Research on wireless sensor networks (WSNs) has recently moved from the design and evaluation of protocol stacks to real-life implementation and test of the proposed solutions. It would be desirable to be able to run the implementation of a given protocol stack (or of multiple stacks) over different real-life test-beds obtaining comparable results. This requires standardized interfaces to remotely access and control a federation of test-beds, tools to gather data on the protocol performance without affecting the network operations, as well as ways to standardize how data needed to compute the metrics of interest are gathered and analyzed. This paper describes the design and use of JAMES, a new Test-bed Management System for WSNs that addresses all these challenges. We also discuss the use of JAMES features to ease the experimental evaluation of protocol stacks we have developed. Our experiments show that only a few tens of lines need to be written to be able to execute tests on a given protocol stack and that JAMES operations are transparent to the stack behavior.

The paper presents IRIS, an Integrated Routing and Interest dissemination System for wireless sensor networks. The proposed protocols are designed to work under very low duty cycle operations and are jointly optimized for improved efficiency. Routing towards the sink is achieved by exploiting hop count information which is proactively distributed during the interest dissemination phase. Node densities are locally and dynamically estimated at each node and exploited at the MAC layer by means of a cost based probabilistic scheme. A cross-layer routing/MAC scheme is defined where relays to the sink are selected based on nodes' resources (including energy and queue occupancy). The proposed solution is a step towards the definition of complete, self-adapting and autonomous sensor network systems.

This paper concerns the comparative performance evaluation of protocols for clustering and backbone formation in ad hoc networks characterized by a large number of resource-constrained nodes. Our aim is twofold: we provide the first simulation-based detailed investigation of techniques for clustering and backbone formation that are among the most representative of this area of ad hoc research. Second, we delve into the nature of the selected protocols to assess the effects of the "degree of localization" on their operations, i.e., how being able to execute the protocol based only on local information affects the overall protocol performance. Extensive ns2-based simulation results show that highly localized protocols are rewarded with good performance with respect to all metrics of interest which include protocol duration, energy consumption, message overhead, route length, and backbone size.

This work concerns the comparative performance evaluation of protocols for clustering and backbone formation in ad hoc networks characterized by a large number of resource-constrained nodes. A typical example of these networks are wireless sensor networks. The DCA protocol represents those protocols whose backbone construction method is based on selecting nodes as clusterheads and then joining them to form a connected backbone. The algorithm proposed by Wu and Li has been chosen to exemplify those algorithms that build a connected backbone and then prune away redundant nodes. Finally, the algorithm by Wan et al. has been considered here for its more theoretical properties of producing a backbone with a constant approximation factor, linear time complexity and optimal message complexity. In order to obtain a backbone reasonably small at reasonable cost we propose an enhancement of the DCA algorithm, termed DCA-S, which enriches the DCA backbone construction with a recently proposed and resource effective sparsification rule. DCA-S leads to a robust backbone close in size to that generated by the Wan et al. protocol without significantly degrading the performance in terms of all the other relevant metrics.