OTT 系统在三网融合背景下的推行

随着三网融合的日渐加速，OTT系统已成为业界炙手可热的平台和方案。 OTT提供了基于IP网络的跨屏全业务运营平台，将传统电视收视扩展到IP网络领域。 OTT平台将原本独立的DVB平台与Internet平台联系起来，发挥桥梁的作用，促进了平台间的业务与信息的交换。阐述三网融合背景下OTT系统的方案、功能及未来发展方向。     

DVB specifications for broadcast-related interactive TV services

Following on from the early success of the Digital Video Broadcasting (DVB) Project, the next step is to enable DVB-compliant receivers to support an attractive range of interactive services. Various types of interactive services are described. The implications for standards are then listed and the specifications summarised. The specifications include a set of network-independent protocols, as well as specifications for the most popular types of networks for the interaction channel. These cover the public switched telephone network (PSTN) and its digital equivalent (ISDN), as well as cable TV networks. The opportunity exists to enhance the consumer experience by adding interactivity to digital broadcasting. DVB is putting in place some of the enablers to make this a reality     

A QoS Monitoring System in a Heterogeneous Multi-Domain DVB-H Platform

The MobileTV, IPTV, and DVB standards (DVB-H/T) have been defined to offer mobile users interactive multimedia services with quality of service (QoS) consistency analogous to TV services. However, the market has yet to provide effective and economical solutions for the real-time delivery of such services to the corresponding transmitters over multi-domain IP networks. The monitoring system proposed in this paper enables the QoS in the IP networks involved in the delivery of real-time multimedia content to the transmitters to be ascertained. The system utilizes the QoS parameters defined in MPEG-2 Transport Streams to detect problems occurring in the heterogeneous multi-domain IP networks. The ability to detect problems having an adverse effect on QoS allows appropriate control actions to be determined to recover the QoS across the composite IP network. The design and implementation of the proposed QoS-Monitoring system (QoS-MS) is presented, followed by analysis of experimental results that demonstrate the feasibility of the system.      

基于DVB＋OTT的本地化信息互动运营平台建设

OTT TV服务的出现模糊了传统意义的电信网、广电网和互联网的区别，广电网络如果不积极跟进OTT TV服务，就面临着被边缘化的危险，广电网络可行的一条道路是选择从单一DVB系统向DVB＋OTT演进，介绍基于DVB＋OTT的本地化信息互动运营平台的技术方案与典型应用，为广电网络应对三网融合提供一种参考思路。     

Key concepts for evolution toward beyond 3G networks

Now, when the first commercial 3G services based on Third Generation Partnership Project (3GPP) specifications have been launched around the world, is the right time to start considering the evolution potential of 3G systems. It is assumed that the majority of the traffic in future mobile networks will be generated by content consumption related services, which are realized with IP technologies. Thus, it is necessary to optimize the cellular networks for carrying IP traffic as efficiently as possible. We describe an evolution scenario for the 3G network architecture specified by 3GPP. The IP delivery part of the network architecture is first optimized within each subsystem, while maintaining interoperability with the legacy network. Later, the network is streamlined as a whole to provide the most efficient solution. We show how graceful evolution of the 3GPP system can benefit from possibilities of the new technologies, especially IP-based transport, while maintaining compatibility with existing user equipment and capitalizing on existing infrastructure investments.     

HFC Access Network Design for Switched Broadcast TV Services

The hybrid fiber coax (HFC) is a modern broadband access network, providing advanced interactive services such as Internet access, digital interactive television and cable telephony. The edge costs dominate the cost of launching new services, at the time of deployment (CapEx) as well as for maintenance (OpEx). Therefore next-generation edge devices aim at the convergence of these services and their platforms into a single multi-service infrastructure, thus sharing resources and bandwidth. The focus of this paper is on the HFC access network design for bandwidth-intensive TV services, bringing standard as well as switched broadcast technologies into play. Standard broadcast TV service deployments, offered through the digital video broadcast (DVB) platform, require low installation costs, but the bandwidth consumption increases linearly with the number of available TV channels, even for very unpopular channels. Switched broadcast TV channels, offered on the (Euro-) DOCSIS platform together with other interactive unicast services such as video on demand, are only streamed to a node on the HFC access network if they are requested locally, thus limiting bandwidth consumption for less popular channels. We present an access network design tool, based on an analytical TV traffic model, minimizing the installation cost on the edge devices and study the influence of the most important traffic and content parameters.     

基于地面广播的手机电视

手机电视业务可以利用蜂窝移动网络和地面/卫星数字广播来实现,其相关技术有4种:基于移动网实现技术、基于地面数字广播网实现技术、基于卫星实现技术和基于应用层实现技术。DVB-H和T-DMB是2种典型的地面数字广播电视标准,前者是DVB组织为通过地面数字广播网络向手持终端提供多媒体业务所制订的传输标准,后者是韩国推出的基于欧洲厂商开发的尤里卡147数字音频广播(Eureka-147DAB)的地面数字多媒体广播标准。目前开展手机电视业务面临着标准、频率资源、管制和终端等方面的问题,其运营模式存在移动运营商单独运营、广电单独运营和两者合作运营模式3种。手机电视是广电和通信产业融合的重要尝试,主管部门的协调和技术标准的制订将直接影响未来三网融合的进程。     

A Fusion IP/DVB Networking Environment for Providing Always-On Connectivity and Triple-Play Services to Urban and Rural Areas

This article introduces and validates a concept for the realization of a fusion IP/DVB networking environment that supports the provision of urban and rural always-on connectivity and triple-play services. Specifically, the proposed fusion environment realizes a unified infrastructure that changes traditional, passive urban users into active, information society participants capable of creating, manipulating, and distributing their own content/services over a commonly exploited infrastructure. Further, the environment enables triple-play services and always-on connectivity in rural areas, that is, in regions where there is no termination of the core backbone to the local PSTN/ISDN exchanger. Finally, the article describes important directions for future research to follow to exploit the proposed IP/DVB unified platform for the synergy of emerging broadcasting, telecommunications, wireless, and wired technologies, to alleviate the digital divide that currently exists not only among countries but also within most countries     

Architectures for broadband residential IP services over CATVnetworks

The current state of the art in digital broadband access technologies to support emerging telecommunications services makes imminent the introduction of interactive broadband services-including data, video and the Internet-into the residential market. Over the last few years, much attention has been paid to the development of media access control protocols for cable TV networks that will allow the immediate support of broadband data services as the first step toward enhanced communications services for residential users. We review some of the architectural options that must be carefully considered in order to deliver Internet protocol (IP) services to such users in an efficient yet flexible manner. Future residential cable data services are expected to deliver Internet access, work-at-home applications, small business access, local area network LAN-LAN interconnect, and LAN emulation services over cable (CATV) networks     

Building a cooperative P2P-TV application over a wise network: the approach of the European FP-7 strep NAPA-WINE [very large projects]

Introduction TV services over the Internet can be provided by either exploiting IP multicast functionalities or relying on a pure peer-to-peer (P2P) approach. The first technique will only work on a network infrastructure controlled by a single broadband operator due to limitations of IP multicast facilities. The main goal of the project is the study of a future system suitable for HQTV live streaming over the Internet based on P2P technology, or a P2P-HQTV system. The major focus is on overcoming today's pure layered approach through a cooperative paradigm in which the application and network layers cooperate to optimize the quality of service offered to end users.     

IPTV--三网融合的开端

IPTV与目前的3个运营网（有线电视网、Internet和电信网）及其业务直接相关。但不同运营商对IPTV业务有不同定位。电信运营商认为IPTV业务体现于电视节目在IP网中的组织和传送形式，有线电视网络运营商认为IPTV业务是利用有线电视网来提供数字电视节目和电视节目以外的信息服务。由于IPTV业务分为广播业务和交互型业务两大类，支撑这两类业务的承载网也相应地分别采用单向广播网和双向交互网，因而在承载网层很难融合。融合工作将在业务层发生，即充分利用已经存在的两个承载网来经济、高效地发展业务。IPTV中既拥有广播型业务，又拥有组播型业务，还拥有交互型业务，将是三网融合的开端。     

Fusion of digital television,broadband Internet and mobile communications—Part II: Future service scenarios

This is the second part of the tutorial paper following the previous tutorial paper describing enabling technologies in digital video broadcasting (DVB) system. The paper presents the current and future operational scenarios for DVB via satellite (DVB‐S) system. Review of the current state‐of‐the‐art technologies consisting of integration of broadband Internet and mobile communications and integration of broadband Internet and DVB are given. The future operational scenarios emphasize the fusion of DVB systems with other technologies in terms of network fusion and terminal fusion. For satellite service scenarios, it also takes into consideration mobility management and standard quality‐of‐service mechanism issues, such as integrated services and differentiated services. Several research directions for providing seamless services regardless of network, access technology and terminal in the fusion network are also highlighted in this paper. Copyright © 2007 John Wiley & Sons, Ltd.     

EPON技术提升广电网络的竞争力

网络向全IP网和光纤网转化已经是大势所趋，EPON正是这样一种全光网络。EPON采用单纤加无源光分路器的树状网络结构，和广电HFC网络的树型结构同出一辙。广电采用1550＋EPON技术抢先一步建设全业务网络，必将提高广电网络的竞争力，为广电网络事业的发展带来美好的前景。     

The DVB project: philosophy and core system

The DVB (Digital Video Broadcasting) project was established to develop comprehensive specifications for digital television broadcasting. In three years it has completed work on a range of specifications covering broadcast delivery by all currently used means. The systems are founded on the MPEG-2 coding and multiplex specifications. Additional elements have been added to meet specific broadcasting requirements. The first DVB services in Europe, and in other parts of the world using the systems, will be of conventional quality, but the DVB systems can be used for transporting any data content, or image and sound formats, required by the programme service provider, including HDTV     

A request control scheme for data recovery in DVB‐IPDC systems with spatial and temporal packet loss

Recently, digital video broadcasting‐handheld (DVB‐H) and IP datacast over DVB‐H (DVB‐IPDC) have been developed to support broadcasting services. DVB‐H is designed to support digital video broadcast for handheld devices, whereas DVB‐IPDC can integrate with an IP‐relay network to complement the data loss problem in DVB‐H. Assuming that WiMAX networks are adopted to support DVB‐IPDC, this paper points out two critical problems: group packet loss (GPL) and broadcast data handover (BDH). GPL occurs when there is a burst of retransmission requests for the same pieces of data with high spatial or temporal correlation. BDH happens when some devices that made the above requests handover to new serving cells. To solve these problems, we propose lazy wait and group acknowledgement schemes to alleviate duplicate requests by exploiting their spatial and temporal correlations. This not only reduces the requests submitted by neighboring devices in both space and time domains but also avoids handovering devices from sending duplicate requests in new cells. Through mathematical analysis, we show how to adaptively adjust the timers of lazy wait and group acknowledgement based on channel quality. Simulation results prove that our schemes can efficiently reduce retransmission requests and retransmission packets, thus alleviating congestion in the IP‐relay network. Copyright © 2011 John Wiley & Sons, Ltd.     

High-Speed Time Division Switch for 32-Mbit/s Bearer Rate Signals

This paper describes the high-speed time division switch employed in a 32-Mbit/s bearer signal communications system. System performance is realized by using three technologies. The first is a switch structure referred to as a 2-RAM 2-bank structure which ensures high-speed performance by increasing switching throughput four times over that of the basic structure. The second is the inclusion in the switch of two types of peripheral logic developed using Si-bipolar super-self-aligned process technology. The third is high-speed synchronous transmission of data. A large channel capacity time division switching network is also discussed. In conjunction with the network, these technologies make it possible to realize the ISDN time division switches necessary for such services as TV and high-definition TV communications.     

Clock synchronization for packet networks using a weighted least‐squares error filtering technique and enabling circuit emulation service

Circuit emulation service (CES) allows time‐division multiplexing (TDM) services (T1/E1 and T3/E3 circuits) to be transparently extended across a packet network. With circuit emulation over IP, for instance, TDM data received from an external device at the edge of an IP network is converted to IP packets, sent through the IP network, passed out of the IP network to its destination, and reassembled into TDM bit stream. Clock synchronization is very important for CES. This paper presents a clock synchronization scheme based on a double exponential filtering technique and a linear process model. The linear process model is used to describe the behaviour of clock synchronization errors between a transmitter and a receiver. In the clock synchronization scheme, the transmitter periodically sends explicit time indications or timestamps to a receiver to enable the receiver to synchronize its local clock to the transmitter's clock. A phase‐locked loop (PLL) at the receiver processes the transmitted timestamps to generate timing signal for the receiver. The PLL has a simple implementation and provides both fast responsiveness (i.e. fast acquisition of transmitter frequency at a receiver) and significant jitter reduction in the locked state. Copyright © 2006 John Wiley & Sons, Ltd.     

IMS关键技术及业务应用研究

3GPP UMTS体系标准的R5版本中引入的IMS是为支持移动多媒体业务而设计,是第三代移动通信核心网络的重要组成部分。论文首先对IMS的关键技术做了归纳总结,然后重点介绍了IMS的安全功能。在此基础上讨论了IMS中的业务架构和基本业务。