests are provided. The test results prove that the proposed functionalities perform well in meeting the design objectives. We observe that the Wi-5 solutions give the expected performance gains in most of the conducted test cases

    On-board B-ISDN fast packet switching architectures. Phase 1: Study

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    The broadband integrate services digital network (B-ISDN) is an emerging telecommunications technology that will meet most of the telecommunications networking needs in the mid-1990's to early next century. The satellite-based system is well positioned for providing B-ISDN service with its inherent capabilities of point-to-multipoint and broadcast transmission, virtually unlimited connectivity between any two points within a beam coverage, short deployment time of communications facility, flexible and dynamic reallocation of space segment capacity, and distance insensitive cost. On-board processing satellites, particularly in a multiple spot beam environment, will provide enhanced connectivity, better performance, optimized access and transmission link design, and lower user service cost. The following are described: the user and network aspects of broadband services; the current development status in broadband services; various satellite network architectures including system design issues; and various fast packet switch architectures and their detail designs

    Networks on Chips: Structure and Design Methodologies

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    Design Space Exploration for MPSoC Architectures

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    Multiprocessor system-on-chip (MPSoC) designs utilize the available technology and communication architectures to meet the requirements of the upcoming applications. In MPSoC, the communication platform is both the key enabler, as well as the key differentiator for realizing efficient MPSoCs. It provides product differentiation to meet a diverse, multi-dimensional set of design constraints, including performance, power, energy, reconfigurability, scalability, cost, reliability and time-to-market. The communication resources of a single interconnection platform cannot be fully utilized by all kind of applications, such as the availability of higher communication bandwidth for computation but not data intensive applications is often unfeasible in the practical implementation. This thesis aims to perform the architecture-level design space exploration towards efficient and scalable resource utilization for MPSoC communication architecture. In order to meet the performance requirements within the design constraints, careful selection of MPSoC communication platform, resource aware partitioning and mapping of the application play important role. To enhance the utilization of communication resources, variety of techniques such as resource sharing, multicast to avoid re-transmission of identical data, and adaptive routing can be used. For implementation, these techniques should be customized according to the platform architecture. To address the resource utilization of MPSoC communication platforms, variety of architectures with different design parameters and performance levels, namely Segmented bus (SegBus), Network-on-Chip (NoC) and Three-Dimensional NoC (3D-NoC), are selected. Average packet latency and power consumption are the evaluation parameters for the proposed techniques. In conventional computing architectures, fault on a component makes the connected fault-free components inoperative. Resource sharing approach can utilize the fault-free components to retain the system performance by reducing the impact of faults. Design space exploration also guides to narrow down the selection of MPSoC architecture, which can meet the performance requirements with design constraints.Siirretty Doriast

    VANET SECURITY FRAMEWORK FOR LOW LATENCY SAFETY APPLICATIONS

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    Vehicular Ad hoc Network (VANET) is a communication network for vehicles on the road. The concept of VANET is to create communication between vehicles, such as one vehicle is able to inform another vehicle about the road conditions. Communication is possible by vehicle to vehicle (V2V) and vehicle to road side unit (V2R). Presently, VANET technology is surrounded with security challenges and it is essentially important for VANET to successfully implement a security measure according to the safety applications requirements. Many researchers have proposed a number of solutions to counter security attacks and also to improve certain aspects of security i.e. authentication, privacy, and non-repudiation. The current most suitable security scheme for VANET is an Elliptic Curve Digital Signature Algorithm (ECDSA) asymmetric security mechanism. ECDSA is small in key size but it provides the same level of security as the large key sized scheme. However ECDSA is associated with high computational cost, thus lacking applicability in life-critical safety messaging. Due to that reason, alternative security schemes have been proposed, such as symmetric methods which provide faster communication, but at the expense of reduced security. Hence, hybrid and hardware based solutions have been proposed by researchers to mitigate the issue. However, these solutions still do not satisfy the existing safety applications standard or have larger message size due to increased message drop ratio. In this thesis, a security framework is presented; one that uses both standard asymmetric PKI and symmetric cryptography for faster and secured safety message exchange. The proposed framework is expected to improve the security mechanism in VANET by developing trust relationship among the neighboring nodes, hence forming trusted groups. The trust is established via Trusted Platform Module (TPM) and group communication. In this study, the proposed framework methods are simulated using two propagation models, i.e. two ray ground model and Nakagami model for VANET environment (802.11p). In this simulation, two traffic scenarios such as highway and urban are established. The outcome of both simulation scenarios is analyzed to identify the performance of the proposed methods in terms of latency (End-to-End Delay and Processing Delay). Also, the proposed V2V protocol for a framework is validated using a software in order to establish trust among vehicles
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