Matt Welsh's research while affiliated with Mountain View Pharmaceuticals, Inc. and other places
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Publications (133)
We present nesC, a programming language for networked embedded systems that represent a new design space for application developers. An example of a networked embedded system is a sensor network, which consists of (potentially) thousands of tiny, lowpower "motes," each of which execute concurrent, reactive programs that must operate with severe mem...
The objective of this study was the development of a remote monitoring system to monitor and detect simple motor seizures. Using accelerometer-based kinematic sensors, data were gathered from subjects undergoing medication titration at the Beth Israel Deaconess Medical Center. Over the course of the study, subjects repeatedly performed a predefined...
Micro-aerial vehicle (MAV) swarms are an emerging class of mobile sensing systems. Simulation and staged deployment to prototype testbeds are useful in the early stages of large-scale system design, when hardware is unavailable or deployment at scale is impractical. To faithfully represent the problem domain, a MAV swarm simulator must be able to m...
Micro-aerial vehicle (MAV) swarms are an emerging class of mobile sensing systems. Designing the next generation of such swarms requires the ability to rapidly test algorithms, sensors, and support infrastructure at scale. Simulation is useful in the early stages of such large-scale system design, when hardware is unavailable or deployment at scale...
Research in micro-aerial vehicle (MAV) construction, control, and high-density power sources is enabling swarms of MAVs as a new class of mobile sensing systems. For efficient operation, such systems must adapt to dynamic environments, cope with uncertainty in sensing and control, and operate with limited resources. We propose a novel system archit...
Objective longitudinal monitoring of symptoms related motor fluctuations can provide valuable information for the clinical management of patients with Parkinson's disease. Current methods for long-term monitoring of motor fluctuations, such as patient diaries, are ineffective due to their time consuming and subjective nature. Researchers have shown...
Pervasive environmental monitoring implies a wide range of technical, but
also socio-political challenges, and this applies especially to the sensitive context of
the city. In this paper, we elucidate issues for bringing out pervasive urban sensor
networks and associated concerns relating to fine-grained information provision. We
present the Common...
This whitepaper outlines our vision for developing an open, city-wide sensor network testbed, called CitySense, which will consist of 100+ nodes distributed throughout a city. Our current target for deployment is Cambridge, MA, see Figure
Driven by the confluence between the need to collect data about people's physical, physiological, psychological, cognitive, and behavioral processes in spaces ranging from personal to urban and the recent availability of the technologies that enable this data collection, wireless sensor networks for healthcare have emerged in the recent years. In t...
Passive monitoring is an important tool for measuring, troubleshooting, and protecting modern wireless networks. To date, WiFi monitoring has focused primarily on indoor settings or ephemeral outdoor studies though wardriving. We present Argos, the first urban-scale wireless sensor network designed explicitly to support measurement of ambient WiFi...
Some of the lessons learned regarding successful use of sensor networks for monitoring active and hazardous volcano are presented. The study that involved sensors installed at Reventador volcano also found various myths that persist in the sensor network literature. The myth that nodes are deployed randomly is solved by carefully choosing sensor lo...
Deploying wireless sensor networks to support geophysics presents an interesting challenge. High data-rates required by geophysical instrumentation preclude continuous data collection from even moderately-sized networks. However, geoscientists are used to working directly with complete signals, and therefore uncomfortable with in-network processing...
Objective long-term health monitoring can improve the clinical management of several medical conditions ranging from cardiopulmonary diseases to motor disorders. In this paper, we present our work toward the development of a home-monitoring system. The system is currently used to monitor patients with Parkinson's disease who experience severe motor...
Dyson is a new software architecture for building customizable WLANs. While research in wireless networks has made great strides, these advancements have not seen the light of day in real WLAN deployments. One of the key reasons is that today's WLANs are not architected to embrace change. For example, system administrators cannot fine-tune the asso...
We present MercuryLive, a web-enhanced extension to a body sensor network platform for continuous home-based body motion sensing, interactive supervised data collection sessions, and long-term activity data analysis. The major goal of MercuryLive is to enable practical long-term health monitoring in a home setting and henceforth reduce the effort a...
This paper describes Mercury, a wearable, wireless sen- sor platform for motion analysis of patients being treated for neuromotor disorders, such as Parkinson's Disease, epilepsy, and stroke. In contrast to previous systems intended for short-term use in a laboratory, Mercury is designed to sup- port long-term, longitudinal data collection on patie...
Energy in sensor networks is a distributed, non-transferable resource. Over time, differences in energy availability are likely to arise. Protocols like routing trees may concentrate energy usage at certain nodes. Differences in energy harvesting arising from environmental variations, such as if one node is in the sun and another is in the shade, c...
This paper presents the results of a pilot study to assess the feasibility of using accelerometer data to estimate the severity of symptoms and motor complications in patients with Parkinson's disease. A support vector machine (SVM) classifier was implemented to estimate the severity of tremor, bradykinesia and dyskinesia from accelerometer data fe...
Networking over UHF white spaces is fundamentally different from conventional Wi-Fi along three axes: spatial variation, temporal variation, and fragmentation of the UHF spectrum. Each of these differences gives rise to new challenges for implementing a wireless network in this band. We present the design and implementation of Net7, the first Wi-Fi...
Sensor networks have taken off, but they are still notoriously difficult to program. Our group has deployed sensor networks for volcano monitoring and rehabilitation medicine, and each time we find that tuning the network to achieve the right trade-off in terms of data quality, battery lifetime, and bandwidth usage is quite painful. To make things...
Emergency Medical Services (EMS) are not only responsible for providing prompt and efficient medical care to many different types emergencies, but also for fully documenting each and every event. Unfortunately, the vast majority of EMS events are still documented by hand. The documents are then further processed and entered manually into various bi...
This paper makes the case that operating system designs for sensor networks should focus on the coordination of resource management decisions across the network, rather than merely on individual nodes. We motivate this view by describing the challenges inherent to achieving a globally efficient use of sen- sor network resources, especially when the...
In this paper, we present the vision for an open, urban-scale wireless networking testbed, called CitySense, with the goal of supporting the development and evaluation of novel wireless systems that span an entire city. CitySense is currently under development and will consist of about 100 Linux-based embedded PCs outfitted with dual 802.11a/b/g ra...
This paper presents Pixie, a new sensor node operating system de- signed to support the needs of data-intensive applications. These applications, which include high-resolution monitoring of acoustic, seismic, acceleration, and other signals, involve high data rates and extensive in-network processing. Given the fundamentally resource- limited natur...
An emerging class of sensor networks focuses on reliable collection of high-resolution signals from across the network. In these applications, the system is capable of acquiring more data than can be delivered to the base station, due to severe limits on radio bandwidth and energy. Moreover, these systems are unable to take advantage of conventiona...
Emergency Medical Services (EMS) are not only responsible for providing prompt and efficient medical care to many different types emergencies, but also for fully documenting each and every event. Unfortunately, the vast majority of EMS events are still documented by hand. The documents are then further processed and entered manually into various bi...
Severely resource-constrained devices present a confounding challenge to the functional programmer: we are used to having powerful abstraction facilities at our fingertips, but how can we make use of these tools on a device with an 8- or 16-bit CPU and at most tens of kilobytes of RAM? Motivated by this challenge, we have developed Flask, a domain...
Severely resource-constrained devices present a confounding challenge to the functional programmer: we are used to having powerful abstraction facilities at our fingertips, but how can we make use of these tools on a device with an 8- or 16-bit CPU and at most tens of kilobytes of RAM? Motivated by this challenge, we have developed Flask, a domain...
Reventador Volcano entered an eruptive phase in 2005 which included a wide variety of seismic and infrasonic activity. These are described and illustrated: volcano-tectonic, harmonic tremor, drumbeats, chugging and spasmodic tremor, long period and very long period events. The recording of this simultaneous activity on an array of three broadband,...
We present a critical evaluation of the first known implementation of elliptic curve cryptography over F 2 p for sensor networks based on the 8-bit, 7.3828-MHz MICA2 mote. We offer, along the way, a primer for those interested in the field of cryptography for sensor networks. We discuss, in particular, the decisions underlying our design and altern...
We describe LiveNet, a set of tools and analysis methods for reconstructing the complex behavior of a deployed sensor network. LiveNet is based
on the use of multiple passive packet sniffers co-located with the network, which collect packet traces that are merged to
form a global picture of the network’s operation. The merged trace can be used to r...
This project demonstrates the feasibility of using cost- effective, flexible, and scalable sensor networks to address critical bottlenecks of the emergency response process. For years, emergency medical service providers conducted patient care by manually measuring vital signs, documenting assessments on paper, and communicating over handheld radio...
In this paper, we present the vision for an open, urban-scale wireless networking testbed, called CitySense, with the goal of supporting the development and evaluation of novel wireless systems that span an entire city. CitySense is currently under development and will consist of about 100 Linux-based embedded PCs outfitted with dual 802.11a/b/g ra...
Emergency Medical Services (EMS) are not only responsible for providing prompt and efficient medical care to many different types emergencies, but also for fully documenting each and every event. Unfortunately, the vast majority of EMS events are still documented by hand. The documents are then further processed and entered manually into various bi...
This paper presents Trantor, an architecture for extensible wireless LANs. Trantor enables rapid innovation by removing standardization from the path of introducing new technologies. This is achieved largely by moving the intelligence away from wireless clients and into the infrastructure. In addition to providing extensibility, this approach can a...
A growing class of sensor network applications require high data rates and computationally-intensive node-level processing. When deployed into environments where resources are limited and variable, achieving good performance requires applications to adjust their behavior as resource availability changes. This paper presents Pixie, a new sensor netw...
This paper 1 describes the design of a wireless urban sensor network testbed, CitySense. This first-of-its-kind testbed enables wireless networking researchers to perform repeatable experiments in a real-world environment. Studies that were previously limited to simulation and the laboratory can be vali-dated through long-lived experiments in real-...
The work presented in this paper concerns the development of a body sensor network to monitor changes in the severity of symptoms in patients with Parkinson's disease. We analyzed the impact of different features derived from wearable sensor (i.e. accelerometer) data on the reliability of the prediction of clinical scores that capture the severity...
A great deal of recent work has investigated new programming abstractions and models for sensor networks. However, the complexity of such systems demands a great deal of effort to develop appropriate compilers and runtime platforms to achieve good performance. We will demonstrate Flask [5], a new programming platform for sensor networks that decoup...
Advances in semiconductor technology have resulted in the creation of miniature medical embedded systems that can wirelessly monitor the vital signs of patients. These lightweight medical systems can aid providers in large disasters who become overwhelmed with the large number of patients, limited resources, and insufficient information. In a mass...
In this paper, we present a robust, decentralized approach to RF-based location tracking. Our system, called MoteTrack, is
based on low-power radio transceivers coupled with a modest amount of computation and storage capabilities. MoteTrack does
not rely upon any back-end server or network infrastructure: the location of each mobile node is compute...
During mass casualty incidents, an enormous amount of data, including the vital signs of the patients, the location of the patients, and the location of the first responders must be gathered and communicated efficiently. The Advanced Health and Disaster Aid Network (AID-N) used participatory design methods to develop an electronic triage system tha...
The development of high-level programming environments is essential if wireless sensor networks are to be accessible to nonexperts. In this paper, we present the Regiment system, which consists of a high-level language for spatiotemporal macroprogramming, along with a compiler that translates global programs into node-level code. In Regiment, the p...
The goal of this project is to develop wireless sensors and analysis methods to monitor patients with various motor dysfunctions. We are currently targeting two specific applications: facilitating medication titration in patients with Parkinson's disease and assessing motor recovery in stroke survivors undergoing rehabilitation. In our vision, the...
We present work to develop a wireless wearable sensor system for monitoring patients with Parkinson's disease (PD) in their homes. For monitoring outside the laboratory, a wearable system must not only record data, but also efficiently process data on-board. This manuscript details the analysis of data collected using tethered wearable sensors. Opt...
Advancements in wireless technologies can enable patient monitors to be far more versatile than ones that are used today. We developed wireless vital sign sensors that operate on a robust, infrastructure-independent, and instantaneously deployable wireless communication network. These sensors were easily and rapidly deployed in a diverse variety of...
Blogs and RSS feeds are becoming increasingly popular. The blogging site LiveJournal has over 11 million user accounts, and according to one report, over 1.6 million postings are made to blogs every day. The "Blogosphere" is a new hotbed of Internet-based media that represents a shift from mostly static content to dynamic, continuously-updated disc...
We are developing a low power, low-cost wireless sensor array to conduct real-time signal processing of earthquakes at active volcanoes. The sensor array, which integrates data from both seismic and acoustic sensors, is based on Moteiv TMote Sky wireless sensor nodes (www.moteiv.com). The nodes feature a Texas Instruments MSP430 microcontroller, 48...
The convergence of embedded sensors and pervasive high-performance networking is giving rise to a new class of distributed applications, which we refer to as Internet-scale sensing (ISS). ISS systems consist of a large number of geographically distributed data sources tied into a framework for collecting, filtering, and processing potentially large...
The development of a reliable large-scale wireless sensor network (WSN) is very difficult because of resource constraints, energy budget, and demanding application requirements. Three OS features-OS protection, virtual memory, and preemptive scheduling-can ...
Many emerging sensor network applications involve mobile nodes with communication patterns requiring any-to-any routing topolo-gies. We should be able to build upon the MANET work to im-plement these systems. However, translating these protocols into real implementations on resource-constrained sensor nodes raises a number of challenges. In this pa...
In order for new and emerging physiologic sensors to play increasingly larger roles in the monitoring and management of ill and injured patients, the information they generate must be standardized in an XML format so that it can be integrated with the developing patient care record. To satisfy this need, we have built a prototype sensor gateway tha...
Augmenting heavy and power-hungry data collection equipment with lighten smaller wireless sensor network nodes leads to faster, larger deployments. Arrays comprising dozens of wireless sensor nodes are now possible, allowing scientific studies that aren't feasible with traditional instrumentation. Designing sensor networks to support volcanic studi...
The Advanced Health and Disaster Aid Network (AID-N) project seeks to identify unmet needs of emergency response teams in the Washington, DC area during mass casualty incidents and conduct feasibility tests of technology-based solutions. The decentralized electronic triage and sensing system uses low power, electronic triage sensors to monitor the...
We present a science-centric evaluation of a 19-day sensor net- work deployment at Reventador, an active volcano in Ecuador. Each of the 16 sensors continuously sampled seismic and acoustic data at 100 Hz. Nodes used an event-detection algorithm to trigger on interesting volcanic activity and initiate reliable data transfer to the base station. Dur...
Emergency Medical Services (EMS) are not only responsible for providing prompt and efficient medical care to many different types emergencies, but also for fully documenting each and every event. Unfortunately, the vast majority of EMS events are still documented by hand. The documents are then further processed and entered manually into various bi...
To use their pool of resources efficiently, distributed stream-processing systems push query operators to nodes within the network. Currently, these operators, ranging from simple filters to custom business logic, are placed manually at intermediate nodes along the transmission path to meet application-specific performance goals. Determining placem...
Emergency Medical Services (EMS) are not only responsible for providing prompt and efficient medical care to many different types emergencies, but also for fully documenting each and every event. Unfortunately, the vast majority of EMS events are still documented by hand. The documents are then further processed and entered manually into various bi...
Rapid response to the onset of volcanic activity allows for the early assessment of hazard and risk [Tilling, 1989]. Data from remote volcanoes and volcanoes in countries with poor communication infrastructure can only be obtained via remote sensing [Harris et al., 2000]. By linking notifications of activity from ground-based and space-based system...
Reventador Volcano, Ecuador, became significantly active in the spring of 2005. We deployed three PASSCAL style stations with broad band seismic sensors during a period of six weeks in August and September. Infrasonic microphones were also deployed at each station. One station located on the flanks of the cone recorded numerous seismic events with...
We developed a wireless sensor network for monitoring seismoacoustic
activity at Volcano Reventador, Ecuador. Wireless sensor networks are a
new technology and our group is among the first to apply them to
monitoring volcanoes. The small size, low power, and wireless
communication capabilities can greatly simplify deployments of large
sensor arrays...
We present a novel radio interference based sensor localization method for wireless sensor networks. The technique relies on a pair of nodes emitting radio waves simultaneously at slightly different frequencies. The carrier frequency of the composite ...
Synchronicity is a useful abstraction in many sensor network applications. Communication scheduling, coordinated duty cycling, and time synchronization can make use of a synchronicity primitive that achieves a tight alignment of individual nodes' firing phases. In this paper we present the Reachback Firefly Algorithm (RFA), a decentralized synchron...
We developed and deployed a wireless sensor network for monitoring seismoacoustic activity at Volcán Reventador, Ecuador. Wireless sensor networks are a new technology and our group is among the first to apply them to monitoring volcanoes. The small size, low power, and wireless communication capabilities can greatly simplify deployments of large s...
As wireless sensor networks have emerged as a exciting new area of research in computer science, many of the logistical challenges facing those who wish to develop, deploy, and debug applications on realistic large-scale sensor networks have gone unmet. Manually reprogramming nodes, deploying them into the physical environment, and instrumenting th...
There is widespread agreement that a higher level programming model for sensor networks is needed. A variety of models have been developed, but the community is far from consensus. We propose an intermediate language to speed up the exploration of this design space. Our language, called the token machine language (TML) can be targeted by compilers...
In this paper, we present a robust, decentralized approach to RF-based location tracking. Our system, called MoteTrack, is based on low-power radio transceivers coupled with a modest amount of computation and storage capabilities. MoteTrack does not rely upon any back-end server or network infrastructure: the location of each mobile node is compute...
Distributed stream-based applications, such as continuous query systems, have network scale and time characteristics that challenge traditional distributed query optimization. The optimization sub-problems of plan generation and service placement should be integrated to meet these challenges. These tasks have typically been treated as independent s...
Stream-based overlay networks (SBONs) are one approach to implementing large-scale stream processing systems. A fundamental consideration in an SBON is that of service placement, which determines the physical location of in-network processing services or operators, in such a way that network resources are used efficiently. Service placement consist...
Patients at a disaster scene can greatly benefit from technologies that continuously monitor their vital status and track their locations until they are admitted to the hospital. We have designed and developed a real-time patient monitoring system that integrates vital signs sensors, location sensors, ad-hoc networking, electronic patient records,...
This paper addresses the problem of resource allocation in sensor networks. We are concerned with how to allocate limited energy, radio bandwidth, and other resources to maximize the value of each node's contribution to the network. Sensor networks present a novel resource allocation challenge: given extremely limited re- sources, varying node capa...
This paper describes our experiences using a wireless sensor network to monitor volcanic eruptions with low-frequency acoustic sensors. We developed a wireless sensor array and deployed it in July 2004 at Volcan Tingurahua, an active volcano in central Ecuador. The network collected infrasonic (low-frequency acoustic) signals at 102 Hz, transmittin...
Most emergency medical service (EMS) events are documented by hand. We have implemented a new paradigm: the electronic Patient Care Record (PCR) for emergency medical field usage with a system called iRevive that functions as a mobile database application. This paper discusses a field trial of iRevive in the context of improving the design and usab...
We present TinyOS, a flexible, application-specific operating system for sensor networks. Sen-sor networks consist of (potentially) thousands of tiny, low-power nodes, each of which ex-ecute concurrent, reactive programs that must operate with severe memory and power con-straints. The sensor network challenges of limited resources, event-centric co...
The growing wireless sensor network research community lacks a standard method for evaluating hardware platforms. Traditional benchmark suites do not sufficiently address the needs of sensor network designers. This work provides motivation for a benchmark suite and details an approach for benchmarking TinyOS compatible hardware. To aid the developm...
Wireless sensor networks, consisting of small, low-power devices integrating a modest amount of CPU, memory, and wireless communication, could play an important role in volcanic monitoring applications. Wireless sensor nodes have lower power requirements, are easier to deploy, can can support a larger number of sensors distributed over a wider area...
We present the first known implementation of elliptic curve cryptography over F<sub>2p</sub> for sensor networks based on the 8-bit, 7.3828-MHz MICA2 mote. Through instrumentation of UC Berkeley's TinySec module, we argue that, although secret-key cryptography has been tractable in this domain for some time, there has remained a need for an efficie...
Developing sensor network applications demands a new set of tools to aid programmers. A number of simulation environments have been de- veloped that provide varying degrees of scalability, realism, and detail for understanding the behavior of sensor networks. To date, however, none of these tools have addressed one of the most important aspects of...
Sensor networks, a new class of devices has the potential to revolutionize the capture, processing, and communication of critical data for use by first responders. CodeBlue integrates sensor nodes and other wireless devices into a disaster response setting and provides facilities for ad hoc network formation, resource naming and discovery, security...
This paper presents market-based macroprogramming (MBM), a new paradigm for achieving globally efficient behavior in sensor networks. Rather than programming the individual, low-level behaviors of sensor nodes, MBM defines a virtual market where nodes sell "actions" (such as taking a sensor reading or aggregating data) in response to global price i...
This paper presents market-based macroprogramming (MBM), a new paradigm for achieving globally efficient behavior in sensor networks. Rather than programming the individual, low-level behaviors of sensor nodes, MBM defines a virtual market where nodes sell "actions" (such as taking a sensor reading or aggregating data) in response to global price i...
Research in sensor networks, continuous queries (CQ), and other domains has been motivated by powerful applications that aim to aggregate, assimilate, and interact with scores of sensor networks in parallel. Numerous system ingredients are necessary to make these applications possible. Sensor network research is building some of these components fr...
Integrating wireless sensor networks with the traditional wired grid poses several challenges. The technical challenges center on the development of sensors and sensor network infrastructure, including the need to comply with emerging APIs for grid and Web services. Process-driven challenges, which center on the development and adoption of new busi...
Wireless transmitters deployed throughout an indoor environment offer the opportunity for accurate location tracking of mobile users. Using radio signal information alone, it is possible to determine the location of a roaming node at close to meter-level accuracy. We are particularly concerned with applications in which the robustness of the locati...
