Do you know FTTH

Fibre (Fiber) To The Home (FTTH) is a transmission method for optical fiber communication. It is to directly connect the fiber to the user’s home (where the user needs it).

This type of optical fiber communication method and strategy is different from FTTN, FTTC, HFC (Hybrid Fiber Coaxial), etc., which are all dependent on traditional metal wires, including twisted pair and coaxial cable, for the “last mile” information. transmission.


The advantages of FTTH are mainly five points: First, it is a passive network. From the central office to the user, the middle can basically be passive. Second, its bandwidth is relatively wide, and the long-distance is just in line with the operator. The large-scale application; third, because it is the business carried on the fiber, so there is no problem; Fourth, because its bandwidth is wider, the supported protocols are more flexible; fifth, with the development of technology, The methods including point-to-point, 1.25G and FTTH have developed relatively complete functions.

In the optical access family, there is FTTB (Fibre To The Building) fiber to the building, FTTC (Fibre To The Curb) fiber to the roadside, FTTSA (Fibre To The Service Area) fiber to the service area and so on.

The fiber is directly connected to the user’s home, and its bandwidth, wavelength, and transmission technology are not limited. It is suitable for introducing various new services. It is the ideal service transparent network and the ultimate way for the development of the access network.

Although the development speed of mobile communication is amazing, due to its limited bandwidth, the terminal volume is unlikely to be too large, and the display screen is limited, people still pursue fixed terminals with relatively superior performance, that is, hope to achieve fiber to the home. The fascination of fiber-to-the-home is that it has great bandwidth. It is the best solution to solve the “last mile” bottleneck from the Internet backbone to the user’s desktop.

With the upgrading of technology, the cost of fiber to the home is greatly reduced, and soon it can be reduced to DSL and HFC network, which makes the practical use of FTTH possible. According to reports, as early as 1997, NTT Corporation of Japan began to develop FTTH. After 2000, the number of users increased due to cost reduction. In the United States in December, the number of FTTH installations increased by more than 200%.

For the fiber-to-the-home market, companies have their own opinions: AT&T in the US is not optimistic about FTTH. At OFC2004, the company believes that bandwidth is not omnipotent, and development of applications and content is the key, so within a considerable period of time The market for FTTH may be small; the US operators Verizon and Sprint are more active, and they have introduced their plans and technical solutions for developing FTTH at OFC2004. In China, fiber-to-the-home is also imperative. The fiber-to-the-home experimental network has also been launched in cities such as Wuhan and Chengdu. It is expected that in 2012, from the coast to the mainland, from east to west, fiber-to-the-home will be launched in China. The climax of construction. It can be said that fiber-to-the-home is a bright spot of fiber-optic communication. With the maturity and practicality of the corresponding technology, the cost is further reduced to the level that the family can withstand. The general trend of FTTH is unstoppable.

In addition, FTTH technology is still used to solve the “last mile” problem in the information superhighway. FTTH+Ethernet than ADSL (ADSL will establish the highest theoretical 8Mbps download bandwidth when dialing, this bandwidth will never change. However, due to the noise detection mechanism of ADSL, if the line condition is not good, the connection established at the beginning is obviously It is impossible to reach the theoretical value, and probably the last is 5Mbps, and this bandwidth will not change.) And ISDN (the popular telephone network form in Europe) transmits much faster. (This article is sourced from the network and edited by thousands of hackers. If there is any infringement, please contact delete.)


Based on the MAC speed limit mode, the delay will increase when the broadband is full.

In terms of speed, FTTH provides 4M uplink and 100M downlink, which are unequal lines. FTTB belongs to the upper and lower peers, and the maximum is 10M.

Advantages of broadband fiber access networks

As far as the world is concerned, most telecom companies develop broadband access based on ADSL. However, ADSL is a broadband access technology based on copper wire. Copper is a worldwide strategic resource, along with international copper cable prices. Continued to climb (20%-30% annual growth in recent years), the cost of copper-based ADSL lines is getting higher and higher, and the raw material of optical fiber is silicon dioxide, which is inexhaustible in nature. Inexhaustible. In fact, the current market price of fiber is already lower than ordinary copper wire, and its life expectancy is much higher than the latter. In new customer line or old cable replacement, fiber has become a more reasonable choice, especially in the trunk section and even the wiring section. Secondly, as an active device, xDSL electromagnetic interference is difficult to avoid, and maintenance costs are getting higher and higher. Optical fibers as passive transmission media can avoid such problems.

Finally, as the fiber-optic process of the entire network continues to extend to the user side, the limitation of the end-to-end broadband connection is increasingly concentrated in the access segment, and the uplink and downlink connection rate of xDSL cannot meet the long-term business needs of high-end users. Although ADSL2+ and VDSL2 technologies are expected to alleviate this pressure, the continued increase in speed and transmission distance is limited and cannot be expected to have an essential breakthrough. Obviously, with the large-scale application of optical fiber in the long-distance network, metropolitan area network and even the main segment of the access network, the logical development trend is to continue to extend the optical fiber to the wiring segment and the incoming line of the access network, and finally realize the fiber-to-the-home. The key question is: How fast is the speed of advancement? This will depend on a variety of factors, including market demand, competitive needs, application stimuli, technological advances, cost reductions, and development of supporting operations systems. The two major world events of China’s 2008 Olympic Games and the 2010 World Expo will also promote the development of FTTH to a certain extent.

Point-to-point active Ethernet system

Historically, Ethernet technology has been the most popular method in enterprise and enterprise application environments and has become the second-largest residential and office utility interface next to power outlets. The main reason is that there are a huge network foundation and long-term experience. All popular operating systems and applications are also compatible with Ethernet. It is cost-effective, scalable, easy to install and open, and has high reliability.

For the public network residential user application environment, the point-to-point active Ethernet system uses the active service concentration point to replace the passive point-to-multipoint system passive device, so that the transmission distance can be extended to 120km.

The main advantage of this technology is dedicated access, bandwidth is guaranteed, each user can enjoy 100Mbit/s or even 1Gbit/s in the wiring segment and the incoming segment; the central office equipment is simple and cheap; the transmission distance is long, the service area is large; the cost Linear increase with the actual increase in the number of users, predictable, no planning, low investment risk, high utilization of device ports, and therefore low cost in low-density user distribution areas.

The disadvantages are that the devices at both ends and the fiber-optic facilities are dedicated. Users cannot share the central office equipment and optical fibers. When the demand grows rapidly and the users are dense, the number of optical fibers and the equipment at both ends, as well as the cost and space requirements, increase rapidly. Great for high-density user areas.

In addition, active Ethernet requires multiple power supplies and backup power supplies, and network management components (including power supplies) increase the complexity of power supply and network management. Third, from the perspective of standardization, active Ethernet does not have a unified standard but uses multiple related standards to produce a variety of incompatible solutions. Finally, another factor that may affect the choice of Ethernet technology is the way traditional video services are offered. For example, some US telecommunications companies (such as Verizon) promise to provide the same quality of traditional analog RF video programs, while Ethernet technology supports traditional analog RF. The transmission of video programs is more difficult.

In FTTH applications, point-to-point Ethernet is mainly used for multi-dwelling unit access. It is divided into two types: single-fiber system and dual-fiber system. The uplink and downlink of the single-fiber system use different wavelengths, and the typical upstream wavelength is 1310nm. The downlink wavelength is 1550 nm and the transmission distance is 15 km. According to the standard TS-1000 developed by the Japan Telecommunications Technical Committee, the interoperability is good and the network complexity is low. The dual-fiber system uses two optical fibers, which follow the IEEE802.3ub standard and use multimode fiber with a transmission distance of only 2km. In order to extend the transmission distance and enhance their management functions, different operators have developed a number of private standards, which make the interoperability of the system very poor.