Contention-based node selection with applications to relay communications and load balancing
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Contention-based node selection with applications to relay communications and load balancing Günther Brandner1* , Christian Bettstetter1,2 and Udo Schilcher1 Abstract This article proposes and analyzes a distributed probabilistic selection protocol in which several nodes perform a random access competition on a shared slotted channel. Nodes that are better suited according to some metric are preferred in the random access and are thus selected with high likelihood. Analytical performance studies are made in terms of reliability, message complexity, and delay. The protocol is applied in two case studies: relay communications and load balancing in wireless networks. In relay communications, a node is selected based on its channel state to serve as relay. In load balancing, a node is selected based on its battery charge state to perform a task. Results indicate that selecting nodes based on the observed metric contributes to better performance and longer network lifetime. 1 Introduction Many network protocols require a distributed solution for selecting a node from a candidate set to perform a certain task. Examples of such scenarios from the area of mobile computing include the selection of a cluster head in multihop networks [1], a relay node in cooperative wireless communications [2], and a gathering node for data processing in sensor networks [3]. This article proposes such a distributed mechanism. The basic concepts are as follows: First, the selection is performed in a contention-based manner with the goal to obtain low signaling overhead. Two random access methods are proposed as alternatives. The first one maximizes the probability of successful selection; the second one reduces the signaling overhead in terms of reply messages sent by candidate nodes. Second, the selection takes into account the specific capability of each node to perform a given task. This capability is quantified in terms of a metric maintained by each node. Nodes with a high metric are well-suited to become selected and are thus preferred in the random access process. The node selection is evaluated in two case studies. The first case study refers to the selection of a relay node *Correspondence: [email protected] 1 Mobile Systems Group, Institute of Networked and Embedded Systems, University of Klagenfurt, Klagenfurt 9020, Austria Full list of author information is available at the end of the article
in a multipath fading environment [2]. Each node maintains a metric describing its current channel quality. The selection process prefers nodes with good channels to be selected as relay. The second case study refers to the selection of nodes performing energy-consuming tasks, and the goal is to balance the load in the network. Using the battery charge state of each node as a selection metric, the proposed selection mechanism contributes toward a longer network lifetime, i.e., it increases the time span until one of the nodes fails due to an empty battery. Many algorithms for node selection in distributed
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