For many years fixed was half covering all communication needs in the world, but a few years ago needs more bandwidth for communications began to grow exponentially, especially following the emergence of Internet.
It started with a maximum bandwidth of 64 Kbps up to the advent of ADSL, which increased gradually speed up to achieve higher bandwidths to 10 Mbps, using pairs of copper wires.
But everything has its limits and the inherent properties of copper involve very high costs in order to increase the transmission speed with metal cables.
To meet the increasing demand for bandwidth was decided to use fiber optics, a transmission medium that also offers more safety and quality. The optical fiber has been widely recognized among all broadcast media as the most appropriate services to offer high bandwidth. The fiber to the home (Fiber To The Home) FTTH is the latest technological advance that can offer high-speed services, only through optical fiber cables and optical elements for connecting the operator with users. FTTH has surpassed 20 million subscribers worldwide and still growing.
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History
In 1975 he settled in Bournemouth, United Kingdom, the first commercial system for fiber optic communications. Six months later, another system was installed in Japan and next year the companies GTE and AT & T respectively installed two systems in California and Chicago, USA.
In the 80 CATV operators began to replace metal cables and optical fiber cable for Hybrid Fiber Coaxial (HFC) systems and FTTC (Fiber To The Curb) fiber to the curb, because the technology did not allow the fiber to subscribers at competitive costs.
The company NTT in Japan made a large investment in research to solve technological problems that would facilitate the expansion and as a result, in 1990, NTT announced the launch of a plan ending in 2025, so that all of these was Japan technology was considered the best for the future. To do this, called the world's leading manufacturers such as AT & T, Fujitsu, Hitachi, Fujikura, etc., Asking them to begin to develop systems for FTTH networks, and in 1994 announced that the installation costs of FTTH systems in the year 2000 would be the same as for wire ropes.
In 2001, NTT began to FTTH service, reducing installation costs dramatically and as a result the number of users began to increase rapidly, which meant that other players follow his example, currently more than 40 countries around the world have deployed FTTH networks.
FTTxFTTx is the generic term for any network architecture for broadband telecommunication networks, using fiber optic cables to replace all or part of the wire ropes used in the last mile connection to the subscriber. The acronym FTT come from Fiber To The (fiber-to) and the letter occupying the seat of the "x" indicates the extent to which the optical fiber arrives, after which even the user's home, the cables are metal.
The various FTTx architectures are:FTTN-Fiber To The Node (fiber to the node).
FTTC - Fiber To The Curb (fiber to the curb).
FTTB - Fiber To The Building (fiber to the building).
FTTH-Fiber To The House (fiber to the home), no metal wires are used.
FTTP / FTTU-Fiber To The Premise (USA) / Fiber To The User, indicate that fiber comes directly from the facility operators to local companies or users who need high speeds and fiber required for exclusive use.
ODN Optical Distribution NetworkA FTTH network can be divided into three main parts: the computer room or central optical distribution network (ODN) and the connection / equipment at the premises of users.
The equipment room (equipment room), head (head end) or central office (central office) and want to call has the necessary equipment to transmit and receive information to / from subscribers and content providers, therefore receiving equipment must have voice, video and data, and then redistribute among users using an Optical Network Terminal (OLT).
The ODN provides optical transmission from the OLT to the user, and vice versa.
The ODN is a critical part of FTTH networks, as the headers and user computers can be easily upgraded for periods of 20, 30 or more years and use the same ODN, so installation should be done in to reliably withstand the test of time.
There are two main types of optical networks:
- Active optical network (Active Optical Network) AON, which is using active elements that require energy to power and allow long distance between the equipment room and subscribers.
- Passive Optical Network (Passive Optical Network) PON, in which all network elements are passive, so no energy is needed to power at any point through the network. Are the most used, especially in large networks and although the maximum distance is 10 to 60 km, is considered sufficient. Passive networks generally do not require any update to a possible change in technology.
PON TechnologiesPON networks differ mainly active technology connected to their ends, giving them different skills and abilities. Current PON are:
- BPON: UPON comes from the former ITU-T G.983 standard, which is based on asynchronous transfer mode ATM (Asynchronous Transfer Mode), which allows download speeds of 155, 622 and 1244 Mbps and upload of 155 or 622 Mbps, an asymmetric or symmetric modes. The maximum distance from the station to the subscribers is 20 km and the maximum number of subscribers per fiber is 32.
- EPON / GEPON: They are based on Ethernet and Gigabit Ethernet traffic respectively, as listed in IEEE 802.3ah. Your download and upload speeds are symmetrical to 1244 Mbps and maximum distance to subscribers is 10 km but is being given to extending to 20 km, 32 subscribers can share each optical fiber that comes from the plant. It is very introduced around the world, but especially in Asia and the Pacific, with over 13 million users.
- GPON: It is an evolution of the BPON standard according to ITU-T G.984 standard and has high upload and download speeds can reach up to 2488 Mbps in symmetrical and asymmetrical modes, you can use ATM traffic, Ethernet and TDM. The maximum number of users per fiber is 64, although it is considering expanding it to 128. The maximum distance subscribers may reach 60 km. All these features are improvements over other technologies, so it has been chosen by the majority of operators have begun deployment after development, such as Telefonica in Spain.
Network TopologiesThe Network to connect with subscribers, have been designed taking into account the expectations and potential user needs, resulting in the following topologies:
- Point to Point (Point to Point), P2P: It consists of a direct connection from the central to the subscriber. A group of point to point from a single source connection results in a star topology. This topology is used for offices or users that require dedicated traffic.
- Point to Multipoint (Point to Multipoint), P2MP: Each of the fibers leaving the bedside provide service to multiple users by passive or active. This topology is also called a tree.
- Ring (Ring): The fibers leave the central returning at the end of his route, enabling users to serve through referrals with dividers, splitters or active elements. This topology offers the possibility of redundancy of connections.
It is possible to build networks that mix different topologies to diversify supply, improve reliability and allow greater flexibility for future expansions or modifications.
The systems most commonly used topologies are P2P and P2MP FTTH.
Instrumentation for FTTH networksThe instrumentation required to install and maintain networks FTTH is different or has different characteristics depending on the work to be done on the network, these functions can be divided into:
- Installing equipment at the plant.
- Installation of ODN Optical Distribution Network.
- Installing high to subscribers.
- Maintenance of plant equipment.
- Maintenance optical distribution network.
- Maintenance subscribers.
Installation and maintenance of headquarters equipmentInstrumentation is required as follows:
- Optical power meter GPON selective, with at least the following measure: wavelengths 1310, 1490 and 1550 nm, maximum power 6 dBm Ž. This instrument enables verification of optical power output of the OLT. (Figure 2).
- Analyzers Video: CATV, VHD, IPTV, MPEG and MPEG2.
- Audio Analyzers: VoIP, PSTN.
- Wiring analyzers.
- Analyze data and protocols: Ethernet, ATM, xDSL (ADSL2, VDSL ...). (Figures 3 and 4).
Analyzers enable verification of compliance with standards possible to use.The installation of the optical distribution network requires the construction equipment and instrumentation for testing or testing.
Construction equipment:
- Fiber Optic Fusion Splicer. (Figure 5).
- Elements of cleaning and inspection of connectors.
Measuring instruments:- OTDR wavelengths in 1310, and 1550 nm and dynamic range
Ž 32dB to launch fiber (Fiber Dumy) Ž 300 meters to locate any possible failure in the system. (Figure 6).
- Source of light with wavelengths 1310, 1490 and 1550 nm ZZ output level -10 dBm and optical power meter, with minimum sensitivity?? -40 DBm to measure the loss of the network or any optical element. (Figure 7).
Instrumentation for high-paid- Fusion or mechanical or connector assembly required field. (Figures 8, 9 and 10).
- Selective Optical Power Meter GPON wavelengths 1310, 1490 and 1550 nm and minimum sensitivity? -40 DBm, will verify that the optical signal reaches the subscriber and issuing the ONT have the appropriate level.
- OTDR wavelength in 1625 or 1650 nm bandpass filter fitted and launch fiber (fiber Dummy) Ž 300 meters to locate any possible failure in the system when the fiber is illuminated. (Figure 11).
- ONT or simulator, to ensure communication with the OLT.
- Elements of cleaning and inspection of connectors.
- Light Source 650 nm visible, for locating faults in fiber and short distances, it is not essential, but desirable for its utility and low cost.
Instrumentation for the maintenance of optical distribution network- OTDR wavelength in 1625 or 1650 nm bandpass filter fitted and launch fiber (fiber Dummy) Ž 300 meters to locate any possible failure in the system when the fiber is illuminated.
Instrumentation Maintenance subscribers- Selective Optical Power Meter GPON wavelengths 1310, 1490 and 1550 nm and -40 dBm minimum sensitivity, which will verify that the optical signal reaches the subscriber and issuing the ONT have the appropriate level.
- OTDR wavelength in 1625 or 1650 nm bandpass filter fitted and launch fiber (fiber Dummy) Ž 300 meters to locate any possible failure in the system when the fiber is illuminated.
- Detector activity show whether the communication between the OLT and ONT is established at optical level.
- Elements of cleaning and inspection of connectors.
The implementation requires technical expertise, with well-trained in conducting mergers or mechanical joints and use of instrumentation, although staff devoted to maintenance requires more knowledge than the facility staff, as they must be able interpreting the results of the measures for the location of faults. It is interesting to define the testing protocols for most common faults in order to reduce time to resolution. Telecom Unitronics specializes in training experts in new technologies through specific courses tailored to the technical needs of each professional.
Telecom Unitronics is a pioneer in introducing the latest solutions for implementation for key new networks, radio frequency or optical fiber. Our philosophy of quality has led us to seek the most advanced solutions by identifying the best manufacturers of test and measurement instrumentation.
Author:
Pedro Notario, TELECOM UNITRONICS Technical Manager
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