Browsing by Author "MacCallum, David"

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    Approximation Solutions for the Resource Management Problem Using the General Cover Problem
    (2001-12-13) Cardei, Mihaela; MacCallum, David; Chen, Sai; Cardei, Ionut; Du, Ding-Zhu
    Time-critical applications and multimedia systems require a mechanism to arbitrate access to shared resources. Resource Management systems provide the necessary services to applications for admission control and adaptation. This paper defines a model for the Resource Management Problemand describes two near-optimal approximation methods for criticality-based selection scheduling of competing applications. The resource management allocation scheme is designed to follow a set of goals. In this paper we focus on maximizing the number of higher-criticality sessions admitted, where a session is an instance of an application executing on a system, using a set of resources, such as CPU, memory and disk IO. First we reduce the Resource Management Problem to the General Cover Problem and thenpresent two approximation solutions with their performance ratio. First solution uses a greedy algorithm and the second one a linear programming algorithm.
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    Wireless Sensor Networks with Energy Efficient Organization
    (2002-12-08) Cardei, Mihaela; MacCallum, David; Cheng, Xiaoyan; Min, Manki; Jia, Xiaohua; Li, Deying; Du, Ding-Zhu; Hung-Chang Du, David
    A critical aspect of applications with wireless sensor networks is network lifetime. Battery-powered sensors are usable as long as they can communicate captured data to a processing node. Sensing and communications consume energy, therefore judicious power management and scheduling caneffectively extend the operational time. One important class of wireless sensor applications consists of deployment of large number of sensors in an area for environmental monitoring. The data collected by the sensors is sent to a central node for processing. In this paper we propose an efficient method to achieve energy savings by organizing the sensor nodes into a maximum number of disjoint dominating sets (DDS) which are activated successively. Only the sensors from the active set are responsible for monitoring the target area and for disseminating the collected data. All other nodes are into a sleep mode, characterized by a low energy consumption. We define the maximum disjoint dominating sets problem and we design a heuristic that computes the sets. Theoretical analysis and performance evaluation results are presented to verify our approach.