Optical packet switching is commonly considered as a possible technology for future telecommunication networks, due to its compatibility with bursty traffic, eg Internet protocol (IP), and efficient use of wavelength ...
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ISBN:
(纸本)0819460524
Optical packet switching is commonly considered as a possible technology for future telecommunication networks, due to its compatibility with bursty traffic, eg Internet protocol (IP), and efficient use of wavelength channels. Current transport networks are voice-optimised and connection oriented, however the amount of data traffic is rapidly increasing, resulting in a continuous increase of average traffic through major exchanges exceeding 30% per annum (in Europe). Thus optical packet switching is seen as a future technology that will support diverse traffic profiles and give more efficient bandwidth utilisation through its ability to provide multiplexing at the packet level. In recent years the significance of optical packet switching as an emerging technology has been identified and researched by a number of research groups. Earlier optical packet switching demonstrators presented switching of mainly ATM compatible synchronously transmitted packets at bit rates up to 2.5b/s with the optical header encoded either in series or in parallel to the payload using the sub-carrier modulation technique. More recent projects have demonstrated switching capabilities at 10Gb/s using more advanced approaches with special encoding schemes for header and header detection, together with sophisticated control mechanisms for contention resolution. The capability of switching optical packets at bit rates up to 160Gb/s has recently been demonstrated. This paper discusses the architectures currently proposed for high speed optical packet switching, including the key techniques of header processing and payload switching. The focus is on a high speed demonstrator [OP Snet] capable of operation at rates > 100 Gb/s.
This paper describes the Next Generation PARLAY X with QoS / QoE in Next Generation network (NGN). PARLAY has introduced the architecture for the development and deployment of services by service providers over 3G net...
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ISBN:
(纸本)3540308199
This paper describes the Next Generation PARLAY X with QoS / QoE in Next Generation network (NGN). PARLAY has introduced the architecture for the development and deployment of services by service providers over 3G network. But the existing PARLAY X does not provide the open Application programming Interface (API) for QoS / QoE. Therefore, to solve this issue, this paper suggests the PARLAY X with QoS / QoE. The object of this paper is to support the architecture and the API of the network service for QoS / QoE in NGN. The PARLAY X can provide users with QoS / QoE in network according to the detected context such as location and speed and user's preference. The architecture of the Next Generation PARLAY X is comprised of the functions for context-awareness, adaptation, and personalization.
We explore the nature of the interaction between organisational culture and XP practice via three empirically-based case studies. The case studies cover a spectrum of organisational cultures. Our findings suggest that...
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ISBN:
(纸本)0769524877
We explore the nature of the interaction between organisational culture and XP practice via three empirically-based case studies. The case studies cover a spectrum of organisational cultures. Our findings suggest that XP can thrive in a range of organisational cultures and that the interaction between organisational culture and XP can be complex & subtle, with consequences for practice.
Wireless sensor networks can be very useful in applications that require the detection of crucial events, in physical environments subjected to critical conditions, and the propagation of data reporting their realizat...
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ISBN:
(纸本)3540264221
Wireless sensor networks can be very useful in applications that require the detection of crucial events, in physical environments subjected to critical conditions, and the propagation of data reporting their realization to a control center. In this paper we propose jWebDust, a generic and modular application environment for developing and managing applications that are based on wireless sensor networks. Our software architecture provides a range of services that allow to create customized applications with minimum implementation effort that are easy to administrate. We move beyond the "networking-centric" view of sensor network research and focus on how the end user (administrator, control center supervisor, etc.) will visualize and interact with the system. We here present its open architecture, the most important design decisions, and discuss its distinct features and functionalities. jWebDust allows heterogeneous components to interoperate (real world sensor networks will rarely be homogeneous) and allows the integrated management and control of multiple such networks by also defining web-based mechanisms to visualize the network state, the results of queries, and a means to inject queries in the network. The architecture also illustrates how existing protocols for various services can interoperate in a bigger framework - such as the tree construction, query routing, etc.
Inter-sensor communication often comprises a significant portion of energy expenditures in a sensor network as compared to sensing and computation. We discuss an integrated approach to dynamically routing measurements...
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Ten years ago, our paper described how a very small system might be developed to control a coin-operated turnstile in a zoo [1]. It arose out of our efforts to understand how requirements, domain knowledge and specifi...
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ISBN:
(纸本)9781581139631
Ten years ago, our paper described how a very small system might be developed to control a coin-operated turnstile in a zoo [1]. It arose out of our efforts to understand how requirements, domain knowledge and specifications fit together, and how specifications could be derived systematically. A particular goal was to understand requirements and specifications for telecommunication systems well enough to handle the feature interaction problem that plagues telecommunication software.A year later we published a more comprehensive version of our requirements framework [3], and began to develop the Distributed Feature Composition (DFC) architecture for telecommunication services [2]. We continued to work on it together until mid-2002. DFC has proven successful in practice, and is now being used in a commercial voice-over-IP *** publishing the requirements framework, we have worked on different kinds of system, and have been confronted with important differences in how its principles apply. It has taken all this time to achieve the goal of understanding requirements for telecommunication services and other connection services. In this domain, requirements are heavily influenced by the fact that services are assemblies of components added to a basic network infrastructure. Our work in another direction has led to a focus on system interaction with the human and physical world, recognising the varying roles of formalisation and formal reasoning in problems of different kinds, and the need for a stronger grip on the relationship between engineering of software and engineering in the *** common lesson of these experiences is that the requirements framework of ten years ago is a good generalization, but specific domains and situations require their own specializations of it.
This paper proposes a trajectory metamodel based on artificial neural network, firstly for integrated conceptual design and trajectory optimization and secondly for close loop guidance using onboard optimization of tr...
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ISBN:
(纸本)5900780597
This paper proposes a trajectory metamodel based on artificial neural network, firstly for integrated conceptual design and trajectory optimization and secondly for close loop guidance using onboard optimization of trajectory in near real time. Genetic Algorithm evaluates weight, propulsion, aerodynamics and flight dynamics to evolve to near optimal solution of minimum launch weight while meeting the constraints. Neural network trajectory metamodel is used by Genetic Algorithm to rapidly find near global minimum. Sequential Quadratic programming (SQP) starts from this initial guess and converges to local optimal solution. The most significant contribution of meta-modeling strategy is the drastic reduction in overall computation time, due to greatly reduced number of exact analysis required. In the guidance application, SQP uses onboard neural network trajectory metamodel to rapidly optimize the profile of angle of attack. Dispersion analysis of open loop and proposed closed loop guidance employing neural network are compared and shows the proposed scheme makes the system more robust against uncertainty in estimation of aerodynamic parameters.
ieee 1451 standard is intended to address the smart transducer interfacing problematic in network environments. Usually, proprietary hardware and software is a very efficient solution to implement the ieee 1451 normat...
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ieee 1451 standard is intended to address the smart transducer interfacing problematic in network environments. Usually, proprietary hardware and software is a very efficient solution to implement the ieee 1451 normative, although can be expensive and inflexible. In contrast, the use of open and standardized tools for implementing the ieee 1451 normative is proposed in this paper. Tools such as Java and Phyton programming languages, Linux, programmable logic technology, personal computer resources and Ethernet architecture were integrated in order to construct a network node based on the ieee 1451 standards. The node can be applied in systems based on the client-server communication model. The evaluation of the employed tools and experimental results are presented
The use of IPSec encryption via virtual private network (VPN) gateways is expected to increase within tactical networks. Robust tactical networks that leverage VPN gateways require the ability to map remote IPSec prot...
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The use of IPSec encryption via virtual private network (VPN) gateways is expected to increase within tactical networks. Robust tactical networks that leverage VPN gateways require the ability to map remote IPSec protected plain text (PT) networks to their VPN gateway's cipher text (CT) network address. Security associations between VPN gateways must allow for refresh and change based upon network connectivity and performance over time. A VPN-based prefix discovery server (PDS) can be implemented to help enable these network mappings and allow performance monitoring and network connection change. The discovery of new VPN gateways can be enabled through a registration process. Optional information for registration can include a VPN gateway's ability to support different types of traffic or gateway preference. Following registration, the VPN gateway can be configured to distribute learned prefixes into the directly attached enclave's interior routing protocol and provide updates to remote PDS(s) as network changes occur. To help analyze the challenges associated with the deployment of tactical networkarchitectures that leverage a PDS, we have developed an open-source based VPN gateway and PDS. The purpose of this paper is to provide an overview of our PDS design, capabilities, lessons learned and recommendations for future architectures
The development of fourth generation or beyond third generation (4G/B3G) networks is driven by the need to offer the subscribers with the convenience of using the same end terminal to obtain seamless services across h...
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The development of fourth generation or beyond third generation (4G/B3G) networks is driven by the need to offer the subscribers with the convenience of using the same end terminal to obtain seamless services across heterogeneous networks. In this paper, we propose a consolidated 4G/B3G architecture that is open, hierarchical, layered and modular with cross-layer coordination and distributed network functionalities. Well-defined message interfaces enable the layers/levels within the architecture to support the cross-layer coordination under dynamic network conditions. Novel augmentations in mobility and resource management schemes are proposed that result in consolidating the corresponding salient areas of 4G/B3G architectures discussed in the literature. Seamless services in the network can be accessed through our reconfigurable multi-antenna end terminal. A common mechanism for control/signaling across heterogeneous networks is adopted to facilitate wireless system discovery and paging. A multicast protocol is proposed to ensure the reliable transfer of control/signaling messages over this incorporated signaling system.
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