The desire to receive data from the Internet
with low speed technology
like trying to suck jelly through a straw.

The traditional public switched telephone network (PSTN) allows the transmission of voice and data within a narrow frequency band (300-3400) Hz. The rapid growth of the Internet and the most widespread access to it using standard analog modems cause congestion in the PSTN, since the latter is not designed for the Internet load, which is characterized by a large average session time and more uneven than the telephone load. The second problem is that for comfortable access of users to the services of the existing network (and primarily the Internet), the transmission speeds that analog modems can provide are no longer sufficient. This applies not only to private (residential) users, but also to the growing category of business users who work from their home offices and who need to connect to corporate networks at a significantly higher data transfer rate than traditional analog modems can provide. .

The complexity of achieving the required speed of connection to the Internet lies in the fundamental principles of building telephone networks, which by their nature are not designed for high-speed data transmission. When Alexander Bell invented the telephone, his imagination went no further than allowing people physically in different places to talk to each other. In addition to the fact that traditional telephone (that is, voice) communication is carried out in a very narrow frequency band, it also allows for much greater signal attenuation than is possible with data transmission. In this case, the biggest problem lies (in the truest sense of the word) between the telephone exchange and the subscriber's home. During the development of telephone communications, a long way has been traveled from manual switches to modern digital telephone exchanges that provide subscribers with a large number of various services, but the same twisted pair cable is laid between the station and the subscriber as at the dawn of telephony. And there are already almost a billion such twisted pairs around the world.

As the cost of user equipment that allows access to the Internet gradually decreases, the connection bandwidth and its cost come to the fore. Everyone who uses the Internet is forced to wait (wait and wait again) until the desired site is found and the required page is loaded. The situation worsens even more if large files (such as photos or videos) need to be uploaded. Moreover, the more users simultaneously work on the Internet, the slower the speed of each of them individually becomes, because a sharp increase in traffic leads to a significant increase in the load on telephone networks. In order to fully realize the full potential of the Internet in the areas of distance learning, commerce and entertainment, it is imperative to overcome the obstacle of insufficient connection speed (and its too high cost). The user wants one high-speed and always-on access. However, despite the fact that the high-speed data network covers the entire country to one degree or another, access to it by end users (the very “last mile”) can be fraught with technical and economic difficulties. Backbone data transmission lines allow gigabits of information to be transferred, but a very small number of end users have the ability to transfer data at least at a speed of several hundred kilobits. Pulling a fiber-optic line to each user is very expensive. Coaxial cables (cable television) allow high-speed transmission, but mostly in one direction. Telephone lines, as they are currently used for telephone communications, have a low data rate. Only broadband technologies, which are the future of the telecommunications industry, can provide access with the necessary high speed.

The telecommunications of the future are based on providing each user with the possibility of high-speed data transmission. But how do you transfer data at high speeds over the critical "last mile"? There are several technological directions to overcome this obstacle. (Although, just because there are several alternative technologies to solve the same problem does not mean that the user has a wide choice of equivalent options from which to choose the best one. In most cases, only one single option will be available to the user.)

The main candidates for solving the last mile problem are the following technologies. These are xDSL digital subscriber line, cable modems, as well as wireless and satellite technologies.

None of these technologies can be considered an ideal solution to the "last mile" problem. Many generally say that there are only two technologies that can solve the problem of the "last mile" cable modems and xDSL. Both of these technologies are based on the use of already existing cable networks, which, which is quite important, cover almost all potential users. Another technology fixed wireless (sometimes called wireless local line) lags behind the two technologies mentioned above in that it requires some infrastructure to start full service.

Other data transfer technologies either simply do not solve the "last mile" problem (not providing sufficient transfer speed) or are too expensive for most potential users. The former include connections using familiar analog modems, which have already reached the maximum data transfer rate over traditional twisted-pair telephone wires. The second category is fiber optic cables. There are people who advocate the complete replacement of the entire telephone cable network with new fiber optic cables that are capable of supporting data transmission at very high speeds. However, not only at present, but also in the foreseeable future, such a widespread replacement will not be carried out due to its high cost. Even for the United States, which is quite prosperous in terms of telecommunications, according to the most optimistic forecasts, the widespread introduction of fiber technologies will take more than a dozen years. At the same time, there are certain configurations of the access network (for example, when a sufficiently large group of users is at a considerable distance from the local station), in which the use of an optical cable is already economically viable. It should be emphasized that in the latter case we are talking about the group use of an optical cable, i.e., its sealing.

It would be a mistake to try to treat the process of solving the last mile problem as a matter of choosing any one technology. In practice, these technologies are initially in unequal conditions. Not all providers occupy the same position in the structure of the networks they intend to use. Therefore, operators that own cable telephone networks are unlikely to use cable modems, and operators that specialize in building wireless communications infrastructure are unlikely to invest in xDSL. On the other hand, thanks to the ability to use various technologies on the “last mile”, operators that own large and branched networks have the opportunity to offer their customers various options for organizing high-speed access. For example, xDSL technologies and a wireless access system, or xDSL and cable modems.

Those regions where broadband coaxial cable networks, and later hybrid optical-coaxial HFC (hybrid fiber / coaxial) networks designed to connect subscribers to a cable television network, have been widely developed, there is a powerful platform for providing high-speed access to home users.

The transmission of terrestrial television broadcasting over coaxial cable networks was proposed by the American E. Parson in 1948. The first such system was created in Seattle and was designed to distribute 5 television (TV) channels. The introduction of cable television systems made it possible to abandon many of the shortcomings inherent in terrestrial TV, and, first of all, to provide high-quality TV to areas of uncertain reception of a television signal over the air. The first CATV systems were collective reception systems that operated first in the meter wave band (47 240 MHz), and then in the decimeter (550 862 MHz in Europe and 600 750 MHz in the USA). These systems were relatively simple and contained a collective antenna, a headend, as well as a coaxial transmission path with the required number of couplers and amplifiers (main and house). Strictly speaking, these were not yet KTV networks, but rather systems for the collective reception of television programs. Naturally, both in terms of the modulation method (AM) and the position on the frequency scale, these systems were identical to the corresponding parameters of the on-air television signal, since they were designed to be received by standard television receivers. As the CATV systems were enlarged, their reliability decreased, in connection with which the issue of operational maintenance of these systems became very acute. Therefore, CATV systems began to be supplemented by remote control systems, which made it possible to control the state of these systems and, first of all, the parameters of the main amplifiers. To transmit information about the state of the system to the headend, a part of the spectrum below the operating frequency range (usually 530 MHz or 550 MHz) was used. An alternative possibility of transferring service information to the headend is to use a standard public switched telephone network (PSTN) telephone modem for this purpose. So in cable TV systems, it became possible in principle to provide the user with interactive network services.

The revolution in the field of telecommunications networks, associated with the emergence and widespread introduction of optical cables, has also affected cable television networks. At this point in the development of CATV networks, the purely coaxial transmission medium has been replaced by the hybrid optical-coaxial HFC medium. In the CATV architecture using HFC, TV broadcast and switched video signals are transported over an optical fiber from the CATV headend to the ONU (optical network unit) optical network unit. The latter connects the optical backbone network with the distribution coaxial network. In the ONU, the signals of the corresponding channels carrying video, voice and data signals are transferred to the frequency range allocated for them. Note that the coaxial segment of the HFC network requires the use of duplex amplifiers that provide two-way signal transmission. The optical network board ONU (optical network unit) also performs some additional functions, which include the separation of "upstream" (from subscribers to the network) and "downstream" (from the network to subscribers) signals. The problem of using the HFC architecture to provide voice telephone services is the insufficient quality of voice services, mainly due to external interference (ingress noise). When transmitting data, the main problem is also external interference created in the "uplink" channel by household appliances such as microwave ovens, refrigerators, etc. Thus, according to available statistics, less than 5% of cable TV networks can use this range for its intended purpose, since this frequency range strongly affected by interference from household electrical appliances (refrigerators, microwave ovens, etc.). Therefore, it is advisable to use a telephone subscriber line as an uplink of the cable TV network.

In the mid-1990s, cable TV operators conducted studies on the possibility of using the cable TV network infrastructure for broadband access to network services for residential users. As a result, devices appeared that were not quite aptly called cable modems. Cable modems are devices that provide high-speed access to data networks through a hybrid optical-coaxial HFC network.

Unlike traditional PSTN modems, cable modems are part of a point-to-multipoint system in which multiple cable modems of different users are connected via a hybrid optical-coaxial medium to a cable TV operator's headend controller. Like xDSL modems, cable modems operate in "always on" mode, i.e., they are constantly connected to the headend.

The use of cable modem technology allows a very elegant solution to the problems of analog subscriber telephone line, trunk lines and resources of switching stations of the public switched telephone network (PSTN). Cable modems transmit Internet traffic directly to the Internet router located at the headend of the cable TV system. The advantage of cable modem technology is also that it (although not always) can use the existing cable infrastructure of cable TV systems. In addition, the element base of cable modems is available and relatively inexpensive, and also (and this is perhaps the main thing) allows for the joint operation of cable modems from different manufacturers. Most cable modems are external devices connected to a personal computer via a standard 10Base-T Ethernet card or USB port; they can also be made in the form of a board inserted into a free slot of the ISA bus, using the plug and play technology for installation. To access the data network, the Cable Modem Termination System (CMTS) based on an access concentrator is used.

The "downlink" bandwidth (from the network to the subscribers) is shared by the entire set of user cable modems. Each standard television channel, occupying 6 MHz of RF spectrum, provides 27 Mbps downstream data using 64 QAM; when using 256 QAM modulation, the data rate can be increased up to 36 Mbps. Data transmission channels in the "upstream" direction theoretically allow data transmission at speeds from 500 Kbps to 10 Mbps using 16 QAM or QPSK technologies (depending on the bandwidth of the frequency spectrum allocated for servicing users). The frequency bands allocated for the transmission of upstream and downstream data are shared between all active users connected to this cable network segment. An individual user can count on a data transfer rate ranging from 500 Kbps to 1.5 Mbps depending on the network architecture and load (a significant figure, especially when compared with analog modems).

Cable TV systems using cable modems are based on a multiple access platform. Due to the fact that the users of these systems divide among themselves the frequency band available to all of them for the data transfer time, as the number of simultaneously active users increases, the data transfer rate for each of them decreases. It would seem that a simple calculation shows that with the simultaneous use of a data transmission channel of 27 Mbit / s by two hundred users, each of them will get 135 Kbit / s at best. How, then, is this system better than an ISDN connection that provides a speed of 128 Kbps? Not so simple. Unlike traditional telephony, in which the subscriber receives a dedicated connection for the duration of the call, cable modems do not occupy a fixed frequency band during the entire data transmission session. As already mentioned, the bandwidth is divided among all active users who use network resources only during the actual reception or transmission of data. Therefore, instead of rigidly assigning 135 Kbps to each of the 200 "active" users, the entire frequency band in each specific fraction of a second is divided only between those users who transmit or receive data the speed can increase dozens of times (after all, those who have downloaded , for example, an Internet page and is trying to figure out what's what, they are not currently "active users"). In the case of constant and high activity of any group of users, the cable operator can always expand the transmission frequency band by allocating another 6 MHz channel for data transmission. Another option to increase the average data rate per user is to move fiber optic cables closer to groups of potential users. This reduces the number of users served by each network segment, which naturally leads to an increase in the bandwidth available to each of them.

If we turn to the facts, then in the world cable modems still have more private users than, for example, ADSL technology. By mid-1999, there were about 1.3 million cable modems in use worldwide for high-speed data transmission, 1 million of which were located in the United States.

By the end of 2002, In Stat / MDR counted about 10.2 million cable modem users in the USA, while DSL lines about 7.6 million (it should be noted that US subscribers traditionally use cable modems more actively compared to subscribers in other countries).

But, in addition to obvious advantages, the technology under consideration also has significant drawbacks. As mentioned above, one of the disadvantages of cable modems (unlike, say, xDSL technologies) is that such data lines are shared lines. The bandwidth available to each individual user connected to a particular node may decrease as the number of users connected to the same node increases. Another disadvantage is that the system is "open" (ie, each individual user is not given their own hard-coded connection). This circumstance reduces the attractiveness of cable modems for business use. The cabling system can be thought of as one large LAN network, so (in theory) there is some possibility of each to each other's connection and access to the other user's data. Obviously, no one wants to use the same shared data transmission system with their competitor. In addition, cable modems provide high-speed access over cable TV lines, mainly to private users, because office buildings and businesses in most cases are not connected to the cable TV network.

Just as the spread of cellular and cordless telephones freed subscribers from the cable connecting the handset to a device connected to the telephone network, WLL (Wireless Local Loop) wireless subscriber line technology opened up access to the public telephone network for all those who had already lost hope of connecting to the telephone network. global telephone network.

This technology can most accurately be defined as the use of radio access to provide broadband network services to individual users. Moreover, this technology can be used not only in those regions where the telephone cable network is not sufficiently developed, but also where the level of development of cable networks is quite high. In this case, operators using broadband wireless access technologies are already in direct competition with local operators.

Broadband wireless lines can be used for high quality data, video and telephone communication. Historically, a telephone line was used for the uplink, but operators are now moving to a full duplex wireless system. The data rate is determined by the width of the frequency spectrum available to the operator and the modulation scheme. For example, the efficiency of digital modulation schemes ranges from 0.7 bps per Hz using BPSK modulation to 3.5 bps per Hz using 16QAM.

As in the case of on-air television broadcasting, wireless data transmission lines are organized according to the line-of-sight principle. The signal is transmitted from an antenna, usually located on a hill or a tall building, to special receiving antennas installed on users' buildings. Obtaining a sufficiently clean frequency spectrum can be quite a challenge; another problem is the requirement for line of sight for most organized lines. The organization of the line is quite simple, because it does not require, for example, such a volume of construction (earth) work as when laying cable systems, but it cannot be guaranteed that an organized line (based on the requirement of line of sight) will work as long as necessary. For example, a house built on a line-of-sight path can simply “cut off” such a data transmission line. As is the case with over-the-air television broadcasts, any obstructions (such as dense tree canopy, hills, tall buildings and even heavy precipitation) can make reception somewhat difficult. Multipath distortion (resulting from signal reflections off buildings and other objects) can also seriously complicate reception. Distance must also be considered, as wireless communications signals can only be received within a certain distance from the transmitter. The solution to this problem can be the installation of a network of repeaters throughout the service area (based on the principle of cellular communication).

The organization of a network based on wireless lines is similar to the structure of a cable network. The main difference is that a digital data signal (for example, containing information requested from the Internet) is modulated into an RF channel, which is transmitted to an antenna installed on the user's building. From the antenna, the coaxial cable goes to the converter, which converts the signal from the microwave range to the frequency range of cable television. After that, the signal goes to the modem located in the user's premises. The modem demodulates the incoming data signal and routes it to a PC or LAN.

Wireless subscriber line technology has several advantages over alternative access technologies. Wireless lines can be deployed in those places where, due to the impossibility of work, density or "antiquity" of development, a cable line simply cannot be laid. Second, for certain distances and localities, wireless access may simply be much more cost effective than alternative technologies. Here it is necessary to take into account both labor costs and the length of the subscriber line.

The cost of cable systems largely depends on the distance between buildings and on the degree of concentration of groups of subscribers. The cost of wireless systems is free from such dependency. The cost of constructing cable systems is also highly dependent on the cost of labor, which is usually constantly rising. At the same time, the cost of wireless systems depends mainly on the cost of subscriber equipment, which tends to become cheaper as technology improves. The third benefit of wireless technology is the much shorter system uptime compared to wired infrastructure.

The fact that radio systems provide area coverage means much easier network planning than cable systems. Wireless systems allow you to respond much more quickly to changes in the needs and number of users, while the planning of cable systems is largely based on preliminary estimates (it's good if the estimates coincide with reality).

There are also more prosaic considerations. If the user refuses your services and directs his attention to another operator, then with the development of cable technologies, all investments in this cable line will be lost. At the same time, when using wireless technology, subscriber equipment can simply be removed and installed in another place at a new subscriber. In addition, it is much easier to maintain the operation and safety of a properly organized wireless line than a cable. In many countries, such as Africa, copper cables buried in the ground are simply stolen (unfortunately, Russia can also be counted among these countries). Even fiber optic cables have some value as a secondary product.

In practice, the ability to use satellites for Internet access and high-speed data transmission is divided into two big tasks the organization of backbone data transmission lines (which is part of big business) and the organization of high-speed access for individual end users. End users include not only individual users, but also large corporations, medium and small enterprises, as well as various offices (including home offices).

In short, satellite systems have several attractive features in terms of providing high-speed data transmission services and Internet access.

Satellite systems allow you to bypass the "congestion" in terrestrial data transmission systems. They can be configured as needed to reflect the asymmetric nature of the Internet, both in terms of individual transactions and geographically. For example, most of the content on the Internet is still located in the United States. Several distinctive features of satellite systems make them an attractive access technology. First of all it is cost-effectiveness for the provider. The coverage area of ​​the satellite is such that it can serve a very large number of subscribers. Moreover, the cost of organizing the service does not depend at all on the geographic location of the user within the satellite coverage area. The satellite channel can be received at any point in the coverage area, regardless of terrain conditions.

Although satellite systems have many advantages, allowing them to be considered as one of the technologies for organizing high-speed data transmission on the “last mile”, there are also negative aspects.

Satellite access systems do not have the highest data transfer rate (about 400 Kbps towards the user) and do not work very fast. Imagine that you want to upload some material to your computer screen. With a click of the mouse, you send a request signal that travels over your phone line, through your ISP, and over the normal path on the Internet, and after answering, the signal is transmitted via satellite, traveling a total of about 70,000 kilometers. Even at the speed of light, such a means of accessing the Internet remains quite slow. This is especially noticeable in the implementation of two-way communication in real time.

Investments in satellite communications systems amount to many billions of dollars, and success and profits are by no means guaranteed. Mention should also be made of traffic security, too long planning cycles for a rapidly changing industry such as telecommunications, and a lack of frequencies that could be easily used.

In addition, the disadvantages of satellite systems include the need to purchase and configure rather expensive equipment. However, there are a number of extreme situations when it is impossible to organize access to the Internet in any other way than via satellite (for example, for a ship located in the middle of the ocean).

Now let's focus on some specific technologies of wireless broadband access. Let's start with a brief review of two fairly well-known ones.

Among the many wireless access technologies, the local multi-cell, point-to-multipoint, LMDS (Local Multipoint Distribution System) signal distribution system is one of the few systems that provides the user with broadband multimedia services. LMDS operates in the frequency range (2832) GHz allocated by the US Federal Communications Commission (FCC) for the operation of broadband subscriber access systems. This system is sometimes referred to as a cellular cable TV system. The use of the cellular principle avoids many of the problems associated with the line-of-sight condition, which is mandatory in the MMDS wireless broadband access system, which is discussed below. Carriers of neighboring cells have the same frequency ratings, but different polarizations. LMDS is able to provide the user with the latest interactive multimedia services, including telephone and high-speed data transmission. This technology allows some providers (for example, long-distance and international service providers) that do not have their own subscriber access infrastructure to provide communication services to business and individual users at a relatively low cost and very quickly. In the LMDS access network architecture, the so-called "last mile" of the access network is wireless. In this case, the user's antenna must be within the line of sight of the LOS (Line of Sight) with a cell site connected to a network that provides the user with all the necessary communication services.

It is highly likely that LMDS will be used in the business environment for LAN interoperability in urban environments. It is also likely that the use of LMDS for the transmission of television programs is too late. In LMDS, as in the MMDS technology discussed below, there is no easy way to increase throughput. This problem is not significant in systems of simplex television broadcasting, where any user can receive any channel. However, for user-outbound traffic for LMDS systems, there is no easy way to increase licensed bandwidth. A similar problem exists in the telephone cellular network.

LMDS is particularly well-suited for urban environments with high population density, and therefore potential users, where small transmitter size and small cell area are quite acceptable, and where this makes the prices for the services provided attractive to the user. However, such small cell sizes may be unacceptable in suburban and rural areas where a large number of transmitters would be required to achieve line-of-sight.

Another fairly well-known broadband wireless access system is the multichannel multipoint or microwave multipoint distribution system of subscriber access MMDS (Multichannel (Microwave) Multipoint Distribution System (Service)) This system is very similar to LMDS, but operates in the 2.4 GHz frequency band, and the operating range MMDS frequencies are limited compared to LMDS. Currently, the MMDS frequency band is used by cable television (CATV) providers to provide broadcast analog television signal to users through the headends of the CATV network. As a result of the telecommunication services liberalization process, this frequency band is also open to other services, including telephone and many interactive services.

Unlike LMDS, MMDS is less sensitive to external influences in the form of rain and thunderstorms. Therefore, the requirements for allowable distance from the cell site are less stringent compared to LMDS. So, MMDS covers an area within a radius of about 80 kilometers, while LMDS has a range of no more than 10 kilometers.

The frequency band 2.22.7 GHz in the MMDS system is used to transmit video signals of 33 television channels from transmitting antennas to receiving user antennas. Subscribers within a zone with a radius of about 50 kilometers can receive these signals. With digital processing and compression of video signals, the number of channels can be increased up to 100150.

MMDS can be used to carry both analog and digital video signals. Reception of an analog television signal requires a relatively simple antenna mounted on the roof of the user's house and a set top box that contains a line-to-video converter and a descrambler. In the case of the digital version of MMDS, a more complex and expensive converter is needed. The currently produced MMDS equipment provides not only the possibility of transmitting television signals, but also the provision of voice and high-speed data transmission services.

As another example of wireless broadband access technologies, let's focus on the DBS (Direct Broadcast Satellite) system. This is a new generation of satellite television broadcasting equipment. When using digital methods for converting and transmitting television signals and a small-sized receiving antenna, this technology becomes very attractive to users. The signal received in digital format is decoded in the STB (Set Top Box) signal splitting/combining and signal conversion unit, which has built-in intelligent functions that ensure the provision of many new services, such as interactive television and the provision of information on demand.

The technology of direct satellite broadcasting BSS (Broadcast satellite services) operates in the Ku band, occupying the frequency spectrum of 12.2 12.7 GHz. DBS users can receive 150 200 video channels using MPEG-2 type compression. In addition to video transmission, some network service providers are planning Ku broadband data transmission. Modern DBS systems support data transmission from the Internet to the subscriber at a speed of up to 400 Kbps, and a standard tone frequency (PM) channel is used to transmit control signals from the subscriber to the network.

Let us now turn to a brief review of the most popular wired broadband access technologies such as xDSL.

xDSL is a family of technologies for high-speed access to network services over an existing copper subscriber telephone line. In the acronym xDSL, the symbol "x" is used to denote a specific type of DSL (Digital Subscriber Line) technology. Any subscriber currently using telephone communication has the opportunity to significantly increase the speed of his connection, primarily with the Internet, using xDSL technologies. Thanks to the variety of DSL technologies, the user can choose the data transfer rate that suits him from 32 Kbps to more than 50 Mbps. In this case, the data transfer rate depends only on the parameters and length of this line.

For some reason, it is believed that the subscriber telephone line has a bandwidth of 4 kHz. This is completely wrong. The subscriber line has a limited bandwidth, because it is provided for by its design, and not because the twisted pair is not capable of transmitting high-frequency signals. With appropriate coding schemes, xDSL technologies can achieve megabit data rates.

The oldest and slowest xDSL technology is IDSL (IDSN Digital Subscriber Line), while the fastest and youngest is VDSL (Very High Speed ​​Digital Subscriber Line). In between are other technologies such as HDSL (High Speed ​​Digital Subscriber Line) technology and ADSL (Asymmetric Digital Subscriber Line) technology; the latter has the greatest potential in the mass consumer market.

DSL technologies make it possible to achieve high data transfer rates. For example, ADSL provides 1.5 8 Mbps downstream and 640 Kbps upstream 1.5 Mbps. VDSL provides 13 52 Mbps downstream and 1.5 2.3 Mbps upstream when choosing asymmetric scheme (for symmetrical VDSL the data rate is 13 26 Mbps). The data transfer rate when using DSL technologies depends on the distance; as the distance increases, the data rate decreases. For example, for ADSL, with a line length of 3 km, a transmission rate of more than 8 Mbps can be achieved, and for a line length of 6 km, a data transmission rate of 1.5 Mbps can be achieved. For VDSL, these numbers are about the same. The speed of 52 Mbps corresponds to a line length of about 300 meters, and the speed of 13 Mbps corresponds to a line length of about 1.5 km. At the same time, these technologies provide simultaneous telephone communication, high-speed Internet access, video-on-demand and one (for ADSL) or three (for VDSL) TV channels of DVD quality. Other DSL technologies can be used for voice and high-speed Internet access, but are not suitable for high-quality real-time video transmission.

DSL technologies have certain advantages. Any subscriber connected to the public telephone network has a copper telephone line that can be used to deploy a data line. That is, it is not required to create a new infrastructure. The system requires only two ADSL devices (at the station and at the user's premises) and a twisted pair of wires (unfortunately, the performance of a DSL line degrades as the distance from the station increases or the quality of the line deteriorates). A DSL line provides a reliable and permanent (unlike analog modems) connection. Compared to other access technologies, DSL requires significantly less investment in terms of the data transfer speed that can be achieved.

xDSL technologies provide the most economical way to meet the needs of users for high-speed data transmission. Different variants of DSL technologies provide different data transfer rates, but in any case, this speed is much higher than the speed of the fastest analog modem.

The diversity of DSL technologies makes it possible to use a specific technology for a specific category of users. In particular, asymmetric ADSL technology is best suited for private users who are more consumers of information, while symmetrical technologies are more suitable for business representatives for whom the flows of transmitted and received information are close in volume. In addition, when using ADSL technology, the analogue telephone and/or ISDN basic access channel (BRI ISDN) is retained. The first feature allows you to keep normal telephone service in case of damage to ADSL equipment, and the second allows you to protect the investment of the telecom operator. xDSL technologies can be considered as a serious competitor for cable modems. Theoretically, cable modems provide faster data transfer rates than, for example, ADSL technology, but in reality, most cable networks are not able to provide access through cable modems using the entire bandwidth of coaxial cable. In cases where cable systems provide an "uplink" data transmission channel, this channel is divided among all users. The development of hybrid fiber/coax systems has mitigated this problem, but such systems are still quite expensive and will take a long time to develop sufficiently. Therefore, xDSL technologies remain the most viable solution to the last mile problem at the moment.

It should be noted that while in Russia the possibilities of obtaining high-speed access based on ADSL technology are limited. A very important role is played by the territorial (one might say, geographical) location of the user, but this is far from the only obstacle. Even if a potential user is covered by a cable TV network or has a telephone line, this does not mean at all that these lines can technically be used for high-speed data transmission. A lot will also depend on who provides the service. Some cable and telephone companies are successfully developing and providing high-speed data services, while others prefer not to bother. Such neglect by some telecom operators to the development of high-speed data transmission is explained by the fact that approximately 90% of the income of telecom operators is the provision of telephone services.

Choice is a hallmark of today's digital telecommunications world. Moreover, all new technologies compete with each other to a certain extent, which allows us to expect an increase in the quality of services provided and a decrease in their cost.

Despite the competition between providers pushing various technologies to market, there is no reason to assume that, in the end, any of the technologies will prevail. All technologies, due to their fundamental differences, have a chance to exist for their share of users. The choice is up to the users.

The optimal access technology should be cheap enough, requiring additional costs only when new users are added; it should provide the user not only with high bandwidth, but also provide the necessary quality of QoS (Quality of Service) transmission for the ordered service (for example, the signal delay time is not more than the maximum allowable, guaranteed unevenness of this delay in the signal transmission bandwidth, the required reliability, etc. .d.). All access methods, including copper or fiber optic cables, cable modems, or wireless systems, meet these requirements to some extent. Unfortunately, none of the technologies meets all the requirements at once.

In conclusion, we note another significant trend in the evolution of broadband subscriber access networks, which follows from the general trend of increasing the throughput of the access network and consists in the emergence of optimal solutions, which are a combination within one network and even an access line of several access methods. Such technologies include, for example, a mixed optical-radio-coaxial access technology HFRC, as well as VDSL technology, which essentially involves the use of a mixed copper-optical transmission medium in a subscriber access network.

The last mile in the provider is the section of the communication line from the provider's switching device to the client's switching device. Simply put, the last mile equipment connects the Internet Service Provider's communications center to your apartment or office. And this very mile is being organized at the moment in a variety of ways - both wired and wireless.

The organization of the "last mile" always implies the presence of the following components: switching equipment for receiving and sending signals and information transmission medium.

General principles of organizing the “last mile”

1. The switching point of the provider should be located in sufficient proximity to the habitat of customers. The distance is calculated depending on the degree of signal attenuation in the transmission medium.
2. The client must have the appropriate equipment capable of connecting to the provider's switching point. The type of equipment depends on how the “last mile” is organized.

Technologies of the organization of the "last mile" are divided into wireless and wired, depending on the nature of the information transmission medium. It is easy to guess that wireless networks are those in which information is transmitted directly over the air (various wave transmission methods: WiFi, WiMAX, radio transmission, optical wireless communication).

Cable networks, respectively, include cable trunks: fiber-optic or metal (, telephone cable, PLC, coaxial cable).

Let's take a look at three of today's most common "last mile" laying technologies.

1. Wireless WiFi connection. The advantages of a wireless connection are obvious: it is convenient, does not require cable runs, and allows several client computers to connect to the channel at once without additional equipment. Disadvantages of this solution: the WiFi coverage area is unstable, heterogeneous and subject to a wide variety of interference.
2. Connection using copper twisted pair. The most common connection method. Cheap and cheerful: a twisted pair cable (UTP category 5e) is laid from the switch located in the building to the user's computers. Despite the ease of installation and the low cost of materials, this method of organizing a network has certain limitations: a twisted pair cable can, but is not desirable, be laid down the street. For outdoor installation, a special shielded FTP cable with an additional protective sheath is used, however, it is not reliable enough in the long run. Copper cable is subject to electromagnetic interference, so you can not place the cable near sources of electromagnetic radiation, along the wiring. The length of the route between the switch provider and the user should not exceed 100 meters.
3. Fiber optic connection. The advantages of fiber-optic technologies: a completely dielectric medium for information transmission (not affected by an electromagnetic field), less restrictions on the length of the route (you can spread the network over a multi-storey extended building from one switching node without additional repeaters, you can combine several buildings), durability (the fiber optic cable will reliably perform its function for 25 years or more) and significantly higher throughput (10, 40 or more gigabits per second). However, the organization of the “last mile” on optical fiber is expensive. Fiber optic duplex cable itself is inexpensive, but installation services can cost a pretty penny. In addition, a fiber optic network requires special equipment to convert the optical signal into an electrical one. At the same time, when connecting communication lines to offices in a modern metropolis, it is more rational to use the most modern and promising fiber-optic technologies.

In addition to these methods, signal transmission over a telephone cable is still in demand (already almost not used DialUp and still quite common ADSL). However, due to the convenience of more modern technologies, these options for laying the “last mile” are already gradually becoming a thing of the past, following the Internet over coaxial cable. Abroad, PLC technology is gaining momentum - the transmission of information over electrical wires, but in our country it has not yet found its buyer.

The concept of the “last mile” in the Russian electric power industry appeared in 2006 as a result of the reform in the energy sector. In addition to other results of this reform, the distribution of electrical networks between federal and regional companies took place: the main electrical networks (with a voltage of 110 kV or more) were at the disposal of the Federal Grid Company (FGC UES), and the distribution networks were transferred to the corresponding Interregional Distribution Grid Companies (MRSK). As a result, ordinary consumers paid both FGC and MRSK for energy, but there was a slight omission in this scheme: a number of large consumers ended up entering into direct contracts with FGC, which reduced their own electricity costs, but led to an increase in the tariff burden on other consumers . To eliminate the existing imbalance, Law No. 250-FZ “On Amendments to Certain Legislative Acts of the Russian Federation in Connection with the Implementation of Measures to Reform the Unified Energy System of Russia” introduced the so-called “last mile” agreements in the electric power industry. According to these agreements, FGC leases to interregional grid companies small sections of backbone networks or other power grid facilities (substations, distribution points, etc.). As a result, direct contracts with FGC became inaccessible for corporations. According to acting Minister of Energy Sergey Shmatko, the last mile mechanism in the electric power industry was developed in order to avoid abrupt changes in tariffs in the energy sector of the regions and an increase in the load on end consumers. Last mile agreements in the electric power industry were introduced as a temporary measure, pending the approval of a new tariff setting policy as part of the reform of the Unified Energy System of Russia.

At the same time, many experts call the “last mile” in the electric power industry legalized piracy and talk about the ill-conceivedness and inefficiency of such an approach. In essence, the “last mile” in the electric power industry is a form of hidden tax on industry. According to some reports, the share of additional load of large enterprises today is about 30% of their electricity costs. It is no coincidence that legal proceedings have begun in the country on the recognition of illegal contracts for the “last mile” in the electric power industry, and on the recovery of unjust enrichment from IDGCs. For example, at the beginning of 2010, Rusal managed to challenge about 800 million rubles paid by the Krasnoyarsk aluminum smelter in favor of IDGC of Siberia under the terms of the “last mile” agreement in the electric power industry. Novolipetsk Metallurgical Plant also claims to reimburse more than 9 billion rubles paid by IDGC of Center, and these are far from isolated cases.

According to the Concept of Russia's Economic Development for the Period up to 2020, the "last mile" contracts in the electric power industry should operate until 2014, after which this cross-subsidization mechanism will cease to operate, and electricity tariffs for the population will reach the market level. It is clear that if the mechanism of the "last mile" in the electric power industry is abandoned, the funds lost by IDGCs will be distributed among small consumers, and this may lead to a sharp increase in tariffs, especially if the region has a high proportion of large consumers. Therefore, in parallel with this, it is planned to implement a mechanism for targeted support for low-income groups of the population, however, as Yury Lipatov, chairman of the State Duma Committee on Energy, notes, specific methods of social protection have not yet been worked out. It remains to be expected that this issue will be given more attention in the next two years, while the last mile in the electric power industry is still in effect.

On the eve of 2014, the problem of the “last mile” again became topical and acute in the electric power industry. And to be more precise, it did not lose its sharpness from the very beginning of its existence. Now they are talking about this more loudly, because the Russian government for 2014 raised the question of its modification, or liquidation. In order to understand the complexity of the problem, let's analyze the situation from the beginning of its occurrence.

The concept of "last mile" is inextricably linked with cross-subsidization - this is a mechanism for setting electricity tariffs, in which the reduction in payments for the population occurs due to an increase in tariffs for large consumers. One such example of cross-subsidization is the last mile contract. This mechanism appeared in the Russian power industry in 2006 and was supposed to be a temporary measure until new tariffs are approved. But, as they say, there is nothing more permanent than temporary.

The "last mile" agreements were the initiative of the RAO "UES of Russia" reformers. When the power industry was divided by types of business, the backbone networks were transferred to FGC (Federal Grid Company), and the distribution grids were transferred to MRSKs (Interregional Distribution Grid Companies). As a result, consumers paid both FGC and MRSK for energy. But there was one flaw in this system. Some large enterprises, realizing their obvious disadvantages in this matter, began to conclude direct contracts with FGC, of ​​course - this reduced their electricity costs, but the tariff burden on other consumers automatically increased. To resolve the existing imbalance, Law No. 250-FZ “On Amendments to Certain Legislative Acts of the Russian Federation in Connection with the Implementation of Measures to Reform the Unified Energy System of Russia” was introduced and so-called “last mile” agreements were developed.

Under the terms of these agreements, FGC leases small sections of backbone networks or other power grid facilities (substations, distribution points, etc.) to interregional grid companies. Accordingly, in this case, the conclusion of direct contracts with FGC by large consumers, as they did before, became impossible. Simply put, this added another link in the chain between the producer of electrical energy and its consumer, in order to increase the cost of electricity consumption for the latter. These measures provided for the reduction of the tariff burden on small consumers at the expense of large enterprises.

Naturally, this state of affairs could not suit large consumers of electricity. Many experts refer to the "last mile" in the electricity industry as legalized piracy and say that this approach is ill-conceived and inefficient. If you look, the "last mile" is essentially a hidden tax on industry. According to expert research, the additional load of large enterprises today is about 30% of their electricity costs. With the advent of the "last mile", for example, a company such as Sibur began to spend 300 million rubles on electricity. per year more than before, and the UC Rusal plant - Krasnoyarsk Aluminum - by 1 billion rubles. In 2012, experts from the Skolkovo Energy Center estimated the volume of the “last mile” at 58 billion rubles. Interregional grid distribution companies receive additional income without high costs and have the opportunity to slightly reduce payments for the population. The artificiality of the “last mile” mechanism was recognized by the government in 2011, but due to the complexity of the whole situation, not finding opportunities to solve it, Igor Sechin, who was in charge of the energy industry at that time, postponed the decision of the issue to 2014.

Of course, all this time, industrialists have been trying to get away from this system, starting long legal battles with IDGCs. Businesses are suing grid companies to get back huge amounts of money previously paid out. For example, SUAL managed to refuse to pay 393 million rubles to IDGC of Urals through the court, UC Rusal received 9 billion rubles back in the same way. But in this matter, the courts more often take the side of network companies. This is largely due to the fact that the "last mile" system allows to reduce the tariff for electricity transmission for the population. IDGCs, in turn, do not sit idly by and try to sue the lost revenues from the regional authorities, who, in their opinion, incorrectly calculated tariffs.

If the problem is solved simply by canceling the “last mile” agreements, then IDGCs will lose up to 40 billion rubles. in year. The missing money will have to come from somewhere. This can be done through an increase in tariffs for their consumers, in this case, small businesses and the population. Of course, this will lead to a significant increase in electricity bills for the latter, because in some regions large consumers account for up to 40-60% of the total volume of energy sold. In this situation, only FGC loses nothing, because it takes the minimum rent from IDGCs, transferring only a small section of the network to the regional company. To date, FGC has 70 "last mile" agreements, and their validity or cancellation will not affect the company's income in any way.

In an attempt to solve the problem, the Russian Ministry of Energy once suggested that large consumers voluntarily renew their "last mile" contracts with grid companies. But the outcome here is obvious from the very beginning - none of the consumers will agree to give their money and go to the “last mile” mechanism. Energy Minister Alexander Novak proposed his own solution to the problem. It consists in the fact that companies should be prohibited from direct connection to FGC networks, but at the same time, lowering coefficients should be set for consumers at high voltage - 20-30% of the cost of the MRSK tariff. Governors will have the right to further reduce the tariff. But this option did not suit the consumers themselves. “With the Ministry of Energy, we discussed various forms of the reduction factor and how to apply it. But in the version of the bill, which was submitted for the second reading, there is neither the time frame for solving the problem, nor the size of the discounts, nor the criteria for assessing the need to receive this discount,” Vasily Kiselev commented on the situation. The Ministry of Economic Development also opposed Alexander Novak's proposals. “The decision proposed by the Ministry of Energy means transferring the entire burden of taking responsibility from the federal center to the regions. This is actually the preservation of the problems of the regions, for which Moscow will then pay, ”said Sergey Belyakov, deputy head of the Ministry of Economic Development, in an interview with the Prime agency. The Ministry of Economic Development will insist on its own project to eliminate the "last mile". It consists in establishing two tariffs - for the population and for enterprises, and to entrust the management of these tariffs to the FTS.

They tried to solve the problem on November 7 of this year. Information has officially appeared about the signing by President Vladimir Putin of a law abolishing the “last mile” in Russia from January 1, 2014. The mechanism for the termination of cross-subsidization is indicated in the Federal Law of November 6, 2013 No. 308-FZ “On Amendments to the Federal Law “On the Electric Power Industry” and Article 81 “On Joint Stock Companies”. The President divided the Urals Federal District of the “last mile” so that there would be no tariff jump. Its action is canceled in the Kurgan and Sverdlovsk regions. It also follows from the law that the “crossroads” will be preserved on the territory of the four regions of the Ural Federal District. Namely, until July 1, 2017, the "last mile" will be valid in 16 subjects of the Russian Federation, including the Tyumen and Chelyabinsk regions, KhMAO-Yugra and Yamal. Until July 1, 2029, it will remain in the Amur Region, the Jewish Autonomous Region, Buryatia and the Trans-Baikal Territory. For local consumers, a special voltage tariff level will apply here, consisting of the FGC tariff and the average cross-subsidization rate in the region.

It is also noted in the law that the cross-subsidization rate in 2014 in the respective region will depend on the division of the cross-subsidization amount by the volume of useful electricity supply to consumers who are not related to the population or persons equated to it. From July 1, 2017, the rate is calculated annually as the difference between the indicator of the previous year and a value that is at least 7% of the rate determined as of January 1, 2014.

Ivan Grachev, Chairman of the Energy Committee of the State Duma of the Russian Federation, in an interview with Pravda URFO stressed that when developing the bill and identifying regions where the process of abandoning the “last mile” would be softened, the legislators proceeded from the fact that in the subjects of the federation “there are large variations in transitions to payments from industry to the population.

“Out of 20 regions, some have cross-subsidization for a long time, while others end in three years, the amounts that are allocated for compensation were prescribed. It is very difficult to judge whether this is a good or a bad option, because if we had not adopted this law, and this was due to the resistance of large companies, such as Basel, the railway, then in all regions there would have been an instant collapse with a significant increase in the tariff for the population. They would like to quickly relieve the burden on the population, and the regions themselves began to write letters, beat drums that they could not be abandoned immediately without the “last mile”. What they managed to do - that's what they all agreed on together. A compromise option was chosen, probably not the best in the world, but as it is.”

Sergey Beiden, an analyst at FC Otkritie, finds big problems in the implementation of this law: “The risks that the law can be implemented are not very big. It is clear why the "last mile" was left in the Urals and Western Siberia. Since, according to my estimates, for IDGC of Urals, the “last mile” is about 13–14% of revenue. It is clear why the mechanism was left in the Chelyabinsk region, if we remove 14% of the revenue, then this will be a significant blow, and operating costs should be gradually reduced to compensate for the abolition of cross-subsidization. In those regions where the intersection has been canceled, in order to compensate for it, an additional 7% tariff increase is provided from January 1, 2014, which is highly doubtful. Because tariffs have already increased by 8-9% since July 1, therefore, if the tariff goes up further, the total tariff increase will reach 15-16%. Moreover, there is a limit on the final price increase at the level of inflation. The risk that this will be done is quite large,” the analyst says. Given the danger of the consequences of the adopted law, network companies are already counting losses. If the shortfall in income is not compensated, they may lose, according to the estimates of the Ministry of Energy of the Russian Federation, 46 billion rubles.

It is hardly appropriate to speak of a compromise in this case. Energy, whatever one may say, remain in the obvious minus. The consequences for small companies and the population are also not entirely clear. One thing is clear - this is far from the last stage of solving the problem. In general, one gets the impression that the question of the "last mile" becomes eternal.

Last mile technologies are technical means that allow to provide communication to the end user. At present, the development of communication technologies is accompanied by an active growth in the “appetite” of subscribers using resource-intensive applications that are increasingly demanding on the performance and bandwidth of data transmission networks. Therefore, the question becomes more and more clear to operators: “How is it more profitable and efficient to organize an access infrastructure for existing and new subscribers?”

• By 2000, the Ethernet standard, as the most accessible and convenient, became the main technology for organizing access for home and corporate subscribers, since operator and client devices based on this protocol provided sufficient data transfer rates at a low cost of equipment. Ethernet has consistently provided data rates of 10 Mbps, 100 Mbps, 1 Gbps, and 10 Gbps, satisfying most of the user demands of its time.
• The technological features of Metro Ethernet also determined the scope of the standard: large cities and towns with high population density and short distances from the communication center to the subscriber.
• At the same time, the task of eliminating the digital divide, which is especially relevant for Russia, is forcing operators to look for solutions to organize high-speed access throughout the country. In addition, many operators are close to the need to upgrade their legacy copper infrastructure, and given the current situation, the choice in favor of Ethernet does not seem so obvious. The high demands of subscribers and the need to find cost-effective solutions in a competitive environment are forcing even market leaders to take a closer look at new technologies that allow not only to solve today's problems, but also form the basis for future network development.

In particular, PON technologies can become the basis for providing access in sparsely populated regions, when the installation of additional concentration devices is impractical.

Technologies for connecting subscribers

Russian operators are actively developing several technologies for connecting subscribers to their networks, and each of them has its own advantages and disadvantages. The choice of technology is determined by several factors: the needs of the subscriber, technical conditions and the economic feasibility of implementing access by the provider.

According to research conducted by J'son & Partners Consulting in 2010, DSL remained the most popular subscriber connection technology in Russia. It was followed by Metro Ethernet and DOCSIS.

To understand the differences, let's take a closer look at each technology family.

xDSL - simple and affordable

If it is necessary to provide a subscriber with access to Internet resources, the easiest way is to use the existing infrastructure that was created during the laying of telephone lines, power transmission networks, radio points or other communications. That is why the DSL (Digital Subscriber Line) family of technologies has become so widespread throughout the world. The operator only needs to install special DSLAN multiplexers on his side, and a DSL modem on the subscriber's side.

The obvious disadvantage of xDSL is the physical limitation of the data rate.

The most popular ADSL 2+ standard can provide a flow of only 24 Mbit / s to the subscriber under ideal connection conditions, and taking into account the quality and length of copper wires used in the post-Soviet space for telephony, the actual data transfer rate is on average 1-5 Mbps Overcoming this speed barrier within the framework of xDSL technologies seems to be a very expensive and difficult task today, and organizing communication at a distance of more than 5 km from the concentrator installation site is an unattainable goal at all.

MetroEthernet is a popular technology for new networks

The second most popular connection method is the Ethernet standard. Its use requires laying a separate cable to each subscriber, but it allows you to solve the issue with the bandwidth of the access infrastructure. As the physical medium, "copper" is still used here, more precisely, one or more twisted pairs of wires. Thanks to the Fast Ethernet protocol, which is quite affordable and operates at a speed of 100 Mbps, significantly ahead of xDSL providers, many providers have successfully solved the problem of organizing an access infrastructure, but even today the resources of the created networks are not enough. Even ordinary subscribers are actively switching to unlimited tariffs with data transfer rates up to 30 Mbps and higher, which means that in order to provide the required parameters, it is necessary to successively switch to equipment that supports GbE (1 Gbps) and 10GbE (10 Gbps) protocols. With).

The disadvantages of Metro Ethernet (FTTB) technology include a small connection distance (the distance between the operator and subscriber equipment). In most large cities with dense buildings, this problem is hardly relevant, however, in rural areas, summer cottages, cottage villages, the use of Metro Ethernet technology significantly increases the cost of fiber optics.

The need for higher speeds leads to a disproportionate increase in operator costs with an increase in the subscriber base, since the equipment of the GbE, lOGbE standards, as well as the upcoming 40GbE and lOOGbE, turns out to be very expensive.

According to the creator of the Ethernet standard, Bob Metcalfe, the technology for transmitting Ethernet data at a speed of 1 Tbit / s will be developed by 2015, but this will require solving many problems associated with physical phenomena.

Coaxial networks - the traditional approach

The third most popular connection method is the use of DOCSIS coaxial networks using TV cable. Unlike ADSL, DOCSIS 2.0 technology allows data transmission at high speeds - up to 43 Mbps to the subscriber and up to 30 Mbps from the subscriber. At the same time, the provider, as with the use of DSL technology, does not have to lay additional cables; you only need to install a terminal device on the client side that allows you to connect a computer or a wireless router. However, investments in data infrastructure, including switching devices and intermediate amplifiers, can also be significant.

Wireless networks - where others can't

In cases where cable laying is difficult, operators resort to the use of wireless communication technologies. Despite certain attempts to promote Wi-Fi in Russia, this technology has not taken root as a means of providing “last mile” communications. Able to serve several subscribers at the same access point at the same time, access points of the latest variation of the 802.1 In protocol provide a data transfer rate of 300 Mbps. However, in practice it is rarely achieved, since it is limited by environmental parameters. The access speed also decreases as the subscriber moves away from the base station, and already at a distance of about 500 m it is limited to 802.11b parameters - 11 Mbps. Connection is also possible over long distances, up to 10 km, but this requires the use of very expensive directional antennas.

An alternative to Wi-Fi when servicing subscribers over vast areas is WiMAX technology, which allows providing Internet access at a speed of up to 75 Mbit / s for each subscriber within a radius of 25-80 km. The WiMAX 2 standard being developed today will make it possible to overcome the barrier of 1 Gbit / s, working already at distances of up to 150 km. However, in any case, WiMAX equipment remains expensive and requires careful tuning of antennas for optimal results and high speed of the access infrastructure.

But the most popular type of wireless communication in Russia is the 3G networks of mobile operators, gradually moving to 4G - higher data transfer rates. In this case, to connect subscribers, only coverage of the appropriate density and a USB modem are required, which, in turn, is installed in a router or directly on a PC. However, the tariff policy of operators is such that without reducing the data transfer rate, today you can only work with 256 or 512 Mbps channels - in other cases, when you download a certain number of gigabytes through a cellular operator, the speed drops to 64 or even 32 kbps.

Fiber optic networks - great prospects

Optical fibers have the unique feature of transmitting signals over long distances at high speeds. So, in September 2012, the Japanese company NTT demonstrated data transmission at a speed of 1 Pbps (1,000,000 Gbps) over a distance of 52.4 km over a single fiber bundle without the use of intermediate equipment, proving that the resources of this technology are still long remain inexhaustible.

The topology of a fiber optic network can be organized as a ring, a point-to-point infrastructure, or a tree, and the tree can be built on the basis of active or passive nodes. Passive optical networks PON (Passive Optical Networks) are most suitable for organizing subscriber access, allowing you to connect the maximum number of subscribers with minimal equipment and cable costs. In this case, many subscribers serve a single central switch OLT (Optical Line Terminal), passive repeaters ensure the transmission of the entire data stream to subscribers, and ONT (Optical Network Terminal) client devices snatch only information addressed to them from it. All ONTs transmit upstream at the same wavelength using the Time Divided Multiple Access (TDMA) concept.

The technology of data transmission over optical networks, of course, has great potential due to the use of a minimum number of active components and resources of optical networks. However, at the initial stage, its development was hampered by the lack of accepted standards and the high cost of equipment.

The FSAN consortium, established in 1995, formed the first specification for passive data transmission in GPON optical networks only in 2003. During the development of the first version of PON based on the ATM standard, the data transfer rate increased from 155 Mbps to 622 Mbps per subscriber . The transition to the basic Ethernet protocol in 2004 created the EPON standard, which offers speeds up to 1 Gbps, but has much less potential for quality control of the QoS service. And today's most popular GPON standard supports up to 128 subscriber nodes per fiber and provides data transfer rates up to 2.5 Gb / s to the subscriber and 1.6 Gb / s from the subscriber, significantly outperforming competing technologies in terms of speed / cost ratio. For a long time, the spread of xPON technology was held back by the high cost of ONT client devices, which are gradually becoming cheaper. For example, on average, a GPON subscriber device has become 30% more affordable over three years at a price of 11,000 rubles. against 17 thousand in 2009, and this trend continues to gain momentum. QTECH currently produces the most affordable ONT terminals, which actually simply have an Ethernet interface, converting the signal into an available one for working on any PC or laptop, or for connecting a router.

Today, GPON technology is becoming the most promising for deploying networks in sparsely populated areas.

GPON perspectives

Today, GPON technology is becoming the most promising for deploying networks in sparsely populated areas. For example, the federal operator Rostelecom uses GPON to expand the capabilities of broadband access networks in various regions of Russia. High data transfer rate, which is 2488 Mbps to the subscriber and 622, 1244 or 2488 Mbps from the subscriber (depending on the specific device model), provides a qualitative expansion of the Internet access bandwidth for each subscriber. Optical multiplexing capabilities allow operators to further increase bandwidth and add and remove subscriber units without changing the existing network infrastructure, offering subscribers exactly the speed they are willing to pay for.

The use of passive optical networks provides the operator with noise immunity of communication channels, as well as the use of all popular protocols and communication technologies IGMP, DHCP, STP, TCP / IP, etc. In the absence of intermediate active elements, control of subscriber devices and updating their software are carried out centrally and automatically thereby saving investment in new equipment.

New equipment - new opportunities

Modern GPON devices - OLT switches and ONT client devices - have become functional. Various port sizes and densities allow operators to choose solutions that will allow them to strike a balance between the number of connected subscribers and costs. For example, compact models of 1U QTECH (GPON OLT) switches are equipped with eight GPON ports and eight 10/100/1000Base-T or 1000Base-X interfaces), allowing you to connect up to 256 subscribers through single-port ONT terminals. Larger Form Factor Switches

4U GPON OLT, in turn, combine high port density with redundancy capabilities. In such models, two control boards, two power supplies and four boards providing switching of GPON boards are provided. Thus, the operator gets the opportunity to connect up to 1024 subscribers on one switch, while guaranteeing the fault tolerance of the communication environment.

As for ONT terminals, operators provide them to customers for rent, lease or simply sell them by installments, and in some cases they use one terminal to serve several subscribers at once, who are already connected via the Ethernet interface of the ONT device (many modern terminal models have a built-in LAN hub). In the case of affordable QTECH terminals, the possibility of direct connection of end users using GPON technology is also promising. At the same time, no additional add-ons or protocol negotiation are required - passive optical networks allow you to immediately provide access to Internet resources in the usual way, but at a higher speed and lower costs for the operator.

Each of the technologies allows solving certain problems when building an access infrastructure for various categories of subscribers. To benefit from each of them, operators need to formulate an up-to-date network development strategy, taking into account regional features and technical characteristics of the already created infrastructure.

Undoubtedly, DSL-based solutions will continue to be used to connect facilities that are remote from backbone communication networks, but already have a copper infrastructure, as well as to organize Internet access for private subscribers at low rates with a low connection speed.

Ethernet adapters, built into all modern personal computers, will ensure the widespread use of this technology for connecting end devices. An increase in the speed of the Ethernet protocol will make it possible to effectively develop an access infrastructure for objects with a small number of subscribers and limited distances. In this case, it will not be necessary to install a large number of active hubs.

Wireless networks will continue to provide connectivity for hard-to-reach sites and be used to conveniently connect end devices in combination with other technologies such as Ethernet, DSL and optical networks.

xPON technologies, which have been in the shadow for a long time, are becoming more and more relevant due to the wide scalability, high data transfer rate and active reduction in the cost of subscriber terminals. Perhaps, it is these solutions that are able to meet the growing demands of subscribers for speed, while simultaneously solving the operator's task of reducing the complexity and increasing the reliability of the access infrastructure. PON technologies can play a special role in the construction of data transmission networks for remote and sparsely populated regions, where the ability to allocate a wide data transmission bandwidth over long distances without additional equipment is a key success factor.

East Thematic selection “Ethernet technology. IP networks."