Evolutions in Network Components Impacting FTTH Deployment in Brownfield Multi Dwelling Units

Transcription

1 Evolutions in Network Components Impacting FTTH Deployment in Brownfield Multi Dwelling Units Linnea M. Wilkes, Global MDU Business Development Manager, 3M Jerry Jackson, Marketing Manager, 3M Table of Contents Introduction...2 Drop Cable Evolution...3 Cable Pathway Alternatives.5 ONT (Optical Network Terminal) Migration.9 Connectivity Methods with Speed, Flexibility and Less Waste.10 Conclusion..13

2 I. Introduction: Deploying fiber in MDUs (Multi Dwelling Units) has been a challenge for service providers. In fact, it s been considered the final frontier for FTTH (Fiber-to-the-Home) deployments. No two buildings are alike, no solution fits all. This equates to significant engineering and installation time and yes, that ugly word that all providers hate: Cost. To complicate matters, OSP (Outside Plant) solutions didn t translate easily into a MDU environment where available space and overcoming aesthetic objections were significant challenges. Old buildings were already wired with multiple cable media, creating congestion both in riser and horizontal applications. Adding conduits and pulling new fiber cables within walls or above ceilings and creating new cable pathways added more cost and quite possibly, required access to customer living space prior to a service request placed by the tenant. And not surprisingly, building owners and HOAs (Home Owner Associations) were hesitant to add additional apparatus and cables that further disturbed the look and value of their properties and homes. This paper will review the evolution of key network components which have influenced FTTH deployment methods, specifically in brownfield MDUs. It will provide an evaluation of a variety of options available for each component and suggest how these options aid in resolving some of the pain points faced by service providers in delivering their product to consumers; time and cost to install, aesthetic challenges, and minimized tenant disruption: The drop cable evolution: bend-insensitive fibers (from SMF-28 to G.657.B3), reduced cable diameters (from 5 mm jacketed cable to the use of 900µm tight-buffered fiber as a drop), and the increasing acceptance globally of FRP (Fiber Reinforced Polymer) drop cables. Cable pathway alternatives: crown molding, square latch molding (or trunking ), micro duct, and/or the elimination of cable pathways altogether and instead, the use of jacketed cables adhered directly to wall surfaces with adhesives or staples. ONT migration: hardened ONTs, SFU (Single Family Unit) wall-mount ONTs, and SFU desktop ONTs. Connectivity methods with increased speed, greater flexibility, and less cable waste: fusion spliced pigtails, pre-connectorized drop cables, and field termination FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 2 of 14

3 II. Drop Cable Evolution In MDUs, installing fiber cable within the acceptable bend radius often proves difficult. The cable cannot be installed flush to the wall or baseboard around corners, producing unsightly gaps. Also, the technician can ignore the minimum bend requirement, leading to service complaints. In 2002, the first bend-insensitive fiber cable was launched in the U.S. It was capable of a 10 mm bend radius without affecting signal performance. Since then, manufacturers have improved upon first-generation bendable fiber, developing fiber with an allowable bend radius of 7.5 mm and even as little as 5 mm, which can easily achieve a 90-degree bend. Initially, the most common MDU bend-insensitive drop cable had a 3 mm cable jacket. These cables were 50, 100 or 200 feet in length and typically pre-connectorized. Their size and ability to achieve bend radii as small as 7.5 mm made them rugged enough for use in MDU applications entailing multiple bends. See Figure 1 illustrating a MDU application for 3 mm drop cables below. Figure 1: 3 mm jacketed drop cables terminated in a FDH (Fiber Distribution Hub) As service providers became more and more focused on MDU applications due to their density and economies of scale, they began to demand more from their drop cables. This led to the emergence of a 5 mm UBIF (ultra bend-insensitive fiber) drop. While able to maintain an even tighter bend radius then their bend-insensitive brethren (5 mm), these drops were more bulky and difficult to conceal from consumers. Since they were quite rugged, they could easily be stapled to walls for quick installation in apartments, but this solution wasn t attractive to some tenants. And where concrete walls existed, the cables were impractical. An illustration of a 5 mm drop cable is shown in Figure 2 below FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 3 of 14

4 Figure 2: 5 mm UBIF drop cable And, as more providers pressed building owners to allow tenants access to their services, the more they realized that the service wasn t always the toughest sell. Often times, finding a network solution (apparatus and optical cabling) that was aesthetically acceptable to building owners and tenants was more challenging. This forced providers to challenge suppliers and evaluate solutions that enabled smaller cabling and cable pathway solutions. One of these options involved the use of 900µm fiber in horizontal cabling applications in North America. See Figure 3 below. Figure 3: 900µm fiber used in a horizontal cabling application Historically, 900µm tight-buffered fiber was used alone in short lengths for electronics applications (short coils inside metal housings with electronic components) and never used in long lengths for applications such as FTTH. However, by using bend-insensitive 900µm fiber, cable pathways and apparatus used to contain fiber slack and store terminations could be made smaller. See an example in Figure 4 below FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 4 of 14

5 Fiber Pathway Figure 4: Installation of fiber pathway containing 900µm fiber and small network apparatus Conversely, the Asia market utilized FRP drop cable. This cable contains 250µm fiber and FRP as reinforcing strength members. The cable can be easily routed along base boards, but feeding the cable through conduits can be difficult because of the outer sheath s high friction material. A cross-section of FRP cable can be found in Figure 5 below. Figure 5: Cross-section of a traditional FRP drop cable As time passed, FRP cable evolved. The emergence of low-friction FRP enabled service providers access to a jacketed cable with a special sheath which aids in the passing of fiber cables in congested ducts. This allowed more providers to utilize existing cable pathways those previously too congested to add new/additional cables. This was a good thing, as tenants will elect to place cables behind walls - where they are not visible - whenever possible. However, this next generation cable removed the polymer strength members and replaced them with metal wires, which could require grounding of the cable. See an image of FRP cable in Figure 6 below FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 5 of 14

6 Figure 6: Low friction cable III. Cable Pathway Alternatives In new construction, communications cables are planned for in advance and often hidden behind the walls of the building. Older buildings, however, require cable pathway creation techniques that are aesthetically pleasing to owners and tenants. Durable, long lasting installations and high quality service are paramount. And, from a service provider perspective, these cable pathways must be cost-effective. One common cable pathway creation method involves the use of rigid crown moldings off-set about 1 to 2 inches from the ceiling. This allows jacketed drop cables to be tucked behind them and concealed from view. While often the most aesthetically pleasing option, it is also one of the most costly and disruptive to install. See Figure 7 below. Figure 7: Crown molding installed at an off-set Another alternative is to use two-piece plastic square latch molding consisting of a base and a cover. These products are somewhat lower cost, but still require significant custom fitting during installation since the molding is sold in standard lengths. To place cables inside, removal and replacement of the covers is required. In a 300 foot or greater hallway, that s a lot of covers! See an example of square latch molding in Figure 8 below FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 6 of 14

7 Figure 8: Two-piece square latch molding The use of micro ducts behind walls and above ceilings is also a common method for concealing communications cables. Micro ducts first must be installed and later, cables fished or routed through them. Often times the use of micro ducts required core drilling, the process of boring holes through one or multiple floors of a building. This is not only expensive and time consuming but, when done through stacked closets in multiple apartments on multiple floors, requires tenants to be at home during the installation process an inconvenience. The benefit of micro duct, however, is that cables and the ducts can be almost completely concealed. See Figure 9 of micro ducts placed in a riser closet below. Figure 9: Micro ducts used to conceal fiber optic cables In other circumstances, particularly in apartments with more complex layouts consisting of a greater number of bends and turns, ultra bend-insensitive cables, capable of maintaining a bend radius as small as 5 mm (ITU G.657.B3), are often simply stapled to the walls. While generally considered optically acceptable if this classification of fiber is used, a special crowned staple is needed. An illustration of this application can be found in Figure 10 below FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 7 of 14

8 Figure 10: Application of cable using staples And while stapling cables to walls is quick and easy, many apartment walls are concrete, making stapling virtually impossible. In general, stapling is noisy, creates dust, and looks industrial, at best. Visually, most building owners are unlikely to accept such a solution. In 2009, an adhesive-backed fiber pathway was introduced. Constructed from an extruded PVC duct, the pathway is factory-filled with up to µm tight-buffered bend-insensitive fibers (G.657.B2) and laminated with adhesive so it can be directly installed onto a wall surface using the pre-attached adhesive without the use of a raceway, conduit, or micro duct. Installation occurs in visible locations and is not to be hidden inside conduit, riser, or plenum spaces. See Figure 11 below. Fiber Pathway Figure 11: Multi fiber pathway installation Designed to be deployed in hallways of existing MDUs serviced by FTTH networks, the pathway addresses many of the challenges of traditional horizontal optical cabling solutions. Because the pathway uses bend-insensitive 900µm fiber as the medium to distribute fiber optic services, the pathway itself can be made smaller than traditional optical cable pathway solutions designed to contain multiple 2, 3 or 5 mm jacketed cables. This makes the system more discrete and less noticeable to tenants FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 8 of 14

9 Furthermore, because those fibers are factory-installed, installation of the cable pathway and drop cables can be completed in one simple step. Specially designed installation tooling enables a quick, easy installation process that can save service providers up to 35% in installation costs on each floor that it is installed. And because adhesive is used to mount the pathway to the wall, installation is less disruptive than traditional methods. Further evolutions in fiber pathways led to the introduction of a single fiber solution for inside the apartment. See a product installation in Figure 12 below. Figure 12: Single fiber pathway installation Used with or without the multi fiber hallway solution, the single fiber pathway provides an even smaller cable pathway. Still factory-installed, this fiber is ultra bend-insensitive (ITU G.657.B3) and selected for use to allow reduced corner radius, for improved aesthetic. Installation is easy, quiet and also a viable solution for concrete walls, because it is laminated with adhesive. IV. ONT Migration When North American service providers began deploying fiber in MDUs, ONTs designed for single family homes were the most likely option. Mounted on the outside of a house, single-family ONTs serve one family. An example is in Figure 13 below. Figure 13: Single-family outdoor ONT However, the outside plant option isn t feasible for many MDUs the last thing building owners want is dozens of boxes clinging to exterior walls, especially of valuable, high-rent properties. These same ONTs are too expensive since singlefamily ONTs have to be ruggedized in order to withstand the elements features no 2011 FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 9 of 14

10 longer necessary if used indoors. Providers adapted by placing re-designed ONTs inside closets usually a utility or coat closet just inside each living unit. An example of these wall mount ONTs can be found in Figure 14 below. Figure 14: Wall-mount ONT and back-up battery installed in MDU closet The closeted ONT turned out to be a workable but less than optimal solution. Among the disadvantages: Many apartments and condos have small closets, and ONTs take up precious storage space undesirable to many subscribers. The ONT requires a power source, usually unavailable in a closet, requiring the installation of new electrical wiring and outlets. That added to service installation time and cost, as well as inconvenience to residents. And, running coaxial or Cat. 5 cable from the closet ONT to the subscriber s TVs, phones and computers can require lengthy cable feeds, adding cost. Service providers and their suppliers quickly responded by developing the desktop ONT. First used in the U.S. in 2009, the desktop ONT is significantly smaller and lighter and than its single-family counterpart. Looking much like a wireless router, a device most tenants were familiar with, the desktop ONT could be placed in open living areas without objection. Figure 15 shows a desktop ONT installed in an apartment. Figure 15: Desktop ONT and back-up battery 2011 FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 10 of 14

11 Smaller than a typical cable modem, the desktop ONT can be located next to the flat-screen TV, where it can take advantage of existing power outlets and apartment wiring, reducing installation time and cost. Desktop ONTs cost less and use up to 30 percent less power than their single family counterparts, an added benefit for subscribers or building owners. Cost-effective and aesthetically pleasing, the desktop ONT marks a significant step forward in FTTH deployment to MDUs. V. Connectivity Methods with Speed, Flexibility and Less Waste For MDU applications, service providers have traditionally deployed either factory terminated patch cords or fusion spliced pigtails/connectors. Both of these technologies have excellent optical performance with good performance in the field after installation. Patch cords have the advantages of: No tools required No splices Simple plug-n-play installation minimizes the skill set required Issues during deployment can arise, such as: Cable slack storage Cable length too short Inventory of different cable lengths Cable waste and increased installation time when a connector is damaged and the entire patch cord must be replaced Figure 16: SC/APC Patch Cord Fusion spliced pigtails have been utilized to alleviate these issues, so: Drop cable length can be customized to the MDU situation Inventory can be minimized by using reels of cable and connectors to eliminate the need for various patch cord lengths Fusion splicing can create its own issues, such as: Large, up front expense for fusion splice machine Special training/expertise required Electrical power required Figure 17: Fusion Splicer Because of the expense and training required, not all technicians in the field may have a fusion splicer, which slows deployment and creates installation inefficiencies. Advancements in mechanical fiber connectivity have combined the fusion splicing benefits of field customized cable lengths and reduced cable inventory with a simple, easy to use tool set that is low cost. There are 2 potential mechanical connectivity solutions: No polish connector which utilizes a mechanical splice with an index matching gel and a factory-polished connector end face 2011 FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 11 of 14

12 No gel, no splice connector which utilizes a mechanical fiber grip and a simple hand tool to polish the fiber end face Both have been tested successfully to rigorous indoor and outdoor performance specifications from -40 F to 167 F, such as Telcordia GR-1081-CORE Generic Requirements for Field-Mountable Optical Fiber Connectors. No polish, mechanical splice connector A large US service provider is deploying a SC/APC angle splice version of the no polish, mechanical splice connector in MDU applications. Utilizing a simple, low cost hand-held installation tool and a keyed, angle cleave mechanical splice with index matching gel, the connector performance is excellent with a typical insertion loss less than 0.3dB and reflections less than -60dB. Even though the connector is being initially deployed in indoor MDU applications, it was tested for outdoor applications. The service provider required connector installation in temperatures from 23 F to 114 F and stable optical performance from -40 F to 176 F. This ensures the connector will meet the service provider s long term network reliability requirements, even if the connector is installed in the outside plant. Figure 18: No polish, mechanical splice connector Figure 19: Assembly Tool Figure 20: No polish connector installed in MDU hallway No splice, no gel connector In this next generation, field-mount connector technology, a field fiber is cleaved, inserted through the connector so it extends through the ferrule and permanently locked in place mechanically. It is temperature balanced and utilizes hand actuated installation tools. By designing the connector with materials that have specific thermal properties, the fiber tip and connector ferrule move together when the connector is heated and cooled. This results in very stable optical performance from -40 F to 176 F for indoor and outdoor applications. Figure 21: No splice, no gel connector 2011 FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 12 of 14

13 To install, the fiber is cleaved, inserted through the connector, locked in place with a metal element and finished with a simple polishing tool. This hand tool utilizes a polishing film and an orbital mechanism to provide over 36 inches of polishing with a single turn of the handle. Once completed, the connector is cleaned and ready for use. Figure 22: Fiber is locked in connector with tool Figure 23: Hand tool polishes fiber tip with one 360 turn of the handle This technology has been successfully deployed at another large US service provider with excellent success in a MDU environment. Similar to the no polish mechanical splice connector, this connector has been deployed in the MDU indoor environment, but has been tested for outdoor applications. As FTTH deployment expands, new technologies such as mechanical connectivity are increasing the speed of deployment, decreasing equipment costs while maintaining required optical performance. Figure 24: No gel, no splice connector installed in indoor wall outlet box VI. Conclusion As service providers increased their emphasis on passing MDUs with fiber optic services, suppliers responded with the evolution of key network components which in turn influenced FTTH deployment methods, specifically in brownfield MDUs. These components include, but are not limited to, drop cables, horizontal cable pathways, ONTs, and drop cable connectivity methods. These evolutions aimed at resolving some of the 2011 FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 13 of 14

14 pain points faced by service providers in delivering their product to consumers; time and cost to install, aesthetic challenges, and minimized tenant disruption. As more and more MDUs get passed with fiber, these deployment methods will become more common as the challenges in MDU deployments to brownfield buildings are unlikely to go away due to the uniqueness of each building and its installation conditions FTTH Conference & Expo: Lighting the Economy Orlando, Florida Page 14 of 14