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Academic Journal of Suriname 2017, 8, 708-714 Technology Full-length paper

Fiber Optic Access Networks (FTTX, PON, EFM)

Serge Dompig 1, Alexei Ortiz 2, Doric Ramlakhan 3 Graduate student in Communications Systems, Faculty of Technical Sciences, Pinar del Rio University, Pinar del Rio, Cuba 1; Department of , Faculty of Technical Sciences, Pinar del Rio University, Pinar del Rio, Cuba 2; Manager at Build and Integrate, Telesur, Paramaribo, Suriname 3

Abstract This work intends to make an evaluation or analysis of access networks as a means of high speed data transmission. We will describe the different types of fiber optic access networks such as the FTTx, PON, EFM networks, among other networks that are of great importance today.

Keywords: network, access, fiber optics, , , technology

Introduction The purpose of this research article is to give resources interconnected with each other, a broad insight in the technologies of managed in some way, interacting to meet the networks, specifically, fiber optic needs of the users who use it. access networks. In this work PON and FTTx networks are the main focus as they are of Broadband great importance in the evolution of access The term broadband commonly refers to networks. The first access networks were high-speed . Broadband can be made up of copper by means of a Switched simply defined as a fast connection to the Telephone Network (PSTN). Currently other internet that is always on. It allows a user to technologies like fiber optics allow a huge send emails, surf the web, download images and music, watch videos, join a web increase in access . 2 conference, and much more. Definitions Telecommunications network Telecommunications refers to the exchange An access network encompasses connections of information by electronic and electrical that extend from a central communication means over a significant distance. A switching facility (called the central office) to complete arrangement is individual businesses, organizations, and made up of two or more stations equipped homes. This network connects subscribers to with transmitter and receiver devices. 1 A a particular service provider and, through the telecommunications network as a set of carrier network, to other networks such as the Internet.3

Correspondence to: Serge Dompig, University of Pinar del Río, Cuba, e-mail: [email protected], Tel: 08978285

Available on-line June 7 , 2017

1 What Is Telecommunications? - Definition from Techopedia. Techopedia.com. https://www.techopedia.com/definition/5570/telecommunications, accessed november 4, 2016. 2 What Is Broadband? | Broadband for America. http://www.broadbandforamerica.com/about-broadband/broadband, accessed november 4, 2016. 3 *Gerd keiser (2006) FTTX Concepts and Applications. John Wiley & Sons. U.S.A. pag 4, 173.

Acad J Sur 2017 (8) 708-714 709 S. Dompig

Optical fiber of homes and businesses being served by the Optical fiber is a means of transmission, network. PON architecture is further explained usually used in data networks, consisting of a in paragraph 3. very thin wire of transparent material, glass or plastic materials, by which pulses of light Fiber-to-the- allows the provision of representing the data to be transmitted are sent. broadband services, such as high-speed Optical fiber consists of two concentric Internet. High-speed communications proto- circles. The inner circle is the nucleus, which cols, such as broadband cable access or some has a high degree of purity, i.e. it ensures form of (DSL) are used minimal attenuation when transmitting between the cabinet and the clients. FTTN is information. The outer circle is the lining, capable of delivering 20 to 25 Mbps which covers the environment. (Megabytes per second) to customers, which allows the simultaneous delivery of services, FTTx such as four streams of TV programming, an FTTx (Fiber-to-the-x or Fiber-to-x) is a HDTV channel, and Internet access.* (See generic term to designate any broadband Figure 2). access over Optical Fiber that totally or partially replaces the access loop copper. The FTTx acronym originates as generalization of the different configurations deployed (FTTN, FTTC, FTTB, FTTH), these being the most important. (See Figure 1).

Figure 2: FTTn Access Network.

FTTc FTTc, for fiber-to-the-curb or fiber-to-cabinet, describes running optical fiber cables from central office equipment to a communication switch located within 1000 ft (about 300 m) of a home or enterprise. , twisted- pair copper wires, optical fiber lines, or some other transmission medium is used to connect the curbside equipment to customers in a Figure 1: FTTx Access Network building. FTTc broadband comes in two variants which offer a downstream line speed FTTn of 80 mbps or 40 mbps but the actual FTTn , for fiber-to-the-neighborhood or node, maximum speed of the service will be slightly 4 refers to a PON architecture in which optical slower than this at around 78 / 39Mbps. fiber cables run to within 3000ft (about 1 km)

4 Thinkbroadband | Fibre Broadband (FTTC / FTTH) Guide. http://www.thinkbroadband.com/guide/fibre-broadband.html, accessed november 2, 2016. Acad J Sur 2017 (8) 708-714 Fiber Optic Access Networks (FTTX, PON, EFM) 710

FTTc refers to the installation and use of fiber with fiber optic lines. Such wiring would give optic cable directly to the curbs or sidewalks us very high bandwidth and make services near houses or any business environment as a possible like VoD (video on demand) and replacement for ordinary telephone service. online multimedia presentations that arrive Think about eliminating all the phone lines you without noticeable delay. (See Figure 3). see in your neighborhood and replacing them

Figure 3: FTTc Access Network.

FTTb A subset of FTTH is fiber-to-the-building (FTTb). FTTb is used primarily in densely populated settings in which MDUs(multiple dwelling units) such as apartment buildings, condominiums and hotels are prevalent. Fiber is terminated in the building where the final subscribers of the building or the house are accessed by the VDSL2 (Very high bit rate Digital Subscriber Line 2) technology on copper or Gigabit over Figure 4: FTTb Access Network. 5 CAT5 . In this way, fiber laying can be done progressively, in less time and at a lower cost, 6 advanced services, such as triple play, reusing the subscriber's infrastructure. (See , broadband internet and television, figure 4). to households and business subscribers. The FTTh technology proposes the use of optical FTTh fiber to the user's home. The access network FTTh is based on the use of optical fiber cables between the subscriber and the last distribution and Optical distribution systems adapted to node can be realized with one or two Optical this technology for the distribution of fibers dedicated to each user creating an Active Optical Network (AON) or a Passive Optical

5 What Is an Ethernet Extender? | Ethernet Extender PoE Extender Secure Encryption. https://ethernetextender.com/what-are-ethernet-extenders/, accessed november 4, 2016. 6 Piyush Selvalia. (2016). Driving the New FTTHybrid | OSP Magazine. http://www.ospmag.com/issue/article/driving-new-ftthybrid, accessed november 4, 2016.

Acad J Sur 2017 (8) 708-714 711 S. Dompig

Network (PON) using a tree structure with a logies and point-to-multipoint(P2MP), which fiber on the network side and several fibers on is often combined with a passive optical the user side. These two most widely used network (PON) technology. 7 (See figure 5). topologies are point-to-point(P2P), which typically uses Ethernet transmission techno-

Figure 5: P2P topology (5A) and P2MP topology (5B)

Pon Technology The use of these systems considerably reduces The PON is a point-to-multipoint network over costs and they are used in FTTh networks.8 a passive fiber plant comprising fibers and A is basically formed splitters/combiners, and with active equipment by: at the ends. Similar to active Ethernet network, • An OLT [Optical Line Terminal] module passive optical network has a point to located at the central node. multipoint network architecture as shown in • An optical splitter. figure 5A. However, it does not require outside • Several ONUs (Optical Network plant electronics. Rather than placing an Units)/ONTs (Optical Network Ter- Ethernet switch at the outside plant, it uses a minals) that are located at the user's passive optical splitter instead. PON allows to premises. eliminate all the active components existing between the server and the client introducing Transmission is then performed between the in its place passive optical components to OLT and the ONU communicating through the guide the traffic by the network. The optical splitter, whose function depends on whether branching component (Optical Splitter) is the the channel is up or down. In short, PON works key technology that allows the access network in broadcast mode using optical splitters or to be electrically passive. buses. (See figure 6).

7 FTTH Handbook (2016) 7th edition. D&O Committee. Europa. 8. Pag. 14. 8 Lin, Chinlon (2006) Broadband Optical Access Networks and Fiber to the Home. John Wiley & Sons. England. Pag 25-26. Acad J Sur 2017 (8), 708-714 Fiber Optic Access Networks (FTTX, PON, EFM) 712

Figure 6: PON Access Networks 155.52 Mb/s or 622.08 Mb/s while the upstream at 155.520 Mbps. By means of a wavelength- ‹ EPON technology. EPON is developed scheme, all the components required for based on Ethernet technologies, and transmission in Upstream, Downstream and enables seamless integration with IP and RF video overlay are divided. Ethernet technologies with a capability of 1Gbps in both directions. Technologies of PON networks 9 ‹ 10G EPON. With the necessity to There are three main types of PONs depending provide adequate downstream and on the data multiplexing scheme. The currently upstream bandwidth to support MDU’s deployed PON technology is time division the motivation was given to meet the multiplexing (TDM) PON, where traffic emerging high bandwidth demands. The from/to multiple ONUs(optical network units) 10G EPON supports both symmetric 10 are TDM multiplexed onto the upstream/ Gb/s downstream and upstream, and downstream wavelength. Wavelength division asymmetric 10 Gb/s downstream and 1 multiplexing (WDM) PON and orthogonal Gb/s upstream data rates. frequency division multiplexing (OFDM) ‹ GPON technology. This technology PON constitute another two types of PON defines the GPON encapsulation method technologies. The latter two are considered as (GEM) to achieve efficient packaging of future PON technologies. user traffic, with frame segmentation to better provide quality of service (QoS) The currently deployed TDM PON systems for delay-sensitive traffic such as voice are: and video applications. It is gaining a lot of ground in the segment of fiber optic ‹ BPON technology. With the objective of access networks with a 2.488 Gb/s of achieving early and cost effective downstream bandwidth and 1.244 Gb/s deployment of broadband optical access of upstream bandwidth. systems, BPON offers numerous ‹ NG-PON (Next-generation PO N). NG- broadband services including ATM, PON specifies both asymmetric and Ethernet access, and video distribution. symmetric 10G-PONs. The downstream transmission is a continuous ATM stream at a bit rate of

9 Nirwan, Ansari, and Zhang Jingjing (2013) Media Access Control and Resource Allocation: For Next Generation Passive Optical Networks. 1st edition. Springer Science & Business Media. U.S.A. pag 12-17. Acad J Sur 2017 (8) 708-714 713 S. Dompig

These are respectively: each ONT and use a defined time interval for the transmission in the ascending channel. (see ∑ Asymmetric 10G-PON also referred to figure 8). as XG-PON1, provides the downstream data rate of 9.95328 Gbit/s and the upstream data rate of 2.48832 Gbit/s. ∑ Symmetric 10G-PON, referred to as XG- PON2, achieves 10 Gbit/s in both upstream and downstream.

Traffic exchange in TDM PON networks • Downward traffic. In the downstream channel (from the OLT to the subscribers), there is only one transmitter located at the OLT, and data to individual Figur e 8. Upward traffic in GPON ** ONTs is transmitted using TDM (Time

Division Multiplexing) that consists of Advantages PON networks 11 transmitting several signals simultaneously on • the same link (transmission medium). For this Increased coverage up to 20 km (from the effect, the time is divided into periods or time central station). With DSL technologies as slots, assigning a time slot to each signal. (See maximum covers up to 5.5 km. • figure 7). They offer greater bandwidth for the user. • Improved service quality and simpli- fication of the network due to the immunity they present to electro-magnetic noise. • Minimization of optical fiber deployment thanks to its topology. • Reduction of consumption thanks to the simplification of equipment. • Cheaper than point to point.

Disadvantages PON networks. 12 Figure 7: Downward traffic in GPON 10 • They have less range than an active optical • Upward traffic. network, meaning subscribers must be In the upstream channel (from subscriber to the geographically closer to the central source OLT), access to a shared fiber channel is of the data. guaranteed by the use of the TDMA (Time • PONs make it difficult to isolate a failure Division Multiple Access) mechanism. The when they occur. ONT takes traffic from the user's port and • The bandwidth in a PON is not dedicated to maps it to GEM frames, the data is transmitted individual subscribers meaning data through time slots assigned by the OLT as an transmission speed may slow down during access control mechanism to avoid collisions. peak usage times in an effect known as Considering that the splitter is a passive latency. Latency quickly degrades services element, packet synchronism is required, such as audio and video, which need a therefore the OLT must know the distance to smooth rate to maintain quality. which each ONT is, measure the delay with

10 ** International Telecommunication Union (ITU). (2009). Optical fibres, cables and systems. Switzerland. Retrieved from www.itu.int. pag. 242 11 Andres Felipe Berrio Catoño. (2014). Sistemas de Transmisión - FTTx - xPON. Retrieved December 4, 2016, from https://sx-de- tx.wikispaces.com/FTTx+-+xPON accessed november 4, 2016. 12 AON and PON Advantages and Disadvantages. (2015). Retrieved May 7, 2017, from http://www.sopto.com/st/ftth-knowledge/aon-and-pon- advantages-and-disadvantages Acad J Sur 2017 (8), 708-714 Fiber Optic Access Networks (FTTX, PON, EFM) 714

PON or AON deployment 13 Conclusions Basically, passive optical networks are a better After completing this small article of research choice for network operators who want to on fiber optic access network technologies, the supply a very large number of subscribers. conclusions are as follows: These operators tend to aim more for the mass ‹ Optical networks unlock the access and private customer market. On the other bottleneck by increasing bandwidth hand active optical technology is more suitable and quality of service. for private network operators, that either lay ‹ They promise a huge increase in access their own fiber optic infrastructure, or use bandwidth up to hundreds of Gbps. debundled fiber optic lines (Fiber Local ‹ Fiber is and will be the main solution to Loops). AON is perfect for high-profit end deliver new generation networks customer segments (such as for example busi- because of its virtually unlimited band- ness customers, multi-dwellings, universities, width. local authorities etc.), as in these cases ‹ Fiber access networks can be classified flexibility, quality and security are demanded. into two types: • By the use of active elements EFM (Ethernet in the First Mile) (AON networks). Ethernet in the First Mile (EFM) refers to the • By the use of passive elements IEEE 802.3ah-2004 standard, which is an (PON networks). amendment to the base 802.3 Ethernet ‹ PON networks have many advantages standard, adding specifications for extending but still have a downside in the limited the delivery of Ethernet services in access length and bandwidth they offer if networks using previously unsupported copper compared to AON networks. and fiber techniques. From the customer's ‹ PON networks are a better choice for point of view it is their "first" mile, although network operators who want to supply from the access network's point of view it is a very large number of subscribers. known as the "". 14 Although it is often ‹ AON networks are more suitable for used for businesses, it can also be known as private network operators who want to Ethernet to the Home(ETTH). EPON(Ethernet supply high-profit end customer seg- PON) is one of the networks in ethernet in the ments, as in these cases flexibility, first mile. quality and security are demanded. ‹ The term FTTx refers to “fiber to the Applications 15 x,” where x could refer to one of • Connectivity Internet. several popular deployment scenarios • Transparent LAN service (point to point representing the proximity of the fiber LAN to LAN). section to the client's business or home. • L2VPN (point to point or multipoint to ‹ FTTx is an intermediate step for multipoint LAN to LAN). delivering better symmetric and asym- • Extranet. metric speeds to the users premises and • LAN to Frame Relay / ATM VPN. answers today’s bandwidth needs. For • Connectivity to backup center. many telecom and ISP providers, FTTx • Storage area networks (SANS). networks are the best economic solu- • Metro transport (backhaul) tion for delivering high-end speeds to their customers. • VoIP

13 KEYMILE International GmbH. (2008). AON vs. PON (p. 13). Austria. Retrieved from www.keymile.com 14 Industrial Ethernet Extenders | Case Communications. http://dev.casecomms.com.gridhosted.co.uk/product-overview/industrial-ethernet-extenders/, accessed november 7, 2016 15 Schmidberg, Eduardo (2009) MetroEthernet. Paper presented at the Technic Seminar, IEEE. Pag 17. http://www.ieee.org.ar/downloads/metroethernet.pdf. Acad J Sur 2017 (8) 708-714