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Many factors affect resource management in computational Grid such as heterogeneous resources, scalability and performance. Computational Grid has adopted web services technology to deal with environmental heterogeneity and to enhance interoperability and scalability. In this paper, we present a Service Oriented Manager (SOM) that can be implemented to manage heterogeneous resources in computational...
Over recent years the depth to which we have grown to rely on networked computer systems as part of the critical national infrastructure has become ever more apparent. Concern over difficulties caused by accidental failures has led to a realisation of the potential for damage that could be caused by targeted attacks and cyber warfare. Current approaches to addressing these problems have tended to...
This work analyzes the downstream impediments of centralized local access networks with LAN capability and proposes an efficient downstream scheme over a distributed upstream control plane, where OLT is relieved from the burden of upstream control function and inter-ONU communication.
In this paper we present a new admission control (AC) for IEEE 802.16. The AC aims to accept new connections according to the negotiated service class (UGS, rtPS, nrTPS, and BE). To achieve this goal we propose to use the token bucket concept that provide QoS for real time traffics without degrading the QoS of non real time traffic. To show the benefit of the proposed AC, an analytical model based...
A broadside-coupled structure is used to build a planar bandpass filter with ultra-wideband (UWB) performance. The design is aimed at achieving a passband that covers the frequency range from 3.1 GHz to 10.6 GHz as required by the modern UWB indoor and outdoor communication systems. To achieve a wide upper stopband, a stepped impedance resonator is employed to suppress the harmonic responses outside...
A spectrum sensing technique for Cognitive Radio (CR) Networks based on the Sequential Analysis of A.Wald is applied to partially coherent channel scenarios. It is shown that using Wald's test, it is possible to reduce the number of samples required to detect the presence of the primary user by approximately a factor of 2 in comparison to the well known Neyman-Pearson test. An expression for the Wald...
Numerous approaches to storing XML data in relational databases have been proposed that take advantage of the maturity of relational database management systems. Index structures to support these approaches have been developed to speed-up XML query processing. Typical drawbacks of these approaches include the lack of support for twig queries and the large storage requirements for the index structures...
Mobile ad-hoc networks (MANETs) are dynamic in nature. Links between nodes may constantly change due to mobility. The performance of the transmission control protocol (TCP) degrades in such an environment mainly due to its inability to differentiate between congestion and link failures which are frequent in MANETs. Several TCP variants were proposed to adapt TCP to a mobile environment. In addition,...
This paper presents the design and analysis of smart antenna systems used for the detection and estimation of correlated radio signals encountered in multipath environments using circular antenna arrays. The MUSIC algorithm along with spatial smoothing is used for this purpose. A Matlab-based graphical user interface (GUI) toolbox is designed specifically for this purpose. The toolbox allows for studying...
In this paper, two estimators are proposed for calculating fine timing and channel impulse response (CIR) of a CD-OFDM based communication system. The proposed low complexity algorithms are designed to operate with asynchronous nodes having independent timing and carrier frequency offsets. These algorithms fully exploit the specially designed structure of time domain preamble used for cooperative...
In wireless sensor networks, sensor data messages are transmitted to a sink node by using wireless multihop transmission with help of intermediate sensor nodes. In event-based sensor networks, no or few sensor data messages are transmitted in usual and burst sensor data messages are required to be transmitted when a sensor detects occurrence of a certain event. It may cause congestion along a multihop...
Although IEEE 802.11e standard is approved for better QoS support, the bandwidth allocation to individual access categories (ACs) can unpredictably vary, preventing efficient QoS provisioning. In this paper, we propose a scheme that jointly maximizes channel capacity and provides network-wide service differentiation to provide fine grained proportional bandwidth allocation to ACs without depending...
We study a multiple-access system with a primary user (PU) and a secondary user (SU) utilizing the same frequency band and communicating with a common receiver. Both users transmit with a fixed transmission rate by employing a channel inversion power control scheme. The SU transmits with a certain probability that depends on the sensing outcome, its queue length and whether it has a new packet arrival...
Multi-hop wireless broadcast is a critical component in ad-hoc wireless networks. Vehicular Ad-hoc Networks (VANET) in particular utilize broadcast as a primary communication mechanism in many applications. Such networks exhibit situations of very high node densities so it is important that the broadcast protocols used to support applications on these networks scale well to high densities. This work...
Web development frameworks (WDFs) that incorporate both Workflow paradigms and the Model View Controller (MVC) are known as WMVC-WFDs. Such frameworks guide the developer in generating the flow of control between the various components. Despite the pressing need for a visual environment to help developers manage the overwhelming number workflows during development, we have not come across any work...
Several centralized algorithms have been proposed for upstream bandwidth-allocation in passive optical networks (PONs); making the optical line terminal (OLT) in the central office the intelligent device that arbitrates time-division access to the shared upstream channel. When the distance between the OLT and optical network units (ONUs) is extended from 20 km to beyond 100 km, as suggested by next...
In the next generation heterogeneous wireless networks, a user with a multi-interface terminal may have network access from different service providers using various technologies. Vertical Handover (VHO) is the capability to switch on-going connections from one Radio Access Network (RAN) to another. This switching is based on the discovered accesses, QoS constraints, operator policies, user preferences...
A web usage mining and visualization tool for analyzing the efficiency of design and structure of index pages is presented. The tool uses visual views to identify optimal locations for links and classes of links in a page. The tool automatically generates the recommended redesign of the page. Measures used to accomplish that are visit frequencies, time spent, and a combined time and visit approach...
The strict avalanche criterion (SAC) is a desirable property of traditional symmetric-key cryptographic algorithms. The SAC is said to be satisfied if, whenever a single input bit is complemented, each of the output bits changes with a probability of one half. In terms of the block ciphers context, such a small change in either the key or the plaintext should cause a drastic change in the ciphertext...
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