Creation of a broadband network based on gpon technology qualification work of bachelor

Broadband over Powerline (BPL) BPL is the delivery of broadband over the existing low- and medium-voltage electric power distribution network. BPL speeds are comparable to DSL and cable modem speeds. BPL can be provided to homes using existing electrical connections and outlets. BPL is an emerging technology that is available in very limited areas. It has significant potential because power lines are installed virtually everywhere, alleviating the need to build new broadband facilities for every customer.
1.2 Technologies of broadband subscriber access on copper core communication cables
The growing demand for new services provided a sufficient number of conventional copper-wire subscriber lines predetermined the development of "digital subscriber lines" technologies (the English term is Digital Subscriber Loop). Let's start with the "X" heading the well-known abbreviation xDSL. In this case, " X "is" something " invented by developers to distinguish a particular solution from a wide range of DSL technologies.The technologies, called xDSL by the English abbreviation, made it possible to organize high - speed digital transmission over existing subscriber lines, as shown in Picture 1. Thus, new services that required a digital transmission method began to be provided using the existing cable distribution network. According to the original definition, DSL is a three-channel line that connects the user's ISDN terminal to the telephone company's switching system over four conventional telephone wires. Using the Basic Rate Interface (two 64 Kbit/s switched channels and one 16 Kbit/s packet-switched data channel), DSL provides simultaneous duplex transport of speech and data, as well as signal and other service information. It is interesting that much later, in the mid-90s, to identify the "progenitor" of the family of high-speed copper technologies, the letter I was added to the unchanged "root" of DSL. This was intended to indicate the implementation of DSL using ISDN technology, which provided duplex transmission at a speed of 160 kbit / s over a single twisted pair.

Picure 1.1 - Organization of the ADSL channel

Thus, with the advent of ADSL technologies, it became possible to turn a twisted pair of telephone wires into a high-speed data transmission path. This made it possible to give a "second life" to copper-core communication lines. ADSL2+ technology, which has an input channel speed of up to 24 Mbit / s, is capable of transmitting HD content at the level of cable networks. This makes it profitable for the average user to use it. Especially if we take into account the relatively inexpensive equipment. But if there is a significant margin for the incoming channel speed, then the return channel speed is low (ADSL has 1 Mbit / s, ADSL2+ has 3.5 Mbit/sec) restricts ADSL users. Low upload speed is a serious hindrance to fast internal file sharing between users. There is another important disadvantage of all xDSL networks associated with the purely physical use of a subscriber's copper line. Due to" crosstalk " in twisted pair, the telecom operator can only use up to 30% of the cable capacity. For example, if there are 10x2 pairs, you can use only 3 pairs, and 100x2-30 pairs, respectively. Thus, when connecting subscribers, in most cases, the "who made it" principle is used. If the service provider company does not have the means to upgrade an existing communication line, subscribers may have to wait indefinitely for an opportunity to connect to the network. With the advent of ADSL technologies, it became possible to turn a twisted pair of telephone wires into a high-speed data transmission path. This made it possible to give a "second life" to copper-core communication lines. ADSL2+ technology, which has an input channel speed of up to 24 Mbit / s, is capable of transmitting HD content at the level of cable networks. This makes it profitable for the average user to use it. Especially if we take into account the relatively inexpensive equipment. But if there is a significant margin for the incoming channel speed, then the return channel speed is low (ADSL has 1 Mbit / s, ADSL2+ has 3.5 Mbit/sec) restricts ADSL users. Low upload speed is a serious hindrance to fast internal file sharing between users. There is another important disadvantage of all xDSL networks associated with the purely physical use of a subscriber's copper line. Due to" crosstalk " in twisted pair, the telecom operator can only use up to 30% of the cable capacity. For example, if there are 10x2 pairs, you can use only 3 pairs, and 100x2-30 pairs, respectively. Thus, when connecting subscribers, in most cases, the "who made it" principle is used. If the service provider company does not have the means to upgrade an existing communication line, subscribers may have to wait indefinitely for an opportunity to connect to the network.
1.3 Active broadband access
FTTB (Fiber-To-The-Building) data transmission technology is a fiber-optic network to a building or structure with subsequent switching to end users located in this building via a copper cable. This technology is currently one of the most advanced and faster compared to other technologies, moreover, it has an advantage over other technologies in addition to data transfer speed, in the absence of any additional equipment. Increased reliability. As is known from practice, the largest number of failures occurs not on fiber-optic networks, but on coaxial networks. Due to the presence of no more than one amplifier cascaded on (for example, an entrance amplifier), the probability of failure is low. The simplicity of building parallel digital networks is the most important advantage of FTTB technology. At the same time, a separate optical fiber is allocated for a parallel digital network (instead of a core for a reverse channel). Reduction of ingression noise is achieved due to the small number of subscribers connected to a single op-amp. Moreover, when using collective cable modems (CM), ingression noise (the main sources of noise in the reverse channel) coming from subscribers is virtually eliminated, since the CM is turned on at the input of a house amplifier, which does not include a reverse channel amplifier. Higher speeds of digital streams in the reverse direction with a constant number of frequency channels are due exclusively to the number of upstream receivers (reverse direction receivers) installed as part of the cable modem headend (CMTS). An increase in the number of upstream receivers (hence, an increase in total speeds in the reverse direction) while maintaining the carrier-to-noise ratio (C/N) was made possible by reducing the number of subscribers loaded per op-amp. Ease of implementation of new digital technologies superimposed on existing FTT networks. A classic example is the new promising EttH (Ethernet to the Home) technology developed by Teleste (Finland) and gaining more and more popularity around the world. Ethernet over Coaxial (EoC), which provides delivery of Ethernet frames over the coaxial TV cable of residential distribution networks. There is such an innovative solution as Virtual Fiber ("virtual fiber"), which provides delivery of Ethernet (100 Mbit / s) over existing cable TV networks. Moreover, "virtual fiber" can work in KTV networks in parallel with Docsis. The 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, the output stage of the op-amp (namely, the value of its maximum output level and the price policy of the op-amp is determined) is not subject to strict requirements both in terms of gain and output level. Operation at low input optical powers is achieved due to the fact that the subsequent 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 (therefore, the cost of fiber-optic communication lines in general decreases) with a large number of op-amps.

Optical receiver

Optical transmitter

Coupler

Optical transmitter
Picture 1.2 - Organization of the FTTB channe.
FTTB technology is optimal and very convenient for Russian cities of medium and large sizes. The advantages and disadvantages of these approaches stem from the specifics of implementing this technology: centralization of equipment on the provider's side leads to simplified operation, but at the same time requires certain conditions to ensure both power supply and equipment safety (in particular, the use of vandal-proof cabinets). A significant disadvantage is the need to formalize contractual relations for the placement of equipment and obtaining power supply with operating organizations/HOAs. Often, this one negative can outweigh all the advantages of the FTTB option. The need to provide guaranteed power supply leads to the need to install uninterruptible power supplies in the cabinets with the provider's equipment, which leads, firstly, to the need to increase the size of the cabinets, and secondly, the cost of the solution becomes more expensive and increases possible financial losses in the event of equipment theft or vandalism. Also, do not forget to limit the possible length of the twisted pair from the cabinet, without losing speed. It must not exceed 100 meters. Thus, the most accurate calculations of the density of subscribers connected to this equipment are necessary in order to use it to the maximum. The technology is optimal and very convenient for Russian cities of medium and large sizes. The advantages and disadvantages of these approaches stem from the specifics of implementing this technology: centralization of equipment on the provider's side leads to simplified operation, but at the same time requires certain conditions to ensure both power supply and equipment safety (in particular, the use of vandal-proof cabinets). A significant disadvantage is the need to formalize contractual relations for the placement of equipment and obtaining power supply with operational organizations for servicing housing and communal services. Often, this one negative can outweigh all the advantages of the FTTB option. The need to provide guaranteed power supply leads to the need to install uninterruptible power supplies in the cabinets with the provider's equipment, which leads, firstly, to the need to increase the size of the cabinets, and secondly, the cost of the solution becomes more expensive and increases possible financial losses in the event of equipment theft or vandalism. Also, do not forget to limit the possible length of the twisted pair from the cabinet, without losing speed. It must not exceed 100 meters. Thus, the most accurate calculations of the density of subscribers connected to this equipment are necessary in order to use it to the maximum.
1.4 Passive broadband access
Fiber optics is the basis of modern infocommunication systems. Its influence and importance is growing: more and more organizations and firms are engaged in business related to fiber optics, more and more complex solutions are being used, more complex problems are being solved. The first steps in PON technology were taken in 1995, when a group of 7 companies (British Telecom, France Telecom, Deutsche Telecom, NTT, KPN, Telefonica and Telecom Italia) created a consortium to implement the idea of multiple access over a single fiber. This organization, supported by ITU-T, is called FSAN (full service access network). Many new members, both operators and equipment manufacturers, joined in the late 1990s. The purpose of FSAN was to develop general guidelines and requirements for PON equipment so that equipment manufacturers and operators could co-exist together in a competitive market for PON access systems. Today, FSAN has 40 operators and manufacturers and works closely with standards organizations such as ITU-T, ETSI and ATM Forum. The widespread adoption of optical access systems is caused by a sharp rise in the price of copper and the need to increase throughput. However, the transition to optics is largely determined by the costs required to implement a particular technology, in particular, PON technology. Three years ago, analysts at Probe Group conducted a study related to the introduction of Passive optical network technology (Passive Optical Network - PON), and concluded that "the paralyzed PON market is beginning to show signs of life." Today, this segment of the telecommunications market has grown tenfold, which has affected the business development of equipment manufacturers, network integrators and service providers. In turn, there are attractive services for consumers that provide high-quality video streaming. However, this requires an appropriate infrastructure, otherwise providers will be very annoyed by competitors with more advanced networks. However, it's not just the technical and commercial arguments that support this technology. The current state of the telecommunications business (recovery from the crisis), as well as legal requirements in a number of countries, contribute to the development of the PON-based access market. The first steps in PON technology were taken in 1995, when a group of 7 companies (British Telecom, France Telecom, Deutsche Telecom, NTT, KPN, Telefonica and Telecom Italia) created a consortium to implement the idea of multiple access over a single fiber. This organization, supported by ITU-T, is called FSAN (full service access network). Many new members, both operators and equipment manufacturers, joined in the late 1990s. The purpose of FSAN was to develop general guidelines and requirements for PON equipment so that equipment manufacturers and operators could co-exist together in a competitive market for PON access systems. Today, FSAN has 40 operators and manufacturers and works closely with standards organizations such as ITU-T, ETSI and ATM Forum. The main idea of the PON architecture is to use just one transceiver module in an OLT (English optical line terminal) to transmit informationto and receive information from multiple ONT.

Picture 1.3-PON Network Architecture

The number of subscriber nodes connected to a single OLT transceiver module can be as large as the power budget and maximum speed of the transceiver equipment allow. To transmit the information flow from OLT to ONT - a direct (descending) stream, as a rule, a wavelength of 1490 nmis used . On the contrary, data streams from different subscriber nodes to the central node, which together form a reverse (upstream) stream, are transmitted at a wavelength of 1310 nm. The television signal is transmitted at a wavelength of 1550 nm. OLT and ONT have built-in WDM multiplexers that separate outgoing and incoming streams