fiber-to-the-home
Fiber to the home English is FTTH (Fiber to the home), which is a transmission method of optical fiber communication. As the name implies, it directly connects the optical fiber to the user terminal. FTTH is an access method in FTTx, so what is FTTx?
FTTX is a general term for various application types of broadband optical access networks. “X” has many variants, which can be fiber to the building (FTTB), fiber to the transfer box (FTTCab), fiber to the curb (FTTC), fiber optic To the desktop (FTTD), fiber to the home (FTTH), fiber to the premises (FTTP), fiber to the office (FTTO), fiber to the user (FTTu), etc.
FTTx technology ranges from central office equipment in regional telecommunication equipment rooms to user terminal equipment, including optical line terminal OLT (Optical Line Terminal), optical network unit ONU (Optical Network Unit), and optical network terminal ONT (Optical Network Terminal).
Typical FTTx concept
Main features of FTTx structure
It can be seen from the figure that all FTTH is connected to the terminal by the optical fiber network, and the terminal connected to this is called the optical network terminal (ONT). FTTB or FTTC is connected to the building (Building) or curb (Curb) through the optical fiber network, and then connected to the terminal through the copper twisted pair network or wirelessly. Twisted pair network or wireless connection to network terminal (NT). FTTCab is similar to FTTC, except that its ONU is located in the telecommunication switch box (Cabinet). FTTB, FTTC, and FTTCab in the figure all belong to “partial” fiber-to-the-home, which means that the optical fiber is not directly connected to the end user, but reaches the vicinity of the end user, and then connects to the end user through a twisted pair network. In FTTCab, the ONU in the telecommunication transfer box is usually 1000-2000m away from the end users. In this case, one ONU unit can support about 500 end users. In FTTC, the ONU is closer to the terminal users, 200-1000m, and can support 8-32 terminal users. The network between OLT and ONT/ONU is called optical distribution network ODN, and its distance can reach 20km, as shown in the figure.
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FTTH related terms
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FTTH (Fiber to the Home) Fiber to the Home
FTTB (Fiber to the Building) fiber to the building
FTTO (Fiber to the Office) Fiber to the Office
FTTC (Fiber to the Curb) fiber to the curb
ODN (Optical Distribution Network) optical distribution network
OLT (Optical Line Terminal) optical line terminal
ONU (Optical Network Unit) optical network unit
PON (Passive Optical Network) passive optical network
EPON (Ethernet Passive Optical Network) Ethernet-based passive optical network
GPON (Gigabit-capable Passive Optical Network Gigabit-capable Passive Optical Network
NT (Network Terminator) network terminal
ONT (Optical Network Terminator) optical network terminal, electronic equipment located in the user’s house
P2MP (Point to Multipoint) point to multipoint
CO (Center Office) central office, the central location for providing services
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FTTH market situation
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At the 2020 FTTH Virtual Conference on December 3, the 2020~2026 FTTH market forecast data compiled by IDATE and FTTH Council Europe indicated that by 2026, the number of subscribers in 27+ EU and UK countries will further increase to approximately 148 million, while The number of subscribers in the 38+ EU and UK countries will reach about 208 million, and the coverage of FTTH/B will reach 73.3% in 2026, a significant increase from 23.4% in 2012.
It is predicted that the number of users in some countries will increase sharply compared with 2019. For example, Germany will increase by +730%, the UK will increase by +548%, and Italy will increase by +218%. In terms of country rankings, Russia may continue to lead, but Germany is expected to rise to second place in 2026 and eighth in 2020.
FTTH Market Forecast
FTTH European Market Ranking
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FTTH Technology Development
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As a kind of access technology, FTTH has been recognized at present, and the technology has already matured. There are two common fiber access technologies for FTTH, P2P (point-to-point technology) and P2MP (point-to-multipoint PON).
P2P (Peer-to-peer) is a peer-to-peer network technology that allows two users without public IPs to communicate directly.
PON (Passive Optical Network) is a passive optical network, which means that the ODN (Optical Distribution Network) between the OLT (Optical Line Terminal) and the ONU (Optical Network Unit) does not have any active equipment, and only uses optical fibers and passive components. PON mainly adopts a point-to-multipoint network structure and is the main technology for realizing FTTB/FTTH.
PON technology can be divided into narrowband PON technology for narrowband TDM service access, BPON (APON) based on ATM transmission for broadband access, EPON technology based on Ethernet packet transmission, and GPON that takes into account ATM/Ethernet/TDM integration technology. These three are all PON technologies that have been commercialized to realize FTTX at present.
FTTH technology development
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Introduction to Optical Access Network ODN
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What are ODNs? ODN is an optical distribution network, which is an optical transmission physical channel between OLT and ONU. Composition, the most important part of which is the optical splitter. Optical distribution network (ODN) mainly has two light splitting methods: primary light splitting and secondary light splitting.
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Primary Spectroscopy and Secondary Spectroscopy
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The structure of the first-level optical splitting is OLT-optical splitter-ONU, and the optical splitters from OLT to ONU are all parallel. When using one-level optical splitting, the splitter is generally installed at the junction of the distribution light. The structure of the two-stage optical splitting is OLT-optical splitter 1-optical splitter 2-ONU, and the optical splitter between the OLT and the ONU is cascaded. When two-level optical splitting is used, the first-level splitter is generally installed at the distribution optical intersection, and the second-level splitter is generally installed at the fiber distribution box.
The first-level splitter can only be connected to one splitter. Generally, a splitter with a large number of splitters is used, such as 1:32 or 1:64. Generally, 1:8 or 1:16 splitters are used at the first-level splitting point, and 1:4 or 1:8 splitters are used at the second-level splitting point. Typically, primary splitting solutions are used in congested city centers or town areas to reduce costs and ease maintenance of Optical Distributed Network (ODN) nodes. On the other hand, the secondary optical splitting solution is used in roadside or rural places to cover a wide range of ODN nodes, saving resources and saving money.
Primary Spectroscopy and Secondary Spectroscopy
Optical splitter working principle
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Optical splitter is a core passive device in FTTH system. An optical splitter, also called an optical beam splitter, is an integrated waveguide optical power distribution device that can split an input optical signal into two or more output optical signals, and the optical input power is evenly distributed on all output ports. For example, an optical splitter with a splitting ratio of 1:4 can divide an optical signal into four equally, and then transmit it in four different channels. At present, the splitting ratio of the optical splitter is generally 1:N or 2:N, such as 1:4, 1:8, 1:16, 1:32, 2:16, 2:32.
The working principle of the optical splitter is: when the single-mode fiber transmits the optical signal, the energy of the light is not completely concentrated in the fiber core, and a small amount is propagated through the cladding close to the fiber core, that is to say , if the cores of the two optical fibers are close enough, the mode field of the light transmitted in one optical fiber can enter the other optical fiber, and the optical signal is redistributed in the two optical fibers.
Optical splitter working principle
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Optical Splitter VS WDM Wavelength Division Multiplexer
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To put it simply, a WDM wavelength division multiplexer combines a series of optical signals carrying information but with different wavelengths into one bundle and transmits them along a single optical fiber; Signal separation communication technology. This technology can transmit multiple signals on one optical fiber at the same time, and each signal is transmitted by light of a specific wavelength, which is a wavelength channel. In the same optical fiber, two or more optical wavelength signals are transmitted through different optical channels at the same time, which is called optical wavelength division multiplexing technology or WDM. The splitter is to divide the light of one wavelength into multiple beams according to the usage.
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Classification of optical splitters
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According to different light splitting principles and manufacturing processes, optical splitters can be divided into two types: fused tapered (FBT) and planar waveguide (PLC).
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PLC optical splitter
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A planar waveguide optical splitter (PLC Splitter) is an integrated waveguide optical power distribution device based on a quartz substrate. Its main function is to split optical signals from one optical fiber to multiple optical fibers. The device is composed of an optical splitter chip coupled with an optical fiber array at both ends. The chip is the core component. The quality of the chip and the splitting channel directly affect the price of the entire splitter. The chip has one input port and N output ports waveguide. The optical fiber array is located on the upper surface of the chip and sealed with a casing to form an optical splitter with one input and N output optical fibers.
PLC optical splitter
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Fused Bi-tapered (FBT) Optical Splitter
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Fused tapering technology is to bundle two or more optical fibers with the coating removed, and then melt and stretch them on the tapered machine, and monitor the change of split ratio in real time. Keep one fiber (cut off the rest) as the input end, and the other end as the multi-channel output end.
Fused Bi-tapered (FBT) Optical Splitter
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FBT VS PLC
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The distribution method of the split ratio is also one of the main differences between the two. The splitting variability of the pull-tapered splitter is the biggest advantage of this device. The light splitting of the PLC splitter is evenly divided, and the signal can be evenly distributed to the users. For example, a 1×32 PLC splitter can divide the optical signal into 32 parts on average, and then transmit it in 32 different channels. Sometimes, due to the inconsistency of the number of users and the distance, it is necessary to allocate the optical power of different lines. At this time, devices with different splitting ratios are required, and FBT splitters are used.
FBT VS PLC
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Classification of PLC optical splitters
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In addition, optical splitters can also be terminated with different types of connectors. The packaging methods are usually box type or stainless steel tube type. Box type optical splitters generally use 2mm or 3mm outer diameter optical cables, while stainless steel tube type Optical splitters generally use optical cables with an outer diameter of 0.9mm.
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Device structure
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Bare fiber type PLC splitters leave bare fibers at all ends. It is mainly suitable for occasions that are not frequently disassembled, such as cable connector boxes, optical fiber distribution panels, etc.
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micro package structure
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The miniature optical splitter is a miniature steel pipe package, which can be divided into pigtails with connectors and pigtails without connectors. Connectors are usually available in SC, LC, FC and ST types. Can be installed in optical cable splice box, module box, distribution box.
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Fan-Out PLC Splitter
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The fan-out PLC splitter usually uses 0.9mm optical fiber, and through a bundled fan-out kit, a single fiber branch is branched out, which can be terminated with different types of connectors. Can be effectively installed in fiber optic DP boxes, fiber optic splice boxes or other small terminal boxes.
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ABS Box PLC Splitter
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The box-packaged splitter is currently the most used type by operators. The ABS package is compact and the application is more flexible.
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Rack Mount PLC Splitter
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The rack-mount optical splitter is designed for standard 19″ cabinet installation, which can meet the high wiring density requirements of data centers or server rooms. It is generally packaged in a metal box, which is easy to install in fiber optic projects.
Play a good role in protecting the PLC splitter device. There are various adapter mounting interfaces such as SC, LC, FC or ST connectors. Rack-mount optical splitters are widely used in FTTX projects, cable TV systems and data communication centers.
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Wall-mounted PLC splitter
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The box body of the wall-mounted PLC splitter is usually made of ABS material, which provides reliable protection for the direct connection, termination or branch connection of the optical fiber. Double-layer structure, the upper layer is a PLC splitter, and the lower layer is a splice tray. The wall-mounted optical splitter is used in the terminal access link in the FTTH access system to connect and protect optical devices. The wall-mounted optical splitter is suitable for corridors, basements and computer rooms, etc., and is also suitable for outdoor wall-mounted and pole-mounted installations.
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LGX type PLC splitter
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LGX encapsulates the optical splitter in a small metal box, which can be installed in a 19-inch 1U/2U/3U chassis. The input and output ends have a pigtail structure, which can be easily connected to the ODF panel adapter, saving time. LGX’s compact and miniature design, plug and play, can be easily installed in optical fiber distribution boxes, ODF sub-frames, optical fiber terminal boxes and optical cable transfer boxes.
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Plug-in PLC splitter
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The plug-in PLC splitter is installed and fixed in the plug-in box, and the interface types include SC/FC/LC, etc. It is mainly suitable for corridors or outdoor light splitting points under FTTH access mode. Commonly used 1X4, 8, 16, 32 and 2X8, 16, 32 PLC splitters are used as plug-ins for installation in customer-specific enclosures, especially corridor enclosures.
