Today the high speed internet has become increasingly important for the people to get all the resources, benefits and all the other downloadable stuff available on the internet. As there are a lot of activities like online courses and other high bandwidth requiring video streaming witch do not work well with low bandwidth connections Now at the moment the only way to tackle this problem is the implementation of FTTH. FTTH provides a huge amount of bandwidth with the help of fiber optic overlay as compared to other types of network overlay. The idea is to connect every destination with the fiber optic medium to provide a huge bandwidth and to increase the speed of the overall network.
Key Words: Fiber optics, Networks, Bandwidth.
1. Introduction
It stands for: Fiber-To-The-Home. FTTH refers to a broadband telecommunications system based on fiber optic cables and associated optical electronics for delivery of multiple advanced services such as triple play telephone, broadband internet, and television to homes and businesses [1]. This new communication medium will be provided by optical fiber systems to residential communities and commercial developments by partnering with developers. Today the high speed internet access and triple play services are mundane for many people around the world.[2] The hunger for speed is still growing and a much tougher competition between cable companies with their coax networks and the telecommunication companies with their copper networks led to the cognition that the speed capacity of copper wires reached its limits and that only optical fiber can provide sufficient bandwidth for the future. So Fiber-To-The-Home (FTTH) became the major issue for broadband access networks. In this paper various benefits of deploying the FTTH network is discussed along with the different technologies through which the FTTH can be deployed. The penetration of FTTH technology in various countries and the major suppliers of FTTH infrastructure are also defined in this paper [4].
2. Defining the term
The term FTTH refers to a broadband telecommunications system based on fiber optic cables. FTTH is a specific term used for providing the Fiber optic network connection at home or premises. Where as the more general term used for the fiber optic connection is FTTx. Where x refers to any destination where the fiber optics network is being deployed. The various and the most closest points available to the customers are: FTTH, FTTB, FTTP, FTTO and FTTR. Here FTTB is (Fiber-To-The-Building), FTTP is (Fiber-To-The-Premises), FTTO is (Fiber-To-The-Office), FTTR is (Fiber-To-The-Riser). All these terms are very much used interchangeably sometimes as they have very thin difference between their usage and name means[1].
3. Overview of FTTH
FTTH is a description of the PON-based broadband access network technology that uses fiber optics running all the way from the internet backbone to the home or premises. Sometimes other acronyms like FTTx, FTTP, FTTB are used but they are essentially interchangeable as discussed earlier. FTTH is becoming the catch-all descriptor for all fiber to the home, premises, business, and “x technologies”. The overlay of FTTH is possible with the help of a number of devices in PON technology. The devices/stations used would be an OLT (Optical Line Terminal) which is the central office providing the FTTH connection and along with every OLT there is an ONU (Optical Network Unit) working on the destination considered as CPE (Customer Premises Equipment). FTTH being a passive network (because of using PON technology) it uses optical signals to operate and no electrical devices like routers are used which dramatically reduces the cost of network maintenance as well as it eliminates the need for a DC power network[3]. The bandwidth of FTTH can be imagined with that it can support 2.5 million calls simultaneously [5]. Along with providing a triple play i.e. telephone, broadband internet, and television to homes and businesses. With a huge bandwidth and having no maintenance issues FTTH gives the best value to its customers.
4. Design of FTTH
The main difference between FTTH and other types of FTTx network is amount of Fiber Optics used in deploying the network which in turn increases the overall speed of the of the network. For instance in FTTN (Fiber-To-The-Node) more then 1000ft (300m) is Metallic cables the rest is Optical Fibers which actually reduces the actual capabilities of Fiber Optics network. In FTTC (Fiber-To-The-Curb) about less the 1000ft (300m) is the metallic cables and the rest is the fiber optic which again decreses the capabilities of Fiber Optics. In FTTB (Fiber-To-The-Building) the Fiber Optics is carried to the building andthe rest is again done with metallic cables. But in FTTH its Fiber Optics that is used the deploy the whole network till the destination which obviously makes FTTH the fastest network with the largest bandwidth with no compromise on speed. Making FTTH overlay network best in its tribe.
The technology used for deploying FTTH network is PON (Passive Optical Network) technology. This approach differs from most of the telecommunications networks in place today by featuring "passive" operation. Active networks like DSL, VDSL and cable have active components in the network backbone equipment, in the central office, in the neighborhood network infrastructure, and in the CPE (customer premises equipment). PONs have only passive light transmission components in the neighborhood infrastructure with active components only in the OLT or central office and the customer premises equipment [3].
Fig.2. A general PON deployed network with an Optical Splitter in between OLT & CPE
The PON technology networks works with passive components. The elimination of active components means that the access network consists of one bi-directional light source and a number of passive splitters that divide the data stream into the individual links to each customer. At the central office, the termination point is in PON optical line terminal (OLT) equipment. At the customer premises, the termination point is in optical network terminals or ONTs also called optical network units or ONUs. These are in the customer premises equipment, or CPE. Between the OLT and the ONT/ONUs is the passive optical network comprising fiber links and passive splitters and couplers. The ONU devices provided at each customers end serves as a signal discriminator for triple play i.e. for telephone, broadband internet, and television to homes and businesses.
The FTTH endpoints i.e. the central office OLT (Optical Line Terminal) contains storage/video server, ISPs, Class5 switch and VoIP Gateway and the ONU (Optical Network Unit) handles the discrimination of the triple play function i.e. it provides telephone, broadband internet and television simultaneously. The passive optical splitter generates optical signals and is responsible for the connectivity between the OLT (Optical Line Terminal) and ONU (Optical Network Unit). ONU is an equipment which is part of the Gigabit Ethernet Passive Optical Network (GEPON) systems. ONU is used side by side with OLT and is an alternate for the old copper based systems. ONU provides the subscribers with various types of broadbandservices like VoIP, HDTV, Video Conferences. ONU syatem also have advantages like High integration, Flexibility in application, High stability, Easy to manage, Flexibility in extending and building up the network and Provision of QoS function.
Optical line terminal is one of the key components used in GEPON networks, the optical line terminal is usually put in the central control room. Our typical optical line terminal adopts 19 inch size rack design, it is with 3U height and 16 slots, every 2 of them is offered to one OLT module, supporting 8 OLT module max and 256 remote ONU equipment. This system make it a stable big bandwidth data transmission over 10 to 20km distance. It is able to supply transmit function at L2/L3 wire speed. Each PON line supports 1Gbps upstream and downstream symmetrical bandwidth [12].
The optical line terminal features high QOS and flexible dynamic bandwidth allocation, it can implement any change from 1M to 1G access bandwidth. This optical line terminal supports auto-discovery and auto-register, user line testing, remote ONU fiber failure and power failure alert. It also contains abundant operation and manageable features such as MAC address limited and leached, IP address limited and leached, bandwidth control, VLAN and flow control. The optical line terminal also features the network management function.
The ONT (Optical Network Unit) basically transforms the fiber optical signals into electrical signals at the customers end and provides reliable fiber optic Ethernet services to residential as well as business users by using fiber based network infrastructure [12].
Fig.3. The FTTH endpoints: Central Office(OLT) & ONU.
5. Technology Benefits FTTH
Astonishingly fast Internet access with simultaneous delivery of high definition IPTV and voice over IP services -- all at a cost comparable to a single, low-speed DSL service. These are the tantalizing benefits of Fiber to the Home (FTTH) broadband access technologies. Many have heard of internet, or HDTV, or fiber to the home (FTTH) networks. But many may consider FTTH as the next technology hype, perhaps unaware of the benefits and large potential FTTH has. Though FTTH is getting beyond its infancy state. In the USA there are now over 6 million subscribers of services of fiber networks, many via Verizon FioS or AT&T U-verse services. In Japan the number of subscribers is more than double of the USA, worldwide there are over 30 million subscribers [3].
First of all, and most important, FTTH offers so much bandwidth capacity that grow in data demand (TV, internet, phone) for the next decades will be covered. FTTH is ready for future demand, like for instance 3D high definition TV still being developed at this moment. Or just imagine the growth in online games that has taken place during the last years. FTTH will be able to provide gigabits per second, via a very reliable network. Everybody who has seen a demonstration of a fiber to the home network vs. a copper/DSL network is sold on the concept [6].
Fig.4. Bandwidth comparison FTTH, DSL & Cable.
The features of FTTH are highlighted as follows:
- No more separate wiring for telephone, TV. cables or DSL modems. Single fiber optic cable provides enough bandwidth for eac of these to work simultaneously.
- Single fiber optic cable delivering all the required services IP based.
- Using Fiber Optic medium can increase DSL speed by approximately 10 times.
- A single fiber pair can carry more than 2.5 million phone calls simultaneously [ source: Federal Communications Commission ].
- Being a passive network it dramatically minimizes the network maintenance cost, requirements, as well as eliminating the need for a DC power network.
- It is a single fiber to the end user with industry standard user interfaces, including voice, high-speed data, analog or digital CATV, DBS and video on demand.
- The usage of all IP based services can be used simultaneously.
- New worldwide generation of connectivity for IP based services.
- FTTH is reliable, secure and scalable to nearly unlimited bandwidth.
- Will add market value to the development as it saves a lot of time.
- [6], [9], [10].
6. FTTH PON Technology
There are three types of PON technology in which FTTH networks can be deployed. First one is EPON which is the advanced or the upgraded form of APON. GE-PON also known as EPON and the GPON. One important distinction between the standards is operational speed. BPON is relatively low speed with 155 Mbps upstream/622 Mbps downstream operation. GE-PON/EPON supports 1.0 Gbps symmetrical operation. GPON promises 2.5/1.25 Gbps asymmetrical operation [6].
Another key distinction is the protocol support for transport of data packets between access network equipment. BPON is based on ATM, GE-PON uses native Ethernet and GPON supports ATM, Ethernet and WDM using a superset multi-protocol layer.
BPON suffers from the very aggressive optical timing of ATM and the high complexity of the ATM transport layer. ATM-based FTTH solutions face the problems posed by the provisioning (requires ATM-based central office equipment), complexity (in timing requirements and protocol complexity) and subsequent cost of components. This cost is exacerbated by the relatively small market for traditional ATM equipment used in the backbone telecommunications network.
GE-PON or Ethernet in the First Mile has been ratified as the IEEE 802.3ah EFM standard and is already widely deployed in Asia. It uses Ethernet as its native protocol and simplifies timing and lowers costs by using symmetrical 1 Gbps data streams using standard 1Gbps Ethernet optical components. Like other Ethernet equipment found in the extended network, Ethernet-based FTTH equipment is much lower-cost relative to ATM-based equipment and the streamlined protocol support for an extended Ethernet protocol simplifies development. Specific to PMC-Sierra, the GigaPASS architecture that is designed for gigabit throughput for GE-PON devices is adaptable for use with GPON devices as well.
Table.1. Attributes of different PON technology.
7. FTTH Infrastructure Elements
Expending outwards from the access node towards the subscriber the key infrastructure elements needed are:
· Access Node.
· Feeder Cabling.
· Primary Fibre Concentration Points (FCP).
· Distribution Cabling.
· Secondary Fibre Concentration Points (FCP).
· Drop Cabling.
· Internal Cabling (subscriber end).
Access Node refers to Building communications room or separate POP building. Feeder Cabling refers to large size optical cables and supporting infrastructure e.g. ducting or poles. Primary Fibre Concentration Points refers to easy access underground or pole mounted cable closure or external fibre cabinet (passive – no active equipment) with large fibre distribution capacity. Distribution Cabling refers to Medium size optical cables and supporting infrastructure e.g. ducting or poles. Secondary Fibre Concentration Point (FCP) refers to Small easy access underground or pole cable joint closure or external pedestal cabinet (passive– no active equipment) with medium/low fibre capacity and large drop cable capacity. Drop Cabling refers to Low fibre count cables or blown fibre units/ ducting or tubing to connecting subscriber premises. Internal Cabling refers to external building fibre entry devices, internal fibre cabling and final termination unit, which may be part of the ONU [7].
8. FTTH Infrastructure Suppliers
Currently, two major service providers are rolling out FTTH fiber optic access plans: AT&T, with U-verse, Verizon, with FiOS, while Comcast is rolling out a competing technology called Docsis 3.0. Consumers are increasingly streaming and downloading large files, like movies, and engaging in video-chatting, using the small cameras that are attached to many new laptops. Both AT&T and Verizon offer "high-speed" connections of speeds up to 10 Mbps - but with the demand that services like video-chatting and streaming video put on networks, the 50 MBPS offered by Docsis 3.0 and FiOS look far more appealing. As a comparison, DSL has a speed of 1.5 Mbps. The telecom giants jumping on the FTTH bandwagon signals that fiber optics is set to go mainstream, and demand for fiber optics infrastructure will grow. It's likely that larger telecom infrastructure companies like Alcatel and Tellabs will receive most of the fiber optics business, but smaller firms like Emcore could also get in the game [7].
The first major suppliers for the FTTH infrastructure AT&T U-Verse maxes out at 18 Mbps, but is cheaper than Comcast and FiOS (excluding New York) at only $100/month. U-Verse uses both FTTH and FTTN technology, depending on the area. The FTTN model is faster and cheaper to deploy then FTTH, but the copper connections to the homes sacrifices speed compared to FTTH. U-Verse is currently in parts of California, Connecticut, Georgia, Indiana, Illinois, Missouri, Michigan, Ohio, Oklahoma, Texas, and Wisconsin. AT&T plans to service 1 million homes by 2008 and 30 million home by 2010.
While on the other hand the other major supplier Verizon FiOS is the largest fiber optic network in the US. FiOS offers a downstream speed of 50 Mbps and costs $90/month in New York, but $140/month in Massachusetts, Rhode Island, Connecticut, New Jersey, and Florida. To give an idea of how fast 50 mbps really is, at 50 mbps an HD movie can be downloaded in 13 minutes and a 60 minute video can be downloaded in a mere 8 seconds. In the 16 states that Verizon plans on introducing its FiOS system, the company reported that it expects to spend close to $23 billion from 2004 to 2010 in network installation. Verizon is dominating FTTH as it is responsible for over 70% of the FTTH connections in the US. By the end of 2007, FiOS had 9.3 million customers and Verizon expects to have 12 million customers by the end of 2008 [8].
Apart from these suppliers other infrastructure suppliers for FTTH are Alcatel (ALU),Tellabs (TLAB), EMCORE (EMKR), AFL Telecommunications, Tyco Electronics, Preformed Line Products, ANADIGICS, Corning, ADC Telecommunications.
9. Penetration of FTTH
The greatest rate of FTTH/FTTB adoption is occuring in Asia. About 21% of homes in Hong Kong have FTTH and South Korea has 19.6% of homes connected to FTTH. The main reason for the huge penetration in Asia, as opposed to the US, is that the governments of countries such as Japan and South Korea are specifically promoting this technology as a part of their national strategy.
The United states had about a 1.3% penetration in 2007, but does have a large amount of fiber optic cables in the ground left unused from the dot com bust. Many of the telecom companies were laying cable at a faster rate than they were getting customers, but now these companies can start utilizing this installed base thanks to the renewed growth of demand from consumers. In 2007, the number of US households with FTTH doubled from 2006. The major proponent of FTTH is Verizon. Verizon is responsible for about 70% of the households passed by fiber optic networks and added about 203,000 customers to their FiOS service in 2nd quarter of 2007 alone [11].
The acknowledged leader in FTTH deployments is Japan. The world's largest telecommunications carrier NTT began volume deployments of gigabit Ethernet PON FTTH in 2003 and ramped up rapidly in 2004 and 2005. By the first half of 2005, in Japan there were more new installations of FTTH to connect consumers to the Internet than there were new DSL connections, marking a major milestone for the entire worldwide FTTH industry [11].
Fig.5. Penetration of FTTH technology in different countries.
The single most important factor to spur widespread deployment of FTTH in the broadband access network is lowering the cost of equipment. There is no question of the performance advantages of FTTH technology over DSL and cable access technologies. FTTH delivers far greater bandwidth. There is no question that consumers will rapidly adopt FTTH technology if the cost is comparable to existing access solutions [11].
Telecommunications service providers who will profit from the new integrated communications services they can offer consumers are driving the deployment of FTTH technologies. They know that consumers will leap at the chance to obtain Internet access that is thousands of times faster than DSL and cable solutions if that service is comparable in cost and comes with extras such as the ability to add hundreds of high definition video channels and services such as video on demand.
Prices for fiber optic cable and transceivers have dropped significantly since the 1990s so that today, point-to-multipoint fiber infrastructure offers reach, scalability, and almost unlimited bandwidth at a cost that makes FTTH deployment practical. By deploying FTTH infrastructure, service providers and telecommunications carriers can put into place a long-term service solution that can provide a host of existing and as yet unimagined services for the consumer and for business. Unlike active copper-based infrastructure designed to last only a few years, passive fiber links do not deteriorate in the field and last indefinitely unless they are cut or removed.
With the potential to reshape the relationship between consumers and the telecommunications carriers and service providers, FTTH offers an opportunity that few carriers can afford to pass up. Consequently, there is worldwide interest in successful deployment of FTTH broadband access networks [11].
10. Future of FTTH
Future FTTH access systems are expected to have at least 100 Mbps per subscriber (asymmetric or symmetric). There are more then one possibility for achieving such bit rates depending on the starting basis.
Active Ethernet can be easily upgraded by upgrading or replacing the transceivers in ONT and OLT. 100 Mbps appears to be the most deployed bit rate but 1 Gbps has also been deployed. So far active Ethernet even meets bandwidth demands in the presence and in the near future. A comprehensive upgrade to 1 Gbps transceivers would satisfy the future demands for more bandwidth. A future installation of 10 Gbps is depending on the available transceivers (especially for the ONT) and the development of Ethernet itself. Additionally, 1 Gbps is still enough to challenge future PONs. Future PONs are divided into DM based next generation PONs (NG-PON) and WDM based WDM-PONs. Because of the sharing bandwidth nature of TDM based PONs they can only meet demands in the near future by using 10 Gbps as shared bit rate [1].
Finally, the future of FTTH is on its way but still needs more research for the mass deployment. Espacially cost reductions are at focus to assure feasibility. A combination of WDM PONs and NG-PONs might dominate the remote future. Meanwhile EPON dominates the Asia region, GPON is about to dominate in North America and Europe remains a diverse market with focus on active Ethernet [1].
12. Refe
[1]www.hftleipzig.de/pnet/files/IHF/Dokumente/FTTH_Foerster.pdf
[2] http://www.opticnetworks.net/What_is_FTTH.html
[3] http://www.pmc-sierra.com/ftth-pon/ftth_overview.html
[4] http://www.wikinvest.com/concept/Fiber-to-the-Home_ (FTTH)
[5] Federal Communications Commision
[6] http://www.pmc-sierra.com/ftth-pon/ftth_technology.html
[7]http://www.ftthcouncil.eu/documents/studies/WhitePaperFTTHInfra_DEF.pdf
[8] http://en.wikipedia.org/wiki/GPON
[10]http://www.opticnetworks.net/Benefits_of_FTTH.html
[11] http://www.ready-links.com/ftth.html
[12] http://home.howstuffworks.com/fiber-to-the-home.htm/printable.
