Optimized distributed delivery of continuous-media documents over unreliable communication links

Abstract

Video-on-Demand (VoD) applications place very high requirements on the delivery medium. High-quality services should provide for a timely delivery of the data-stream to the clients plus a minimum of playback disturbances. The major contributions of this paper are that it proposes a multiserver, multi-installment (MSMI) solution approach (sending the document in several installments from each server) to the delivery problem and achieves a minimization of the client waiting time, also referred to as the access time (AT ) or start-up latency in the literature. By using multiple spatially distributed servers, we are able to exploit slow connections that would otherwise prevent the deployment of Video-On-Demand-like services, to offer such services in an optimal manner. Additionally, the delivery and playback schedule that is computed by our approach is loss-aware in the sense that it is flexible enough to accommodate packet losses without interrupts. The mathematical framework presented covers both computation and optimization problems associated with the delivery schedule, offering a complete set of guidelines for designing MSMI VoD services. The optimizations presented include the ordering of the servers and determining the number of installments based on the packet-loss probabilities of the communication links. Our analysis guarantees the validity of a delivery schedule recommended by the system by providing a percentage of confidence for an uninterrupted playback at the client site. This, in a way, quantifies the degree of quality of service rendered by the system and the MSMI strategy proposed. The paper is concluded by a rigorous simulation study that showcases the substantial advantages of the proposed approach and explores how optimization of the schedule parameters affects performance.

A Robust Spanning Tree Topology for Data Collection and Dissemination in Distributed Environments

“…By making a small, adjustable portion of each installment overlap with the adjoining section, the system is able to withstand a certain amount of data loss without compromising the continuous nature of the delivery. Similar to our work, Barlas and Veeravalli [9] assume no knowledge of where network disruptions will occur. Given the desired probability of interrupt-free playback, the authors show how to compute the appropriate amount of overlap.…”

“…In [9], Barlas and Veeravalli present a technique for the delivery of continuous-media documents over unreliable communication links. Progress in this area is important in order to realize the widespread adoption of video-ondemand services over the Internet.…”

“…Progress in this area is important in order to realize the widespread adoption of video-ondemand services over the Internet. The solution presented in [9] is to deliver multiple installments of the document to the client. Each installment is transferred from a different, distributed server.…”

Optimizing Continuous Media Delivery by Multiple Distributed Servers to Multiple Clients Using a Genetic Algorithm

“…The derivations presented in subsections 4.1 and 4.2 are simplifications of work presented in [3]. In this paper we focus on examining the behavior of a large scale system involving many clients and servers using a multi-server delivery strategy.…”

“…The framework needed for scheduling such a delivery has been originally presented in [20] and further expanded and refined in subsequent publications [3] for the case of a single client. In this paper we address the problem of how a system with multiple clients and servers behaves and what are the characteristics of the services offered.…”