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Abstract. Wireless ad hoc and sensor networks need to deal with unstable links. In practice the link quality between neighboring nodes fluctuates significantly over time. In this paper we evaluate the impact of topology control on routing performance. We propose a dynamic version of the XTC topology control algorithm. This simple and strictly local protocol removes unreliable and redundant links from the network. By means of physical experiments on an indoor mica2 testbed we study the beneficial effects of topology control on source routing, one of the most common routing schemes for ad hoc and sensor networks. In particular we compare the performance of source routing with and without topology control. Our results show that topology control reduces route failures, increases network throughput, and diminishes average packet delay.

Environmental monitoring is one of the driving applications in the domain of sensor networks. The lifetime of such systems is envisioned to exceed several years. To achieve this longevity in unattended operation it is crucial to minimize energy consumption of the battery-powered sensor nodes. This paper proposes Dozer, a data gathering protocol meeting the requirements of periodic data collection and ultra-low power consumption. The protocol comprises MAC-layer, topology control, and routing all coordinated to reduce energy wastage of the communication subsystem. Using a tree-based network structure, packets are reliably routed towards the data sink. Parents thereby schedule precise rendezvous times for all communication with their children. In a deployed network consisting of 40 TinyOSenabled sensor nodes, Dozer achieves radio duty cycles in the magnitude of 0.2%.

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