William M. Merrill

Methods for scalable self-assembly of ad hoc wireless sensor networks

In distributed wireless sensing applications such as unattended ground sensor systems, remote planetary exploration, and condition-based maintenance, where the deployment site is remote and/or the scale of the network is large, individual emplacement and configuration of the sensor nodes is difficult. Hence, network self-assembly and continuous network self-organization during the lifetime of the network in a reliable, efficient, and scalable manner are crucial for successful deployment and operation of such networks. This paper provides an overview of the concept of network self-assembly for ad hoc wireless sensor networks at the link layer, with descriptions of results from implementation of a novel network formation mechanism for wireless unattended ground sensor applications using a multicluster hierarchical topology and a novel dual-radio architecture.

Open standard development platforms for distributed sensor networks

In the development of distributed security sensor networks a large variety of prototype systems have been implemented and tested. However these systems tend to be developer specific and require substantial overhead in demonstrating more than one application. To bridge the gap between embedded, networked systems and desktop simulation environments, systems are necessary which are easily deployable and allow extended operation of distributed sensor networks, while allowing the flexibility to quickly test and evaluate a variety of operational algorithms. To enable fast optimization by leveraging the widest development community, open standards for such a portable development system are desired. An open development system allows individual developers and small groups to focus on and optimize specific aspects of a distributed sensor network within realistic deployment constraints, prior to complete integration and deployment of a system within a specific application. By providing an embedded sensor and processing platform with integrated wired and wireless networking, a modular software suite separating access and control of individual processes, and open APIs, algorithm development and software optimization can be greatly accelerated and more robustly tested. To meet the unique needs of distributed sensor network applications, additional separation must be provided between the access to various subsystems, for example real-time embedded control versus tasks with less stringent timing requirements. An open platform that separates these requirements allows developers to accelerate testing and development of applications by focusing on individual components of the distributed sensor system, such as target tracking or low power networking. The WINS NG 2.0 developers platform, provided by Sensoria Corporation for the DARPA/ITO Sensor Information Technology (SensIT) program, provides one example of such a system. This systems bridge the gap between dedicated desktop development environments and embedded application-specif

Energy-aware networked embedded systems for tactical unattended ground sensors

A system architecture, and a hardware implementation leveraging the architecture, has been developed for energy-aware, networked, embedded systems designed for use in tactical unattended ground sensor (UGS) applications. This modular system architecture is designed around a flexible bus design that meets the needs for low-power embedded systems, incorporating support for 32-bit inter-module data transfers, module synchronization, power control, and power distribution. A Linux-based software framework operating on the main system processor has been developed to provide application developers with the ability to easily leverage the hardware functionality of the system. The low-power design methods employed in the system design are discussed along with a system implementation using these methods.