We believe we have demonstrated for the first time wavelength-division multiplexing (WDM) all-optical IP tag switching with wavelength conversion and subcarrier multiplexed addressing. Switching over four wavelengths ...
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ISBN:
(纸本)155752582X
We believe we have demonstrated for the first time wavelength-division multiplexing (WDM) all-optical IP tag switching with wavelength conversion and subcarrier multiplexed addressing. Switching over four wavelengths covering 16 nm was demonstrated with noninverting wavelength conversion of 2.5 Gbps payloads and burst mode recovery of tag/headers.
Software quality models are tools for focusing software enhancement efforts. Such efforts are essential for mission-critical embedded software, such as telecommunications systems, because customer-discovered faults ha...
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Software quality models are tools for focusing software enhancement efforts. Such efforts are essential for mission-critical embedded software, such as telecommunications systems, because customer-discovered faults have very serious consequences and are very expensive to repair. We present an empirical study that evaluated software quality models over several releases to address the question, "How long will a model yield useful predictions?" We also introduce the Classification And Regression Trees (CART) algorithm to software reliability engineering practitioners. We present our method for exploiting CART features to achieve a preferred balance between the two types of misclassification rates. This is desirable because misclassifications of fault-prone modules often have much more severe consequences than misclassifications of those that are not fault-prone. We developed two classification-tree models based on four consecutive releases of a very large legacy telecommunications system. Forty-two software product, process, and execution metrics were candidate predictors. The first software quality model used measurements of the first release as the training data set and measurements of the subsequent three releases as evaluation data sets. The second model used measurements of the second release as the training data set and measurements of the subsequent two releases as evaluation data sets. Both models had accuracy that would be useful to developers.
In DS-CDMA systems, soft handoff techniques provide seamless connections of mobile call between cells. The reserved capacity for soft handoff calls is required to sufficiently support calls in a soft handoff region. H...
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In DS-CDMA systems, soft handoff techniques provide seamless connections of mobile call between cells. The reserved capacity for soft handoff calls is required to sufficiently support calls in a soft handoff region. However, since the capacity required by soft handoff calls varies according to environmental factors, the conventional fixed reserved capacity can be excessive if the required channel capacity by soft handoff calls is small and this may cause a considerable amount of unnecessary blocking of new calls. We propose an adaptive channel reservation scheme which reserves channel capacity as much act necessary according to the variation of soft handoff requests. A simulation result shows that the blocking probability of new coils is reduced by 33% compared with the conventional fixed channel reservation scheme and that it is even larger as the offered load decreases or the maximum reserved capacity increases.
In all-optical networks with wavelength-division multiplexing several connections can share a physical link if the signals are transmitted on different wavelengths. As the number of available wavelengths is limited in...
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The emerging technologies such as software components and the Internet challenge the way software is produced and marketed. The social, technical and organizational aspects of the software business will change signifi...
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This paper focuses on the design of signaling and mobility control protocols for wireless ATM (W-ATM) systems based on the intelligent network (IN) concepts. The employed signaling protocol architecture aims for priva...
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The divergence between the development of the control system and its environment of technical devices in a complex new machine is difficult to handle and usually not addressed by existent development methods. The pres...
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The divergence between the development of the control system and its environment of technical devices in a complex new machine is difficult to handle and usually not addressed by existent development methods. The presented approach considers these questions and at the same time preserves the essential separation of functional and interface domains. Within each domain progress can be made independently using dedicated software tools. Generators provide implementations running with simulation models as well as partial or complete target implementations. The code is statically deterministic and runs in a simple environment with only a few processes. To confirm the real-time behavior of an implementation the generators also provide worst-case traces. Automatic code generation from models and specifications minimizes programming efforts and coding errors. The concept has been proven in a number of industrial and academic projects.
The most important approaches on Internet economics make various assumptions on pricing policies and services. This study introduces main reasonings for and against pricing as a method to reduce congestion of Internet...
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The most important approaches on Internet economics make various assumptions on pricing policies and services. This study introduces main reasonings for and against pricing as a method to reduce congestion of Internet services. These criteria encompass features of the economic model, the pricing mechanism, and the network model. Moreover necessary basics are outlined to handle general influences. Advantages and drawbacks of economics for communication services are discussed to reveal a structured picture of today's situation, which is driven by technological and economic factors at the same time. Based on a sketchy overview of related work a new volume-based approach for pricing communication services in the Internet is proposed and an implementation architecture is introduced.
The emerging asynchronous transfer mode (ATM) technology provides an end-to-end quality-of-service (QoS) for communication services. However within the local communication area traditionally stochastic network technol...
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The emerging asynchronous transfer mode (ATM) technology provides an end-to-end quality-of-service (QoS) for communication services. However within the local communication area traditionally stochastic network technology like Ethernet has been utilized. Therefore, an alternative approach to provide end-to-end ATM services without a complete replacement of traditional local area networking equipment, has been developed. ATM services are offered over Ethernet, where end-systems are attached via an Ethernet segment to an Ethernet-ATM attachment device (ASHMEN). Applications use common ATM signaling and ATM protocols, such as the ATM adaptation layer 5 (AAL 5) protocol, to setup and maintain end-to-end ATM connectivity. The developed protocol architecture includes a protocol mapping from AAL 5 frames into Ethernet frames which has been efficiently implemented in a UNIX-based workstation environment. QoS guarantees can be provided within the ATM network as usual and are offered additionally within the Ethernet segment which is made possible with Ethernet switching technology and a resource management module implemented in the Ethernet-ATM attachment device.
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