Search

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.

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.

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).

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.