Behrooz A. Shirazi

Dynamic Service Composition in Pervasive Computing

Service-oriented architectures (SOAs) promise to provide transparency to resource access by exposing the resources available as services. SOAs have been employed within pervasive computing systems to provide essential support to user tasks by creating services representing the available resources. The mechanism of combining two or more basic services into a possibly complex service is known as service composition. Existing solutions to service composition employ a template-matching approach, where the user needs are expressed as a request template, and through composition, a system would identify services to populate the entities within the request template. However, with the dynamism involved in pervasive environments, the user needs have to be met by exploiting available resources, even when an exact match does not exist. In this paper, we present a novel service composition mechanism for pervasive computing. We employ the service-oriented middleware platform called pervasive information communities organization (PICO) to model and represent resources as services. The proposed service composition mechanism models services as directed attributed graphs, maintains a repository of service graphs, and dynamically combines multiple basic services into complex services. Further, we present a hierarchical overlay structure created among the devices to exploit the resource unevenness, resulting in the capability of providing essential service-related support to resource-poor devices. Results of extensive simulation studies are presented to illustrate the suitability of the proposed mechanism in meeting the challenges of pervasive computing user mobility, heterogeneity, and the uncertain nature of involved resources.

PICO: a middleware framework for pervasive computing

The pervasive information community organization is a framework for creating mission-oriented dynamic communities of autonomous software entities that perform tasks for users and devices. PICOs telemedicine example scenario demonstrates its potential as a simple, unique, and versatile middleware framework for pervasive computing.

TreeMAC: Localized TDMA MAC protocol for real-time high-data-rate sensor networks

Earlier sensor network MAC protocols focus on energy conservation in low-duty cycle applications, while some recent applications involve real-time high-data-rate signals. This motivates us to design an innovative localized TDMA MAC protocol to achieve high throughput and low congestion in data collection sensor networks, besides energy conservation. TreeMAC divides a time cycle into frames and frame into slots. Parent determines childrens frame assignment based on their relative bandwidth demand, and each node calculates its own slot assignment based on its hop-count to the sink. This innovative 2-dimensional frame-slot assignment algorithm has the following nice theory properties. Firstly, given any node, at any time slot, there is at most one active sender in its neighborhood (including itself). Secondly, the packet scheduling with TreeMAC is bufferless, which therefore minimizes the probability of network congestion. Thirdly, the data throughput to gateway is at least 1/3 of the optimum assuming reliable links. Our experiments on a 24 node test bed demonstrate that TreeMAC protocol significantly improves network throughput and energy efficiency, by comparing to the TinyOSs default CSMA MAC protocol and a recent TDMA MAC protocol Funneling-MAC [8].

Air-dropped sensor network for real-time high-fidelity volcano monitoring

This paper presents the design and deployment experience of an air-dropped wireless sensor network for volcano hazard monitoring. The deployment of five stations into the rugged crater of Mount St. Helens only took one hour with a helicopter. The stations communicate with each other through an amplified 802.15.4 radio and establish a self-forming and self-healing multi-hop wireless network. The distance between stations is up to 2 km. Each sensor station collects and delivers real-time continuous seismic, infrasonic, lightning, GPS raw data to a gateway. The main contribution of this paper is the design and evaluation of a robust sensor network to replace data loggers and provide real-time long-term volcano monitoring. The system supports UTC-time synchronized data acquisition with 1ms accuracy, and is online configurable. It has been tested in the lab environment, the outdoor campus and the volcano crater. Despite the heavy rain, snow, and ice as well as gusts exceeding 120 miles per hour, the sensor network has achieved a remarkable packet delivery ratio above 99% with an overall system uptime of about 93.8% over the 1.5 months evaluation period after deployment. Our initial deployment experiences with the system have alleviated the doubts of domain scientists and prove to them that a low-cost sensor network system can support real-time monitoring in extremely harsh environments.

DFRN: a new approach for duplication based scheduling for distributed memory multiprocessor systems

Duplication based scheduling (DBS) is a relatively new approach for solving multiprocessor scheduling problems. The problem is defined as finding an optimal schedule which minimizes the parallel execution time of an application on a target system. We classify DBS algorithms into two categories according to the task duplication method used. We then present our new DBS algorithm that extracts the strong features of the two categories of DBS algorithms. Our simulation study shows that the proposed algorithm achieves considerable performance improvement over existing DBS algorithms with equal or less time complexity. We analytically obtain the boundary condition for the worst case behavior of the proposed algorithm and also prove that the algorithm generates an optimal schedule for a tree structured input directed acyclic graph.

General-purpose systolic arrays

The extension of systolic array architecture from fixed- or special-purpose architectures to general-purpose, SIMD (single-instruction stream, multiple-data stream), MIMD (multiple-instruction stream, multiple-data stream) architectures, and hybrid architectures that combine both commercial and FPGA (field-programmable gate array) technologies is chronicled. The authors present a taxonomy for systolic organizations, discuss each architectures methods of exploiting concurrencies, and compare performance attributes of each. The authors also describe a number of implementation issues that determine a systolic arrays performance efficiency, such as algorithms and mapping, system integration through memory subsystems, cell granularity, and extensibility to a wide variety of topologies.<<ETX>>

Specification and modeling of dynamic, distributed real-time systems

Time constrained systems which operate in dynamic environments may have unknown worst case scenarios, may have large variances in the sizes of the data and event sets that they process (and thus, have large variances in execution latencies and resource requirements), and may not be statically characterizable, even by time invariant statistical distributions. The paper presents a specification language for describing environment dependent features. Also presented is an abstract model that is constructed (statically) from the specifications, and is augmented (dynamically,) with the state of environment dependent features. The model is used to define techniques for QoS (quality of service) monitoring, QoS diagnosis, and resource allocation analysis. Experimental results show the effectiveness of the approach for specification of real time QoS, detection and diagnosis of QoS failures, and restoration of acceptable QoS via reallocation of distributed computer and network resources.

Design and Deployment of Sensor Network for Real-Time High-Fidelity Volcano Monitoring

This paper presents the design and deployment experience of an air-dropped wireless sensor network for volcano hazard monitoring. The deployment of five self-contained stations into the rugged crater of Mount St. Helens only took one hour with a helicopter. The stations communicate with each other through an amplified 802.15.4 radio and establish a self-forming and self-healing multihop wireless network. The transmit distance between stations was up to 8 km with favorable topography. Each sensor station collects and delivers real-time continuous seismic, infrasonic, lightning, GPS raw data to a gateway. The main contribution of this paper is the design of a robust sensor network optimized for rapid deployment during periods of volcanic unrest and provide real-time long-term volcano monitoring. The system supports UTC-time-synchronized data acquisition with 1 ms accuracy, and is remotely configurable. It has been tested in the lab environment, the outdoor campus, and the volcano crater. Despite the heavy rain, snow, and ice as well as gusts exceeding 160 km per hour, the sensor network has achieved a remarkable packet delivery ratio above 99 percent with an overall system uptime of about 93.8 percent over the 1.5 months evaluation period after deployment. Our initial deployment experiences with the system demonstrated to discipline scientists that a low-cost sensor network system can support real-time monitoring in extremely harsh environments.

Home automation and security for mobile devices

As mobile devices continue to grow in popularity and functionality, the demand for advanced ubiquitous mobile applications in our daily lives also increases. This paper deals with the design and implementation of HASec, a Home Automation and Security system for mobile devices, that leverages mobile technology to provide essential security to our homes and associated control operations. In particular, with the help of mobile devices, HASec operates and controls motion detectors and video cameras for remote sensing and surveillance, streams live video and records it for future playback, and finally manages operations on home appliances, such as turning ON/OFF a television or microwave or altering the intensity of lighting around the house. The proposed home security solution hinges on our novel integration of cameras and motion detectors into a mobile application. For instance, when motion is detected, the cameras automatically initiate recording and the iOS device alerts the homeowner of the possible intrusion. HASec has two main components interacting with each other: the iOS application that executes on the mobile device and server-side scripts that run in a cloud. Although HA-Sec is implemented for Apples iOS devices such as iPhone, iPod Touch, and iPad, it can be easily ported to other mobile platforms. Furthermore, our application is not only limited to smart-phones but also can be used by feature phones through their browsers.

DeSiDeRaTa: QoS Management Technology for Dynamic, Scalable, Dependable, Real-Time Systems

Abstract The DeSiDeRaTa project is producing technology to enable the engineering of the emerging generation of distributed real-time systems. Such systems have rigorous Quality of Service (QoS) objectives. They must behave in a dependable manner, respond to threats in a timely fashion and provide continuous availability, even within hostile and unknown environments. To provide the desired QoS in such a context, the DeSiDeRaTa project focuses on QoS specification, dynamic QoS management middleware, and benchmarking of dynamic real-time systems. This paper discusses each of these aspects, and presents experimental results of applying DeSiDeRaTa technology to a dynamic realtime benchmark system.