Efficient resource reservation based on communication paradigms for multicast multimedia applications

In modern multimedia applications, heterogeneous hosts may get involved in a complicated multicast communication paradigm. For facilitating the analysis on resource reservation in such an environment, a useful model for describing the multicast communication paradigm, termed the CP graph, is presented in this paper. Based on this model, we develop a set of reservation modeling frameworks, respectively employing the RSVP reservation scheme and a proposed scheme. We prove the proposed scheme is able to achieve more efficient reservation than the RSVP scheme, while incurs very limited information and processing overheads. We simulate two applications: one with a distant learning scenario and the other B2B bargain scenario. The simulation results confirm the effectiveness of our scheme.     

SVC分层视频流在有线网络中的多码率组播优化

主要研究了可分级视频编码（SVC）在有线网络中进行多码率组播时,对于视频传输质量以及路由选择进行联合优化的问题。为了获得有线网络中视频流分层接收的最优化,提出了基于网络编码约束的凸优化模型,并且在SVC编码约束下保证了每个接收节点以递增的顺序获得分层的视频流,最终能够联合地优化组播的路由以及相应的码率。而使用分解理论中的原始分解和对偶分解方法,将原来较为复杂的优化问题分解为两层优化子问题,并且提出了求解整个联合优化问题的分布式解法。     

Cognitive radio assisted quality compensation for scalable video multicast in cellular networks

Existing multicast schemes always employ the scalable video coding (SVC) to accommodate heterogeneous channel conditions. Although this method achieves a high spectral efficiency, it will lead to serious quality imbalance problem, i.e., the viewers who hold a better link conditions can obtain high video quality, but the viewers with bad reception conditions can only receive the video with poor quality. In this paper, we propose a novel Cognitive Radio Assisted Quality Compensation (CRAQC) scheme for enhancing the video quality of bad reception viewers. In CRAQC, the bad reception viewers can obtain from the good reception viewers the video content they cannot receive directly from the base station using cognitive relay links. One novel and promising design of the proposed scheme is that it considers a cooperative transmission style in relay process, in which viewers with the same relay content can simultaneously broadcast this content in the same channel, and therefore achieve the benefits of space diversity to the receiver. Through extensive simulations, we demonstrate that CRAQC is able to significantly improve the video performance of the bad reception viewers.     

Efficient solutions to multicast routing in communication networks

An important problem in both wireless and wired communication networks is to be able to efficiently multicst information to a group of network sites. Multicasting reduces the transmission overhead of both wireless and wired networks and the time it takes for all the nodes in the subset to receive the information. Since transmission bandwidth is a scarce commodity especially in wireless networks, efficient and near minimum-cost multicast algorithms are particularly useful in the wireless context. In this paper, we discuss methods of establishing efficient and near minimum-cost multicast routing in communication networks. In particular, we discuss an efficient implementation of a widely used multicast routing method which can construct a multicast tree with a cost no greater than twice the cost of an optimal tree. We also present two efficient multicast tree constructions for a general version of the multicast routing problem in which a network consists of different classes of nodes, where each class can have one or more nodes of the same characteristic which is different from the characteristics of nodes from other classes. Because of their efficient running times, these multicast routing methods are particularly useful in the mobile communication environments where topology changes will imply recomputation of the multicast trees. Furthermore, the proposed efficient and near minimum-cost multicast routing methods are particularly suited to the wireless communication environments, where transmission bandwidth is more scarce than wired communication environments.Partially supported by NSF/LaSER under grant number EHR-9108765, by LEQSF grant number 94-RD-A-39, by NASA under grant number NAG 5-2842.     

Error-resilient scalable compression based on distributed video coding

Distributed Video Coding (DVC) is a new paradigm for video compression based on the information theoretical results of Slepian–Wolf (SW) and Wyner–Ziv (WZ). In this work, a performance analysis of image and video coding schemes based on DVC is presented, addressing temporal, quality and spatial scalability. More specifically, conventional coding is used to obtain a base layer while WZ coding generates the enhancement layers. At the decoder, the base layer is used to construct Side Information (SI) for the DVC decoding process. Initially, we show that the scalable DVC approach is codec-independent, which means that it is independent from the method used to encode the base layer. Moreover, the influence of the base layer quality on the overall performance of the schemes is studied. Finally, evaluation of the proposed schemes is performed in both cases, with and without transmission errors. The simulation results show that scalable DVC has a lower compression efficiency than conventional scalable coding (i.e. scalable video coding and JPEG2000 for video and image, respectively) in error-free conditions. On the other hand, the DVC-based schemes show better error resilience as they outperform conventional scalable coding in error-prone conditions. More specifically, the Rate Distortion (RD) performance of the proposed schemes for image coding is compared with respect to Reed Solomon (RS) protected JPEG2000. While the latter exhibits a cliff effect as its performance dramatically decreases after a certain error rate, the performance of the DVC-based schemes decreases in a steady way with error rate increase.     

一种基于主动代理的增强型分层多播算法——AELM

为一种典型的多速率视频多播算法,RLM 通过动态地加入和退出一定的多播组来实现对网络的拥塞控制。然而,RLM 算法存在要求用户协同工作、反应时间长以及对路由表项容量要求高的问题。本文通过引入主动代理反馈机制以及历史相关决策因子对其进行了改进,提出了一种基于主动代理的增强型分层多播算法——AELM。试验表明本文的算法能够解决 RLM 算法存在的问题。     

Resilient peer-to-peer streaming of scalable video over hierarchical multicast trees with backup parent pools

This paper introduces a new cross layer tree-based peer-to-peer design using hierarchical cluster layers and a new method for selection of “backup parent pools” for resilient streaming of scalable video to provide highest quality of experience for all peers. Backup parent pools are selected during the process of multicast tree construction based on information provided by the hierarchical clusters. The proposed tree construction method aims to minimize bottlenecks that may be caused by non-leaf nodes with low upload bandwidth. Performance of the proposed system is demonstrated by extensive test results using a wide range of simulation scenarios. Comparison of the results with those of some recent works indicates that the proposed system is clearly superior in several aspects.     

Transparent encryption with scalable video communication: Lower-latency,CABAC-based schemes

Selective encryption masks all of the content without completely hiding it, as full encryption would do at a cost in encryption delay and increased bandwidth. Many commercial applications of video encryption do not even require selective encryption, because greater utility can be gained from transparent encryption, i.e. allowing prospective viewers to glimpse a reduced quality version of the content as a taster. Our lightweight selective encryption scheme when applied to scalable video coding is well suited to transparent encryption. The paper illustrates the gains in reducing delay and increased distortion arising from a transparent encryption that leaves reduced quality base layer in the clear. Reduced encryption of B-frames is a further step beyond transparent encryption in which the computational overhead reduction is traded against content security and limited distortion. This spectrum of video encryption possibilities is analyzed in this paper, though all of the schemes maintain decoder compatibility and add no bitrate overhead as a result of jointly encoding and encrypting the input video by virtue of carefully selecting the entropy coding parameters that are encrypted. The schemes are suitable both for H.264 and HEVC codecs, though demonstrated in the paper for H.264. Selected Content Adaptive Binary Arithmetic Coding (CABAC) parameters are encrypted by a lightweight Exclusive OR technique, which is chosen for practicality.     

Cryptanalysis of scalable multicast security protocol

We show that the scalable multicast security protocol based on RSA, proposed by R. Molva and A. Pannetrat (see ACM Trans. Inform. Syst. Security, vol.3, no.3, p.136-60, 2000), is insecure against collusion attacks.     

基于网格的组密钥管理

目前,尚未有一个综合的信任机制解决方案来满足网格安全与信任需求.网格中,群组通信是实现大规模信息资源共享的一种重要方式,但是如何保障组播的安全性却是一个十分复杂的问题.而组密钥管理策略是保障组播安全性的重要方式之一,所以对基于网格的组密钥管理的研究非常迫切.     

A large scalable ATM multicast switch

This paper focuses on designing a large N×N high-performance broad-band ATM switch. Despite advances in architectural designs, practical switch dimensions continue to be severely limited by both the technological and physical constraints of packaging. Here, we focus on augmentation in a “single-switch” design: we provide ways to construct arbitrarily large switches out of modest-size components and retain overall delay/throughput performance. We propose a growable switch architecture based on several key principles: 1) the knockout principle exploits the statistical behavior of cell arrivals, and thereby reduces the interconnect complexity; 2) output queueing yields the best possible delay/throughput performance; 3) distributed control in routing (multicast) cells through the interconnect fabric without internal path conflicts; and 4) simple basic building blocks facilitate scalability. Other attractive features of the proposed architecture include: 1) intrinsic broadcast and multicast capabilities; 2) built-in priority sorting functionality; and 3) the guarantee of first-in, first-out cell sequence, To achieve 10^-14 cell loss probability, only maximum size 32×16 basic building modules are required, and no crossover interconnects exist between modules in a three-dimensional configuration     

Relay selection for multi-source network-coded D2D multicast communications in heterogeneous networks

Wireless Networks - Multicast service is considered as a useful transmission mode for future mobile social services to deliver the traffic to multiple mobile users simultaneously. Device-to-device...     

基于OpenFlow的SVC流媒体时延自适应分级传输方法

针对当前互联网流媒体传输的时延敏感性问题,提出一种基于OpenFlow的SVC（scalable video coding,可分级视频编码）流媒体时延自适应分级传输方法,该方法有效结合SVC流媒体可分级和OpenFlow灵活可编程的特性,在网络带宽受限和链路拥塞的复杂网络环境下,通过构建基础层和增强层2个独立路由,实现了动态网络下SVC流媒体分级自适应高效传输。仿真结果表明,该方法在提升SVC流媒体传输效率和质量,改善用户体验方面有重要作用。     

Resilient multicast conversational video

We propose a feedback-based protocol for resilient multicast videoconferencing in error-prone networks. Unlike previous approaches, our scheme not only improves video quality at error-prone receivers, but it also maximizes the overall video quality of the session and achieves efficient usage of the available bandwidth. This protocol uses a decentralized repair request algorithm with (i) a new multicast suppression technique that protects critical correction requests and eliminates duplicated or overlapped control packets, and (ii) a new error resilience scheme based on multicast repair packets that convey predictive correction information to the video session. We present experimental videoconferencing results that demonstrate the effectiveness of the protocol in ad hoc WLANs.     

Optimal deterministic timeouts for reliable scalable multicast

Reliable multicast protocols suffer from the problem of feedback implosion. To avoid this problem, the number of receivers sending feedback in case of loss must be small. However, losses experienced by different receivers are strongly correlated, since receivers share common resources in the multicast tree. One approach to feedback implosion avoidance relies on delaying feedback at the receivers. We present deterministic timeouts for reliable multicast (DTRM), a distributed algorithm to compute optimal deterministic timeouts for each receiver in a multicast tree as a function of the tree topology and the sender-to-receiver round-trip delays. DTRM has several desirable properties. First, feedback implosion is provably avoided for a single loss anywhere in the tree, provided delay jitter is bounded. Second, the computation of the timeouts can be entirely distributed; receivers and intermediate nodes only rely on local topology information. Third, the timeouts computed by DTRM are optimal with respect to the maximum response time     

Highly scalable video compression with scalable motion coding

A scalable video coder cannot be equally efficient over a wide range of bit rates unless both the video data and the motion information are scalable. We propose a wavelet-based, highly scalable video compression scheme with rate-scalable motion coding. The proposed method involves the construction of quality layers for the coded sample data and a separate set of quality layers for the coded motion parameters. When the motion layers are truncated, the decoder receives a quantized version of the motion parameters used to code the sample data. The effect of motion parameter quantization on the reconstructed video distortion is described by a linear model. The optimal tradeoff between the motion and subband bit rates is determined after compression. We propose two methods to determine the optimal tradeoff, one of which explicitly utilizes the linear model. This method performs comparably to a brute force search method, reinforcing the validity of the linear model itself. Experimental results indicate that the cost of scalability is small. In addition, considerable performance improvements are observed at low bit rates, relative to lossless coding of the motion information.     

A protocol for scalable loop-free multicast routing

In network multimedia applications such as multiparty teleconferencing, users often need to send the same information to several (but not necessarily all) other users. To manage such one-to-many or many-to-many communication efficiently in wide-area internetworks, it is imperative to support and perform multicast routing. Multicast routing sends a single copy of a message from a source to multiple receivers over a communication link that is shared by the paths to the receivers. Loop-freedom is an especially important consideration in multicasting because applications using multicasting tend to be multimedia and bandwidth intensive, and loops in multicast routing duplicate looping packets. We present and verify a new multicast routing protocol, called multicast Internet protocol (MIP), which offers a simple and flexible approach to constructing both group-shared and shortest-paths multicast trees. MIP can be sender-initiated or receiver-initiated or both; therefore, it can be tailored to the particular nature of an application's group dynamics and size. MIP is independent of the underlying unicast routing algorithms used. MIP is robust and adapts under dynamic network conditions (topology or link cost changes) to maintain loop-free multicast routing. Under stable network conditions, MIP has no maintenance or control message overhead. We prove that MIP is loop-free at every instant, and that it is deadlock-free and obtains multicast routing trees within a finite time after the occurrence of an arbitrary sequence of topology or unicast changes     

Joint resource optimization for nonorthogonal multiple access-enhanced scalable video coding multicast in unmanned aerial vehicle-assisted radio-access networks

A joint resource-optimization scheme is investigated for nonorthogonal multiple access (NOMA)-enhanced scalable video coding (SVC) multicast in unmanned aerial vehicle (UAV)-assisted radio-access networks (RANs). This scheme allows a ground base station and UAVs to simultaneously multicast successive video layers in SVC with successive interference cancellation in NOMA. A video quality-maximization problem is formulated as a mixed-integer nonlinear programming problem to determine the UAV deployment and association, RAN spectrum allocation for multicast groups, and UAV transmit power. The optimization problem is decoupled into the UAV deployment–association, spectrum-partition, and UAV transmit-power–control subproblems. A heuristic strategy is designed to determine the UAV deployment and association patterns. An upgraded knapsack algorithm is developed to solve spectrum partition, followed by fast UAV power fine-tuning to further boost the performance. The simulation results confirm that the proposed scheme improves the average peak signal-to-noise ratio, aggregate video-reception rate, and spectrum utilization over various baselines.     

一种基于IP组播的视频切换软件设计及应用

针对广泛使用的数字视频监控系统,设计了一种基于IP组播技术的视频监控与切换软件,实现对H.264格式视频的监控和在视频源与监视器之间进行选择切换.为提高视频流数据包的转发性能,将过滤、拆包、重组等处理过程放在网络接口驱动层实现,并且可以以组播方式将同一视频信号转发到不同的视频接收设备.实践证明,基于该软件构建的视频切换系统,能够满足视频转发的实时性要求,并可以使系统结构更简化,有效降低硬件成本.     

基于视频转码与IP组播的网络影院系统设计

云教室方案是由服务器+云终端+交换机+云教室管理平台组成,采用先进的云计算和虚拟化技术构建的云教室软硬件一体化平台,不仅能够满足各种教学软件的授课要求,还可以满足流畅播放高清视频的教学要求。其中的网络影院就是可以让老师在教师机上通过VLC播放媒体文件,学生在云终端上不必下载视频文件就可以实时流畅观看到该视频。文章利用VLC的实时视频转码和组播功能,并结合云终端Linux系统的GStreamer流媒体播放框架构建的网络影院系统,不仅能够支持720P高清视频的流畅播放,而且对视频源格式无限制,从而扩大了云教室方案的应用场景。