Recent advances in wireless sensor networks have led to many new routing protocols specifically designed for sensor networks. Almost all of these routing protocols considered energy efficiency as the ultimate objectiv...
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ISBN:
(纸本)0769519210
Recent advances in wireless sensor networks have led to many new routing protocols specifically designed for sensor networks. Almost all of these routing protocols considered energy efficiency as the ultimate objective in order to maximize the whole network lifetime. However, the introduction of video and imaging sensors has posed additional challenges. Transmission of video and imaging data requires both energy and QoS aware routing in order to ensure efficient usage of the sensors and effective access to the gathered measurements. In this paper, we propose an energy-aware QoS routing protocol, which can also run efficiently with best-effort traffic. The protocol finds a least-cost, delay-constrained path for real-time data in terms of link cost that captures nodes' energy reserve, transmission energy, error rate and other communication parameters. Moreover, throughput for non-real-time data is maximized by adjusting the service rate for both real-time and non-real-time data at sensor nodes. Simulation results have demonstrated the effectiveness of our approach.
The increasing use of computers to manage everyday business poses problems for workers when they are away from their home environment. There are two key problems: How can a mobile worker share a limited part of their ...
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ISBN:
(纸本)0769519210
The increasing use of computers to manage everyday business poses problems for workers when they are away from their home environment. There are two key problems: How can a mobile worker share a limited part of their home environment with colleagues in a foreign environment while maintaining its security,? How can a mobile worker identify and interact with local services available in a foreign environment? This paper describes a scheme for controlling access to pervasive Web services together with a tangible user interface for their presentation.
Recently, a new server-less architecture is proposed for building low-cost yet scalable video streaming systems. In this architecture, video blocks are distributed among user hosts and these hosts cooperate to stream ...
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ISBN:
(纸本)0769520235
Recently, a new server-less architecture is proposed for building low-cost yet scalable video streaming systems. In this architecture, video blocks are distributed among user hosts and these hosts cooperate to stream video blocks to one another. To improve reliability, data and capacity redundancy are introduced to sustain node failures. However, the data placement as well as the redundant data in the system will need to be updated whenever new nodes join the system. Results show that the redundancy update overhead is very significant and even exceeds that in data reorganization. In this study, we present a new Transpositional Redundant Data Update algorithm that takes advantage of the structure of Reed-Solomon Erasure Correction codes and employs a special encoding scheme to significantly reduce the redundancy update overhead, especially when updates are performed in batch.
We study the performance of TFRC-based traffic running across a 3G network. The goal is to evaluate the impact of three different queue management schemes on the end-to-end performance provided by TFRC. We show that d...
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ISBN:
(纸本)0769519210
We study the performance of TFRC-based traffic running across a 3G network. The goal is to evaluate the impact of three different queue management schemes on the end-to-end performance provided by TFRC. We show that drop-on-full queuing is absolutely inappropriate for TFRC traffic running over 3G links since it leads to burst packet drops and oscillatory behaviour in TFRC. Although, this is mostly avoided with RED (Random Early Discard) queuing, we find large initial probing phases of TFRC when using RED. With a simpler active queue management scheme we propose, PDPC, this probing phase is significantly reduced.
In this paper, we present the design and implementation of a VRML97 multi-user layer, which is introduced in the EVE distributed virtual reality platform. Main consideration of our multi-user extension is the ease of ...
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ISBN:
(纸本)0769519210
In this paper, we present the design and implementation of a VRML97 multi-user layer, which is introduced in the EVE distributed virtual reality platform. Main consideration of our multi-user extension is the ease of transforming single-user virtual worlds to multi-user virtual worlds, as well as the conformity with any standard VRML97 browser. Furthermore, we present the EVE's communication plaform, which can be used in order to support Collaborative Virtual Environments (CVEs). Main issues regarding the effective network communication as well as the initialization of the 3D scene are discussed in this paper.
In sensor networks, it is crucial to design and employ energy-efficient communication protocols, since nodes are battery-powered and thus their lifetimes are limited. This paper studies data dissemination in two-tiere...
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The current sensor networks are assumed to be designed for specific applications, having strongly coupled data communication protocols. The future sensor networks are envisioned as comprising heterogeneous devices ass...
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In applications where data needs to be shared among distributed components it is desirable to have overall data consistency at all times. This is crucial for safety-critical systems, where inconsistency can lead to fa...
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ISBN:
(纸本)0769519210
In applications where data needs to be shared among distributed components it is desirable to have overall data consistency at all times. This is crucial for safety-critical systems, where inconsistency can lead to failures. Overall continuous data consistency is, however, rarely possible to achieve. For distributedsystems, a relaxed view based on the temporal validity of data can be proven sufficient. If components in a distributed computer-based system have different temporal validity constraints for the same data, then as long as these constraints are satisfied overall system inconsistency is not harmful. We propose the use of a formal analysis technique for guaranteeing temporal validity of shared data. The approach is based on a real-time temporal logic of knowledge suitable for verification through model checking. It allows us to check that the shared data in the system is consistent "enough" and cannot be a source of failure. We illustrate the approach with an open dynamic real-time distributed computer-based system.
This paper presents a token-based accounting mechanism that alleviates the free riding problem in P2P networks. The approach is complemented by distributed pricing as a flexible and viable scheme to incite users to sh...
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ISBN:
(纸本)0769520235
This paper presents a token-based accounting mechanism that alleviates the free riding problem in P2P networks. The approach is complemented by distributed pricing as a flexible and viable scheme to incite users to share valuable content and to efficiently balance requests among all peers based on economic decisions.
Scientific visualization, especially for massive data sets, has emerged in different disciplines recently. Generally, distributed scientific visualization applications require multiple resources, e.g., high-end comput...
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ISBN:
(纸本)0769520235
Scientific visualization, especially for massive data sets, has emerged in different disciplines recently. Generally, distributed scientific visualization applications require multiple resources, e.g., high-end computing resources to process data, high speed network for data transfer and large size database for data storage. Furthermore, these applications will meet research challenges, e.g., heterogeneous resources, geographically distributed environment and considerable communication delay. This paper studies an application of distributed massive data rendering. We present infrastructure of the distributed rendering environment and explain how Grid technologies are used in this application. Dynamic Pixel Bucket Partition (DPBP) algorithm is a new algorithm proposed for task allocation of distributed rendering application in computational Grids. Experiments in real test ted shows the performance of DPBP algorithm and the framework.
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