Browsing by Subject "Distributed Scheduling"

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    Auction based scheduling for distributed systems
    (2005) Zarifoğlu, Emrah
    Businesses deal with huge databases over a geographically distributed supply network. When this is combined with scheduling and planning needs, it becomes too difficult to handle. Recently, Fast Consumer Goods sector tends to consolidate their manufacturing facilities on a single supplier serving to a distributed customer network. This decentralized structure causes imperfect information sharing between customers and the supplier. We model this problem as a single machine distributed scheduling problem with job agents representing the customers and the machine agent representing the supplier. For benchmarking purpose, we analyzed the problem under three different scenarios: decentralized utility case (realistic case), centralized utility case, centralized cost case (classical single machine early/tardy problem). We developed Auction Based Algorithm by exploiting the opportunity to use game theoretic approach to solve the problem in the decentralized utility case. We used optimization techniques (Lagrangean Relaxation and Branch-and-Bound) for the centralized cases. Results of our extensive computational experiments indicate that Auction Based Algorithm converges to the upper bound found for the total utility measure.
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    Distributed scheduling
    (1999) Toptal, Ayşegül
    Distributed Scheduling (DS) is a new paradigm that enables the local decisionmakers make their own schedules by considering local objectives and constraints within the boundaries and the overall objective of the whole system. Local schedules from different parts of the system are then combined together to form a final schedule. Since each local decision-maker acts independently from each other, the communication system in a distributed architecture should be carefully designed to achieve better overall system performance. These systems are preferred over the traditional systems due to the ability to update the schedule, flexibility, reactivity and shorter lead times. In this thesis, we review the existing work on DS and propose a new classification framework. We also develop a number of bidding based DS algorithms. These algorithms are tested under various manufacturing environments.
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    OLSR-Aware cross-layer channel access scheduling in wireless mesh networks
    (2009) Kaş, Miray
    A wireless mesh network (WMN) is a communications network in which the nodes are organized to form a mesh topology. WMNs are expected to resolve the limitations and significantly improve the performance of wireless ad-hoc, local area, personal area, and metropolitan area networks, which is the reason that they are experiencing fast-breaking progress and deployments. WMNs typically employ spatial TDMA (STDMA) based channel access schemes which are suitable for the high traffic demands of WMNs. Current research trends focus on using loosening the strict layered network implementation in order to look for possible ways of performance improvements. In this thesis, we propose two STDMA-based cross-layer OLSR-Aware channel access scheduling schemes (one distributed, one centralized) that aim better utilizing the network capacity and increasing the overall application throughput by using OLSR-specific routing layer information in link layer scheduling. The proposed centralized algorithm provides a modification of the traditional vertex coloring algorithm while the distributed algorithm is a fully distributed pseudo-random algorithm in which each node makes decisions using local information. Proposed schemes are compared against one another and against their Non-OLSR-Aware versions via extensive ns-2 simulations. Our simulation results indicate that MAC layer can obtain OLSR-specific information with no extra control overhead and utilizing OLSR-specific information significantly improves the overall network performance both in distributed and centralized schemes. We further show that link layer algorithms that target the maximization of concurrent slot allocations do not necessarily increase the application throughput.