高清视频直播业务应用研究

当前互联网视频质量普遍偏低,高清视频将是未来互联网视频的发展趋势。利用应用层组播技术承载高清视频直播业务能有效地降低网络建设成本、解决P2P及传统CDN技术承载视频直播业务中存在的问题。通过分析应用层组播原理,提出一种基于应用层组播技术的新型网络架构,分析了通过应用层组播实现互联网高清视频直播业务的技术特点、商业模式、市场推广策略和关键流程等。     

P2P与组播结合实现高质量IP视频直播承载

本文首先研究了高质量IP视频直播技术要求特点,然后分别对P2P及组播承载高质量IP视频直播进行分析,发现两者均存在一定的缺点。本文提出了一种P2P与组播结合实现高质量IP视频直播承载的技术方案,很好地解决了以上问题。     

P2P与组播结合实现高质量IP视频直播承载

本文首先研究了高质量IP视频直播技术要求特点，然后分别对P2P及组播承载高质量IP视频直播进行分析，发现两者均存在一定的缺点。本文提出了一种P2P与组播结合实现高质量IP视频直播承载的技术方案，很好地解决了以上问题。     

OTN和PTN的联合组网研究

在对光传送网(OTN)和分组传输网(PTN)进行分析的基础上,提出了OTN和PTN联合组网的问题,讨论了OTN和PTN的联合组网方案,着重研究了PTN业务在大带宽OTN通道中如何传送的问题,即PTN业务如何适配到OTN网络中。最后,对OTN和PTN联合组网的发展趋势进行了展望。     

三网融合下的广电省干传送网建设

简要介绍了OTN技术及广电省干传送网建设背景,着重对安徽广电省干OTN传送网的光缆网建设方案、设备组网方案、ASON保护方式、网络承载能力及网管建设进行了详细论述。     

IP组播技术在局域网视频直播系统中的运用探讨

基于局域网环境下,针对视频直播系统的设计而言,则需要以提高网络运行效率这一目标下,为满足受众群体观看视频直播之需的同时,降低网络负担,并实现网络资源的充分运用。基于此,可将IP组播技术应用于该系统的实际之中,进而实现这一目标。本文针对如何将IP组播技术应用到局域网视频直播系统之中进行了研究与探讨,以供参考。     

OTN电交叉技术及组网应用分析

光传送网（OTN）技术正逐步取代SDH／MSTP、WDM技术,成为光传送网主流技术。本文在对OTN电交叉技术和设备以及国内运营商网络业务需求特点进行深入分析的基础上,提出了采用OTN电交叉技术组建环形网和网状网的建设方案。     

OTN和PTN的联合组网研究

在对光传送网（OTN）和分组传输网（PTN）进行分析的基础上,提出了0TN和PTN联合组网的问题,讨论了OTN和PTN的联合组网方案,着重研究了PTN业务在大带宽OTN通道中如何传送的问题,即PTN业务如何适配到0TN网络中。最后,对OTN和PTN联合组网的发展趋势进行了展望。     

OTN智能光网的应用探析

通信网络承载的业务随着社会的发展发生了翻天覆地的变化宽带、视频以及IPTV等数据业务有了突飞猛进的发展,这些都对运营商的传送网络提出更多的要求.OTN的出现使传输网的一些问题得到解决,其未来的发展及应用是我们所关注的重点.本文主要从OTN的特点、OTN关键技术以及OTN智能光网的应用几个方面对OTN智能光网的应用进行了分析.     

OTN保护方式探索

任何形式的传送网都必须考虑网络的生存性,光传送网也不例外。OTN保护的相关标准还不完善,但是随着运营商对OTN网络需求的增加,各个光通讯设备开发商开始探索OTN保护的实现方式。本文简单阐述了ITUT建议的关于OTN的保护方式,提出了对OTN新保护方式的探索。本文给出了环互连,光复用段保护环和m:n的线性保护的实现方案。     

Efficient scalable video multicast based on network-coded communication

In order to increase the efficiency of mobile video transmission in a 5G network, this paper investigates a cooperative multicast of scalable video using network coding with adaptive modulation and coding over dedicated relay-based cellular networks. Different scalable video layers prefer different protection degrees, and user equipments (UEs) in different locations experience different packet loss rates in wireless networks. Guaranteeing that all UEs experience a certain level of video quality is one of the biggest challenges in scalable video multicast. Using the number of satisfied UEs as a metric, the proposed efficient scalable video multicast based on network-coded cooperation (SVM-NC) scheme, combined with adaptive modulation and coding, enhances the attainable system performance under strict time and bandwidth resource constraints for guaranteed smooth playback. Various simulations were performed for performance evaluation. The proposed scheme ensures that the expected percentage of satisfied UEs approximately achieves the maximum number of UEs in a multicast group by using network-coded cooperation over dedicated relay-based cellular networks. In addition, the peak signal-to-noise ratio metric is asymptotic to the maximum performance of high-resolution video quality offered by service providers.     

Random linear network coding with ladder-shaped global coding matrix for robust video transmission

Robust video multicast in erasure networks using network coding (NC) to reduce the impact of packet loss is studied in this paper. In our proposed solution, random linear network coding (RLNC) is adopted at intermediate nodes of the network. RLNC linearly combines a group of packets by randomly selecting weighting coefficients on a finite field, and the loss of an RLNC-coded packet is equivalent to the loss of one constraint in a linear system of equations required for RLNC decoding. Unless the global coding coefficient matrix, or simply called the global coding matrix (GCM), is of full rank, a receive node cannot reconstruct all source packets. To address this rank deficiency problem, we propose to construct a special-structured GCM, called the ladder-shaped GCM (LGCM), for layered H.264/SVC (scalable video coding) video multicast. The ladder shape of the sparse coding matrix is maintained throughout the RLNC process to achieve two objectives: (1) to enable partial decoding of a block; and (2) to provide unequal erasure protection for H.264/SVC priority layers. Furthermore, quality degradation is minimized by optimizing the amount of redundancy assigned to each layer, and graceful quality degradation is achieved by error concealment (EC). Simulation results are given to demonstrate the superior performance of the proposed RLNC–LGCM scheme over the traditional RLNC with a generalGCM.     

分组交换技术在光传输网中的研究与设计

针对用电路交换技术传输OTN信号面临容量、速率受限的问题,研究了基于包结构的光传送网的优势并提出实现方案。文中首先介绍了分组交换网络和光传送网相结合的基本结构,以及OTN帧结构及混合网络中标准的包格式,最后描述了一个将OTN技术和数据包技术相融合的可实现结构。该结构能将光信道数据单元解复用为低阶形式,并将其切割为离散的数据包。切割好的数据包由标准包接口送往包交换芯片进行交换,交换后的数据包进入重组模块,将其重组为连续的数据流,再由复用模块将光信道数据单元复用到其高阶形态发送出去。     

Robust video multicast with joint network coding and video interleaving

In this work, we propose a cross-layer solution to robust video multicast in erasure networks based on random linear network coding (RLNC) in the network layer and video interleaving (VI) in the application layer, and call it the joint RLNC-VI scheme. In the RLNC implementation, we partition one video coding unit (VCU) into several priority levels using scalable properties of H.264/SVC video. Packets from the same priority level of several VCUs form one RLNC generation, and unequal protection is applied to different generations. RLNC provides redundancy for video packets in the network layer and has proved to be useful in a multicast environment. Then, we propose a new packet-level interleaving scheme, called the RLNC-facilitated interleaving scheme, where each received packet corresponds to a new constraint on source packets. As a result, it can facilitate the RLNC decoding at the destination node. Furthermore, we study the problem of optimal interleaving design, which selects the optimal interleaving degree and the optimal redundancy of each generation. The tradeoff between delay and received video quality due to the choice of different VCUs is also examined. It is shown by simulation results that the proposed RLNC-VI scheme outperforms the pure RLNC method for robust video multicast in erasure networks. This can be explained by two reasons. First, the VI scheme distributes the impact of the loss (or erasure) of one VCU into partial data loss over multiple neighboring VCUs. Second, the original video content can be easily recovered with spatial/temporal error concealment (EC) in the joint RLNC-VI scheme.     

Adaptive error-resilience transcoding using prioritized intra-refresh for video multicast over wireless networks

In this paper, we propose a two-pass error-resilience transcoding scheme based on adaptive intra-refresh for inserting error-resilience features to a compressed video at the intermediate transcoder of a three-tier streaming system. The proposed transcoder adaptively adjusts the intra-refresh rate according to the video content and the channel's packet-loss rate to protect the most important macroblocks against packet loss. In this work, we consider the problem of multicast of video to multiple clients having disparate channel-loss profiles. We propose a MINMAX loss rate estimation scheme to determine a single intra-refresh rate for all the clients in a multicast group. For the scenario that a quality variation constraint is imposed on the users, we also propose a grouping method to partition a multicast group of heterogeneous users into a minimal number of subgroups to minimize the channel bandwidth consumption while meeting the quality variation constraint. Experimental results show that the proposed method can effectively mitigate the error propagation due to packet loss as well as achieve fairness among clients in a multicast.     

Fair Bandwidth Allocation Using Effective Multicast Traffic Share in TDM-PONs

In this paper, the effects of optical traffic-sharing on the performance of multicast video delivery in terms of the efficiency of bandwidth allocation and the fairness of link-sharing are discussed for the downstream direction of a time-division-multiplexed passive optical network (TDM-PON). We analyze the practical issues associated with multicast packet switching and transmission control in a TDM-PON and also propose a fair bandwidth allocation mechanism, called share-based proportional bandwidth allocation (S-PBA), to effectively support multicast services. In order to provide an optical network unit with a fair amount of link bandwidth and high throughput independent of traffic type, S-PBA arbitrates the amount of unicast timeslot by using effective multicast traffic share, which is determined based on multicast traffic load distribution and traffic-sharing density. Analytic and simulation results clearly validate the effectiveness of the proposed mechanism. This work is applicable to multicast video delivery or multicast traffic transmission in general, such as voice traffic, or a combination of both in the case of video conferencing, for example.     

面向IP的分组传送网发展思路

业务IP化触发了新一代光传送网——分组传送网的兴起,业务IP化对光传送网提出了更大带宽传送、更加灵活组网等新挑战。实现IP与传送融合的分组传送网定位于满足IP业务的高效传送、灵活组网、高可扩展性和高可靠性等方面。分组传送概念在不同发展阶段和不同网络层次所表现的形式不尽相同,在骨干网主要表现为IP over波分复用（WDM）／光传送网（OTN）／可重构光分插复用（ROADM）的大带宽传送,而在城域网范围主要表现为以传送多协议标签交换（T—MPLS）和电信级以太网（CE）为代表的分组交换和传送技术。     

Two algorithms for multi‐constrained optimal multicast routing

Multimedia applications, such as video‐conferencing and video‐on‐demand, often require quality of service (QoS) guarantees from the network, typically in the form of minimum bandwidth, maximum delay, jitter and packet loss constraints, among others. The problem of multicast routing subject to various forms of QoS constraints has been studied extensively. However, most previous efforts have focused on special situations where a single or a pair of constraints is considered. In general, routing under multiple constraints, even in the unicast case is an NP‐complete problem. We present in this paper two practical and efficient algorithms, called multi‐constrained QoS dependent multicast routing (M_QDMR) and (multicasting routing with multi‐constrained optimal path selection (M_MCOP)), for QoS‐based multicast routing under multiple constraints with cost optimization. We provide proof in the paper that our algorithms are correct. Furthermore, through extensive simulations, we illustrate the effectiveness and efficiency of our proposals and demonstrate their significant performance improvement in creating multicast trees with lower cost and higher success probability. Copyright © 2003 John Wiley & Sons, Ltd.