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1、1,Cable Modem技术,北京四达时代通讯网络技术有限公司 2001年2月,议题,介绍 相关技术 解决方案 相关接入 成功案例,3,新一代服务商多业务,如何适应新的业务？,4,传统的最后一公里接入技术（窄带）,PSTN V.34 28.8-33.6Kbps V.90 56Kbps ISDN 2B channels 128Kbps Wireless GSM/TDMA/CDMA/CDPD 28.8Kbps Application bandwidth requirements grow over time, legacy last mile access methods may not be
2、adequate in the near future,5,宽带的最后一公里接入技术,有线电视网-Cable DOCSIS/MCNS industry standard 27Mbps downstream, 2-4Mbps upstream 电信-ADSL CAP, DMT and G.Lite 7 Mbps downstream, 1 Mbps upstream 无线网 UMTS/CDMA-2000 and other emerging standards 256Kbps to 2Mbps, wireless DSL,6,具有的优势,Synchronous Working Mode 188
3、byte MPEG II Frame Band Width Sharing With Different Priority QoS Guarantee Long Distance 50 to 80 km Cost Save,7,Cable Modem引入,议题,介绍 相关技术 解决方案 相关接入 成功案例,9,HFC 有线电视网,Headend,Hub,Hub,Hub,COAX,Tap,Drop,Settop,TV,6MHz,HBO,CNN,ESPN,2000 Homes,10,11,12,13,14,15,RF 频谱分配,0,100,200,300,400,500,600,700,800,上
4、行 5-65,模拟下行 87-550,数字下行 550-860,Frequency (Mhz),16,数字调制技术,QPSK,QAM-16,QAM-64,Q,I,Q,I,Q,I,01,11,00,10,17,传输数率,Freq Range MHz,TDMA Carrier,QAM-256 8 b/Sym,QAM-64 6 b/Sym,QAM-16 4 b/Sym,QPSK 2 b/Sym,54-860,54-860,54-860,54-860,5-42,5-42,5-42,5-42,Channel Width MHz,6,8,6,8,1.6,3.2,1.6,3.2,Baud Rate MSps
5、,5.3605,7.15,5.057,6.74,1.28,2.56,1.28,2.56,Raw Bit Rate Mbps,42.88,57.2,30.34,40.44,5.12,10.24,2.56,5.12,Payload Rate Mbps,38,57,27,36,4.6,9,2.3,4.6,18,RF 测量,工具 Spectrum Analyzers Scale - log base 10 功率 Absolute (dBmV) Relative (dB),噪声 S/N - Signal to Noise ratio of base band signal C/N - Carrier t
6、o Noise ratio of modulated signal,19,数字调制方式的选择,Importance of Carrier-Noise Ratio,Good CNR,Poor CNR,Noise causes constellation points to close and overlap.,20,下行载噪比,Downstream Channel EIA CH 111, 717.00 MHz,PAL Video Signal CH 114, 733.25 MHz,CM needs -15 to +15 dBmV. QAM-64 needs 30 dB C/N QAM-256 n
7、eeds 35 dB C/N,Adjust QAM signal to 0-10 dB below peak video levels,21,DS Link Maintenance Messages,CMTS,CM,UCD,SYNC,MAP,Timestamp,US/DS Channel ID,Channel Parameters,US Channel ID,Back-off Parameters,RNG-RSP,MAC Address,Temporary SID,Mini-slot Allocation Table,RNG-REQ,MAC Address,SID 0,22,DS Reques
8、t / Grant Mechanism,CMTS,CM1,R1,Request,MAP,Mini-slot Mapping,MAP,Request,CM2,R2,R1,Request Interval Contention,PAYLOAD,G1,CM waits for request interval and transmits Request Frame asking for mini-slots.,The CMTS signals the mini-slot grant in a succeeding MAP message.,23,上行载噪比,Peak Over Time,Single
9、 Sweep,上行通道 20.00 MHz,Low Band Noise,CMTS needs -10 to +10 dBmV. QPSK needs 15 dB C/N QAM-16 needs 25 dB C/N,24,CM-1,CM-2,CM-1,CM-3,CM-4,CM-5,Time, t,Frequency (MHz),42,5,Modulation: QPSK / QAM-16 Symbol Rates: 0.16 - 2.56 Msps Channel Bandwidth: 0.20 - 3.20 MHz,Upstream FDMA/TDMA,25,全双工滤波器,调制器,解调器,
10、FEC/交织,MAC处理器,去交织/FEC,数据成帧,数据编码,存贮器,CPU,网络接口卡,PC机,有线电视网,CM电缆调制解调器结构,26,Request/Grant Mechanism DHCP Time-of-Day CM Configuration File TFTP Cisco Network Registor（CNR）,相关概念,27,启动（startup) 扫描下行、上行频率，寻找标准控制信息包 测距 获得配置文件 通过DHCP获得IP地址 CNR注册 数据交换（data exchange),CM网络数据服务分两个步骤,28,uBR7246,Cat 2912,节目源,uBR924
11、B,uBR924A,RF,739.25MHz,US,DS,Up stream fr: 40MHz,FE,DHCP、TFTP、CNR Server,上变频器C8U,混 合 器,.,1、锁定参数 2、时间同步 3、配置文件 4、获得地址 5、数据传输,CM工作流程,29,相关标准,DOCSIS 1.0 DOCSIS 1.1,30,DOCSIS 1.0规范,对用户端电缆调制解调器与电缆头端的电缆调制解调器终端系统（CMTS）之间的相互作用做了详细的规定 该规范支持来自各台电缆调制解调器的单一一条数据流，并且这些调制解调器之间存在有限的服务类型差异 在这种环境中，所有使用网络的应用都争夺上游带宽，因此
12、，向某一应用或用户提交定义的服务质量（QoS）成为问题,31,DOCSIS 1.1包括下列改进,数据包根据内容分类为不同的服务流 通过管理可以对服务流进行配置，或动态地根据应用的启动和停止创建服务流和删除服务流 为使低时延服务可以在低带宽上游通道中运行，需要对大型包进行分段 可以很好的提供QOS、RSVP,议题,介绍 相关技术 解决方案 相关接入 成功案例,33,HFC 有线电视网,Headend,Cisco Systems Confidential,Hub,Hub,Hub,COAX,Tap,Drop,Settop,TV,6 MHz,HBO,CNN,ESPN,2000 Homes,34,35,
13、相关设备,1、前端设备 uBR7223 uBR7246 2、用户端设备 uBR904 uBR924,36,Tier 3: Small MSO/ISP,Tier 1: Large MSO/ISPs,性能及密度,MSO Network Size,Small,Large,Medium Robust Functionality,uBR7xxx,uBR7246,uBR7223,Tier 1 and 2: Medium/Large MSO/ISPs,uBR7200 产品定位,37,Products - Cisco uBR7200 Roadmap,C2H98,C1H98,MC11 DOCSIS 1.0,MC
14、16A, MC14A MC12A, MC11A DOCSIS 1.0,uBR7223,uBR7246,38,2000,4000,典型的每用户分配带宽,Typical Cost at Head End/Hub Is HomePassed More Bandwidth is available with more HE gear,For QAM64:27Mbps/(2000*50%*10%)=270Kbps For QPSK: 2.56Mbps/(2000*50%*10%)=25.6Kbps,Cisco CMTS产品系列,uBR7246VXR,uBR7223,uBR7100,uBR10012,uB
15、R7246,DOCSIS 0.9,DOCSIS 1.0,DOCSIS 1.0+,DOCSIS 1.1,MC11,MC11/12/14/16C,MC16S,MC16E,Pt-to-Pt Wireless,MC28,MPEG,DVB,Pt-to-Multi Wireless,硬件平台,线卡,软件,DVB 1.2,MC520,40,前端设备特性,New Product Leadership World Class BGP Routing Full DOCSIS Compliance RF Ruggedized Chassis Modular Rack Mount Package Solid and Proven Foundation Standard Cisco 7200 Base Cisco IOS Software Foundation Best In Class Support Training, Consulting, CCIE 24x7x365 Multilevel Support,uBR 7246 Universal B
