Third International Conference on Peer-to-Peer Computing (P2P 03)

Sensor networks, that consist of potentially several thousands of nodes each with sensing (heat, sound, light, magnetism, etc.) and wireless communication capabilities, provide great opportunities for monitoring spatial information about a region of interest. Although spatial query execution has been studied extensively in the context of database systems (e.g., indexing technologies), these solutions are not directly applicable in the context of sensor networks due to the decentralized nature of the sensor networks and the limited computational power and energy scarcity of individual sensor nodes.

In this paper, we present a peer-to-peer indexing structure, namely peer-tree, in order to address the problem of energy- and time-ef.cient execution of spatial queries (such as nearest-neighbor queries) in sensor networks. Loosely speaking, our peer-tree structure can be interpreted as a peer-to-peer version of the centralized R-tree index structure. Using the peer-tree as a building block, we present a peer-to-peer query processing model where a query can be posed in any node of the network without the need of a central server. For achieving minimal energy consumption and minimal response time, our query processing model ensures that only the relevant nodes for the correct execution of a query are involved in the query execution.

Range Addressable Network: A P2P Cache Architecture for Data Ranges

Peer-to-peer computing paradigm is emerging as a scalable and robust model for sharing media objects. In this paper, we propose an architecture and describe the associated algorithms and data structures to support the execution of range selection queries over data scattered across a P2P network especially for resource discovery in grid environments.

We develop a distributed data structure referred to as a range addressable network that provides the following two quality-of-service guarantees: (i) the located peer is one with the smallest superset of the query range (important from the application perspective), and (ii) in a P2P network of n peers, a query is routed through O(log n) peers before the intended peer is found (important from the system perspective).

Our preliminary experimental evaluation indicates that the range addressable network has desirable properties of scalability and load-balancing, which are crucial for the success of a large-scale P2P system.

Connectivity Based Node Clustering in Decentralized Peer-to-Peer Networks

Connectivity based node clustering has wide ranging applications in decentralized Peer-to-Peer (P2P) networks such as P2P file sharing systems, mobile ad-hoc networks, P2P sensor networks and so forth. This paper describes a Connectivity-based Distributed Node Clustering scheme (CDC). This scheme presents a scalable and an efficient solution for discovering connectivity based clusters in peer networks. In contrast to centralized graph clustering algorithms, the CDC scheme is completely decentralized and it only assumes the knowledge of neighbor nodes, instead of requiring a global knowledge of the network (graph) to be available. An important feature of the CDC scheme is its ability to cluster the entire network automatically or to discover clusters around a given set of nodes. We provide experimental evaluations of the CDC scheme, addressing its effectiveness in discovering good quality clusters. Our experiments show that utilizing message-based connectivity structure can considerably reduce the messaging cost, and provide better utilization of resources, which in turn improves the quality of service of the applications executing over decentralized peer-to-peer networks.

-- FranzStrasser - 18 Dec 2003