缩略语
AON ADSL ATM APON BPON BRAS CDM CATV CTC DDN DP
DSLAM DBA EPON FTTB FTTC FTTH FTTN FTTO FCS FDM FSAN GEM GFP GPON GTC HDSL HDTV ISDN ITMS IGMP ISP IPG IMS LCAS LAN LLC LLID
Active Optical Network
Asymmetric Digital Subscriber Line Asynchronous Transfer Mode ATM Passive Optical Network
Broadband Passive Optical Network Broadband Remote Access Server Code Division Multiplexing Community Antenna Television Convolutional Turbo Code Digital Data Network Distribution Point
Digital Subscriber Line Access Multiplexer Dynamic Bandwidth Assignment Ethernet Passive Optical Network Fiber To The Building Fiber To The Curb/Cab Fiber To The Home Fiber To The Node Fiber To The Office Frame Check Sequence
Frequency Division Multiplexing Full Service Access Networks GPON Encapsulation Method Generic Framing Procedure
Gigabit Passive Optical Network GPON Transmission Convergence High Digital Subscriber Line High Definition Television
Integrated Services Digital Network
Integrated Terminal Management System Integrated Group Management Protocol Internet Services Provider Inter-packet Gap
IP Multimedia Subsystem
Link Capacity Adjustment SCEheme Local Area Network Logic Link Control Logical Link Identifier
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有源光网络
非对称数字用户线 异步转移模式 ATM无源光网络 宽带无源光网络 宽带接入服务器 码分复用 有线电视 卷积Turbo码 用户数据网 分配点
数字用户线接入复用器 动态带宽分配
基于以太网方式的无源光网络
光纤到楼 光纤到路边
光纤到家（户） 光纤到节点
光纤到公司/办公室 帧校验序列 频分复用 全业务接入网 GPON封装方式 通用成帧规程
吉比特无源光网络 GPON传输汇聚 高速数字用户线 高清晰度电视 综合业务数字网 终端管理系统
因特网组播管理协议 Internet服务提供商 帧间隔
IP多媒体子系统 链接容量调整方案 局域网
逻辑链路控制 逻辑链路标识
MGCP MAC MDU MTU OMCI OAM OAN ODN OLT ONT OFDM PTN PON POS PCBd PHY
PLOAM
PLOu PMD POTS P2P P2MP PSTN QoS SNI SNMP SFU TDM TDMA UNI VDSL VLAN VOD WDM WiFi WLAN Media Gateway Control Protocol Medium Access Control Multiple Dwelling Unit
Maximum Transmission Unit
ONT Management Control Interface
Operation Administration and Maintenance Optical Access Network Optical Distribution Network Optical Line Terminal Optical Network Unit
Orthogonal Frequency Division Multiplexing Packet Transport Network Passive Optical Network Passive Optical Splitter
Physical Control Block downstream Physical layer
Physical Layer Operations, Administration and
Maintenance
Physical Layer Overhead upstream Physical Medium Dependent Plain Old Telephone Service Point to Point Point to Multipoint Public Switched Telephone Network Quality of Service Service Note Interface
Simple Network Management Protocol Single Family Unit Time Division Multiplexing Time Division Multiple Access User-Network Interface Very high data rate Digital Subscriber Line Virtual LAN Video On Demand Wavelength Division Multiplexing Wireless Fidelity
Wireless Local Area Networks - 39 -
媒体网关控制协议 媒介接入控制 多用户单元 最大传输单元
ONT管理控制接口 操作管理维护 光接入网 光分配网 光线路终端 光网络单元
正交频分复用技术 分组传送网 无源光网络
无源光分路器/耦合器 下行物理层控制块 物理层 物理层OAM
上行物理层开销
物理媒质相关（子层）传统普通电话业务 点到点 点到多点
公共电话交换网 服务质量 业务节点接口
简单网络管理协议 单住户单元 时分复用 时分多址
用户-网络接口 超高速数字用户线 虚拟局域网 视频点播技术 波分复用
无线保真（无线宽带）无线局域网
附 录
一、 英文原文
Worldwide development of FTTH
Martin F¨orster
Definitions and terms for Fiber-to-the-Home
Before looking at current Fiber-to-the-Home networks worldwide it is crucial to define the term FTTH. In general the designation for the utilization of optical fibers in the access network is Fiber-to-the-x (FTTx). The x refers to the location of the optical fiber endpoint next to the customer. This endpoint of the optical fiber is the optical-electrical interface and is located in some kind of transmission equipment, called Optical Network Unit (ONU) or Optical Network Termination (ONT). ONU and ONT are not exactly the same for ONU is used when the optical fiber terminates in a telecommunication cabinet next to several homes or businesses and ONT is used for the termination of the optical fiber within the customer premises. So in terms of FTTH we talk about an ONT at the endpoint. The beginning point of the access network is located in a Central Office and is called Optical Line Termination (OLT).
Defining FTTH means defining the endpoint of the optical fiber. Besides FTTH there exist also the terms FTTB, FTTC, FTTN, FTTO, FTTP and FTTR. The closest point to the customer are FTTH, FTTB, FTTP, FTTO and FTTR.
Fiber-to-the-Business and FTTO are the same term for providing an optical path to the premises of a business customer. The differentiation of FTTB and FTTR depends on the location of the ONT inside a building, but FTTR is a rarely used term and is to be neglected. And FTTP encompasses FTTB and FTTH. Finally, the line must be drawn between FTTB and FTTH. It is obvious that the part ‘Home’ in FTTH usually indicates the use of this term for the group of private customers with a huge number of access points. Therefore the focus of FTTH developments is the private customer and the mass deployment. The distinction between ‘Building’ and ‘Home’ is more complicated. For example an ONT located in a single family dwelling unit (SFU) can be classified as FTTB and FTTH. But is the ONT located somewhere inside an apartment building exclusive the apartments itself, only the term FTTB is the correct term. It should be observed that these definitions are individual decisions in some cases, thence one shouldn’t rely on these terms to severely. Additionally, the term FTTP is a more general circumscription for both.
Finally the most important terms are FTTC, FTTO and FTTP inclusive of FTTB and FTTH.
Overview of FTTH subscribers worldwide
The worldwide situation of FTTH is very inhomogeneous on a larger scale and the status of the FTTH deployment and the utilization of standards in a country depends on the local
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telecommunication companies, regional distinctions, history of broadband Internet access in that country and individual technical issues. So every country and even every telecommunication company can be a different case. Fortunately, there are basic similarities in the utilization of standards and the progress of FTTH. So there can be identified three big FTTH markets: Asia-Pacific, Europe and North America.
According to the FTTH Council there are 32 million FTTH connections worldwide. More than 27 million connections are accounted by the Asian region. Figure 1 displays the household penetration for FTTB/H worldwide. The top four positions are occupied by the Asian countries South Korea, Hong Kong, Japan and Taiwan, although the majority architecture is only in Japan FTTH. In fact Japan is the country with the most FTTH connected households in the word followed by China with 7.5 million households.
Secondly, the North American region reported more than 3.3 million FTTH connected households and the United States is with 3.3 million FTTH connected households third in the total rank after China. Additionally, the United States is the economy with the largest total growth of FTTH subscribers per year.
The European region reported 1.4 million FTTH connections with Scandinavian countries and Slovenia leading the penetration rate. The Netherlands and Italy are also listed in the chart with a penetration rate of 1.4 per cent. Big economies like Great Britain, France and Germany are not listed but are about the engage in FTTH connections.
Figure 1 Worldwide FTTH household penetration
South Korea and China
A brief look on South Korea and China reveals similar considerations as in Japan. Both countries have a higher concentration on FTTC and FTTB, but FTTH makes up for that. In South Korea APON was evaluated in the late 90s and around 2001 BPON was considered for mass deployment. But the mass deployment for true FTTH showed up to expansive compared to ADSL and a BPON deployment in a FTTC structure would have vanished the advantages of PONs. So BPON wasn’t deployed on a large scale. Today the main architecture in South Korea is EPON.
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WDM-PONs are considered for deployments in the future and were successfully demonstrated in 2005.
China also started with the ATM based APON in 2001. But like in South Korea APON respectively its successor BPON have not been deployed on a larger scale due to its complexity and high equipment costs. Today, many vendors in China are focusing on EPON but also on Point-to- Point Ethernet (P2P Ethernet) and Gigabit-capable PON (GPON), EPON is deployed in areas with high population densities and GPON is mainly deployed for enterprises. P2P Ethernet is preferred to EPON for residential homes when they have an awkward disposition and it comes into consideration for business cases with higher bandwidth needs.
The United States
In the United States the competition between telecommunication operators and cable operators has been always strong. For a long time there have been more subscribers for cable-based Internet access than for xDSL-based Internet access. In 2006 it seemed that the growth of xDSL subscribers has been faster than the growth of cable subscribers. In order to make the initiative and prepare for higher bandwidth Internet access and triple-play major telecommunication operators like SBC (now AT&T) and Verizon committed themselves to a large-scale deployment of FTTH access networks in their respective regions. In 2004 Verizon started with its large-scale deployment of fiber networks based on BPON (622 Mbps downstream, 155 Mbps upstream and a RF video overlay in compliance with ITU-T G.983.3). SBC started also with its BPON deployment in the last quarter of 2005 without a video overlay (instead of that they are focusing on IP based services like IP video). They installed FTTH in greenfield areas and FTTN+VDSL in brownfield areas. Verizon started deployment of GPON in 2007 and SBC also plans to move to GPON soon.
GPON as recommended in the ITU-T G.984.x series has the same architecture like the PONs before. It is a direct advancement of BPON and pays credit to the widespread use of Ethernet. Therefore it uses DBA and OAM messages like in BPON. GPON is able to carry all service types. The downstream bit rate can be 1.2 Gbps or 2.4 Gbps and 155 Mbps, 622 Mbps, 1.2 Gbps or 2.4 Gbps in upstream direction. Verizon is using 2.4 Gbps downstream and 1.2 Gbps upstream. The split ratio of GPON is recommended with 1:64 but can be up to 1:128. But Verizon prefers to use split ratios of 1:32 for single family FTTP deployment. That makes in the ‘worst-case’ 75 Mbps downstream and 37.5 Mbps upstream. An real advancement in GPON is the encryption of the information part with the Advanced Encryption Standard.
The downstream frame has a fixed-length of 125μs. The Physical Control Block for frames going downstream (PCBd) contains the information used to control and manage the network (including OAM). Behind that is the payload which can consist of optional ATM segments and a variable-length GPON encapsulation method (GEM) segment. The GME segment can carry any kind of data and has a length of up to 1500 bytes. Larger data is fragmented as it is in Ethernet. The encapsulation offers proper management for multiple service flows from different ONTs. The upstream frame has a variable length and consists of a header and a payload part. The header is less complex than in the downstream frame but is still enclosing information for control and management and carries OAM messages and the dynamic bandwidth report for the DBA algorithm inside the OLT as well. The payload also consists of a GEM segment and an optional ATM segment. In the upstream direction a guard time of 25.6ns is inserted between every ONT packet due to higher bit rates and therefore smaller pulse widths.
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