4D TeleCast: Towards Large Scale Multi-site and Multi-view Dissemination of 3DTI Contents

3D Tele-immersive systems create real-time multi-stream and multi-view 3D collaborative contents from multiple sites to allow interactive shared activities in virtual environments. Applications of 3DTI include online sports, tele-health, remote learning and collaborative arts. In addition to interactive participants in 3DTI environments, we envision a large number of passive non-interactive viewers that (a) watch the interactive activities in 3DTI shared environments, and (b) select views of the activities at run time. To achieve this vision, we present 4D TeleCast, a novel multi-stream 3D content distribution framework for non-interactive viewers providing the functionality of multi-view selection. It addresses the following challenges: (1) supporting a large number of concurrent multi-stream viewers as well as multi-views, (2) preserving the unique nature of 3DTI multi-stream and multi-view dependencies at the viewers, and (3) allowing dynamic viewer behavior such as view changes and large-scale simultaneous viewer arrivals or departures. We divide the problem space into two: (1) multi-stream overlay construction problem that aims to minimize the cost of distribution of multi-stream contents, and maximize the number of concurrent viewers with sufficient viewer dynamism in terms of their resources and availabilities, and (2) effective resource utilization problem that aims to preserve the multi-stream dependencies in a view considering the heterogeneous resource constraints at the viewers. We evaluate 4D TeleCast using extensive simulations with 3DTI activity data and PlanetLab traces.published or submitted for publicationis peer reviewe

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

Abstract—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 Qual-ity 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

A network-state management service

Abstract-We present Statesman, a network-state management service that allows multiple network management applications to operate independently, while maintaining network-wide safety and performance invariants. Network state captures various aspects of the network such as which links are alive and how switches are forwarding traffic. Statesman uses three views of the network state. In observed state, it maintains an up-to-date view of the actual network state. Applications read this state and propose state changes based on their individual goals. Using a model of dependencies among state variables, Statesman merges these proposed states into a target state that is guaranteed to maintain the safety and performance invariants. It then updates the network to the target state. Statesman has been deployed in ten Microsoft Azure datacenters for several months, and three distinct applications have been built on it. We use the experience from this deployment to demonstrate how Statesman enables each application to meet its goals, while maintaining network-wide invariants

Scaling Data-Plane Logging in Large Scale Networks

Understanding and troubleshooting wide area networks (such as military backbone networks and ISP networks) are challenging tasks due to their large, distributed, and highly dynamic nature. Building a system that can record and replay fine-grained behaviors of such networks would simplify this problem by allowing operators to recreate the sequence and precise ordering of events (e.g., packet-level forwarding decisions, route changes, failures) taking place in their networks. However, doing this at large scales seems intractable due to the vast amount of information that would need to be logged. In this paper, we propose a scalable and reliable framework to monitor fine-grained data-plane behavior within a large network. We give a feasible architecture for a distributed logging facility, a tree-based data structure for log compression and show how this logged information helps network operators to detect and debug anomalous behavior of the network. Experimental results obtained through trace-driven simulations and Click software router experiments show that our design is lightweight in terms of processing time, memory requirement and control overhead, yet still achieves over 99%precision in capturing network events.NSF CNS 1053781NSF NeTSE 1012194NSF NeTS 0964081NSF CSR 0834480NSF CSR 0720702International Fulbright S&T Awardpublished or submitted for publicationis peer reviewe

Understanding the Human Perceptions in Tele-Immersive Shared Activity

Both comparative category rating (CCR) and degradation category rating (DCR) methods have been heavily employed in the subjective evaluations of media systems. The resulting metrics, comparative mean-opinion-score (CMOS) and degradation mean-opinion-score (DMOS), can be used to describe the system subjective quality. However, the subjective metrics may work unsuccessfully when the variance of participant votes is large. The diversity in human interests can appear due to the tradeoffs of multiple quality dimensions, which concurrently dominate the overall quality of the media system. In this paper, we conduct a user study with 19 participants to evaluate the subjective quality of two tele-immersive shared activities (TISA), where media samples of different qualities are evaluated in case of each activity. Our study aims at (1) showing the effectiveness and limitation of CMOS and DMOS using real subjective data, and (2) demonstrating the heterogeneous impacts of TISAs on human perceptions.NSF CNS 0834480, 0964081, 1012194, IIP 1110178published or submitted for publicationnot peer reviewe

OpenSession: SDN-based cross-layer multi-stream management protocol for 3D teleimmersion

Abstract—Video conferencing applications pose fundamentally different service requirements than traditional data traffic on the Internet. Strong real-time interactivity is very important among participants unlike video streaming in VoD applications. Requirements are even more stringent in multi-stream and multi-site teleimmersive applications due to strong dependencies across geographically distributed streams. In this paper, we propose OpenSession, a cross-layer session-network control protocol for multi-stream multi-site 3D teleimmersion (3DTI) that improves interactivity, resource utilization and scalability. OpenSession decouples application layer data and control plane functionalities, and partially offloads the data plane functionalities to network layer switches. To control network layer switches during the session run-time, OpenSession leverages support from Software Defined Networking (e.g., OpenFlow). Through extensive evalua-tion with multi-stream 3D teleimmersion among four distributed sites and PlanetLab-based larger 3DTI setup, we show that OpenSession improves 3DTI interactivity and resource usage at the data plane. Furthermore, OpenSession keeps data plane robust against host failures and frequent route updates. I

Alchemi vs Globus: a performance comparison

Alchemi and the Globus Toolkit are open source software toolkits for implementing a Grid. Although both toolkits are designed for the same purpose, their architecture and underlying technology are completely different. Thus, a performance comparison of a Grid implementation in Alchemi with a similar Grid implementation in the Globus Toolkit will be interesting. We built a testbed to compare the performance of the two toolkits. This paper includes tables and graphs to illustrate the comparison. 1