Pooja Agarwal

Design Principles for Power Grid Cyber-Infrastructure Authentication Protocols

Recently, there has been an increased focus and a sense of urgency in developing standards for Power Grid systems centered on the need for interoperability. Given the threat against these systems an important goal is the development of effective cyber security standards. However, past experience shows that security protocols are prone to design errors. Focusing on authentication protocols, in this work we discuss key design principles and engineering practices that we believe can help ensure the correctness and effectiveness of standards for authentication in Power Grid protocols; e.g., DNP3. This work builds on past work in the area of principles of authentication in Internet protocols but focuses the discussion on the constraints of the Power Grid; in particular, the need for efficient and highly available systems.

Color-plus-depth level-of-detail in 3D tele-immersive video: a psychophysical approach

This paper presents a psychophysical study that measures the perceptual thresholds of a new factor called Color-plus-Depth Level-of-Detail peculiar to polygon-based 3D tele-immersive video. The results demonstrate the existence of Just Noticeable Degradation and Just Unacceptable Degradation thresholds on the factor. In light of the results, we describe the design and implementation of a real-time perception-based quality adaptor for 3D tele-immersive video. Our experimental results show that the adaptation scheme can reduce resource usage while considerably enhancing the overall perceived visual quality.

I'm the Jedi! - A Case Study of User Experience in 3D Tele-immersive Gaming

In this paper, we present the results from a quantitative and qualitative study of distributed gaming in 3D tele-immersive (3DTI) environments. We explore the Quality of Experience (QoE) of users in the new cyber-physical gaming environment. Guided by a theoretical QoE model, we conducted a case study and evaluated the impact of various Quality of Service (QoS) metrics (e.g., end-to-end delay, visual quality, etc.) on 3DTI gaming experience. We also identified a number of non-technical factors that are not captured by the original theoretical model, such as age, social interaction, and physical setup. Our analysis highlights new implications for the next-generation gaming system design, as well as a more comprehensive conceptual framework that captures non-technical influences for user experience in such environments.

Towards the understanding of human perceptual quality in tele-immersive shared activity

ITU-T G.1070 [7] is widely cited for evaluating the subjective quality of the video conferencing, but its findings cannot be applied to the tele-immersion. The reasons are two fold. First, a tele-immersive system offers end users an unmatched realistic and immersive experience by allowing them to collaborate in the joint virtual space. Second, the human activities in the shared space are not limited to the conferencing conversation. In this paper, we conduct a user study with 19 participants to investigate the human perceptions of two tele-immersive shared activities, where media samples of different qualities are evaluated using the comparative category rating method [9] in case of each activity. We compare our subjective results to those presented in G.1070, and demonstrate heterogeneous human perceptual impacts in different activities.

Lossless compression of synchronized phasor measurements

By reporting time-synchronized phasor magnitudes and phase angles at rates at or above the system frequency, phasor measurement units promise to dramatically increase our ability to understand both historical and real-time power system conditions. This new information does not come without a cost, however, and one potential barrier to the effective utilization of this new data source is the increased amount of information transmission and storage capability these devices require. One way to mitigate the increased storage requirements of synchrophasor data is to compress the data, although this compression should not come at the cost of reduced accuracy. This paper proposes a new method for the lossless compression of voltage magnitude and phase data in which known characteristics of the power system are used to improve upon common, off-the-shelf compression techniques. The method is evaluated with real and simulated PMU data to show its effectiveness.

Bundle of Streams: Concept and Evaluation in Distributed Interactive Multimedia Environments

Distributed Interactive Multimedia Environments (DIMEs) enable geographically distributed people to interact with each other in a joint media-rich virtual environment for a wide range of activities, such as art performance, medical consultation, sport training, etc. The real-time collaboration is made possible by exchanging a set of multi-modal sensory streams over the network in real time. The characterization and evaluation of such multi-stream interactive environments is challenging because the traditional Quality of Service metrics (e.g., delay, jitter) are limited to a per stream basis. In this work, we present a novel cyber-physical, spatio-temporal QoS model that includes new metrics to measure and evaluate QoS for a bundle of streams and across bundles of streams. The new model allows better assessment of performance of any DIME application which employs multiple sensors. We validate our model by comparing the QoS performance of bundle of streams over three transport protocols - UDP, DCCP, and TCP in a 3D tele-immersive test bed.

QoS and resource management in distributed interactive multimedia environments

Quality of Service (QoS) is becoming an integral part of current ubiquitous Distributed Interactive Multimedia Environments (DIMEs) because of their high resource and real-time interactivity demands. It is highly influenced by the management techniques of available resources in these cyber-physical environments. We consider QoS and resource management influenced by two most important resources; the computing (CPU) and networking resources. In this paper, we survey existing DIME-relevant QoS and resource management techniques for these two resources, present their taxonomy, compare them, and show their impacts on DIMEs. Finally, we discuss appropriateness of those techniques in a sample DIME scenario.

CZLoD: A psychophysical approach for 3D tele-immersive video

This article presents a psychophysical study that measures the perceptual thresholds of a new factor called Color-plus-Depth Level-of-Details (CZLoD) peculiar to polygon-based 3D tele-immersive video. The results demonstrate the existence of Just Noticeable Degradation and Just Unacceptable Degradation thresholds on the factor. In light of the results, we design and implement a real-time perception-based quality adaptor for 3D tele-immersive video. Our experimental results show that the adaptation scheme can reduce resource usage (e.g., CPU cycles) while considerably enhancing the overall perceived visual quality. Our analysis confirms the potential temporal and spatial performance benefits achievable with CZLoD adaptation.

SAS kernel: streaming as a service kernel for correlated multi-streaming

This paper presents a novel paradigm of Streaming as a Service (SAS) to model correlated multi-streaming in Distributed Interactive Multimedia Environments. We propose SAS Kernel, a generic, distributed, and modular service kernel realizing SAS paradigm. SAS Kernel features high exibility by employing a configurable interface to allow for input of correlated multi-streams (bundle of streams) from diverse types of sensory devices. It is also highly extensible by allowing user-controlled functions to be applied to bundle of streams in runtime. Experiments with real-world applications demonstrate that the SAS Kernel incurs low overhead in delay, CPU, and bandwidth demands.

A psychophysical approach for real-time 3D video processing

This paper presents a psychophysical approach to control a new factor called Color-plus-Depth Level-of-Detail in polygon-based 3D tele-immersive video. Based on our psychophysical study that demonstrates the existence of perceptual thresholds on the factor, we present a real-time perception-based quality adaptor for 3D tele-immersive video. Our experimental results show that the adaptation scheme can reduce resource usage while considerably enhancing the overall perceived visual quality.