Thoughts on the development of broadband access and optical fiber in China
Broadband network mainly refers to the broadband network infrastructure and various application services carried out by using the broadband network. Its development has formed an emerging industry including broadband services and manufacturing, and has constructed a business enterprise carrying out economic activities, social management and public service activities, the public The basic platform for digital life.
1. Development of international broadband access
In recent years, broadband networks have developed rapidly around the world and have become an important source of business revenue for telecom operators. As of March 2009, global broadband users had reached 429 million, of which digital subscriber lines (DSL) still dominated the broadband market, accounting for 64.6%; cable modem users accounted for 20.7%; optical fiber broadband users reached 5 340 Ten thousand, accounting for 12.4%, but the user growth rate is the fastest (the growth rate of optical fiber broadband in the first quarter of 2009 was 5.69%, and the DSL and cable modem were 3.7% and 3.8%, respectively).
Broadband access area development varies greatly. From the perspective of the deployment progress of optical fiber broadband, it shows the overall characteristics of "Japan and South Korea are aggressive, North America is active, and Europe is starting." At present, the penetration rate of fiber optic homes in 20 countries and regions has exceeded 1%, of which South Korea has 44% The penetration rate of households is leading the rest of the world, Hong Kong, Japan and Taiwan rank second to fourth with 28%, 27% and 12% respectively; from the perspective of construction mode, Japan is mainly based on fiber-to-the-home (FTTH), fiber To the floor / roadside (FTTB / C) as a supplement, while North America presents the characteristics of coexistence of FTTH and FTTB / C; from the perspective of the technology used, Japan mainly uses EPON technology, while North America and Europe chose GPON.
The rapid development of broadband access mainly depends on technology-driven, market-driven, and policy-driven.
(1) Technology drive
In recent years, the industrial chain of optical access technologies represented by EPON and GPON has gradually matured, technology and products have been continuously improved, prices have gradually decreased, and the time for the scale application of optical fiber access networks has come. In comparison, EPON technology and industry chain have been very mature. In recent years, GPON technology has developed rapidly, and technology and industry chain have gradually matured.
(2) Market driven
In many developed countries, various network application systems are very mature and perfect. Online office, online shopping, online games, film and television entertainment, and online education are more popular. Internet access has become an indispensable means of daily life for the people, laying the foundation for the rapid development of broadband access. Application foundation.
(3) Policy driven
Many countries have adopted some policy measures to support broadband development, including: proposing national development strategies or related plans to determine development goals; government investment or tax relief to support network construction and related research and development, especially in the field of broadband universal services; different from copper cables The non-binding policy must be opened, the opening of optical fiber access should be appropriately relaxed, and the enthusiasm of operating companies should be increased; the time limit for telecom companies to obtain IPTV licenses should be accelerated.
In response to the financial crisis, some countries have made broadband a key investment direction. Of the US $ 800 billion economic stimulus plan of the Obama administration, about US $ 7 billion is used for broadband subsidies; of the British 200 billion euro economic stimulus plan, about 5 billion euros are used to upgrade broadband infrastructure; Germany plans 2.38 US $ 100 million will be used to deploy broadband infrastructure in sparsely populated areas to achieve broadband penetration in China by 2010.
2. China's broadband access technology and applications
2.1 Rapid development, the overall level needs to be improved
The number of broadband users in China ranks first in the world, and the household penetration rate is comparable to the world level, but it has a certain gap with the level of developed countries, and the population penetration rate has a large gap with the level of developed countries in the world.
China's broadband users have developed very rapidly in recent years. By the end of 2008, the number of broadband users in China had reached 84 million, the number of broadband users has ranked first in the world, and the household penetration rate reached the world average of 22.6% (calculated based on 370 million households in China) , But less than half of the 30 countries of the Organisation for Economic Co-operation and Development (OECD), far from the average of 86% in the top 10 countries and regions in the world, and less than 4% in rural areas. The population penetration rate has only reached 6.5%, which is far from the level of developed countries in the world (the average of the top 10 countries and regions in the world is 33.2%).
The broadband capacity that China's broadband network can provide has a certain gap with developed countries in the world, and rural areas are particularly weak.
According to statistics, China â€™s current broadband network provides an average network access bandwidth of 4 Mbit / s, and the actual bandwidth used is less than 1 Mbit / s, which is far from the average level of 9.2 Mbit / s in the OECD 30 countries and is much lower than South Korea. At the level of 50 Mbit / s in Japan, the broadband coverage of administrative villages in rural areas is about 67%, and the average bandwidth is around 1 Mbit / s.
2.2 DSL access is the main, fiber access has entered a period of scale development, wireless access development is generally
By the end of 2008, DSL users in China were 6,072.6 million, accounting for 80%. In the past two years, Chinese telecom operators have vigorously promoted the progress of optical fiber and copper, and implemented the optical fiber strategy of the access network. By the end of March 2009, the overall construction scale of China's optical fiber access network using passive optical network (PON) technology has exceeded 1 10 million broadband user ports, and will continue to accelerate the pace of optical fiber access, to achieve as far as possible the extension of optical fiber to the user, the city to increase the rate, the rural area to expand coverage, fiber broadband construction is mainly based on FTTB / C, supplemented by FTTH. According to statistics, there are about 3 million fiber access users (using PON technology) in China, of which there are less than 100,000 fiber-to-the-home users, which is far from the penetration rate of 14 million in Japan and 44% in South Korea. . Wireless access (fixed wireless access, Wi-Fi, etc.) is generally developed due to various reasons such as market positioning, spectrum control, and technical capabilities, and is currently only necessary to supplement wired access.
3. Prediction of China's broadband access level and impact on industrial pull and related policy recommendations
3.1 Prediction of the development level of broadband access around 2012
According to various data, China â€™s broadband access development will reach the following levels by 2012: the number of broadband users will reach 175 million, the population penetration rate will reach 13.0%, and the household penetration rate will reach 47.8%; the broadband coverage in urban areas will reach 90%, commercial buildings have an optical cable reach rate of 100%, urban households have an 8 Mbit / s access rate coverage rate of 95%, and 20 Mbit / s and above access rates reach 75%; rural village administrative villages have an optical cable reach rate exceeding 90% (remote areas use optical fiber plus wireless mode), the administrative village 2 Mbit / s access rate coverage rate reaches 90%, 4 Mbit / s access rate coverage rate reaches 80%. The forecast of the number of broadband access users in China and its proportion in the number of Internet access users is shown in Figure 1.
3.2 The development of broadband to the industry and consumption in the next 3 years
According to preliminary estimates, with the support of a certain amount of funds and fiscal and taxation policies from the state, China â€™s broadband network investment scale is about 200 billion yuan in three years, which can directly boost the value-added of consumption (broadband access business income) for a total of about 120 billion yuan in three years (according to Three-year broadband users have increased by an average of 20 million yuan per year, and the user's average revenue per user (ARPU) value is calculated at 80 yuan), and accordingly promote the development of related industries such as network equipment and information terminal equipment production. Among them, the investment in the upstream network equipment and fiber optic cable manufacturing industry drove about 100 billion yuan (calculated based on the manufacturing industry â€™s gross profit of 25% and the total input of raw materials and fixed assets depreciation accounted for 60%), driving information terminals (computers , Netbooks, etc.) sales of 75 billion yuan (52 million new users in 3 years, of which 50% have to buy information terminals, the price of a single terminal is 3,000 yuan).
3.3 Policy recommendations for the development of broadband
It is recommended to formulate China's broadband development plan on the basis of the national informatization development strategy, propose China's broadband development strategy, determine the goals of China's broadband development, formulate an overall implementation plan, and propose corresponding policies and safeguards.
Suggest specific measures to promote China's broadband development:
(1) Establish a comprehensive system to promote broadband development from the national to the local level, make full use of the enthusiasm of local governments to develop broadband infrastructure and business applications, and incorporate broadband construction into the scope of urban infrastructure construction. Relevant management regulations and guarantee measures were issued for network construction.
(2) In accordance with the subregional, phased, and step-by-step steps to actively and steadily promote broadband development in the eastern and central regions, cities, and rural areas, it is recommended to first implement and establish a Chinese demonstration site in an economically developed region, and accumulate experience to promote it to China.
(3) Support broadband construction by direct investment in guiding funds, interest-bearing loans, tax reductions, etc., especially to encourage broadband construction in rural areas and economically underdeveloped areas. In economically underdeveloped rural areas, broadband services should be included in the implementation of the universal service framework, and direct financial subsidies should be used to lower the threshold for farmers to use broadband and increase the broadband penetration rate in rural areas.
(4) Formulate relevant policies and improve supporting measures, mainly in terms of laws and regulations, market supervision, fiscal and taxation, industrial development, technological innovation, etc., issue corresponding management measures around China's broadband development, accelerate the upgrade of the broadband industry chain, improve broadband Build the environment and promote the development of broadband applications.
4. Optical fiber broadband is an inevitable choice for the development of fixed-line broadband access
From the overall development trend, the development trend of broadband access network is moving from the traditional copper wire access network to the goal of "wired copper retrogression, wireless broadband mobility, wired and wireless complement each other, and seamless access". It should be said that optical fiber broadband is an inevitable choice for the development of fixed-line broadband access.
With the implementation of operator restructuring and the issuance of 3G licenses, it has become clear that the three major telecom operators in China have implemented full-service operations. As a basic bearer network, the wired access network needs to carry various services such as voice, data, video and even enterprise access and mobile base station backhaul. The traditional copper wire access network is limited by signal transmission attenuation, and the coverage of general end offices is within 3km, and there are many end offices. This poses challenges to the construction of the operator's computer room and supporting facilities and the control of operating costs. . The distribution of end offices is scattered, and the metropolitan convergence layer needs to be added, which directly leads to more network layers within the metropolitan area, complicated structure, and increased network operation and maintenance costs. The introduction of the optical access network covers a range of 20km, which ensures that the optical line terminal (OLT) can be upgraded to the traditional metropolitan convergence node from the beginning of the optical access network construction, thereby simplifying the access network convergence layer The network structure also saves the number of end offices. Regardless of the network upgrade and reconstruction of traditional fixed-line operators, or the new broadband operators who lack computer room resources, it is very important to build new networks. Therefore, while accelerating the application of optical fiber access, we should pay attention to overall planning and centralized setting of OLTs to achieve "large capacity and few nodes" deployment and optimize the network structure of the wired access network. In addition, the characteristics of the "large capacity, high access bandwidth, high reliability, and multi-service quality of service (QoS) level support capability" of the optical access network also determine the direction of the access network to a unified, convergent, and efficient carrier platform Evolution has become a reality.
In actual construction, the optical access network also faces multiple challenges, and some issues need to be considered comprehensively.
4.1 Construction and operation and maintenance
In addition to the consideration of system equipment, the implementation of "optical access to copper" and the construction of optical fiber broadband networks should also strengthen the overall planning of access to optical cables, OLT, ODN; at the same time, we must strengthen the front-end and back-end linkages, power supply guarantee, IT support, engineering construction, Various operations such as operation and maintenance will transform access capabilities into business and service capabilities as soon as possible. Judging from the actual situation, many of the problems currently faced in the deployment of optical fiber broadband are due to the basic level of the operator's network construction of the optical fiber access network, as well as the lack of operation and maintenance capabilities and experience, especially the problems of operation and maintenance. Especially prominent.
This is mainly manifested in several aspects. First, the equipment is complicated to set up, configure, and upgrade; the types of equipment and the number of network elements increase, and management and maintenance are complicated; multi-service configuration and service release involve multiple devices and multiple sets of background support systems, which are complicated to operate. Second, as the optical fiber gradually moves down, the number of remote nodes that need to be maintained and managed increases exponentially; the remote equipment exits the equipment room, the operating environment of the equipment is poor, and the failure rate increases; the equipment is widely distributed and the workload of on-site troubleshooting is large. These problems all put high demands on the equipment management, equipment provisioning, service distribution, fault monitoring, and network security control capabilities of optical fiber broadband.
4.2 PONOLT capacity setting
The trend of "large capacity, few offices, flat network" means that the number of users covered by the OLT increases, and accordingly, new requirements are placed on the capacity of the OLT. In other words, the number of single-board PON ports, single-board bus bandwidth, upstream port capacity of the OLT equipment, and the switching capacity of the system need to be improved accordingly. At present, large-capacity OLT equipment with 800G switching capacity, 8 PON ports per board, and 10G uplink ports have appeared in the industry, reflecting this trend.
In the case of a simplified network layer, OLT equipment gives priority to direct uplink broadband access remote service / service router (BRAS / SR) equipment. In addition, in the future, the capacity of OLT will be larger and larger, the number of users covered will be larger, and the requirements for the reliability of optical fiber broadband network will be higher and higher. At this time, for the PON device itself, it is necessary to consider the protection of important components of the OLT device (such as the redundant protection of the power board, main control board, and uplink board). In terms of networking protection, for important customers or critical services, the OLT needs to provide dual uplink protection to avoid single points of failure and achieve reliable access.
In the early stage of the construction of optical fiber broadband, for OLT devices directly connected to BRAS / SR, the redundancy protection of the uplink link can be achieved through link bundling or virtual routing redundancy protocol (VRRP); subsequently, carrier-grade Ethernet can be introduced Protection technology, to achieve millisecond protection between the OLT main and backup links, and OLT BRAS / SR dual home configuration.
4.3 Fiber Broadband Requirements for PONONU
In FTTB / C mode, the optical network unit (ONU) of the PON remote equipment should ensure the needs of the network and services in terms of function and performance. PON ONU equipment should support VLAN 1: 1 and N: 1 conversion functions, cross-virtual local area network (VLAN) multicast replication and other functions; meet QoS deployment requirements, support 802.1P and priority-based queue scheduling; ONU should be based on business development needs Provide built-in voice function.
Different building applications have different requirements for the ONU port density. Generally, 8, 16, 24, and 32 ports can cover various environments. The ratio of ONU wide and narrow bands should be selected according to the business penetration rate. In order to ensure long-term operation performance, ONU should be able to work in the environment of -10 â„ƒ ~ 55 â„ƒ, and has a good heat dissipation design. The card-type ONU can use a fan for heat dissipation, but the fan life is at least more than 50,000 hours. For the integrated ONU, considering the impact of the special installation environment of the corridor on the residents, the natural heat dissipation design should be adopted, and the fan is not recommended. The ONU should also have good lightning protection performance. The power port and DSL / POTS port have 4 kV lightning protection capabilities, and provide remote monitoring of temperature, mains / battery, access control and other methods. The ONU mainly adopts the local power supply of 220 V AC or -48 V DC, and can be equipped with batteries or UPS backup power according to actual needs. The shape of the ONU equipment should meet the installation requirements of the narrow corridor environment, and should not be too high.
Facing the coming era of full-service operation, ONU, as an end access device, can also support the application scenarios of base station bearer and small and medium business user dedicated line access according to the needs of operators. In ONU's widely-used optical copper entry and exit scenarios, the ONU platform architecture should support the smooth upgrade from the existing ADSL2 + to VDSL2 or LAN to support the smooth upgrade of service bandwidth.
4.4 Management of optical fiber broadband equipment
After the introduction of the PON system, network management and maintenance faced new problems: the number of access points increased, services changed from a single service to multiple services, service management was more refined, and the amount of maintenance of optical cable networks increased. After the large-scale deployment of the optical access network using PON, the number of ONUs is very large, and it is also very important for the operation management and maintenance of ONUs.
The management and maintenance of PON ONU in FTTB mode adopts OAM + SNMP protocol (EPON) or OMCI + SNMP joint management. The operation, management and maintenance (OAM) or OMCI is responsible for the management of PON protocol related functions; the simple network management protocol (SNMP) interface is responsible for the related functions of ports, protocols and services. The PON ONU management in FTTH mode adopts OAM / OMCI + TR-069 joint management.
For the management and configuration of PON OLT and ONU equipment adopting FTTB mode, the northbound interface mode can be provided on the basis of the manufacturer's PON equipment network management, or the SNMP MIB library mode can be directly opened by the PON equipment, supporting IP metropolitan area network management and soft switching network management , Remote configuration management of business information such as VLAN, QoS and voice access.
The built-in voice access equipment in FTTH mode can be managed by TR-069-based ACS or temporarily managed by the PON network management system. In principle, a separate network management system for FTTH voice access equipment will not be built. For FTTB's built-in voice access equipment, different manufacturers' network management systems can manage their own network element equipment. For a small number of newly built external integrated access equipment (IAD), it can be considered to be included in the PON network management system of the same manufacturer. The access gateway equipment should be managed by the softswitch network management.
4.5 Comprehensive service carrying capacity
The construction of the optical fiber broadband network should fully consider meeting the needs of future multi-service unified bearer, with the bearing capacity differentiated and differentiated by customers and services, and satisfying the high-quality access of voice and video services. The optical fiber broadband access network should deploy a QoS policy based on 802.1P, and deploy corresponding priority queues on the OLT and ONU equipment, with corresponding service flow classification, priority marking, and priority queue scheduling, to achieve business priority-based Packet forwarding to ensure the quality of different services.
In terms of wireless local area network (WLAN) function, in order to meet the needs of future network development, PON equipment should support VLAN Stacking function. Among them, the outer VLAN TAG can be used to mark services, and can also be used to represent OLT equipment; the inner VLAN TAG can be used to represent different users or different services of the same user, and supports 1: 1 and N: 1 VLAN mapping functions.
4.6 Impact of multi-service bearer on the service control layer
The service access control layer is divided into single-edge and multi-edge structures. All the service traffic of a user ends on the same service access control device, which is a single-edge structure. A user's different services are terminated on different service access control devices, which is a multi-edge structure.
The support capability of the integrated service bearer of the optical fiber broadband network will have a corresponding impact on the service control layer of the metropolitan area network. For important government and enterprise customers through SR access; for public users and small and medium-sized government and enterprise customers, such as the IP metropolitan area network is equipped with fully functional and high-performance BRAS equipment, the single-edge structure networking is preferred; for large business volume, BRAS equipment can not support multi-service access control well, and can adopt multi-edge structure networking. The same metropolitan area network can use single-edge and multi-edge hybrid networking at the same time.
Considering the needs of multiple services such as IPTV, WLAN and VoIP as a whole, the introduction of DHCP should be considered in the IP metropolitan area network, and a DHCP platform should be gradually built. The DHCP platform management system can be deployed centrally. When the security, reliability, and scalability requirements of the DHCP system are not high, enable the DHCP Server function directly on the BRAS / SR. According to the actual needs of the business, combined with the transformation of Radius and related support systems, the IPoE access authentication method that can be centrally managed is introduced to adapt to the services of permanent online and multicast requirements.
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