Deployment-support networks (DSNs) have been proposed as a novel tool for the development, test, deployment, and validation of wireless sensor networks. They are expected to enhance scalability and flexibility in deployment by eliminating cable connections. In this paper, we describe our implementation of a DSN, giving details on the algorithms for topology control and maintenance. We provide various measurements of DSNs spanning up to 71 BTnode rev3 devices, featuring the largest Bluetooth scatternet reported to date. We also discuss our experience gained in the development and experimentation. Our results strongly suggest that our implementation scales well to a large number of nodes.

Clock synchronization is a crucial basic service in ad-hoc sensor networks. Most proposed algorithms employ hierarchical communication structures that may be expensive to maintain when nodes are mobile and network topologies are dynamic. Interval-based synchronization has been proposed as particularly suited for sensor networks, as it does not require any particular communication pattern. In this paper, we show that node mobility puts no burden on interval-based synchronization, but actually helps it. This is not the case for time-estimate-based approaches that rely on specific communication patterns. Mobility resilience therefore further strengthens the case of interval-based clock synchronization for ad-hoc sensor networks

Interval-based synchronization provides the nodes of a distributed system with guaranteed bounds on a common time. This is a crucial piece of infrastructure in many distributed sensing and actuating systems. In this paper, we propose a modification to a known interval-based synchronization algorithm; our new algorithm obtains substantially better results in sensor-network scenarios by taking advantage of the typical drift diversity of the nodes' clocks. We propose a model for synchronization in ad-hoc, sporadic-communication scenarios. The model allows us to identify the worst and the best case in terms of achievable time uncertainty and to show the worst-case optimality of the discussed algorithms. Simulations show that in the average case, our modification significantly reduces the time uncertainty.

Clock synchronization is a crucial basic service in typical sensor networks, since the observations of distributed sensors more often than not need to be ordered ("a happened before b") or otherwise related ("a and b happened within a time window of size x") in time. Ad-hoc networks may exhibit characteristics which make the use of traditional clock-synchronization algorithms infeasible. Recently, algorithms suitable for ad-hoc networks have been presented.We first propose an improvement to an existing algorithm. While needing less computation and no more communication or memory than the original algorithm, our new algorithm always yields equal or better results and thus outperforms the original algorithm. We then examine how even better synchronization can be obtained, possibly at the cost of additional computation, communication, and memory. To this end, we introduce a model for internal synchronization. This model allows us to find an algorithm which makes use of all the data a node can obtain from the network for a given communication pattern and thus provides optimal synchronization in our model.

Large-scale deployment of sensor networks is more and more becoming an issue to researchers and industry alike. The recently revised BTnode architecture provides two wireless radios and facilitates the interconnection of heterogeneous devices. Apart from offering interesting new opportunities in using multi-frontend devices in sensor-network research, this architecture is optimally suited for deployment-support networks as introduced in the following.