Catálogo de publicaciones - libros

In mobile sensor networks, the problem, i.e., maximizing and/or maintaining overall sensing coverage, is a fundamental research issue attracting many researchers. Existing coverage improvement algorithms such as sensor self-deployment algorithms and sensor relocation protocols enhance coverage with limitations due to their specialized design purposes. In this paper, we propose an integrated self-deployment and coverage maintenance scheme, which solves the coverage improvement problem in a complete sense. The proposed scheme is an integration of four algorithms: a node redundancy determination algorithm, a sensor self-deployment algorithm, a sensor relocation protocol, and a sensor replenishment protocol. By this scheme, redundant sensors are placed together with non-redundant ones in the target field at random; non-redundant sensors autonomously scatter to form a network with maximal coverage after initial placement; all the sensors collaborate to compensate coverage loss throughout network lifetime. Mentionably, we notice that no existing scheme besides ours take into account the impact on coverage from nodal sensing range diminishment. At the end, we summarize the paper and discuss our future work.

Recently, many peer-to-peer (P2P) systems have been introduced to implement large scale resource sharing systems. Such P2P systems exhibit interesting features like self configuration, self-healing and complete decentralization, which make the systems appealing for deployment in ad hoc environments as well. This paper proposes a power-aware peer-to-peer system specially designed for the ad-hoc networks based on Gnutella with hierarchical structure. The objectives of this paper is to enhance performance as well as to prolong the lifespan of the participating P2P nodes. To pursue the objectives, the proposed system chooses ultrapeers which can serve the overlay network better, by considering battery power, connectivity with other peers and commitment level of each node. It also introduces proactive approach for distributing ultrapeer information to reduce P2P overheads. According to the simulation results, the proposed system provides higher query success rate, shorter query response time, less overhead and extended lifespan of peers.

We approach the problem of load balancing for wireless multi-hop networks by distributed optimisation. We implement an approximation algorithm for minimising the maximum network congestion as a modification to the routing protocol. The algorithm is based on shortest-path computations that are integrated into the route discovery and maintenance process. The resulting Balanced Multipath Source Routing () protocol does not need to disseminate global information throughout the network. Our simulations with the ns2 simulator show a gain of 14% to 69% in the throughput, depending on the setup, compared to for a high network load.