Browsing by Author "Kusmierek, Ewa"

Now showing 1 - 6 of 6
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    A Network-Aware Approach for Video and Metadata Streaming
    (2007-04-30) Raghuveer, Aravindan; Kusmierek, Ewa; DuHung-Chang, David
    Providing Quality of Service (QoS) for Internet-based video streaming applications requires the server and/or client to be network-aware and adaptive. We present a dynamic rate and quality adaptation algorithm where the server varies its sending rate (without varying the quality level) to adapt to the network and client conditions and only as a last resort, does quality adaptation. We place the adaptation logic at the client since it has better knowledge about both the demand (buffer conditions, variable bit-rate requirements) and supply (network conditions). Our approach is unique because the server's sending rate is calculated based on the client's varying demand (consumption rate) and the network status. Also, we do not model the network as a black-box but instead augment endpoint observations with a feedback from the network to represent its status more precisely. To make an informed adaptation decision, the client requires sizes of all frames in the variable bit rate video. But the overhead involved in sending this metadata is significant. So we propose a lossy compression technique to reduce the amount of control information and consequently the overhead. We also present a scheduling algorithm, DART(Dynamic Scheduling Algorithm for Reduced Trace delivery), to deliver the compressed control information to the client. This algorithm can be used to deliver any form of metadata (like subtitles, alerts etc), especially in applications like IP-TV. Simulations show that the proposed techniques can significantly improve user perceived QoS when compared to other popular adaptation methods.
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    An Architecture for Proxy-Assisted Periodic Broadcast for Large Scale Video Streaming
    (2003-09-17) Kusmierek, Ewa; DuHung-Chang, David; Dong, Yingfei
    Many multimedia applications rely on video streaming techniques. However, large scale video delivery is still very challenging since it requires a large amount of resources such as storage space, network bandwidth and I/Obandwidth. In this paper we propose a proxy-assisted periodic broadcast architecture for video delivery to a large number of clients over the Internet. Our video delivery technique is based on a combination of periodic broadcast by central server and proxy server caching. A proxy server caches either part or the whole video based on the video popularity. We assume that each proxy server may have different capability and that the video popularity in each community can be different and dynamically changing. A video stored in the central server is partitioned into two parts, a server prefix and a server suffix, based onthe aggregated demand for the video from all communities. In principle, the server prefix is delivered by unicast and the server suffix is delivered by periodic broadcast. Such an approach allows to significantly reduce the required I/O bandwidth at a server. The combination of proxy prefix and server prefix defines a wide spectrum of different videodelivery modes. The transmission of a video can be either partially unicast or partially period broadcast depending on the relationship between proxy prefix and server prefix. We further define and solve the optimization problems for proxy prefix selection and server prefixselection in order to minimize the total resource requirements. Performance of our system is evaluated through a number of tests.
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    An Efficient Client Collaboration Framework for Large-Scale Streaming
    (2005-08-08) Kusmierek, Ewa; Dong, Yingfei; DuHung-Chang, David
    In this paper, we propose a loopback approach in a two-level streaming architecture to exploit collaborative client/proxy buffers for improving the quality and efficiency of large-scale streaming applications. At the upper level we use a Content Delivery Network (CDN) to deliver video from a central server to proxy servers. At the lower level a proxy server delivers video with the help of collaborative client caches. In particular, a proxy server and its clients in a local domain cache different portions of a video and form delivery loops. In each loop, a single video stream originates at the proxy, passes through a number of clients, and finally is passed back to the proxy. As a result, with limited bandwidth and storage space contributed by collaborative clients, we are able to significantly reduce the required network bandwidth, I/O bandwidth, and cache space of a proxy. Furthermore, we develop a local repair scheme to address the client failure issue for enhancing service quality and eliminating most required repairing load at the central server. For popular videos, our local repair scheme is able to handle most of single-client failures without service disruption and retransmissions from the central server. Our analysis and simulations have shown the effectiveness of the proposed Loopback Scheme.
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    Highly Adaptive Lookup Systems for Peer-to-Peer Computing
    (2004-02-20) Kusmierek, Ewa; DuHung-Chang, David; Beyer, James C.
    The performance of file sharing peer-to-peer systems depends to a large degree on the speed of lookup operation. A number of proposed solutions rely on distributed hashing techniques. Traditionally nodes are assigned fixed length identifiers which does not allow the table to expand or shrink with the increase or decrease in the node count. With the fixed length identifiers, the performance deteriorates when the number of nodes reaches a high value. On the other hand, the overhead of maintaining per-node state (i.e., information of all adjacent nodes) can be unnecessarily large if the number of nodes is small. The focus of our study is to propose a way to combine the distributed and dynamic nature of the system in a way that allows large and unpredictable changes in both the number and the distribution of nodes while providing scalability and good performance. Our approach is based on dynamic distributed hashing techniques; node identifier length varies with the number of nodes in the system. Hence, the system can adapt to the changing conditions and maintain good performance. In this paper, we describe the operations of the proposed adaptive system and verify its performance through simulations.
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    Proxy-Assisted Periodic Broadcast for Video Streaming with Multiple Servers
    (2003-09-17) Kusmierek, Ewa; DuHung-Chang, David
    Large scale video streaming over Internet requires a large amount of resources such as server I/O bandwidth, network bandwidth. A number of video delivery techniques can be used to lower these requirements. Periodic broadcast by a central server combined with proxy caching offers a significant reduction of the aggregate network and server I/O bandwidth usage. However, the resources available to a single server are still limited. In this paper we propose a system with multiple geographically distributed servers. Multiple servers beside offering increased resources and service availability, allow a further reduction ofnetwork bandwidth usage. The challenge is how to use multiple servers efficiently. We first analyze the dependence of the resource requirements on the number and locations of the servers in a proxy-assisted periodicbroadcast video delivery system. Based on the character of the function describing such a dependence, we formulate and solve the problem of video location and delivery in a way that minimizes resource usage. We explore the trade-offs between network and I/O bandwidth requirements. We evaluate our proposed solutions through a number of tests.
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    Random Packet Marking for Differentiated Services
    (2000-03-17) Kusmierek, Ewa; Koodli, Rajeev
    RPM is a packet marking scheme designed to perform marking on the aggregate traffic belonging to a single Assured Forwarding class at the DS domain ingress node. Decision about drop precedence for each packet is based on the comparison between the arrival rate and two prescribed rates, committed information rate (CIR) and peak information rate (PIR), which are specified in the customer-ISP contract. Colors representing drop precedence are assigned randomly with the probability, which is a function of the arrival rate, CIR and PIR. RPM does not require maintaining any per-flow state. The percentage of packets marked as green, yellow and red for each flow is roughly proportional to the flow's share of bandwidth. Marking probability function can also be modified to allow different degree of conformance to the contract.