Design of multicast delivery for providing VCR functionality ininteractive video-on-demand systems

Multicast delivery is one of the solutions to reduce the cost in a large video-on-demand (VoD) system. However, multicast transmission makes much more difficult the implementation of interactive functions for individual users and introduces start-up delays for the users, which contradicts the idea of on-demand services. In this paper, we first try to explore and evaluate the performance of different multicast VoD systems. A new scheme called single-rate multicast double-rate unicast (SRMDRU) is then developed to minimize the system resources for supporting full VCR functionality in a multicast VoD system. This scheme also allows multicast systems to support true VoD services so customers can be served as soon as the system receives the requests. Computer simulations show that the multicast systems using the SRMDRU scheme perform much better than other multicast systems in terms of system blocking probabilities     

Providing VCR Functionality in Multicast Video-on-Demand Systems Using Adaptive Batching

The adaptive batching technique is shown to have better performance than the static scheme in terms of total bandwidth requirement and customer reneging probability in multicast video-on-demand (VoD) systems. In this paper, we first analyze the performance of providing VCR functions in the multicast VoD system using adaptive batching. The result shows that the system may not take any advantage from the adaptive approach if VCR operations are incorporated. In view of this, we then explore the buffer reservation and VCR resume delay to further improve the adaptive system. The trade-off among the buffer size, resume delay, and stream requirement is extensively investigated. It is found that a 30-s resume delay or 20% buffer reservation can significantly reduce the batching stream requirement in the adaptive multicast VoD system.     

Interactive Broadcasting System for VBR Encoded Videos

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 buttering delay to provide interactive VoD services.     

Routing protocol development for quality of service optimization of video‐on‐demand system over mobile ad hoc networks

A video‐on‐demand (VoD) application system over mobile ad hoc networks typically requires particular quality of service (QoS) parameters to be achieved. In this paper, we have proposed a novel QoS‐based routing protocol called as mobile VoD protocol. This protocol has been developed for improving the QoS of the mobile VoD system (normal Mobi_VoD approach). The protocol uses customer caching scheme for storing the first fragment of the entire video in the mobile customers and thereafter broadcast them when the new mobile customers missed the portion of the already transmitted first fragment for reducing the service delay of the customer, consequently optimizing QoS parameters. Various scenarios have been studied, and the efficacy of simulation results proves that the proposed system architecture in which the mobile customers use an ad hoc network caching scheme (mobile VoD protocol) is more efficient and performs better than the existing system (ad hoc on‐demand distance vector protocol) when compared in terms of QoS parameters such as the end‐to‐end delay, energy consumption, packet delivery ratio, throughput, and overhead.     

UVoD: An unified architecture for video-on-demand services

Existing video-on-demand (VoD) systems can be classified into two categories: true-VoD (TVoD) and near-VoD (NVoD). TVoD systems allocate a dedicated channel for every user to achieve short latency. NVoD systems make use of multicast technologies to enable multiple users to share a single channel to reduce system cost. This paper proposes a VoD architecture called UVoD that unifies the existing TVoD and NVoD architectures by integrating unicast with multicast transmissions. A performance model of the system is derived and numerical results show that one can achieve significant performance gain over TVoD (over 500%) under the same latency constraints     

A hybrid delivery strategy for a video-on-demand system with customer reneging behavior

A new delivery strategy is proposed for a video-on-demand system to allocate transmission resources according to the popularity of videos. A video is delivered to customers through one of three channels, namely broadcast, multicast and unicast, depending on whether the video is very hot, hot or cold, respectively. An algorithm is developed to select the appropriate delivery channel for the videos so that not only the overall bandwidth of the system is minimized but also a preset quality of service is provided for each customer. An analytical model is also developed to evaluate the bandwidth requirement of the whole system with VCR functionality. The result shows that a significant bandwidth reduction can be achieved when using our proposed delivery strategy.     

Provision of continuous VCR functions in interactive broadcast VoD systems

Video broadcasting is one of the feasible solutions to implement a large-scale video-on-demand (VoD) system. Nevertheless, it is still an open issue for the provision of continuous VCR functions in a delay insensitive broadcast VoD system. In this paper, we propose to jointly optimize an active buffer management scheme with contingency channels to support the VCR functions in an efficient protocol called partitioned broadcasting. We develop a greedy channel management scheme by exploiting the property of the broadcasting protocol such that the system bandwidth capacity can be fully utilized. Incorporating the channel management scheme with the partitioned video broadcast, the VoD system not only provides delay insensitive services but also handles all the interactive requests. Extensive simulation results demonstrate that the partitioned broadcasting system outperforms the traditional system based on the staggered broadcasting protocols. It is found that 20 broadcasting channels and 10 contingency channels are sufficient to support on average 720 customers for a single video with less that one second start-up delay and all types of VCR functions.     

浅析卷烟准时配送的实现

在卷烟制造企业的产品销售中,能否准时地将卷烟配送到商业客户的手中,提高配送效率,是新常态下服务满意度提升的一个重要条件。那么在网络和信息系统发达的今天,传统的企业必须与互联网拥抱在一起,寻求效率和满意度提升新途径。立足于固有的资源,为实现客户满意度提升和客户订货需求的增加,如果仅仅采用企业原有知识和技能框架是不足以满足要求的。我们要了解的是什么使客户能够创造出核心的价值得以实现业务的增值。由于小批量多批次订货模式的改变,如何保证产品准时到货,如何利用互联网及信息系统为客户提供可感知的便利操作。本文对卷烟如何实现准时配送的问题进行一个浅析。     

Challenges and opportunities of delivering IP-based residential television services

This article describes the main challenges of implementing an end-to-end architecture for delivery of high-quality, IP-based residential TV services to residential customers. The IP-based approach can be implemented with an IP multicast overlay network with traditional routers or use IP-multicast-aware ATM switching systems. Both approaches use IP multicast to transport MPEG-2 broadcast video and can work on any access architecture, especially on copper-based architectures (xDSL) such as ASDL and VDSL. The main challenges met while implementing the IP-based architecture are competitive positioning relative to traditional CATV architectures, overall architecture, head-end architecture and quality issues, traffic engineering for stringent QoS requirements, IP multicast requirements, and business case considerations. The IP-based approach described leverages Internet technology advancements and capitalizes on the impacts of Internet on interactive entertainment. Video channel manipulation at the head-end is dependent on access bandwidth and affects video quality. Video traffic management to meet stringent QoS requirements is challenging at the IP layer. High-capacity, responsive IP multicasting is essential to achieving high service quality. Cost-effective IP multicasting is a critical component of the business case.     

EPON系统LLID组播实现初探

作为光纤到户(FTTH)的理想解决方案之一,以太无源光网络(EPON)提供了1Gbit／s的上下行带宽。组播实现了IP网络中点到多点的高效数据传输,能够有效地节约网络带宽和降低网络负载。随着视频点播、电视会议和远程教育等各种高尊宽要求业务的推广,组播技术的加入,将会使EPON能够更加自如地迎接各种新兴的高带宽要求的多媒体业务的挑战。文章作者根据EPON的特点,增加了组播逻辑链路标识(LLID),结合运用因特网组用户管理协议(IGMP)snooping以及操作管理维护(OAM),在EPON系统中实现了一套LLID组播机制。     

Video-on-Demand Networks: Design Approaches and Future Challenges

IP network based deployments of interactive video-on-demand (VoD) systems are today very limited in scope, but there is a strong belief among telecommunication companies that this market will expand exponentially in the next few years. In this article, we outline the components of VoD architectures and survey the current approaches to their design. We strive to identify the research challenges that must be addressed in the development of design tools that can determine how to expand upon an existing network infrastructure to support video-on-demand. The long tail of content and extensive growth in usage are expected to have a major impact on the streaming and storage requirements of such systems. Hybrid VoD architectures that incorporate peer-to-peer exchange are an extremely promising paradigm, but there are many challenges in developing operational and economically feasible peer-to-peer systems. VoD networks generate sufficient traffic that their impact should be considered in planning general network infrastructure expansions     

基于Web Service快递管理系统解决方案

为了将Web Service技术应用于快递管理系统,充分发挥其在异构系统间的可互操作性,采用将系统的表示功能和业务功能分层的方法,设计并实现了一个多层、通用的快递管理系统解决方案。该方案不仅面向客户开放soap接口,系统内部的各层之间也利用soap接口通信。该方案在某物流公司试运行,经统计可以承载该公司80%以上的业务,具有结构清晰,扩展性强,易客户定制化及二次开发等特点。     

Multicast‐aware power allocation in multiple spot‐beam satellite communication systems

In this paper, we address the problem of user heterogeneity in satellite multicast from the perspective of resource allocation in a multiple spot‐beam satellite system that supports both unicast and multicast flows. Satellite communication systems, with their wide‐area coverage and direct access to large number of users, clearly have an inherent advantage in supporting multicast applications. In order to remain competitive against other broadband technologies, however, next generation satellite systems will be required to support both unicast and multicast flows and offer optimal sharing of system resources between these flows. We show that user heterogeneity across spot‐beam queues may result in lower allocated session rates for active flows, and be perceived as unsatisfactory by potential users when both unicast and multicast flows are active in the system. We propose an optimization‐based approach that allocates resources with the goal of smoothing user heterogeneity, and show that resulting session rates are higher on the average for both unicast and multicast flows. This is achieved through the re‐distribution of system power among spot‐beam queues, by taking into account the load on the queues and the channel states. We conclude that it is possible to increase the average session rates of multicast flows by 25–100%, and the rates of unicast flows by 15–40% compared to the pre‐optimization levels. Copyright © 2006 John Wiley & Sons, Ltd.     

Performance model of interactive video-on-demand systems

An interactive video-on-demand (VoD) system allows users to access video services, such as movies, electronic encyclopedia, interactive games, and educational videos from video servers on a broadband network. This paper develops a performance evaluation tool for the system design. In particular, a user activity model is developed to describe the usage of system resources, i.e., network bandwidth and video server usage, by a user as it interacts with the service. In addition, we allow batching of user requests, and the effect of such batching is captured in a batching model. Our proposed queueing model integrates both the user activity and the batching model. This model can be used to determine the requirements of network bandwidth and video server and, hence, the trade-off in communication and storage costs for different system resource configurations     

Cost analysis of multicast transport architectures in multiservicenetworks

The paper provides a cost analysis of multicast channels in terms of transport resources allocated by the network. The analysis takes into account the diverse transport requirements of applications in multiservice networks such as multisource broadcasting of data to a common set of destinations, bidirectional/unidirectional data transfers among entities, and variable transfer rates of data. The cost model consists of mapping the transport attributes to resource demands and computing the network-wide resource consumptions for data transport. The cost analysis is independent of the specifics of the backbone network transporting the multicast data and, hence, can provide a network-independent measure of the cost-effectiveness of various multicast architectures. The usefulness of the cost model is illustrated by analyzing multicast data transport costs in “group shared tree” (GST) and “source-specific tree” (SST) architectures, with both empirical and simulation studies. The cost analysis methodology can be useful in the design and/or evaluation of multiservice data transport architectures. It can also offer a basis for the network provider to implement customer billing functions in a “pay-for-service” type of network management environment envisaged for multiservice networks     

A taxonomy of multicast data origin authentication: Issues and solutions

Multicasting is an efficient communication mechanism for group-oriented applications such as videoconferencing, broadcasting stock quotes, interactive group games, and video on demand. The lack of security obstructs a large deployment of this efficient communication model. This limitation motivated a host of research works that have addressed the many issues relating to securing the multicast, such as confidentiality, authentication, non-repudiation, integrity, and access control. Many applications, such as broadcasting stock quotes and video-conferencing, require data origin authentication of the received traffic. Hence, data origin authentication is an important component in the multicast security architecture. Multicast data origin authentication must take into consideration the scalability and the efficiency of the underlying cryptographic schemes and mechanisms, because multicast groups can be very large and the exchanged data is likely to be heavy in volume (streaming). Besides, multicast data origin authentication must be robust enough against packet loss because most multicast multimedia applications do not use reliable packet delivery. Therefore, multicast data origin authentication is subject to many concurrent and competitive challenges, when considering these miscellaneous application-level requirements and features. In this article we review and classify recent works dealing with the data origin authentication problem in group communication, and we discuss and compare them with respect to some relevant performance criteria.     

Ensuring mobile communication transmission quality in the year 2000

The traditional view of mobile telecommunications is to allow a customer to communicate away from his base. However, the vision for the end of the century is to make the mobile communication system the first choice for telecommunications. By the year 2000 there will be a large number of mobile systems operating in Europe, from the current analogue cellular systems to digital GSM cellular systems and potentially the Universal Mobile Telecommunication System (UMTS). The challenge is to ensure that customers, be they fixed or mobile, are provided with acceptable speech quality, no matter what system they are using and what it is interconnecting to. The paper examines the speech transmission parameters which effect the perceived quality and shows how they are apportioned within the mobile systems. It then goes on to show how the transmission quality can be optimised through the transmission plan to ensure that the customer perceives acceptable speech quality     

Scaling Group Communication Services with Self-adaptive and Utility-driven Message Routing

Group communication services typically generate large multicast data streams. Delivering such massive data streams to the end system nodes at the edge of the Internet has been a challenging problem in terms of high stress on the network links and high demand on network resources and routing node capacities. Most of existing research has been dedicated on geo-distance based routing with various optimizations to alleviate the performance impact on geo-distance based routing due to unpredictable network dynamics. Most representative techniques are targeted at reducing the delivery path length or optimizing routing path by utilizing network locality. In this paper, we identify the inefficiency of geo-distance based routing protocols in many existing multicast overlay networks in terms of both resource utilization and group communication efficiency. To address this issue, we develop a utility-based routing scheme (UDR) that can provide efficient group communication services in a decentralized geographical overlay network. Our approach makes three unique contributions. First, we introduce a utility function to refine the geo-distance based routing in such a way that the routing path selection can carefully incorporate both geo-distance based metric and the network latency. Second, we enhance our utility driven routing scheme with self-adaptive capability by considering the nodes?? state and network density. Thus, nodes in the multicast network can dynamically accommodate the changes of network conditions based solely on their local knowledge about the network. Third, we devise a suite of optimization techniques to minimize the maintenance cost and computational complexity of our self-adaptive and utility-drive routing scheme. We evaluate our approach through extensive experiments based on a realistic network topology model and show that the UDR method is highly scalable and it effectively enhances the multicast delivery efficiency for large scale group communication services compared to existing geo-distance based routing protocols.     

An interoperable delivery framework for scalable media resources - seamless content delivery in the future mobile internet

In this article an interoperable framework for the delivery of scalable media resources (e.g., in the standardized scalable video coding format) is presented. The framework provides support for video on demand as well as multicast streaming, and performs efficient, generic, and interoperable adaptation of streamed content based on MPEG- 21 Digital Item Adaptation. The server as well as the clients of the streaming framework implement the MPEG Extensible Middleware and utilize the MPEG Query Format for querying the available media resources. The framework has been fully integrated into the VLC media player. The architecture for both VoD and multicast is presented in detail. Finally, a comparison in terms of performance of the generic MPEG-21 metadata-based adaptation approach to an SVC-specific adaptation approach is provided.     

A single-server queue with vacations and gated time-limited service

An M/G/1 queue with server vacations and gated time-limited service is analyzed. At each visit, the server serves the queue up to a fixed amount of time. When the time expires or after all candidate customers have been served, whichever occurs first, the server takes a vacation. The service policy is gated, since only those customers present at the beginning of a server visit (poling instant) are candidates for service during that visit; subsequent arrivals are deferred until the next visit. A functional equation which characterizes the amount of work, U_p, at a polling instant is derived. To solve the equation, a numerical technique is utilized in which the complementary cumulative function for U_p is closely approximated by a weighted sum of Laguerre functions with unknown coefficients. The equation is then transformed into a set of linear equations from which the coefficients can be computed. By the stochastic decomposition and Poisson-arrivals-see-time-averages properties, the average customer response time can be related to the average amount of work found by an arrival. Several numerical examples are included. The model studied is applicable to communication and computer systems where timers are used to allocate service to customers