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Media firms are increasingly using tiered infrastructure to cost-effectively manage heterogeneous resources by strategically allocating digital content across multiple tiers to avoid overcapacitating high-performance, expensive infrastructure tiers. Complex migrations in [...]

Due to its native return channel and its ability to easily address each user individually an IPTV system is very well suited to offer on-demand services. Those services are becoming more popular as there is an undeniable trend that users want to watch the offered content when and where it suits them best. Because multicast can no longer be relied upon for such services, as was the case when offering linear-programming TV, this trend risks to increase the traffic unwieldy over some parts of the IPTV network unless caches are deployed in strategic places within it. Since caches are limited in size and the popularity of on-demand content is volatile (i.e., changing over time), it is not straightforward to decide which objects to cache at which moment in time. This paper introduces and studies a caching algorithm that tracks the popularity of objects to make intelligent caching decisions. We will show that when its parameters are set equal or close to their optimal values this algorithm outperforms traditional algorithms as LRU (Least-Recently Used) and LFU (Least-Frequently Used). After a generic study of the algorithm fed by a user demand model that takes the volatility of the objects into account we will discuss two particular cases of an on-demand service, video-on-demand and catch-up TV, for each of which we give guidelines on how to dimension their associated caches. Index Terms--Caching, interactive TV, internet protocol TV, user modeling.

In this paper, we propose an Adaptive Hybrid Transmission (AHT) scheme for on-demand mobile IPTV service over broadband wireless access network (i.e. mobile WiMAX, 802.16e). Proposed algorithm utilizes hybrid mechanism which combines multi-channel multicasting and unicast scheme to enhance not only service blocking probability but also reduce overall bandwidth consumption of the wireless system which has very limited resources compared to wired networks. An adaptive resource allocation algorithm is also proposed, and is shown to achieve minimum blocking probability. In order to evaluate the performance, we compare proposed algorithm against traditional unicast and multicast schemes. Index Terms--Adaptive, IPTV, mobile, multicast, on-demand, WiMAX.

The required real-time and high-rate transfers for multimedia data severely limit the number of video streams that can be delivered concurrently. Resource-sharing techniques address this problem and can be classified into two main classes: stream merging and periodic broadcasting. We evaluate through extensive simulation major resource-sharing techniques from the two classes, considering different service models and video workloads. We utilize this extensive analysis in developing a workload-aware hybrid solution (WAHS) that combines the advantages of the best performers among resource-sharing techniques. Moreover, we propose a statistical cache management (SCM) approach and derive analytical models for optimal cache allocation to reduce further the demands on the disk I/O when various resource sharing techniques are used. Index Terms--Cache management, performance evaluation, periodic broadcasting, resource sharing, stream merging, video-on-demand (VOD), video streaming.

Peer-to-peer (P2P) and multicast approaches are two common transmission strategies to provide scalable and cost efficient solutions for video-on-demand (VoD) services. The former approach requires small server resources and provides a negligible delay to users, but the bandwidth requirement inside the network will be rapidly increased when more customers join the video session. On the other hand, if the system simply uses a multicast scheme to deliver a video, customers will experience a noticeable delay before watching the video whereas the overall bandwidth requirement will not be significantly increased. In this paper, a new transmission policy denoted peer-to-peer batching (PPB) policy is proposed to efficiently deliver video data in a large scale VoD system by exploiting the multicast capability of the network and P2P paradigm. To avoid the disruption of services, the fault tolerance and recovery mechanism is also developed for PPB. In addition, in order to further improve the scalability of the system, a distributed PPB (DPPP) is also proposed. We then develop a mathematical model to evaluate the performance of each of our proposed policies analytically. Based on this model, system designers are able to study various design options as well as perform system dimensioning. Both analytical and simulation results show that the proposed scheme achieves better system performance compared with existing schemes. Index Terms--Fault exception, multicast, peer-to-peer (P2P), reliability, video-on-demand (VoD).

In providing video-on-demand (VoD) services to a number of clients through networks, the bandwidth requirements of video transmission restrict VoD services. For this reason, many significant broadcasting-based VoD schemes have been proposed to efficiently support services. However, the broadcasting-based VoD schemes approach needs frequency channel hopping, using many channels at the same time and managing many segments of a video. These make it difficult to implement. In this paper, we propose a harmonic staggered broadcasting scheme which has a simple structure and substantially improved VoD efficiency. The proposed scheme substantially reduces the number of segments required and the frequency for switching channels. Also this new scheme performs significantly better than the existing VoD schemes in viewer's waiting time and buffer requirements with simplicity. The numerical results demonstrate that the viewer's waiting time of the harmonic staggered broadcasting scheme is close to the harmonic broadcasting scheme and the buffer requirements of this can be adjusted by a video dividing coefficient h. Index Terms--Bandwidth requirements, harmonic staggered broadcasting scheme, simple structure, video-on-demand, video-on-demand efficiency.

Video broadcasting has been proved to be an efficient technique to increase the scalability of a video-on-demand (VoD) system. In this paper, we address the problems in providing interactive functions for VBR encoded videos in a broadcast VoD system. A traffic smoothing scheme is proposed to support the VCR functions in delivering VBR videos over CBR channels by the staggered broadcasting protocol. By introducing a small buffering delay, the customers are able to join back to the broadcasting groups after the interactive functions. A system model is then developed to determine the optimal parameters such that the system can meet the delay requirement as well as provide the expected quality of service to the customers. The results show that the proposed system framework is very efficient in terms of bandwidth requirement and buffering delay to provide interactive VoD services. Index Terms--Interactive video broadcast, VBR video, video on demand.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.sysarc.2006.07.003 Byline: Dongmahn Seo, Joahyoung Lee, Yoon Kim, Chang Yeol Choi, Manbae Kim, Inbum Jung Keywords: VOD; Cluster system; Streaming media; QoS; Resource aware; Parallel processing Abstract: For Video-On-Demand (VOD) systems, it is important to provide Quality of Service (QoS) to more clients under limited resources. In this paper, the performance scalability in cluster-based VOD servers is studied with several grouping configurations of cluster nodes. To find performance bottlenecks, the monitoring functions are employed and the maximum QoS streams are measured under the various requests including VCR functions. To support more user friendly interface, an embedded set-top model is suggested for the QoS of TV clients. From our detailed experiment results, a new admission control method is proposed that is based on available system resources and the actual amount of resource consumed for QoS streams. The proposed method provides not only more scalable QoS in cluster-based VOD servers but also the enhancement of resource utilization by guaranteeing the maximum number of QoS streams. Author Affiliation: Department of Computer Science and Engineering, Kangwon National University, 192-1 Hyoja 2-Dong, Chuncheon, Kangwon Do 200-701, Republic of Korea Article History: Received 13 August 2005; Revised 21 April 2006; Accepted 3 July 2006 Article Note: (footnote) [star] This research was supported by the MIC (Ministry of Information and Communication), Korea, under the ITRC (Information Technology Research Center) support program supervised by the IITA (Institute of Information Technology Assessment) (IITA-2005-(C1090-0502-0022)). This work was partially supported by the Kangwon Institute of Telecommunications and Basic Research Program of the Korea Science Engineering Foundation (R05-2003-000-12146-0).

One of the primary objectives for media-on-demand systems is the reduction of bandwidth requirements. In this article we show a way how some bandwidth can be saved at the beginning of a media stream transmission. This saving is accomplished by omitting segments at their first transmission if the second transmission is in due time. To increase the number of omissions we propose an algorithm which optimizes the transmission schedule for this aim without modifying its maximum bandwidth requirement. Index Terms--Interactive TV, media-on-demand, media transmission startup, proactive broadcasting protocols, video-on-demand.

For multimedia network services, bandwidth reservation levels for video transmissions are conventionally defined using traffic descriptors that remain static over the entire playback duration of the video transmissions. Aimed at addressing the bandwidth wastefulness of using the static reservation, renegotiated Constant-Bit-Rate (RCBR) mechanism has been proposed to perform dynamic bandwidth allocation with periodical bandwidth renegotiation during any multimedia transmission sessions. However, this mechanism has been only examined via simulations and theoretical analysis previously. In this study, we have conducted rigorous empirical studies on RCBR scheme using a real network testbed to study its performance. Our study reveals interesting results and provides new insight to any practical deployment of RCBR mechanism and service over broadband packet networks. Moreover, a smoothing technique at application layer is proposed and evaluated in RCBR context to maximize the efficiency of RCBR scheme. We present empirical results and analysis, and highlight our observations. Index Terms--Dynamic bandwidth allocation, MPEG, network testbed, quality of service, RCBR, RSVP, video-on-demand.

As different types of wireless networks are converging into an all-IP network, i.e., the Internet, it can be expected that in the near future video-on-demand (VoD) will be widely applied to many interesting services, and users can access these services using heterogeneous terminals via heterogeneous wired/wireless access networks. Many periodic broadcasting protocols have been proposed to reduce the implementation cost of VoD systems. However, most of the protocols assumed homogeneity for user terminals, while in practice, user terminals are usually quite different in their processing power, buffer space, and power. To address this problem, a few periodic broadcasting protocols providing the same video quality for all heterogeneous clients have been proposed recently. In this paper, we proposed a novel heterogeneous VoD broadcasting technique called Catch and Rest (CAR) to accommodate bandwidth heterogeneity without sacrificing user video quality. Then, we provide mathematic analysis to calculate the client bandwidth and buffer space requirements of CAR. Finally, we present our performance evaluation results for CAR. Our results show that under the same system resources (i.e., server and network bandwidth), CAR provides more uniform and acceptable service latency for all heterogeneous clients compared to previous works. Index Terms--Broadcast channels, catch and rest, multimedia communication, multimedia systems, periodic broadcasting, quality-of-service (QoS), video-on-demand (VoD).

In this paper, we present a generalized approach to retrieve a long-duration movie requested using a network-based video-on-demand service infrastructure employing multiple servers. We design and analyze a play-while-retrieve (PWR) playback strategy for this multiserver environment such that the access time (waiting time for the clients) is minimized. For this strategy, we use both the single-installment and multi-installment retrieval strategies to analyze the performance of the service system. For the above-mentioned retrieval strategies, we explicitly derive closed-form expressions for a minimum access time. For the case of multi-installment retrieval strategy, we conduct asymptotic performance analysis that quantifies the ultimate performance bounds of our strategy. We demonstrate analytically the impact of a large-scale network, as well as the impact of indefinitely increasing the number of installments, on the performance of such a multiserver service system. We then address the problem of buffer management at the client site, which is a closely related issue that has a significant influence on the performance of the strategy, and also serves as a key issue in making the service system attractive for clients. We derive relationships that quantify the minimum amount of buffer expected at the client site to have a smooth presentation with this multiserver service structure. Finally, we perform simulation experiments to verify all our theoretical findings. In the experiments, we compare the performance of PWR strategy with that of play-after-retrieve strategy, and discuss certain important points that are crucial for implementing a real-life working multiserver service system. Index Terms--Access time, play-while-retrieve, retrieval strategy, video-on-demand.

The quality of service limitation of today's best-effort networks poses major challenge for low-latency video communication. To combat network losses for real-time and on-demand video communication, which exhibits stronger dependency across packets, a network-adaptive coding scheme is employed to dynamically manage the packet dependency using optimal reference picture selection. The selection of the reference is achieved within a rate-distortion optimization framework and is adapted to the varying network conditions. For network-adaptive streaming of prestored video, based on an accurate loss-distortion model, a prescient scheme that optimizes the dependency of a group of packets is proposed to achieve global optimality as well as improved rate-distortion performance. With the improved trade-off between compression efficiency and error resilience, the proposed system does not require retransmission of lost packets, which makes less than one-second low-latency communication possible. Index Terms--Error resilience, H.264, low latency, network-adaptive video coding, rate-distortion optimization, reference picture selection, video streaming.

Byline: R. Ashok Kumar, K. Hareesh, K. Ganesan, D.H. Manjaiah In a Video-on-Demand (VoD) system, by forwarding video segment client by client, a chain-based scheme is obtained, which reduces the server streams. The problem in the existing schemes is that the same video streams are duplicated and streamed to the different clients, which consumes more system resources. To solve this problem, we proved that a single stream is significant to serve different clients without duplicating the streams; this is accomplished from new architecture for the VoD system, which makes use of Markov Process on the client machines. By this way, more number of clients is chained for single server stream.

Byline: Xabiel G. Paneda, R. Garcia, D. Melendi, M. Vilas, V. Garcia This paper presents the popularity analysis performed on the www.lne.es video-on-demand service. Its principal special characteristics are the wide range of subjects, the type of contents offered and the daily introduction of several new videos. All of this and its similarity with the majority of the digital news services make it an interesting case study. The analysis pays attention to all the elements which can influence content popularity such as the subject, the video characteristics and the new content introduction policy. Moreover, the results are checked in different timescales and periods of time.