In this work we study the combination of multicost routing and variable transmission power in wireless ad-hoc networks. In multicost routing, each link is assigned a cost vector consisting of several parameters. These...
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In this work we study the combination of multicost routing and variable transmission power in wireless ad-hoc networks. In multicost routing, each link is assigned a cost vector consisting of several parameters. These parameters are treated separately and are combined at the end of the algorithm using various optimization functions, corresponding to different routing schemes, for selecting the optimal path. The cost parameters we use are the hop count, the interference caused, the node residual energies, and the node transmission powers. We assume that nodes can use power control to adjust their transmission power to the desired level. The experiments conducted show that the combination of multicost routing and adjustable transmission power can lead to reduced interference and energy consumption, improving network performance and lifetime.
It is more convenient to talk about changes in a domainspecific way than to formulate them at the programming construct level or-even worse-purely lexical level. Using aspect-oriented programming, changes can be modul...
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It is more convenient to talk about changes in a domainspecific way than to formulate them at the programming construct level or-even worse-purely lexical level. Using aspect-oriented programming, changes can be modularized and made reapplicable. In this paper, selected change types in web applications are analyzed. They are expressed in terms of general change types which, in turn, are implemented using aspect-oriented programming. Some of general change types match aspect-oriented design patterns or their combinations.
Data propagation in wireless sensor networks is usually performed as a multihop process. To deliver a single message, the resources of many sensor nodes are used and a lot of energy is spent. Recently, a novel approac...
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Data propagation in wireless sensor networks is usually performed as a multihop process. To deliver a single message, the resources of many sensor nodes are used and a lot of energy is spent. Recently, a novel approach is catching momentum because of important applications; that of having a mobile sink move inside the network area and collects the data with low energy cost. Here we extend this line of research by proposing and evaluating three new protocols. Our protocols are novel in a) investigating the impact of having many mobile sinks; b) in weak models with restricted mobility, proposing and evaluating a mix of static and mobile sinks; and c) proposing a distributed protocol that tends to equally spread the sinks in the network to further improve performance. Our protocols are simple, based on randomization and assume locally obtainable information. We perform an extensive evaluation via simulation; our findings demonstrate that our solutions scale very well with respect to the number of sinks and significantly reduce energy consumption and delivery delay
In this paper, we study the burstification effect on the TCP synchronization and TCP congestion window mechanism. It is shown that short assembly times are optimal for flows with similar characteristics, while large a...
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ISBN:
(纸本)9781424414321
In this paper, we study the burstification effect on the TCP synchronization and TCP congestion window mechanism. It is shown that short assembly times are optimal for flows with similar characteristics, while large assembly time provide a higher notion of fairness. In addition, this paper analyzes the synchronization of multiple TCP flows when aggregated together over the same optical bursts. It is shown that there is a strong TCP synchronization effect upon burst losses, in the sense that flows’ windows increase/decrease simultaneously, resulting to a significant variation of outgoing traffic. These deficiencies may be dealt with employing a multi-queue burst assembly scheme with different timers and taking into account the TCP dynamics.
This paper proposes a power control scheme for the efficient radio bearer selection in the Multimedia Broadcast/Multicast Service (MBMS) framework of Universal Mobile Telecommunications System (UMTS). The choice of th...
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This paper proposes a power control scheme for the efficient radio bearer selection in the Multimedia Broadcast/Multicast Service (MBMS) framework of Universal Mobile Telecommunications System (UMTS). The choice of the most efficient transport channel in terms ofpower consumption is a key point for the MBMS since a wrong transport channel selection for the transmission of the MBMS data could result to a significant decrease in the total capacity of the system. Diferent UMTS transport channels are examined and an algorithm that defines the switching point between dedicated and common radio bearers is proposed The proposed MBMSpower control scheme selects the transport channel that reduces the Node B's transmission power in every cell of the network with multicast users.
In this paper, we present the architectural design of optical burst-buffers that can truly emulate input queuing and accommodate asynchronous burst operation. The architectural design uses wavelength converters and fi...
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In this paper, we present the architectural design of optical burst-buffers that can truly emulate input queuing and accommodate asynchronous burst operation. The architectural design uses wavelength converters and fixed feed-forward delay lines that are combined to form either a multiple-input buffer or a shared buffer. Both schemes are modular, allowing the logarithmic expansion of buffer size with the number of switching elements (wavelength converters).
The existence of good probabilistic models for the job arrival process and the delay components introduced at the different stages of job processing in a grid environment is important for the improved understanding of...
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ISBN:
(纸本)9781424431526
The existence of good probabilistic models for the job arrival process and the delay components introduced at the different stages of job processing in a grid environment is important for the improved understanding of the computing concept envisioned by the Grid. In this study, we present a thorough analysis of the job arrival process in the EGEE infrastructure and the time durations a job spends at different states in the EGEE environment. We define four delay components of the total job delay and model each component separately. We observe that the job inter-arrival times at the grid level can be adequately modeled by a rounded exponential distribution, while the total job delay (from the time it is generated until the time it completes execution) is dominated by the computing element's queuing and worker node's execution times.
Future grid networks should be able to provide quality of service (QoS) guarantees to their users. In this work we propose a framework for grid networks that provides deterministic delay guarantees to its guaranteed s...
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Future grid networks should be able to provide quality of service (QoS) guarantees to their users. In this work we propose a framework for grid networks that provides deterministic delay guarantees to its guaranteed service (GS) users and best effort service to its best effort (BE) users. The proposed framework is theoretically and experimentally analyzed. We also define four types of computational resources based on the type of users (GS, BE) these resources serve and the priority they give them. We implement the proposed QoS framework for grids and verify that it not only satisfies the delay guarantees given to GS users, but also improves performance in terms of deadlines missed and resource use. In our simulations, data from a real grid network are used, validating in this way the appropriateness and usefulness of the proposed framework.
Fault diagnosis has been becoming a significant topic especially in the control of large scale complex systems. The goal is to detect faults as early as possible and provide a timely warning. A key issue is to prevent...
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Fault diagnosis has been becoming a significant topic especially in the control of large scale complex systems. The goal is to detect faults as early as possible and provide a timely warning. A key issue is to prevent local faults to be developed into system failures that may cause safety hazards, stop temporarily the production and possible detrimental environment impact. This can be achieved by fault tolerant witch means that faults are compensated in such a way to prevent system failures. In this work we propose a method for fault tolerant hybrid control systems (FTHCS), which allows retaining acceptable performance under systems faults. The method is tested on an electric power transmission system presented in our previous work.
Distributed virtual environments tend to become a de facto solution for large-scale networked virtual environments. One of the key issues and problems that need to be handled in the design of a scalable and effective ...
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Distributed virtual environments tend to become a de facto solution for large-scale networked virtual environments. One of the key issues and problems that need to be handled in the design of a scalable and effective distributed virtual environment system is the partitioning problem, which refers to the efficient assignment of the system's workload to the available resources of the system. This paper presents an object driven partitioning approach based on the partitioning algorithm of Lui & Chan, who proposed a three step technique for balancing the workload among the servers of the Distributed Virtual Environment.
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