Cory Sharp

Hood: a neighborhood abstraction for sensor networks

This paper proposes a neighborhood programming abstraction for sensor networks, wherein a node can identify a subset of nodes around it by a variety of criteria and share state with those nodes. This abstraction allows developers to design distributed algorithms in terms of the neighborhood abstraction itself, instead of decomposing them into component parts such as messaging protocols, data caches, and neighbor lists. In those applications that are already neighborhood-based, this abstraction is shown to facilitate good application design and to reduce algorithmic complexity, inter-component coupling, and total lines of code. The abstraction as defined here has been successfully used to implement several complex applications and is shown to capture the essence of many more existing distributed sensor network algorithms.

ExScal: elements of an extreme scale wireless sensor network

Project ExScal (for extreme scale) fielded a 1000+ node wireless sensor network and a 200+ node peer-to-peer ad hoc network of 802.11 devices in a 13km by 300m remote area in Florida, USA during December 2004. In comparison with previous deployments, the ExScal application is relatively complex and its networks are the largest ones of either type fielded to date. In this paper, we overview the key requirements of ExScal, the corresponding design of the hardware/software platform and application, and some results of our experiments.

Trio: enabling sustainable and scalable outdoor wireless sensor network deployments

We present the philosophy, design, and initial evaluation of the Trio testbed, a new outdoor sensor network deployment that consists of 557 solar-powered motes, seven gateway nodes, and a root server. The testbed covers an area of approximately 50,000 square meters and was in continuous operation during the last four months of 2005. This new testbed in one of the largest solar-powered outdoor sensor networks ever constructed and it offers a unique platform on which both systems and application software can be tested safely at scale. The testbed is based on Trio, a new mote platform that provides sustainable operation, enables efficient in situ interaction, and supports fail-safe programming. The motivation behind this testbed was to evaluate robust multi-target tracking algorithms at scale. However, using the testbed has stressed the system software, networking protocols, and management tools in ways that have exposed subtle but serious weaknesses that were never discovered using indoor testbeds or smaller deployments. We have been iteratively improving our support software, with the eventual aim of creating a stable hardware-software platform for sustainable, scalable, and flexible testbed deployments

Marionette: using RPC for interactive development and debugging of wireless embedded networks

A main challenge with developing applications for wireless embedded systems is the lack of visibility and control during execution of an application. In this paper, we present a tool suite called Marionette that provides the ability to call functions and to read or write variables on pre-compiled, embedded programs at run-time, without requiring the programmer to add any special code to the application. This rich interface facilitates interactive development and debugging at minimal cost to the node

Flexible hardware abstraction for wireless sensor networks

We present a flexible hardware abstraction architecture (HAA) that balances conflicting requirements of wireless sensor networks (WSNs) applications and the desire for increased portability and streamlined development of applications. Our three-layer design gradually adapts the capabilities of the underlying hardware platforms to the selected platform-independent hardware interface between the operating system core and the application code. At the same time, it allows the applications to utilize a platforms full capabilities-exported at the second layer, when the performance requirements outweigh the need for cross-platform compatibility. We demonstrate the practical value of our approach by presenting how it can be applied to the most important hardware modules that are found in a typical WSN platform. We support our claims using concrete examples from existing hardware abstractions in TinyOS and our implementation of the MSP430 platform that follows the architecture proposed in this paper.

Flexible hardware abstraction of the TI MSP430 microcontroller in TinyOS

Wireless sensor networks (WSNs) promote energy-efficiency as the main design criterion. This introduces rather conflicting requirements for the hardware adaptation layer. Maximizing the efficiency requires that the presentation must closely mimic the underlying hardware model. On the other hand, increasing the level of abstraction simplifies the development, but at the cost of lowered efficiency because it obstructs the link between the application and the hardware. As new microcontrollers and radios are introduced for use in WSNs, applications must be able to effectively use new low power features and peripherals. The MSP430 family of microcontrollers by Texas Instruments is specifically designed for ultra-low-power applications. It incorporates a 16-Bit RISC CPU, peripherals and a clock system. The MSP430F149 is one of the most popular members of the family. As shown in Fig. 1, it has 60 KB Flash, 2 KB of RAM and a flexible clock system sourced by an internal digitally controlled oscillator (DCO) and/or two external oscillators. It also contains a 12-Bit A/D Converter, two independent timers and two USARTs.

Project exscal

Project ExScal (for Extreme Scale) fielded a 1000+ node wireless sensor network and a 200+ node ad hoc network of 802.11 devices in a 1.3km by 300m remote area in Florida during December 2004. In several respects, these networks are likely the largest deployed networks of either type to date. We overview here the key requirements of the project, describe briefly how they were met and experimentally tested, and provide a pointer to our experimental results.