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Yi Cui

Bio: Yi Cui is an academic researcher from Vanderbilt University. The author has contributed to research in topics: Static routing & Peer-to-peer. The author has an hindex of 20, co-authored 53 publications receiving 1693 citations. Previous affiliations of Yi Cui include Microsoft & Google.

Papers published on a yearly basis

Papers
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Journal ArticleDOI
TL;DR: OStream addresses the on-demand media distribution problem in the context of an overlay network, and takes advantage of the strong buffering capabilities of end hosts, and proposes a novel overlay multicast strategy, oStream.
Abstract: Although initially proposed as the deployable alternative to Internet protocol multicast, the application-layer overlay network actually revolutionizes the way network applications can be built, since each overlay node is an end host and is able to carry out more functions than simply forwarding packets. The paper addresses the on-demand media distribution problem in the context of an overlay network. We take advantage of the strong buffering capabilities of end hosts, and propose a novel overlay multicast strategy, oStream. We have performed extensive analysis and performance evaluation with respect to the scalability and the efficiency of oStream. With respect to the required server bandwidth, we show that oStream defeats the theoretical lower bound of traditional multicast-based approaches, under both sequential and nonsequential stream access patterns. oStream is also robust against bursty requests. With respect to bandwidth consumption on the backbone network, we show that the benefit introduced by oStream overshadows the topological inefficiency (e.g., link stress and stretch) introduced by using application-layer multicast.

289 citations

Proceedings ArticleDOI
01 Jun 2003
TL;DR: The proposed peer-to-peer streaming solution to address the on-demand media distribution problem is efficient at utilizing bandwidth resource of supplying peers, scalable at saving server bandwidth consumption, and optimal at maximizing streaming qualities of all peers.
Abstract: In this paper, we propose a peer-to-peer streaming solution to address the on-demand media distribution problem. We identify two issues, namely the asynchrony of user requests and heterogeneity of peer network bandwidth. Our key techniques to address these two issues are cache-and-relay and layer-encoded streaming. A unique challenge of layered peer-to-peer streaming is that the bandwidth and data availability (number of layers received) of each receiving peer are constrained and heterogeneous, which further limits the bandwidth and data availability of its downstream node when it acts as the supplying peer. This challenge distinguishes our work from existing studies on layered multicast. Our experiments show that our solution is efficient at utilizing bandwidth resource of supplying peers, scalable at saving server bandwidth consumption, and optimal at maximizing streaming qualities of all peers.

181 citations

Journal ArticleDOI
TL;DR: An algorithm is designed, which utilizes the unique characteristic of data aggregation, and is proved to reduce the running time of the fastest existing algorithm by a factor of K, K being the number of commodities.
Abstract: This paper studies energy efficient routing for data aggregation in wireless sensor networks. Our goal is to maximize the lifetime of the network, given the energy constraint on each sensor node. Using linear programming (LP) formulation, we model this problem as a multicommodity flow problem, where a commodity represents the data generated from a sensor node and delivered to a base station. A fast approximate algorithm is presented, which is able to compute (1-e)-approximation to the optimal lifetime for any e > 0. Then along this baseline, we further study several advanced topics. First, we design an algorithm, which utilizes the unique characteristic of data aggregation, and is proved to reduce the running time of the fastest existing algorithm by a factor of K, K being the number of commodities. Second, we extend our algorithm to accommodate the same problem in the setting of multiple base stations, and study its impact on network lifetime improvement. All algorithms are evaluated through both solid theoretical analysis and extensive simulation results.

146 citations

Proceedings ArticleDOI
12 Dec 2005
TL;DR: The TEEVE experiments between two tele-immersive rooms residing in different institutions more than 2000 miles apart show that they can sustain communication of up to 12 3D video streams with 4/spl sim/5 3D frames per second for each stream.
Abstract: Tele-immersive 3D multi-camera room environments are starting to emerge and with them new challenging research questions. One important question is how to organize the large amount of visual data, being captured, processed, transmitted and displayed, and their corresponding resources, over current COTS computing and networking infrastructures so that "everybody" would be able to install and use tele-immersive environments for conferencing and other activities. In this paper, we propose a novel cross-layer control and streaming framework over general purpose delivery infrastructure, called TEEVE (tele-immersive environments for everybody). TEEVE aims for effective and adaptive coordination, synchronization, and soft QoS-enabled delivery of tele-immersive visual streams to remote room(s). The TEEVE experiments between two tele-immersive rooms residing in different institutions more than 2000 miles apart show that we can sustain communication of up to 12 3D video streams with 4/spl sim/5 3D frames per second for each stream, yielding 4/spl sim/5 tele-immersive video rate.

97 citations

Journal ArticleDOI
TL;DR: A middleware framework to support user mobility in the ubiquitous computing environment, whose major mobility functions include user-level handoff management and service instantiation across heterogeneous computing platforms is designed.
Abstract: Advancing mobile computing technologies are enabling “ubiquitous personal computing environment”. In this paper, we focus on an important problem in such environment: user mobility. In the case of user mobility, a user is free to access his/her personalized service at anytime, anywhere, through any possible mobile/fixed devices. Providing mobility support in this scenario poses a series of challenges. The most essential problem is to preserve the user's access to the same service despite changes of the accessing host or service provider. Existing system-level mobility solutions are insufficient to address this issue since it is not aware of the application semantics. On the other hand, making each application to be mobility-aware will greatly increase the development overhead. We argue that the middleware layer is the best place to address this problem. On one hand, it is aware of application semantics. On the other hand, by building application-neutral mobility functions in the middleware layer, we eliminate the need to make each application mobility-aware. In this paper, we design a middleware framework to support user mobility in the ubiquitous computing environment. Its major mobility functions include user-level handoff management and service instantiation across heterogeneous computing platforms. We validate the major mobility functions using our prototype middleware system, and test them on two multimedia applications (Mobile Video Player and Mobile Audio Player). To maximally approximate the real-world user-mobility scenario, we have conducted experiments on a variety of computing platforms and communication paradigms, ranging from T1-connected high-end PC to handheld devices with wireless networks. The results show that our middleware framework is able to provide efficient user mobility support in the heterogeneous computing environment.

69 citations


Cited by
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Proceedings ArticleDOI
13 Mar 2005
TL;DR: This paper presents DONet, a data-driven overlay network for live media streaming, and presents an efficient member and partnership management algorithm, together with an intelligent scheduling algorithm that achieves real-time and continuous distribution of streaming contents.
Abstract: This paper presents DONet, a data-driven overlay network for live media streaming. The core operations in DONet are very simple: every node periodically exchanges data availability information with a set of partners, and retrieves unavailable data from one or more partners, or supplies available data to partners. We emphasize three salient features of this data-driven design: 1) easy to implement, as it does not have to construct and maintain a complex global structure; 2) efficient, as data forwarding is dynamically determined according to data availability while not restricted by specific directions; and 3) robust and resilient, as the partnerships enable adaptive and quick switching among multi-suppliers. We show through analysis that DONet is scalable with bounded delay. We also address a set of practical challenges for realizing DONet, and propose an efficient member and partnership management algorithm, together with an intelligent scheduling algorithm that achieves real-time and continuous distribution of streaming contents. We have extensively evaluated the performance of DONet over the PlanetLab. Our experiments, involving almost all the active PlanetLab nodes, demonstrate that DONet achieves quite good streaming quality even under formidable network conditions. Moreover, its control overhead and transmission delay are both kept at low levels. An Internet-based DONet implementation, called CoolStreaming v.0.9, was released on May 30, 2004, which has attracted over 30000 distinct users with more than 4000 simultaneously being online at some peak times. We discuss the key issues toward designing CoolStreaming in this paper, and present several interesting observations from these large-scale tests; in particular, the larger the overlay size, the better the streaming quality it can deliver.

1,310 citations

Proceedings ArticleDOI
06 Jul 2005
TL;DR: The MMI facial expression database is presented, which includes more than 1500 samples of both static images and image sequences of faces in frontal and in profile view displaying various expressions of emotion, single and multiple facial muscle activation.
Abstract: In the last decade, the research topic of automatic analysis of facial expressions has become a central topic in machine vision research. Nonetheless, there is a glaring lack of a comprehensive, readily accessible reference set of face images that could be used as a basis for benchmarks for efforts in the field. This lack of easily accessible, suitable, common testing resource forms the major impediment to comparing and extending the issues concerned with automatic facial expression analysis. In this paper, we discuss a number of issues that make the problem of creating a benchmark facial expression database difficult. We then present the MMI facial expression database, which includes more than 1500 samples of both static images and image sequences of faces in frontal and in profile view displaying various expressions of emotion, single and multiple facial muscle activation. It has been built as a Web-based direct-manipulation application, allowing easy access and easy search of the available images. This database represents the most comprehensive reference set of images for studies on facial expression analysis to date.

1,093 citations

Journal ArticleDOI
TL;DR: This article presents a survey of data-aggregation algorithms in wireless sensor networks and compares and contrast different algorithms on the basis of performance measures such as lifetime, latency, and data accuracy.
Abstract: Wireless sensor networks consist of sensor nodes with sensing and com- munication capabilities. We focus on data-aggregation problems in energy- constrained sensor networks. The main goal of data-aggregation algorithms is to gather and aggregate data in an energy efficient manner so that net- work lifetime is enhanced. In this article we present a survey of data-aggre- gation algorithms in wireless sensor networks. We compare and contrast different algorithms on the basis of performance measures such as lifetime, latency, and data accuracy. We conclude with possible future research directions.

943 citations

Proceedings ArticleDOI
20 Apr 2009
TL;DR: This paper proposes a solution that combines global optimization with local selection techniques to benefit from the advantages of both worlds and significantly outperforms existing solutions in terms of computation time while achieving close-to-optimal results.
Abstract: The run-time binding of web services has been recently put forward in order to support rapid and dynamic web service compositions. With the growing number of alternative web services that provide the same functionality but differ in quality parameters, the service composition becomes a decision problem on which component services should be selected such that user's end-to-end QoS requirements (e.g. availability, response time) and preferences (e.g. price) are satisfied. Although very efficient, local selection strategy fails short in handling global QoS requirements. Solutions based on global optimization, on the other hand, can handle global constraints, but their poor performance renders them inappropriate for applications with dynamic and real-time requirements. In this paper we address this problem and propose a solution that combines global optimization with local selection techniques to benefit from the advantages of both worlds. The proposed solution consists of two steps: first, we use mixed integer programming (MIP) to find the optimal decomposition of global QoS constraints into local constraints. Second, we use distributed local selection to find the best web services that satisfy these local constraints. The results of experimental evaluation indicate that our approach significantly outperforms existing solutions in terms of computation time while achieving close-to-optimal results.

628 citations