FTTH fiber-to-the-home technical points

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

This optical fiber communication method and strategy is also different from FTTN, FTTC, HFC (Hybrid Fiber Coaxial), etc. They all need to rely on traditional metal wires, including twisted pair and coaxial cables, for "last mile" information transmission.

FTTH fiber to the home

advantage

The advantages of FTTH are mainly 5 points: first, it is a passive network, from the central office to the user, it can basically be passive in the middle; second, its bandwidth is relatively wide, and the long distance is just in line with the operator Third, because it is a business carried on optical fibers, there is no problem; fourth, because of its wider bandwidth, the supported protocols are more flexible; fifth, with the development of technology, Including point-to-point, 1.25G and FTTH methods have developed relatively complete functions.

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

The optical 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 most ideal service transparent network and the ultimate way of access network development.

Although the development speed of mobile communication is amazing, due to the limited bandwidth, the terminal volume cannot be too large, and the display screen is limited, people still pursue fixed terminals with relatively superior performance, that is, to achieve fiber-to-the-home. The charm of fiber-to-the-home lies in its enormous bandwidth, and it is the best solution to solve the "last mile" bottleneck phenomenon from the Internet backbone network to the user's desktop.

With the upgrading of technology, the cost of fiber-to-the-home has been greatly reduced, and will soon be comparable to DSL and HFC networks, which makes the practical application of FTTH possible.

In addition, FTTH technology is also used to solve the "last mile" problem in the information highway. FTTH+Ethernet is better than ADSL (ADSL will establish a maximum theoretical download bandwidth of 8Mbps when dialing up, and this bandwidth will never change. However, in fact, 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, maybe 5Mbps in the end, and this bandwidth will not change.) and ISDN (the popular form of telephone network in Europe) transmission speed is much faster. (The material of this article comes from the Internet, edited and arranged by Qianjia Zhike. If there is any infringement, please contact to delete it.)

shortcoming

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

In terms of speed, FTTH provides a maximum of 4M uplink and 100M downlink, which is an unequal line, and FTTB is an up-down peering, with a maximum of 10M.

Advantages of Broadband Optical Fiber Access Network

As far as the world is concerned, most telecommunications companies mainly develop broadband access through ADSL. However, ADSL is a broadband access technology based on copper wire. Copper is a global strategic resource. Continuing to climb (an average annual increase of 20%-30% in recent years), the cost of ADSL lines based on copper cables is getting higher and higher, and the raw material of optical fibers is silica, which is inexhaustible in nature and is used for inexhaustible. In fact, the current market price of optical fiber is lower than that of ordinary copper wire, and its lifespan is much higher than the latter. In the new laying of subscriber lines or the replacement of old cables, optical fibers have become a more reasonable choice, especially in the trunk section and even the distribution section. Secondly, as an active device, the electromagnetic interference of xDSL is unavoidable, and the maintenance cost is getting higher and higher. Optical fiber as a passive transmission medium avoids such problems.

Finally, as the fiberization process of the entire network continues to extend to the user side, the restrictions on end-to-end broadband connections are increasingly concentrated in the access segment, and the uplink and downlink connection rates 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 substantial improvement of their speed and transmission distance is limited, and a substantial breakthrough cannot be expected. Obviously, with the large-scale application of optical fibers in long-distance networks, metropolitan area networks and even the backbone of access networks, the logical development trend is to continue to extend optical fibers to the distribution and lead-in parts of the access network, and finally realize fiber-to-the-home. . The key question is: how fast is the advance? This will depend on a variety of factors, including market demand, competition needs, application incentives, technological advancements, cost reductions, and the development of supporting operation and maintenance systems. China's hosting of the Olympic Games in 2008 and the World Expo in 2010, two major world events, 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 application environments and has become the second largest residential and office utility interface after power outlets. The main reason is that there is a huge network foundation and long-term experience and knowledge, all popular operating systems and applications are also compatible with Ethernet, cost-effective, scalable, easy to install and open, and have high reliability.

For the public network residential user application environment, the point-to-point active Ethernet system adopts the active service concentration point to replace the passive device of the passive point-to-multipoint system, so that the transmission distance can be extended to 120km. The main advantages of this technology are dedicated access, guaranteed bandwidth, and each user can enjoy 100Mbit/s or even 1Gbit/s exclusively in the wiring segment and incoming line segment; the central office equipment is simple and cheap; the transmission distance is long, the service area is large; the cost It increases linearly with the actual growth of the number of users, is predictable, does not require planning, has low investment risk, and has high equipment port utilization, so the cost is lower in low-density user distribution areas.

The disadvantage is that the equipment and optical fiber facilities at both ends are dedicated, and users cannot share the equipment and optical fibers at the central office. When the demand grows rapidly and the users are very dense, the number of optical fibers and equipment at both ends, their cost, and space requirements also increase rapidly. Too suitable for high-density user areas. In addition, active Ethernet requires multi-point power supply and backup power supply, and there are many network management components (including power supply), which increases the complexity of power supply and network management. Third, from the perspective of standardization, Active Ethernet does not have a unified standard, but utilizes multiple related standards, resulting in a variety of incompatible solutions. Finally, another factor that may affect the choice of Ethernet technology is the way traditional video services are provided. For example, some US telecommunications companies (such as Verizon) promise to provide the same quality of traditional analog radio frequency video programs, while Ethernet technology supports traditional analog radio frequency. The transmission of video programs is more difficult.

In FTTH applications, point-to-point Ethernet is mainly used for multi-dwelling unit access, which is divided into two types: single-fiber system and dual-fiber system. The uplink and downlink of the single-fiber system use different wavelengths respectively. The downlink wavelength is 1550nm, and the transmission distance is 15km. It follows the standard TS-1000 formulated by the Japan Telecommunications Technology Committee, so it has better interoperability and lower network complexity. The dual-fiber system uses two optical fibers, follows the IEEE802.3ub standard, adopts multi-mode optical fibers, and the transmission distance is only 2km. In order to extend the transmission distance and enhance their management functions, different operators have formulated many private standards, which makes the interoperability of the system very poor.