No abstract

In this paper, we present the design of a VoIP conferencing system that enables the voice communication of multiple users in the Internet. After studying the conversational dynamics in multi-party conferencing, we identify user-observable metrics that affect the perception of conversational quality and their trade-offs. Based on the dynamics and the behavior on delays, jitters, and losses of Internet traces collected in the PlanetLab, we design the transmission topology and schemes for loss concealments and play-out scheduling. Last, we compare the performance of our system and Skype (Version 3.5.0.214) using repeatable experiments that simulate human participants and network conditions in a multi-party conferencing scenario.

No abstract

3D Tele-immersive systems create real-time multistream 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 multistream 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.

No abstract