基于DOCSIS的HFC网络数据传输安全性简析

本文简要介绍了有线电视宽带网络结构及DOCSIS BPI 协议,从协议层说明了有线电视网络(HFC)做数据传输的安全原理。通过DOCSIS BPI 协议在CMTS与Cable Modem之间对传输数据及协议进行加密,从而做到防止业务的盗接、窃听等,提供高质量的服务。     

HFC接入网MAC层QoS系统模型的实现

HFC接入网采用DOCSIS协议来实现通信,但DOCSIS协议被设计实现非对称业务,随着VoIP这样的对称业务的发展,对HFC接入网提出了新的挑战。在深入分析DOCSIS协议的基础上,提出QoS系统模型,并通过代码给予实现,实验证明该模型在多业务情况下可以很好地满足VOIP的QoS。由于声卡模拟输入输出品质和CODEC的转换品质有直接关系,为了实现HD Voice,采用G.711编解码可以重构原始话音信号,该QoS模型也可以很好地支持G.711。     

业务流机制--EPON的QoS解决方案

EPON是一种非常被看好的带宽综合业务接入网络.但是,如何使EPON支持不同业务的QoS一直是EPON的一大技术难题.参考DOCSIS1.1协议中的业务流机制,提出了解决EPON支持不同业务QoS的方案.     

DOCSIS协议中的业务流管理

业务流的概念是DOCSIS协议MAC层运作的核心。业务流提供了一种实现上、下行QoS管理的机制。业 务流管理是理解和应用DOCSIS协议的一个难点和关键。本文对DOCSIS协议的业务流管理要点进行了阐述。     

面向EPON的DOCSIS EoC解决方案

简要对比了EPON+ EoC与CMTS+CM的优劣,较详细地介绍了DOCSIS EoC解决方案,具体包括DOCSIS EoC物理架构、PON及DOCSIS以太网协议和CMC成本.分析了DOCSIS EoC的QoS保障和DOCSIS EoC系统网管,最后指出DOCSIS EoC是一种适合中国国情的解决方案.     

DOCSIS重大的突破在即

DOCSIS系列标准 DOCSIS(电缆数据系统接口规范)是一种通过有线电视电缆高速传送数据的技术.这种技术最初出现于1995-1996年,随着技术的发展与进步,CableLabs陆续成功地公布了三个技术规范:DOCSIS 1.0、DOCSIS 1.1和DOCSIS2.0.其中DOCSIS 1.0公布于1997年3月.采用这一规范,有线电视运营商从传统的电视娱乐节目业务转变为视频、声音和高速数据通信业务的全面业务提供商.     

基于DOCSIS的视频点播

通过对DOCSIS上传输视频业务和数据业务的分析,指出DOCSIS作为一种主要用于透明传输IP的规范在开展视频点播业务的不足,在此基础上提出了一种在于DOCSIS的视频点播,说明了方案的可行性。     

CM与CMTS之间的交互原理及调制技术分析

如何在有线电视网上开展多功能业务，充分发挥宽带网的优势，使有线电视网真正成为一个综合性的服务网，其关键技术就是将单向有线电视网改为双向有线电视网。有双向网就可进行数字信号交换。本文给出了DOCSIS协议层与OSI协议层的对比，其主要不同点是在物理层与数据链路层DOCSIS MAC子层上。DOCSIS MAC子层不是采用目前计算机网络中任一种局域网MAC子层协议，而是采用了CM与CMTS交互工作方式。参照DOCSIS1.1版本中Radio Frequency Interface规范，论述了CM与CMTS之间交互工作原理，并阐述了数字信号的调制-QPSK与QAM调制，以及它们在CATV双向网中各展所长的互补关系。     

思科引领有线接入技术迈向“云”时代

DOCSIS标准发布近20年,目前已经发展到DOCSIS3.1版本,并且延伸出CCAP、PacketCable等一系列协议,为有线运营商基于光纤/同轴电缆（HFC）的宽带上网及双向视频业务提供了持续改善的使用体验.     

DOCSIS3.0——第三代电缆数据传输系统（7）

第四章DOCSIS3.0概述与工作原理在讲完DOCSIS3.0第一部分物理层规范后,现在我们进入DOCSIS3.0第二部分MAC层和高层协议部分。MAC层协议是DOCSIS的最核心部分,为便于对该部分的理解,本书特别设立第四章,即DOCSIS3．0概述与工作原理。     

DOCSIS2.0协议的上行物理层技术

阐述了对DOCSIS2.0的上行物理层技术规范及其新特点.它是在DOCSIS1.1的基础上增强协议物理层性能的新规范,增加了光纤同轴电缆混合(HFC)网系统的信道容量,提高了抗干扰能力;采用S-CDMA模式的上行物理层技术规范是DOCSIS2.0的新特点,也是理解和应用该协议的关键.     

Network architecture and medium access control for deploying third generation (3G) wireless systems over CATV networks

We propose a novel and cost‐effective approach for the deployment of third generation (3G) wireless systems over hybrid fiber coaxial (HFC) CATV networks. The main goal is to facilitate 3G deployment over the existing CATV plant and reduce the large cost required for building a dedicated last mile infrastructure for 3G access networks. Our proposal reduces the last mile cost by sharing the existing CATV network and using the standard equipment and protocols of data‐over‐cable systems interface specifications (DOCSIS). This allows rapid deployment of 3G wireless systems, facilitates convergence of wireless and wireline networks and paves the way towards all IP wireless networks. Enhancements to the DOCSIS medium access control (MAC) protocol must be implemented in order to support Quality of Service (QoS) guarantees for 3G data and signaling traffic. This paper presents the proposed 3G over CATV network architecture and DOCSIS medium access control (MAC) enhancements for enabling the support of QoS guarantees for 3G data and signaling traffic. The proposed MAC enhancements can reduce the access delay for delay‐sensitive traffic by 30 to 40% over existing DOCSIS MAC without compromising QoS guarantees for other traffic classes, or the DOCSIS channel utilization. Copyright © 2004 John Wiley & Sons, Ltd.     

DOCSIS数据流分析

在阐述DOCSIS接口规范及协议堆栈的基础上,介绍了Cable Modem系统的软、硬件构成,并分析了DOCSIS中Cable Modem系统上、下行数据流的构成、流向和处理过程。     

宽带网络的未来DOCSIS2.0--HFC宽带接入网的未来标准

目前，HFC宽带接入网络在全球已经有了很大发展，特别在北美和欧洲已经占有相当份额的市场。HFC宽带接入网的主要标准DOCSIS在现行的1.0和1.1版本的基础上又推出了DOCSIS2.0版本。针对DOCSIS2.0与DOCSIS1.0/1.1的区别，进行了深入的分析，着重介绍了DOCSIS2.0的优势和特点，并对它们未来的市场前景进行了分析预测。     

The Behavior of TCP Over DOCSIS-Based CATV Networks

This paper studies the impact of the data-over-cable service interface specification (DOCSIS) media-access control (MAC) protocol on the performance of the transmission control protocol (TCP) in hybrid fiber coax (HFC) broadband access networks. We find that the asymmetry ratio expressed in existing work cannot adequately explain the behavior of TCP in DOCSIS-based networks. To better capture the effect of DOCSIS on TCP, we express the asymmetry ratio (denoted by$eta$) in another way (denoted by$k$), considering the time-division multiple-access-like MAC layer operation of DOCSIS. When$eta≫1$, TCP behaves as in a symmetric network, and when$etaleqq 1$, the system acts as in an asymmetric network, and the performance of TCP degrades. We find that the number of simultaneous TCP transfers significantly affects the asymmetry ratio. When the number of active transfers is below two times the maximum number of pending requests in a transmission period, the value of$eta$is larger than one, regardless of the value of$k$. However, when the number of active transfers becomes very large, the effect of DOCSIS on TCP becomes negligible, and the asymmetry ratio is determined by the bandwidth ratio of the channels times the length ratio of data and acknowledgement packets. Based on$eta$, we develop the round-trip delay of sending a data packet for both one-way and two-way transfers, and discuss the buffer requirement at the head end. The accuracy of the analytical model is validated by ns-2 simulations. The analytical result can provide useful guidelines in the design of slot allocation or scheduling mechanisms for any DOCSIS-based broadband access networks, including the emerging IEEE 802.16 WiMAX networks.     

High-bandwidth interface for multimedia communications over fixedwireless systems

Over the past two decades, cable television has largely supplanted over-the-air broadcast as a TV distribution medium. Several years ago, enterprising companies concluded that they could leverage the extremely wide bandwidth of cable TV systems required to deliver broadcast-quality television as a high-speed conduit for broadband data communications. This led to the birth of the cable modem. Early cable-modem equipment was vendor proprietary, so interoperability between different vendors' products was largely nonexistent. To promote interoperability, Cable Labs (the cable TV industry research arm) developed the Data Over Cable Service Interface Specification (DOCSIS 1.0), an IP-centric, point-to-multipoint standard that quickly replaced the proprietary solutions that preceded it. DOCSIS has now become the accepted cable standard. The newly released DOCSIS 1.1 is destined to play an important role in the delivery of high-quality multimedia across fixed wireless communications networks. With this approach, we can take advantage of all the DOCSIS technology modules that exist in the market today, allowing the wireless platform to migrate toward emerging services such as Internet protocol multicasting and voice over IP (VoIP). We describe the state of current technologies that have made fixed-wireless access a viable and compelling choice. We also discuss some emerging technologies that will bring exciting new fixed-wireless services and capabilities into homes and small businesses in the near future     

I-VoD系统中基于优先级的DOCSIS回传策略

以DOCSIS作为回传方式并充分考虑到用户的优先级水平,提出了HFC网络上行信道竞争时隙中接入请求时隙和交互请求时隙动态分配的I-VoD的一种实现方法,为VoD业务和宽带Cable Modem业务的融合提供了一种思路.     

交互式有线电视标准的探讨

当前在交互式有线电视系统领域主要有两个标准：DOCSIS和DVB／DAVIC，介绍和分析了它们的系统模型和协议结构，并对它们的相关特性进行了比较。     

Delivery of low bit rate isochronous streams over the DOCSIS 1.0cable television protocol

The Data Over Cable Systems Interface Specification (DOCSIS) 1.0 protocol enables the delivery of Internet Protocol (IP) traffic over cable TV networks with significantly higher data rates when compared to analogue modems and integrated services digital network (ISDN) links. The availability of greater bandwidth enables the delivery of high quality audio and video services. Such services require bounded delay characteristics. This paper evaluates the capacity and performance characteristics of the DOCSIS 1.0 protocol for the delivery of isochronous streams given the limited quality of service (QOS) features of the protocol and a modem population of up to 500 nodes. Stream rates of up to 64 Kbps with different packet size were considered, suitable for compressed audio, voice and low quality video. Packet concatenation for upstream traffic was also considered. Simulation results indicated that such streams, within the given protocol limitations, can be supported for a particular system population with tradeoffs in terms of system throughput and channel utilisation of up to 50%. The network capacity, in terms of the number of simultaneous streams supported and link utilisation, is significantly affected by packet size. Support for concatenation has limited advantages. Performance benefits from concatenation are more evident when delivering higher rate bitstreams