Web-services have become most common IT enablers today. Cyber attacks such as the distributed denial of service (DDoS) attacks pose availability concerns which may result into service outages and consequently financia...
详细信息
algorithms synthesis is a new approach in the field of design and analysis of algorithms. Darlington (1978) presented a tree structure starting from a high level definition (by defining permutation function) as root-...
详细信息
algorithms synthesis is a new approach in the field of design and analysis of algorithms. Darlington (1978) presented a tree structure starting from a high level definition (by defining permutation function) as root-node and finally obtaining 6 terminal-nodes corresponding to each sorting algorithm he discussed. The algorithms-synthesis approach starts from a high level definition and ultimately results in the required algorithms. An attempt is made to synthesize some scheduling algorithms starting, as Darlington did, from a high level definition, and using program transformation techniques. Three scheduling algorithms are taken into the synthesis: 1. First-Come-First-Serve, 2. Round-Robin, and 3. Selfish-Round-Robin. The rules applied are mainly the unfolding-and-folding technique as examined by Burstall and Darlington (1977).
While fading effects have long been combatted in 2G wireless networks, primarily devoted to voice calls, they are now seen as an opportunity to increase the capacity of 3G networks that incorporate data traffic. The p...
详细信息
While fading effects have long been combatted in 2G wireless networks, primarily devoted to voice calls, they are now seen as an opportunity to increase the capacity of 3G networks that incorporate data traffic. The packet delay tolerance of data applications, such as file transfers and Web browsing for instance, allows the system flexibility in scheduling a user's packets. So-called opportunistic scheduling, which ensures transmission occurs when radio conditions are most favourable, is the key component of currently developed systems like cdma2000 IS-856 and UNITS HSDPA. We compare the performance of some scheduling schemes using a flow-level approach where the random evolution of the number of ongoing flows is explicitly taken into account. Copyright (C) 2005 AEIT.
In this paper, we consider the accessing of batched requests in a linear storage medium. The batch size is assumed fixed and the access probabilities of individual records known. For a given arrangement of records in ...
详细信息
In a peer-to-peer wireless network, efficient distributed scheduling algorithms generally require all active nodes to acquire the state information of their respective neighbors, e.g., their queue lengths. However, in...
详细信息
ISBN:
(纸本)9781479930012
In a peer-to-peer wireless network, efficient distributed scheduling algorithms generally require all active nodes to acquire the state information of their respective neighbors, e.g., their queue lengths. However, information exchange between nodes is challenging in the absence of a collision-free schedule, mainly due to the half duplex design of today's radios. This paper studies medium access control (MAC) with the help of a physical layer technique that allows all nodes to efficiently exchange state messages with one-hop neighbors at the same time. Low-complexity distributed scheduling algorithms using simultaneous message exchange are proposed for two interference models. One of the algorithms is shown to produce schedules realizable by the greedy maximal scheduling algorithm under the node-exclusive interference model. Simulations demonstrate that both algorithms outperform some popular distributed random access schemes.
First, this paper describes several scheduling algorithms of grid spatial database, that is the random scheduling algorithm,. queue length algorithm, visit cost algorithm and queue visit cost algorithm Second, we make...
详细信息
ISBN:
(纸本)9781424435197
First, this paper describes several scheduling algorithms of grid spatial database, that is the random scheduling algorithm,. queue length algorithm, visit cost algorithm and queue visit cost algorithm Second, we make some simulation experiments on the operating capacity, operating time as well as processing unit utilization to these algorithms respectively with task capacity of 500,1000,2000,5000;at last, the results show that queue visit cost algorithm is the best one among them to deal with tasks under the grid spatial database environment, which can improve the efficiency of system operation, and let the system achieve the best operation status.
The performance of ATM switches are mainly influenced by switching fabric and scheduling algorithms. Input buffered switches have the strong advantage of efficient crossbar usage. This paper presents an input-queued c...
详细信息
The performance of ATM switches are mainly influenced by switching fabric and scheduling algorithms. Input buffered switches have the strong advantage of efficient crossbar usage. This paper presents an input-queued crossbar switches fabric supporting high speed switching, analyzes the scheduling algorithms for unicast trafficts and multicast traffic based on virtualoutput queueing (VOQ).Focusing on their performance issues, some typical schedulers are compared.
This paper addresses the problem of static and dynamic variable voltage scheduling of multi-rate periodic task graphs (i.e., tasks with precedence relationships) and aperiodic tasks in heterogeneous distributed real-t...
详细信息
ISBN:
(纸本)0769514413
This paper addresses the problem of static and dynamic variable voltage scheduling of multi-rate periodic task graphs (i.e., tasks with precedence relationships) and aperiodic tasks in heterogeneous distributed real-time embedded systems. Such an embedded system may contain general-purpose processors, field-programmable gate arrays (FPGAs) and application-specific integrated circuits (ASICs). Variable voltage scheduling is performed only on general-purpose processors. The static scheduling algorithm constructs a variable voltage schedule via heuristics based on critical path analysis and task execution order refinement. The algorithm redistributes the slack in the initial schedule and refines task execution order in an efficient manner. The variable voltage schedule guarantees all the hard deadlines and precedence relationships of periodic tasks. The dynamic scheduling algorithm is also based on an initially valid static schedule. The objective of the on-line scheduling algorithm is to provide best-effort service to soft aperiodic tasks, as well as to reduce the system power consumption by deter-mining clock frequencies (and correspondingly supply voltages) for different tasks at run-time, while still guaranteeing the deadlines and precedence relationships of hard real-time periodic tasks.
With ever-increasing demands for bandwidth optical packet/burst switching is used to utilise more of the available capacity of optical networks. In current prototypes of optical switches time and wavelength multiplexi...
详细信息
ISBN:
(纸本)9781479932146;9781479932139
With ever-increasing demands for bandwidth optical packet/burst switching is used to utilise more of the available capacity of optical networks. In current prototypes of optical switches time and wavelength multiplexing are combined to resolve packet contentions by means of Fiber Delay Lines and wavelength converters in the switching elements. Although optical switches have lower energy consumption than their electronic counterparts, it remains substantial. Since wavelength converters contribute significantly to the switches overall energy consumption, they should be used sparingly, rather than continuously. Current scheduling algorithms however do not take the usage of wavelength converters (and the related energy consumption) into account. To this end, we developed and evaluated new cost-based scheduling algorithms, which take both gap and delay into account to schedule an incoming packet. The performance improvement of these algorithms over existing algorithms can be traded off for a significant reduction in up-time of the wavelength converters by introducing a conversion cost in the involved cost function. This is backed by Monte Carlo simulation results, in which the algorithms are applied both in a void-filling and non-void-filling setting. The algorithms are of the same implementation complexity as current algorithms, and thus of immediate value to switch designers.
The performance evaluation is one of the most important issues for packet scheduling algorithms. The algorithms will be varied with the performance criteria. Because the packet scheduling algorithm has multiple perfor...
详细信息
ISBN:
(纸本)0780370937
The performance evaluation is one of the most important issues for packet scheduling algorithms. The algorithms will be varied with the performance criteria. Because the packet scheduling algorithm has multiple performance objects, how to reach multiple objects simultaneously is one difficult problem. This paper provides a set of integrated performance evaluating criteria from network traffic control model, and the criteria integrates several objects, such as the network performance, user's QoS requirement and system fairness. Then it is discussed and analyzed in details. Moreover, the integrated performance evaluating criteria can be applied to performance evaluation and improvement in network traffic control strategy and algorithms.
暂无评论