Distributed algorithm

About: Distributed algorithm is a research topic. Over the lifetime, 20416 publications have been published within this topic receiving 548109 citations.

Cognitive radio testbed: further details and testing of a distributed genetic algorithm based cognitive engine for programmable radios

Abstract: This paper provides details of a distributed genetic algorithm (GA) based cognitive radio engine model for disaster communications and its implementation in a cognitive radio test bed using programmable radios. Future applications include tactical and covert communications. The cognitive system monitor (CSM) module presented here permits cross layer cognition and adaptation of a programmable radio by classifying the observed channel, matching channel behavior with operational goals, and passing these goals to a wireless system genetic algorithm (WSGA) adaptive controller module to evolve and optimize radio operation. The CSM module algorithm provides for parallel distributed operation and includes a learning classifier and meta-GA functions that work from a knowledge base (which may be distributed) in long term memory to synthesize matched channels and operational goals that are retained in short term memory. Experimental results show that the cognitive engine finds the best tradeoff between a host radio's operational parameters in changing wireless conditions, while the baseline adaptive controller only increases or decreases its data rate based on a threshold, often wasting usable bandwidth or excess power when it is not needed due its inability to learn.

Optimal allocation of electronic content

Abstract: The delivery of large files to single users, such as application programs for some versions of the envisioned network computer, or movies, is expected by many to be one of the main requirements of communication networks. This requires expensive high bandwidth capacity as well as fast and high storage servers. This motivates multimedia providers to optimize the delivery distances, as well as the electronic content allocation. A hierarchical architecture for providing the multimedia content was introduced by Nussbaumer, Patel, Schaffa, and Sternbenz (1994). They also introduced the trade-off between bandwidth and storage requirements for the placement of the content servers on the hierarchy tree. They found the best level of the hierarchy for the server location to minimize the total of the costs of communication and storage. Their algorithm is centralized. We solve the more general ease where servers can be located at different levels of the hierarchy. Our algorithm is distributed, and each node requires a limited memory capacity and computational power. Results for related approaches to caching design are of higher complexity. Results for related classic operations research problems are for centralized algorithms, mostly linear programming, that are not easy to convert into distributed algorithms. Instead, we observe that the use of dynamic programming is more natural for distributed implementations. For the specific problem at hand, we also managed to find a natural function (a generalization of the problem) that simplifies the combination operation used in dynamic programming. We also show how to map such contemporary problems to the area of classical plant location problems in operations research.

Distributed Concurrency Control Performance: A Study of Algorithms, Distribution, and Replication

Abstract: Many concurrency control algorithms have been proposed for use in distributed database systems. Despite the large number of available algorithms, and the fact that distributed database systems are becoming a commercial reality, distributed concurrency control performance tradeoffs are still not well understood. In this paper the authors attempt to shed light on some of the important issues by studying the performance of four representative algorithms - distributed 2PL, wound-wait, basic timestamp ordering, and a distributed optimistic algorithm - using a detailed simulation model of a distributed DBMS. The authors examine the performance of these algorithms for various levels of contention, ''distributedness'' of the workload, and data replication. The results should prove useful to designers of future distributed database systems.

Parallel and Distributed Computing: A Survey of Models, Paradigms and Approaches

Abstract: From the Publisher: The use of parallel and distributed computing has grown dramatically in recent years, resulting in a flood of projects, implementations, and buzzwords. Dr. Leopold cuts through the confusion, presenting a logical and comprehensive survey of the different methodologies used for constructing parallel and distributed systems. Methods are presented independently of language and platform.