FTTH Network
What is FTTH?
FTTH stands for Fiber To The Home, is a transmission method for fiber optic communication, which is currently the best mode for full service, high bandwidth fiber optic access requirements.
Specifically, FTTH refers to the installation of optical network units (ONU ONT) at residential or corporate users, and is the closest type of optical access network to the end users except FTTD (Fiber to the Desktop). The significant technical feature of FTTH is not only to provide larger bandwidth, but also to enhance the transparency of the network in data format, rate, wavelength, and protocol, relax the requirements for environmental conditions and power supply, and simplify maintenance and installation. PON technology has become a hot topic of concern for global broadband operators and is considered one of the best technical solutions to achieve FTTH.
There are two main paths for the development of FTTH – active optical networks (AON) and passive optical networks (PON).
Active optical networks have the characteristic of long transmission distances, but they are highly specialized and not suitable for user intensive areas, also the port prices are relatively high. Furthermore, the active nature of the network limits the installation of devices and makes them susceptible to electromagnetic interference in the surrounding environment which increases the number of network failure points and leads to higher maintenance costs.
Passive optical networks, as pure dielectric networks, have a natural ability to resist electromagnetic interference, reducing the number of access network failures, resulting in higher system reliability and lower maintenance costs. At the same time, the FTTH of the passive optical network mode has good transparency and can support various standard applications, making it more suitable for large-scale development users. Passive optical networks are gradually becoming the mainstream development direction of FTTH.
The physical layer of FTTH uses optical fiber, and the use of optical networks provides a good foundation for high bandwidth business transmission capabilities. However, having only the physical layer is not enough. To achieve information transmission, it is more important to have second layer control. So the development of FTTH went through a revolution in the second layer of the network – from ATM to Ethernet, corresponding to the APON and EPON / GPON series respectively.
FTTH Main Business
FTTH is a comprehensive access solution for all businesses. Although the main driving force of FTTH is future broadband video services, FTTH must be able to support various existing narrowband and broadband services, as well as potential new services that may arise in the future. The FTTH system must be able to provide comprehensive access, allowing users to enjoy multiple services simultaneously at the same time.
The main businesses that FTTH should support include:
- Video: HDTV, compressed using MPEG-2 standard, with original image pixels ranging from 1080 x 1920 to 4320 x 7680, and multi-channel high fidelity sound using Dolby Digital 5.1 channel decoder system; Standard DTV, using MPEG-2 standard compression, the pixel size of the original image is around 640 × 720, for normal mono or stereo; Various still image services and low resolution monitoring image services using MPEG-1, MPEG-4, and other compression technologies.
- Data: Data services with various code rates, ranging from a few Kbps to tens of megabytes.
- Voice: including traditional POTS telephone and digital telephone services, multiple high fidelity voices.
- Multimedia: a variety of mixed data, voice, and image services of different qualities.
How Does FTTH Works?
Similar to the “handover wiring method” of communication all plastic telephone cables, FTTH optical distribution network (ODN) is divided into backbone fiber optic cable subsystem, distribution fiber optic cable subsystem, and access home fiber optic cable terminal subsystem.
(1) Backbone fiber optic cable subsystem
This refers to the optical fiber distribution system between the local ODF of fiber access device OLT and the user’s optical fiber cross cabinet. In the fiber optic distribution equipment at these two ends, the fiber optic cables are terminated by hot melting (fusion splicing) and connected to each other through fiber optic pigtails.
(2) Distribution fiber optic cable subsystem
This refers to the fiber optic cable between the optical cross cabinet and the “fiber optic comprehensive distribution box” inside the user’s building. This is an optical distribution panel that directly connects the input fiber optic cable and the output fiber optic cable back-to-back, usually including the splitters.
(3) Optical splitter
Fiber optic splitter is a fiber optic multiplexing device that multiplexes the channels of one or two core optical cables into multiple channels, with a typical splitting ratio of 1:2, 1:4, 1:8 and 1:16; 1:: 32 and 1:64, etc. In the EPON mode FTTH system, due to the transmission rate of 1.2Gb/s, the most commonly used splitting ratio is 1:32,so as to ensure that the user bandwidth reaches 30Mb/s or more.
Different types of optical splitters can be considered based on their placement, including “steel tube type fiber splitters, ABS box type fiber splitters,” “tray type splitters,” and “LGX chassis type splitters.” ABS box type fiber splitters and LGX chassis type splitters are widely used in China, while steel tube splitters are more commonly used abroad, followed by ABS splitter module and lgx splitter module. The most used connectors are SC, but Middle East prefer LC connectors instead.
FTTH Advantages
The main advantages of FTTH are as follows:
- Firstly, it is a passive network, from the office end to the user, it can basically be passive in the middle;
- Secondly, its bandwidth is relatively wide, which is suitable for the large-scale use of operators over long distances;
- Thirdly, because it is a service carried on optical fibers, there is no problem;
- Fourthly, due to its wide bandwidth, the supported protocols are relatively flexible;
- Fifthly, with the development of technology, relatively complete functions have been developed for point-to-point, 1.25G, and FTTH methods.
In the optical access family, there are also FTTB (Fiber To The Building), FTTC (Fiber To The Curb), FTTSA (Fiber To The Service Area), FTTA (Fiber To The Antenna) (base station), FTTP (Fiber To The Premises), FTTD (Fiber To The Desktop), and so on.
Directly connecting optical fibers to the user’s home has no limitations on bandwidth, wavelength, and transmission technology, making it suitable for introducing various new services. It is the most ideal transparent network for business and the ultimate way for the development of access networks.
Although the development speed of mobile communication is astonishing, due to its limited bandwidth, terminal volume cannot be too large, and display screen limitations, people still pursue fixed terminals with relatively superior performance, that is, they hope to achieve fiber to the home. The charm of FTTH lies in its huge bandwidth. It is the best solution to the “last mile” bottleneck from the Internet backbone to the user’s desktop.
