Zhengyi Le

Digital cities of the future: Extending @home assistive technologies for the elderly and the disabled

In the digital city of the future there is the vision of seamless virtual and physical access for every home and between each home and the workplace, as well as critical city infrastructure such as the post office, the bank, hospitals, transportation systems, and other entities. This paper provides an overview of technical and other issues in extending at home (@home) assistive technologies for the elderly and the disabled. The paper starts by giving a vision of what this city is supposed to look like and how a human is to act, navigate and function in it. A framework for extending assistive technologies is proposed that considers individuals belonging to special groups of interest and locations other than their home. Technology has already reached the state of ubiquitous and pervasive sensor devices measuring everything, from temperature to human behavior. Implanting intelligence into and connecting such devices will be of immense use in preventive healthcare, security in industrial installations, greater energy efficiency, and numerous other applications. The paper reviews enabling technologies that exist and focuses on healthcare applications that support a longer and higher quality of life at home for the elderly and the disabled. It discusses intelligent platforms involving agents, context-aware and location-based services, and classification systems that enable advanced monitoring and interpretation of patient status and optimization of the environment to improve medical assessments. The paper concludes with a discussion of some of the challenges that exist in extending @home assistive technologies to @city assistive technologies.

Source location privacy against laptop-class attacks in sensor networks

Sensor networks may be used in many monitoring applications where the locations of the monitored objects are quite sensitive and need to be protected. Previous research mainly focuses on protecting source location against mote-class attackers who only have a local view of the network traffic. In this paper, we focus on how to protect the source location against laptop-class attackers who have a global view of the network traffic. This paper proposes four schemes---naive, global, greedy, and probabilistic---to deal with laptop-class attacks. The naive solution uses maintenance messages sent periodically to hide real event reports. The global and greedy solutions improve the naive solution by reducing the latency of event delivery without increasing communication overhead. The probabilistic solution further improves the performance by reducing communication overhead without sacrificing location privacy. Experiments show that the probabilistic solution is practical for providing source location privacy against a laptop-class attacker.

Abnormal human behavioral pattern detection in assisted living environments

In recent years, there is a growing interest about assisted living environments especially for the elderly who live alone, due to the increasing number of aged people. In order for them to live safe and healthy, we need to detect abnormal behavior that may cause severe and emergent situations for the elderly. In this work, we suggest a method that detects abnormal behavior using wireless sensor networks. We model an episode that is a series of events, which includes spatial and temporal information about the subject being monitored. We define a similarity scoring function that compares two episodes taking into consideration temporal aspects. We propose a way to determine a threshold to divide episodes into two groups that reduces wrong classification. Weights on individual functions that consist the similarity function are determined experimentally so that they can produce the good results in terms of area under curve in receiver operating characteristic (ROC) curve.

Towards an evaluation framework for assistive environments

As the world population is aging, there is an increasing need to support independent living of elderly people. Assistive environments incorporate the latest pervasive and ubiquitous technologies and provide a viable alternative to traditional assistive living. In this paper, we propose an evaluation framework to assess the quality of assistive environments. An assistive environment can be successful only if the potential users are willing to adopt it. The proposed framework identifies a set of attributes that are considered critical to user adoption. Sample metrics, as well as possible approaches to measure them, are also suggested to quantify those attributes. The framework is illustrated using an experimental assistive apartment environment that is being built at the University of Texas at Arlington.

Mobile anchor-free localization for wireless sensor networks

In this paper, we consider how to localize individual nodes in a wireless sensor network when some subset of the network nodes can be in motion at any given time. For situations in which it is not practical or cost-efficient to use GPS or anchor nodes, this paper proposes an Anchor-Free Mobile Geographic Distributed Localization (MGDL) algorithm for wireless sensor networks. Taking advantage of the accelerometers that are present in standard motes, MGDL estimates the distance moved by each node. If this distance is beyond a threshold, then this node will trigger a series of mobile localization procedures to recalculate and update its location in the node itself. Such procedures will be stopped when the node stops moving. Data collected using Tmote Invent nodes (Moteiv Inc.) and simulations show that the proposed detection method can efficiently detect the movement, and that the localization is accurate and the communication is efficient in different static and mobile contexts.

A Hierarchical Key-Insulated Signature Scheme in the CA Trust Model

In key-insulated cryptography, there are many private keys with different indexes and a single, fixed public key. When the trust model includes multiple Certification Authorities (CAs), it can be used to shorten the verification path and mitigate the damage caused by the compromise of a CA’s private key. Existing work requires that the total number of CAs be fixed and that a trusted keystore store all private keys. This paper presents a hierarchical key-insulated signature scheme, called HKI, which converts existing key-insulated methods to a hierarchical scheme. Our scheme allows the system to repeatedly generate a new private key for a new CA and also provides two important features, namely a shortened verification path and mitigated damage. By basing our approach on a general key-insulated scheme, we have made it possible to take advantage of any future improvements in computation complexity, key length, or robustness in current key-insulated methods.

Human behavioral detection and data cleaning in assisted living environment using wireless sensor networks

Due to the increasing number of the elderly, more and more people need to have additional health care such as medical or environmental monitoring information at home or nursing facility. Most elderly people are likely to have a sudden behavioral changes due to their aging or existing health problems. Therefore, it is necessary to have an autonomous system that can monitor them in order to prevent emergent situation in advance. In this paper, we present a wireless sensor network system that can recognize human behavioral patterns of the elderly who lives alone. We model episodes that are series of events for a person who lives in an one-bedroom apartment. We propose data cleaning techniques in both sensor and base station sides for the erroneous environment of wireless sensor networks. Based on these techniques, we try to extract discrete events as close as possible to effective events. We introduce non-real time analysis to recognize human behavioral patterns on the centralized system, which can be further extended to a real-time analysis. We also adopt an existing search technique to apply it to detect similar or abnormal behavior. We experiment the proposed system by gathering behavioral pattern data from the miniature one-bedroom apartment that is equipped with SunSPOTs in our HERACLEIA Laboratory. We look up the resulting episodes from our experiment in the dictionary that is a set of predetermined episodes using the suggested algorithm.

Event-based experiments in an assistive environment using wireless sensor networks and voice recognition

As the population is aging, more and more people require additional health care, either at home, in the work place or in a nursing facility. Now, a need exists for health monitoring outside of hospital conditions. These new conditions make this technology of interest for developing health care monitoring systems that can be deployed in many different environments, including the home. Other systems in development employ a wide range of different sensors, including cameras, and recording the information for processing. These systems all involve using an apartment environment seeded with sensors for detecting human behavior and activities. While these systems are embedded in assistive environments, they do not have a comprehensive approach to describe events, or handle a general and rapid deployment into different configurations using wireless technology. In this paper, we are presenting our ongoing project of deploying sensors into an assistive environment. We currently are using SunSPOT sensor motes, where each one has been programmed for a specific role based on rules describing events. In addition, we are developing a voice recognition system for reaction to human input in the same environment. Our system can be rapidly deployed without requiring additional wiring or unwanted intrusion into the human patients life.

PEON: privacy-enhanced opportunistic networks with applications in assistive environments

Opportunistic Networking holds a great deal of potential for making communications easier and more flexible in pervasive assistive environments. However, security and privacy must be addressed to make these communications acceptable with respect to protecting patient privacy. In this position paper, we propose Privacy-Enhanced Opportunistic Networking (PEON), a system for using opportunistic networking in privacy-preserving way. PEON uses concepts from anonymous communications, rerouting messages through groups of peer nodes to hide the relation between the sources and destinations. By modifying group size, we can trade off between privacy and communication overhead. Further, individual nodes can make a similar trade off by changing the number of intermediate groups. We describe the cryptographic tools needed to facilitate changes in group membership and the design of simulation experiments that we will conduct to evaluate the overhead and effectiveness of our approach.

An event driven framework for assistive CPS environments

Assistive Cyberphysical Systems (ACPS) are pervasive and ubiquitous systems connecting the cyber with the physical worlds, with the aim to assist a humans daily activities both at home and at work. We present an event driven framework with event identification mechanisms that drive actuators, transform a substrate and alter human behavior in a feedback loop process that allows a human to control her ACPS. This framework is a dynamic, context aware, adaptive, self-repairing and high-confidence system that couples computational power with physical substrate (testbed) control and command; it monitors human activities with differential privacy and security capabilities, recognizes events, human needs from lifestyle, and processes environmental and longitudinal health data.