IP Over SDH网络平台的设计与实现

详细介绍了唐山有线电视网络公司IPOverSDH网络平台的设计思路和技术要点,重点讨论了光传输网和数据接入网数据传输通道的实现问题。     

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.     

基于移动Agent平台的多媒体无线情景仿真

在无线多媒体通信系统中,视频信源在发送端按照一定的编码方式进行编码,形成视频帧,然后在网络层和传输层封装成IP数据包,经过无线信道传输到达接收端,在接收端进行解包和恢复,得到视频帧,再形成重建后的视频流。在此过程中,无线信道的传输特性会影响到视频的传输质量。文中在利用Agent平台的基础上,综合NS2仿真工具,建立研究多媒体信息在无线网络中的传输平台。仿真结果表明,由于无线信道特性的不理想,在接收端恢复视频信息与视频信源相比较,会出现一定的失真     

Fiber to the Home Using a PON Infrastructure

Traffic patterns in access networks have evolved from voice- and text-oriented services to video- and image-based services. This change will require new access networks that support high-speed (> 100 Mb/s), symmetric, and guaranteed bandwidths for future video services with high-definition TV quality. To satisfy the required bandwidth over a 20-km transmission distance, single-mode optical fiber is currently the only practical choice. To minimize the cost of implementing an FTTP solution, a passive optical network (PON) that uses a point-to-multipoint architecture is generally considered to be the best approach. There are several multiple-access techniques to share a single PON architecture, and the authors addressed several of these approaches such as time-division multiple access, wavelength-division multiple access, subcarrier multiple access, and code-division multiple access. Among these multiple techniques, they focus on time-division multiplexing (TDM)-PON and wavelength-division multiplexing (WDM)-PON, which will be the most promising candidates for practical future systems. A TDM-PON shares a single-transmission channel with multiple subscribers in time domain. Then, there exists tight coupling between subscribers. A WDM-PON provides point-to-point optical connectivity using a dedicated pair of wavelengths per user. While a TDM-PON appears to be a satisfactory solution for current bandwidth demands, the combination of future data-rate projections and traffic patterns coupled with recent advances in WDM technology may result in WDM-PON becoming the preferred solution for a future proof fiber-based access network     

Efficient Resource Allocation for Policy-Based Wireless/Wireline Interworking

This paper proposes efficient resource allocation techniques for a policy-based wireless/wireline interworking architecture, where quality of service (QoS) provisioning and resource allocation is driven by the service level agreement (SLA). For end-to-end IP QoS delivery, each wireless access domain can independently choose its internal resource management policies to guarantee the customer access SLA (CASLA), while the border-crossing traffic is served by a core network following policy rules to meet the transit domain SLA (TRSLA). Particularly, we propose an engineered priority resource sharing scheme for a voice/data integrated wireless domain, where the policy rules allow cellular-only access or cellular/WLAN interworked access. By such a resource sharing scheme, the CASLA for each service class is met with efficient resource utilization, and the interdomain TRSLA bandwidth requirement can be easily determined. In the transit domain, the traffic load fluctuation from upstream access domains is tackled by an inter-TRSLA resource sharing technique, where the spare capacity from underloaded TRSLAs can be exploited by the overloaded TRSLAs to improve resource utilization. Advantages of the inter-SLA resource sharing technique are that the core network service provider can freely design the policy rules that define underload and overload status, determine the bandwidth reservation, and distribute the spare resources among bandwidth borrowers, while all the policies are supported by a common set of resource allocation techniques.     

基于QoS的下一代网络的研究

随着下一代网络的发展,QoS保障成为下一代网络的一个重要课题.下一代网络的核心是软交换网络,而IP网将是软交换网络的承载网,所以,保障下一代网络的QoS可以从IP网、接入网、接入设备分别入手.文章首先在分析了下一代网络的新特征和一般模型的基础上,重点论述了作为下一代网络承载网的IP网的端到端QoS的保障方法:MPLS与IntServ和DiffServ相结合保障端到端QoS的技术,IntServ与DiffServ结合保障端到端QoS的技术.最后文章对接入网(FTTB LAN接入时)和接入设备(媒体网关,IAD)如何提供QoS也进行了综述.     

Migrating sockets-end system support for networking with quality ofservice guarantees

We present an end system architecture designed to support networking with quality of service (QoS) guarantees. The protocol processing component of the architecture, called migrating sockets, has been designed with minimal hidden scheduling which enables accurate determination of the rate requirement of a user application. The end system provides QoS guarantees using: 1) an adaptive rate-controlled scheduler; 2) rate-based flow control on the send side for access to reserved-rate network connections; and 3) a constant overhead active demultiplexing mechanism on the receive side which can be transparently enabled in wide-area TCP/IP internetworking (although it is not restricted to TCP/IP). To achieve efficiency, migrating sockets lets user applications manage network endpoints with minimal system intervention, provides user level protocols read-only access to routing information, and integrates kernel level support previously built for efficient data movement. Migrating sockets is backward compatible with Unix semantics and Berkeley sockets. It has been used to implement Internet protocols such as TCP, UDP, and IP (including IP multicast), and run existing applications such as vic. Migrating sockets has been implemented in Solaris 2.5.1. We discuss our implementation experience, and present performance results of our system running on Sun Sparc and Ultra workstations, as well as Pentium-II desktops     

IP接入网

文章给出了IP接入网的定义、功能体系,介绍了IP用户终端和ISP链路层协议,重点讨论了适于支持IP接入的几种方式。     

A survey of Mobile IP in cellular and Mobile Ad-Hoc Network environments

The Internet has become ubiquitous and there has been tremendous growth in wireless communications in recent years. Many wireless communication techniques are commercially available, such as the Wireless LAN, Bluetooth, GSM, GPRS and CDMA. Because an all-IP network will be a trend, access to the Internet via wireless communication devices has become an important issue.To reduce power consumption and reuse the limited radio spectrum resources, a cellular network was formed. Cell size is one of the factors in the channel reuse rate. Basically, the channel reuse rate in a smaller cell size is higher than the channel reuse rate in a bigger cell size. Micro-mobility is therefore the inevitable direction for future mobile systems. Frequent and fast movements usually characterize micro-mobility. A cellular architecture would then present a challenge to the frequent handover procedures for a smaller cell size would usually induce a higher handoff frequency.In addition to cellular networks, the ad-hoc network is another network architecture for wireless networks. The ad-hoc network is a non-infrastructure architecture; in which nodes can access services from one another regardless where they are. An excellent routing protocol is crucial for an ad-hoc networking to function at high performance. The main difference between a cellular environment and ad-hoc network is that the ad-hoc method has no fixed infrastructure, allowing nodes to communicate with one another at any time and anywhere.We have mentioned that micro-mobility in a cellular environment would introduce a greater number of handoffs than before. The handoff probability drives the mobile IP mechanism due to signal changes. Using the Mobile IP mechanism, handoff breaking would take place within a micro-mobility environment. Therefore, in this paper, some handoff strategies that take the advantage of the ad-hoc mechanism to improve the handoff performance are investigated.     

组播技术在IPTV中的应用

随着网络技术的发展,IP技术已经成为核心网络承载技术的事实标准。传统业务在IP网络中的开展日趋成为广大研究人员以及各大运营商关注的热点。本文简要介绍了承载在IP网络上的电视业务(网络电视)的基本概念,重点研究了组播技术在网络电视中的应用．并从组网方式、频道快速切换方法、安全、计费以及源特定组播五个方面进行分析并给出了相应的解决策略。     

自动拨号IP电话的设计和实现

为了解决通过公用电话网(PSTN)接入Internet的IP电话终端不在线时的呼叫控制问题,提出了一种自动拨号IP电话的设计方案,借助无线寻呼信道来完成2个IP电话终端最初的呼叫握手过程,并分析了它的网络传输效果与传输延时之间的折衷关系。只有在通话过程中才保持在线,该方案的用户使用成本更低,实地通话达到了预期的效果。     

IP多播在无线接入系统的实现与分析

IP多播是一类重要的基于IP的应用,支持很多业务。无线接入系统使用灵活,作为IP网络的最后一跳,对组网寻址、服务质量构成影响;鉴于无线接入系统存在带宽有限、传输质量逊于有线方式等不足,所以在寻址方面通过合理的无线链路多播机制与IP多播寻址进行映射,在传输质量方面,通过对有线分组进行分片、ARQ、流控等机制,弥补UDP协议无流控、无确认等缺陷,以期提高服务质量。     

Performance evaluation of CSMA/ID MAC protocol for IP over WDM ring networks

In this paper, a packet pre‐classification media access control protocol based on a carrier sense multiple access with idle detection (CSMA/ID) scheme is investigated for supporting IP packets over all‐optical WDM ring networks. The purpose of the protocol is to increase throughput and to decrease the packet transmission delay of IP packets over optical networks in a metropolitan area network. This protocol avoids both packet collision and packet fragmentation. In order to improve the utilization of the network, the packets transmitted from a local area network are first pre‐classified into various class queues of an access point (AP) according to their length. After checking the available space based on the wavelength received by the receivers of the AP, the packets in the queues are transmitted. An analytical model is developed to evaluate the performance of the protocol, with simulation results showing good network efficiency. The proposed network has short‐term variations that introduce unfairness conditions. This problem could be overcome by assigning a quota on individual queues to allow all queues fair access. Copyright © 2008 John Wiley & Sons, Ltd.     

千兆以太网SOPC系统的实现

网络正在成为当今社会通用通信的骨干力量,现代化的设备迫切需要解决如何简洁高速的接入问题。涉及了基于FPGA的嵌入式技术。简要介绍了使用Xilinx的EDK和ISE等工具的设计流程和设计实现支持TCP/IP协议的10M/100M/1000M以太网SOPC系统的工程实例,并对涉及的关键技术进行了说明,列出了实物系统的指标测试结果。     

中国联通兴安盟分公司IP城域网网络优化成果

IP城域网主要承载互联网访问业务,随着网络IP化、业务IP化趋势的加剧,在IP城域网上部署传统的数据业务已经不能满足市场要求,而当一些新型的电信业务,如NGN、3G、IPTV等需要通过IP城域网承载时,现有城域网又无法完成对上述业务的承载工作,这就需要运营商对城域网进行相应的优化改造。本文分析了当前兴安盟联通分公司IP城域网存在的主要问题,探讨了IP城域网优化改造的策略,并针对兴安盟联通分公司IP城域网的实际情况,提出了IP城域网网络优化改造的具体方案。     

IP网中移动软交换核心设备的三网分离优化方案

移动软交换系统是搭建在IP网上的,IP网络接入设备的不断增加将引入不稳定因素,将会对软交换核心设备带来影响,从而影响整个移动通信网络的安全与质量。通过对现有网络拓扑的优化改造,实现软交换核心设备与网管、计费进行三网分离来解决这个问题。     

基于GPON的多业务承载系统研究

随着IPTV、手机电视等IP以太网基础上的多业务的需求越来越大,电信运营商面临各自的接入网在＂三网融合＂形势下的新挑战和新机遇。目前的基于铜缆宽带接入网虽然能够提供基于互联网的视频,但距离真正大规模三网融合业务的运营仍存在较大差距。通过对GPON光网络架构分析,给出了多业务承载网络的QoS功能的实现,并实现端到端QoS质量的保证,通过测试验证了方案的可行性,最后针对国内某省电信运营商GPON试点局建网分析和研究,探索出一套满足电信运营商的三网融合方案。     

卫星IP通信网设计技术

卫星通信网用于传输IP业务时面临一些特有的问题。论述了卫星通信特有的长延时和误码特性对各种IP业务的影响并给出了一些切实可行的解决办法;着重阐述卫星IP通信网设计时,如何进行路由协议选择、提高卫星信道利用率、广播风暴、备份信道切换路由问题以及关注IP信道质量如何衡量等问题,给出了每个问题的解决办法和一些切实可行的措施,对有些问题专门做了研究试验,提供了一些试验测试数据、曲线和有关示意图。     

纯IP架构数字电视前端系统的结构

随着三网融合的不断推进,组建纯IP架构的数字电视网络系统成为不可阻挡的潮流。而数字电视前端系统是广播电视网向IP网络整合的关键部分。对于新建电视台网、新建居民小区以及将要从模拟电视升级到数字电视的城市与地区来说,数字电视前端系统完全可以跨越"IP/QAM调制+HFC网络"的中间架构,直接升级到纯IP架构。这样做的好处是不但顺应了技术发展的趋势,而且将大量节约投资成本,简化系统维护,便于系统升级。主要探讨如何构建纯IP架构的数字电视前端系统,包括前端设备、主干网建设以及用户端结构等方面的内容。     

Extending the capacity of multiple access channels

Multiple access techniques which allow a communication medium to be shared between different users represent one of the most challenging topics in digital communications. In terms of the number of users that can be accommodated on a given channel, there are two distinct classes of multiple access techniques. The first class includes the well-known FDMA, TDMA, and OCDMA. On a channel whose bandwidth is N times the bandwidth of the individual user signals, these techniques can accommodate N users without any mutual interference, but not a single additional user can be supported beyond this limiting number. The second class includes CDMA with pseudo-noise spreading sequences (which we refer to as PN-CDMA) and some other related schemes. PN-CDMA does not have a hard limit on the number of users that can be accommodated, but is subject to multi-user interference which grows linearly with the number of users. In this article, after reviewing the capacity limits of existing multiple access techniques, we describe some newly introduced concepts which allow us to accommodate N users without any interference while also accommodating additional users at the expense of some SNR penalty