Access to the Internet using ftth technology. FTTx technologies - Internet connection. FTTX Access Technology: What It Is

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FTTX Access Technology: What Is It?

FTTX (from English fiber to the X or literally "fiber to point X") is a collection of ways to connect to the Internet using fiber optic cable. Data in this case is transmitted by converting electrical impulses into light and vice versa. This method is very fast, reliable, and efficiently works over long distances without loss of signal quality. The X point can be anywhere from the local communications center to the user's desktop. Fiber optic cable is usually combined with traditional copper cable, which through a special interface (RJ45 or other) connects directly to a computer or other electronic devices... Several providers, in particular Rostelecom, are involved in the development of FTTX networks in the Russian Federation.

The FTTX Internet can be connected in the following main ways:

FTTN (Fiber to the Node). The fiber is routed to a local communications center or node located a few kilometers from end users. Further connection is carried out over a copper cable using VDSL technology. The latter stands for Very high speed Digital Subscriber Line or "high speed digital subscriber line". The predecessor of VDSL is ADSL ("Asymmetric Digital Subscriber Line"), which allows the use of traditional telephone cable for network access and conversation at the same time. Internet via VDSL is limited to 10-50 Mbps (depending on distance). This connection is considered "budgetary" and is used mainly outside of large cities. Currently, VDSL2 technology is being implemented, which provides speeds of about 100 Mbps or even more. The shorter the distance (wire length), the higher the speed. However, VDSL2 requires high-quality copper cable to be installed, which makes widespread use of this technology commercially controversial.

FTTC (Fiber to the Curb). The connection is similar to FTTN, but fiber is brought closer to users to the “border” of a city block or group of buildings. In this case, the length of the additional copper cable does not exceed 300 meters, which makes it possible to increase the data transfer rate up to 50 or even 100 Mbps (VDSL2).
FTTB (Fiber to the Building). Fiber optic is connected to a specific apartment building, office center or private buildings. Then the provider's terminal, which is usually located in the basement or on the technical floor of the building, is connected by copper cable to the users' computers. This method provides Internet access at a speed of 100 Mbps and more. FTTB is used in large cities and for newly erected buildings.

Internet using XPON technology

PON stands for Passive optical network or Passive Optical Network. Unlike active optical networks PON does not use auxiliary electrical equipment (various media converters, routers, switches, etc.) outside the premises where the end user is located. This makes such networks independent from the constant supply of electricity, which is an advantage of this technology.

PON FTTH (fiber to the home) is used for fiber optic connection to the Internet to a private house or apartment. Up to 128 subscribers can be connected to the "trunk" cable via the so-called. "Tree-like" architecture. In each living space, it is necessary to install a specialized modem (with or without Wi-Fi function), which converts optical signals and connects user devices. There are several types of "passive networks" (BPON, GPON, EPON, etc.), denoted by the general abbreviation XPON.

PON technology is sometimes mistakenly referred to as "direct fiber" or "dedicated personal line". In reality, the cable branch is brought only to the user's house or apartment, where the signals are converted. This is a collective connection. Genuine "straight fiber" has no branches and is delivered directly to the user's desktop (Fiber to the desktop or FTTD). This connection is very expensive and difficult to maintain. As a rule, it is provided only to VIP clients, for example, corporate executives, high-ranking government officials, etc.

Users often ask what is the difference between FTTX technology and "optics", implying a connection using XPON. All of these are types of fiber-optic cable networks that are somehow combined with auxiliary equipment (copper cable, special modems, media converters, switches, etc.). XPON technology has its pros and cons.

Among its main advantages:

comparatively high data transfer rate (more than 100 Mbps). Actual speed depends, of course, on the provider chosen by a specific user and the corresponding tariff plan;
the ability to connect via one cable not only the Internet, but also television, telephone, and other additional services;
independence from the local electricity supply (if you have a charged laptop, smartphone, backup battery, etc.);
relative cheapness and availability for the mass consumer.

On the other hand, XPON has some disadvantages:

fragility of fiber optic cable compared to copper. This increases the likelihood of damage when connecting to an apartment or house. Correct laying, installation of a protective box, drilling of additional holes, etc .;
it is necessary to purchase and configure a specialized modem for converting optical signals. A number of providers offer such equipment for rent, on credit or sell at a discounted price, subject to prepayment of their services for a future period of time;
if the fiber is cut, the user loses not only Internet access, but also television, telephone and all services, if they are connected using the same technology.

To date, the most progressive and "advanced" access system is the one that uses an optical cable. For its designation, the abbreviation FTT (x) is used, which translates from English (Fiber to the x) as "optics to (x)", where (x) is the designation of a specific place to which the optical cable is laid. In other words, this abbreviation is intended to mean architecture broadband through an optical cable laid from the central station to some point (x), which should be as close as possible to the subscriber. Depending on its location, three different access architectures are distinguished, denoted by the corresponding abbreviations:

FTTh - the optical cable is laid to the apartment ( Fiber to the home);
FTTb - optical cable is laid to the building ( Fider to the building);
FTTc - the optical cable is laid to the street distributor ( Fiber to the curb).

It should be mentioned that the above architectures replaced what was called FTTn, and implied laying a cable to the network node (Fiber to the node). Nowadays, the most common architecture is FTTh.

The most modern access technology via optical cable (line) is designated by the abbreviation GPONformed from an English expression Gigabit-capable Passive Network, which literally translates as “passive optical network capable of operating at 1Gb speed”. The abbreviation PON is used to denote the technology of laying a passive optical network. This technology uses a tree-like fiber-optic architecture with optical splitters on the cable nodes. It allows you to provide Internet access at speeds exceeding 1 Gbps. The length of optical fiber, laid using PON technology, can be up to 20 km, and current research promises to triple this distance. The idea behind PON technology is to use only one transceiver module to transmit information to a large number of subscribers (and receive information from them). This technology provides the laying of an optical cable to a subscriber's apartment using subscriber equipment (ONT - optical network terminal).

The use of FTT (x) PON access technology can provide subscribers with the following opportunities:

data transmission and reception at speeds up to 100 Mbit / s (1Gb for GPON);
equalize the speed of outgoing and incoming traffic;
to use only one subscriber device (ONT) to receive a wide variety of communication services (Internet, telephony, television), which requires laying only one optical cable;
receive, if necessary technical support remotely, without calling a specialist at home.

Our catalog for FTT (x) networks also includes

Connection to the networks "AzovInternetService" and the Internet is available for private and corporate subscribers using several modern high-speed technologies.

FTTH technology

"Fiber To The Home" - optical fiber to the house (apartment, summer residence, office)
Using this technology, a fiber-optic cable (FOCL) is laid from the signal source to the end user.
The advantages of FTTH architecture are:

the highest channel bandwidth;
fully standardized and most promising network option;
fTTH solutions provide mass service to subscribers at a distance of up to 20 km from the communication center.

FTTH connection is made by connecting an optical cable at the end subscriber with the installation of a "media converter" - a device that converts an optical signal into an electrical one for further wiring around the house using a copper cable (UTP) or using Wi-Fi. Internet access can be carried out at speeds up to 1000 Mbit / s.

FTTB technology

The AzovInternetService company uses FTTB (Fiber To The Building) technology: an optical cable is brought to the house and distributed to apartments using a copper Ethernet cable. This allows providing high-quality Internet access in each apartment at a maximum speed of up to 100 Mbps. Depending on the connection technology, the IP address can be external or internal. FTTB technology is the most advanced today. Its potential allows you to quickly expand network capacity in places where it is needed to provide data services the highest quality... In addition, FTTB provides the same speed for incoming and outgoing data from the computer, unlike other technologies.

With the FTTB option, optical fiber is brought into the house, usually in the basement or attic (which is more cost effective) and connected to an ONU (Optical Network Unit). An optical line terminal OLT (Optical Line Terminal) is installed on the operator's side. OLT is the primary device and determines the parameters of traffic exchange (for example, time intervals for signal reception / transmission) with subscriber ONU devices (or ONT, in the case of FTTH). Further distribution of the network around the house takes place over the "twisted pair".

This approach is advisable to apply in the case of network deployment in apartment buildings and business centers of the middle class. Russian telecom operators are deploying FTTB networks so far only in large cities, but in the future, this technology will be used everywhere. With FTTB, there is no need to run expensive fiber optic cables as with FTTH.

GPON technology

PON (Passive Optical Networks) is a family of rapidly developing, most promising technologies for broadband multiservice access over optical fiber. The essence of the PON technology follows from its name and consists in the fact that its distribution network is built without the use of active components: the branching of the optical signal in a single-fiber optical communication line is carried out using passive optical power splitters - splitters.

Structurally, any passive optical network consists of three main elements - an OLT station terminal, passive optical splitters and an ONT subscriber terminal. The OLT terminal ensures the interaction of the PON network with external networks, the splitters split the optical signal in the PON path section, and the ONT has the necessary interfaces for interaction from the subscriber side.

Based on the PON architecture, point-to-multipoint logical topology solutions are possible. A whole fiber-optic segment of the tree-like architecture, covering dozens of subscribers, can be connected to one port of the central site. At the same time, passive optical splitters (splitters) are installed in intermediate tree nodes and do not require power and maintenance.

The main idea of \u200b\u200bthe PON architecture is the use of only one transceiver module in the OLT to transmit information to and receive information from multiple ONT subscriber devices.
GEPON technology (Gigabit Ethernet Passive Optical Network) is one of the varieties of PON technology and one of the most modern options construction of communication networks providing high speed of information transfer (up to 1.2 Gbps). Main advantage gEPON technologies lies in the fact that it allows optimal use of the fiber-optic resource of the cable. For example, to connect 64 subscribers within a radius of 20 km, it is enough to use just one fiber-optic segment.

The main advantages of GEPON are:

The use of standard 802.3ah mechanisms, which will significantly reduce the cost of equipment in the future;
Increasing the transmission speed up to 1 Gbps in both directions and providing more broadband services;
Providing QoS using 802.1p / TOS mechanisms. It is possible to use strict traffic prioritization mechanisms with eight dedicated queues for each type of traffic. These mechanisms allow the provision of services such as VoIP or VoD with quality assurance;
Possibility of connecting 64 subscriber devices per PON branch and efficient use of optical fiber;
Full support for DBA (Dynamic Bandwidth Allocation) - a mechanism for dynamic bandwidth reallocation in accordance with subscribers' requests and free bandwidth in the PON tree. So subscribers who are provided with a guaranteed bandwidth for data transmission, for example, 1Mb / s, can receive real speed up to 1Gb / s if the PON tree bandwidth remains partially unused (similar to UBR traffic in ATM);
Support for streaming video (IGMP Snooping);
Easy to install and maintain.

FTTB - Fiber To The Building

FTTB technology.

See on page:

FTTB technology... Hybrid fiber-coaxial networks (HFC - Hybrid Fiber Coax) are built using three main technologies (Fig. 1):

FTTH (Fiber To Home) - optics to home.
FTTB (Fiber To Building) - optics to the building (structure). Sometimes you can see the word Block - block. This means that the optics have been brought to the housing block.
FTTC (Fiber To Carb) - optics to a group of houses.

If FTTH is a promising but relatively expensive technology, then FTTB is the “optimal” technology most convenient for Russian cities of medium and large size.

What is usually understood as FTTB technology? This technology is understood as a relatively deep penetration of optics to the subscriber, i.e. operation of an optical node (OS) on average for 100 ... 250 subscribers (for example, a 9 ... 12-storey building with 4 ... 6 entrances). In this case, after the op-amp, no more than one coaxial amplifier is usually cascaded (Fig. 2).

The features of FTTB technology are:

Increased reliability. As is known from practice, the largest number of failures occurs not on fiber-optic lines, but on coaxial networks. Due to the presence of no more than one amplifier connected in cascade (for example, an amplifier at the entrance), the probability of failure is low.

Ease of building parallel digital networks is the most important advantage of FTTB technology. At the same time, a separate optical fiber is allocated for the parallel digital network (instead of a core for the reverse channel).

Reduction of ingression noise achieved due to the small number of subscribers connected to one OS. Moreover, when using collective cable modems (CM), ingression noises (the main sources of noise in the reverse channel) emanating from subscribers are virtually eliminated. The SM is switched on at the input of the house amplifier, which does not include a reverse channel amplifier.

Higher rates of digital streams in reverse direction with a constant number of frequency channels, they are obliged exclusively to the number of upstream receivers (receivers of the reverse direction) installed as part of the cable modem headend (CMTS). An increase in the number of upstream receivers (hence, an increase in the total rates in the reverse direction) while maintaining the carrier-to-noise ratio (C / N) became possible due to a decrease in the number of subscribers loaded on one OS.

Ease of implementation of new digital technologiessuperimposed on existing FTTB networks. A classic example is the new promising technology EttH (Ethernet to the Home), developed by Teleste (Finland) and gaining more and more distribution around the world. Figure 3A shows a snippet of a solution called Ethernet over Coaxial (EoC) that delivers Ethernet frames over coaxial television cable in home distribution networks. The EoC solution does not require additional cable, such as UTP, and provides access to the Ethernet network at a subscriber socket connected to the coaxial cable of the KTV operator. By the way, the EttH technology from Teleste allows operators of FTTC networks to do without laying FOCL to the house when building Ethernet networks. In fig. 3B shows a diagram of the Virtual Fiber solution ("virtual fiber"), which provides Ethernet (100Mbps) delivery over existing networks cable TV... Moreover, "virtual fiber" can work in KTV networks in parallel with Docsis.

Possibility of using economical op amps is achieved due to the simple fact that a powerful house amplifier is installed after the op-amp, therefore, no strict requirements are imposed on the op-amp output stage (namely, the value of its maximum output level determines the op-amp's pricing policy), both in terms of gain and output level ...

Operation at low input optical powers is achieved due to the fact that the downstream house amplifier does not actually contribute to the S / N reduction due to its high output level. It is the operation at low input optical powers that allows the use of a small number of optical transmitters (hence, the cost of fiber-optic communication lines as a whole decreases) with a large number of op amps.

Thus, we can safely say that exactly FTTB technology HFC network is most beneficial for russian conditions exploitation both in terms of pricing policy, and in terms of the implementation of high technical parameters.