Sharmila Ravula

Ecolocation: a sequence based technique for RF localization in wireless sensor networks

In this paper we present a novel sequence-based RF localization algorithm called Ecolocation. Our algorithm determines the location of unknown nodes by examining the ordered sequence of received signal strength (RSS) measurements taken at multiple reference nodes. We employ a constraint-based approach that provides for robust location decoding even in the presence of random RSS fluctuations due to multi-path fading and shadowing. Through extensive systematic simulations, and a representative set of real mote experiments, we show that over a wide range of settings Ecolocation performs better than other state of the art approaches in terms of localization accuracy and precision.

Reconceptualizing a Family of Heterogeneous Embedded Systems via Explicit Architectural Support

It has been widely advocated that software architecture provides an effective set of abstractions for engineering (families of) complex software systems. However, architectural concepts are seldom supported directly at the level of system implementation. In embedded environments in particular, developers are often forced to rely on low-level programming languages. While this is conducive to fine-grain control over the system, it does not lend itself to addressing larger issues such as ensuring architectural integrity or managing an application family. In this paper we describe our experience with fundamentally altering the manner in which a family of embedded applications is designed, analyzed, implemented, deployed, and evolved using explicit architectural constructs. We discuss our strategy, the challenges we faced in the course of our project, the lessons learned in the process, and several open issues that remain unresolved.

A comparative study of DC and AC microgrids in commercial buildings across different climates and operating profiles

Bosch has developed and demonstrated a novel direct current (DC) microgrid system that maximizes the efficiency of locally generated photovoltaic energy while offering high reliability, safety, redundancy, and reduced cost compared to equivalent alternating current (AC) systems. Several demonstration projects validating the system feasibility and expected efficiency gains have been completed and additional ones are in progress. This paper gives an overview of the Bosch DC microgrid system and presents key results from a large simulation study done to estimate the energy savings of the Bosch DC microgrid over conventional AC systems. The study examined the system performance in locations across the United States for several commercial building types and operating profiles. It found that the Bosch DC microgrid uses generated PV energy 6%-8% more efficiently than traditional AC systems.

Exploring the Role of Software Architecture in Dynamic and Fault Tolerant Pervasive Systems

Pervasive systems are rapidly growing in size, complexity, distribution, and heterogeneity. As a result, the traditional practice of developing one-off embedded applications that are often rigid and unmanageable is no longer acceptable. This is particularly evident in a growing class of mobile and dynamic pervasive systems that are highly unpredictable, and thus require flexible and adaptable software support. At the same time, many of these applications are mission critical and have stringent fault tolerance requirements. In this paper, we argue that an effective approach to developing software systems in this domain is to employ the principles of software architecture. We discuss the design and implementation of facilities we have provided in a tool-suite targeted for architecture-based development of fault tolerant pervasive systems.