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Abstract. We propose a new Connected Dominating Set (CDS) based algorithm for clustering in Mobile Ad hoc Networks (MANETs). Our algorithm is based on Wu and Li's [14] algorithm, however we provide significant modifications by considering the degrees of the nodes during marking process and also provide further heuristics to determine the color of a node in the initial phase. We describe, analyze and measure performance of this new algorithm by simulation and show that it performs better than Wu and Li's [14] algorithm especially in the case of dense networks.

Construction of a backbone architecture is an important issue in mobile ad hoc networks(MANET)s to ease routing and resource management. We propose a new fully distributed algorithm for backbone formation in MANETs that constructs a directed ring architecture. We show the operation of the algorithm, analyze its message complexity and provide results in the simulation environment of ns2. Our results conform that the algorithm is scalable in terms of its running time and roundtrip delay against mobility, surface area, number of nodes and number of clusterheads.

We propose two algorithms to form spanning trees in sensor networks. The first algorithm forms hierarchical clusters of spanning trees with a given root, the sink. All of the nodes in the sensor network are then classified iteratively as subroot, intermediate or leaf nodes. At the end of this phase, the local spanning trees are formed, each having a unique subroot (clusterhead) node. The communication and data aggregation towards the sink by an ordinary node then is accomplished by sending data to the local subroot which routes data towards the sink. A modified version of the first algorithm is also provided which ensures that the obtained tree is a breadth-first search tree where a node can modify its parent to yield shorter distances to the root. Once the subspanning trees in the clusters are formed, a communication architecture such as a ring can be formed among the subroots. This hybrid architecture which provides co-existing spanning trees within clusters yields the necessary foundation for a two-level communication protocol in a sensor network as well as providing a structure for a higher level abstraction such as the γ synchronizer where communication between the clusters is performed using the ring similar to an α synchronizer and the intra cluster communication is accomplished using the sub-spanning trees as in the β synchronizers. We discuss the model along with the algorithms, compare them and comment on their performances.

Resource Discovery (RD) is one of the key issues in successful Grid systems. Yet, new methodologies for RD are constantly researched owing to the dynamicity, heterogeneity and large-scale characteristics of Grids. Recently, synergy and convergence between Grid, Agent and Peer-to-Peer (P2P) systems were pointed out clearly. This paper provides a survey and a qualitative comparison of the most promising approaches (P2P techniques and agent systems) for RD. Viability of Grid systems relies mainly on efficient integration of P2P techniques and mobile agent (MA) systems to bring scaling and decentralised control properties to Grids.

We propose an architecture that consists of a ring of clusters for distributed mutual exclusion algorithms in mobile networks. The mobile network is partitioned into a number of clusters periodically using a graph partitioning algorithm called Fixed Centered Partitioning first. Each cluster is represented by a coordinator node on the ring which implements various distributed mutual exclusion algorithms on behalf of any member in the cluster it represents. We show the implementation of Ricart-Agrawala and Token-based algorithms on this architecture. The message complexities for both algorithms are reduced substantially using the proposed architecture . . .

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Grid systems have gained remarkable importance in the last decade since resource requirements of recent applications increased drastically. Resource discovery in grid systems is a fundamental task which provides searching and locating necessary resources for given processes. There are many different approaches in literature for this problem. Grid resource discovery using centralized and hierarchical systems is a widely used approach which has resulted in many tools to become de facto standards of today's grid resource management. In this paper, we propose a survey of recent grid resource discovery studies based on centralized and hierarchical systems. We provide synthesis, analysis and evaluation of these studies by classification. We also give a comparative study of different classes proposed.[13] Elmroth, E. and J. Tordsson (2005) 'An interoperable, standards-based grid resource broker and job submission service', in First International