A resilient transport system for wireless sensor networks
Andrew Thomas Campbell, Chieh‐Yih Wan · 2005
This thesis contributes toward the design of a new resilient transport system for wireless sensor networks. Sensor networks have recently emerged as a vital new area in networking research, one that tightly marries sensing, computing, and wireless communications for the first time. Wireless sensors are embedded in the real world and interact closely with the physical environment in which they reside. These networks must be designed to effectively deal with the network's dynamically changing resources, including available energy, bandwidth, processing power, node density, and connectivity. This dissertation focuses on making the sensor network transport system resilient to such changes—in many cases abrupt changes. We define transport resilience as the ability of the network to deliver a sufficient amount of sensing events to meet the applications' fidelity requirement for a set of different traffic classes while reducing the energy consumption of the network. More specifically, we investigate, study, and analyze two classes of transport resilience: (1) the need to reliably deliver data under various error conditions; and (2) the need to maintain the application's fidelity under congested network conditions. We take an experimental systems research approach to the problem of supporting resilience in sensor networks by building an experimental sensor network testbed and evaluating a set of new resilient transport algorithms under various workloads and changing network conditions. We study the behavior of these algorithms under testbed conditions, and apply what is learned toward the construction of larger and more scalable resilient networks. This thesis makes a number of contributions. First, we propose a new reliable delivery transport paradigm for sensor networks called Pump Slowly Fetch Quickly (PSFQ). PSFQ represents a lightweight, scalable and robust transport protocol that is customizable to meet a wide variety of applications needs (e.g., re-programming, actuation, reliable event delivery). We present the design and implementation of PSFQ, and evaluate the protocol using the ns-2 simulator and an experimental wireless sensor testbed based on Berkeley motes and the TinyOS operating system. The PSFQ protocol represents the first reliable transport proposed for wireless sensors networks. (Abstract shortened by UMI.)