Tài liệu Delivering Services over FTTP pdf

case study Delivering Services over FTTP the Home Town Way Situation Home Town Cable Plus is an integrated service provider operating in the city of Port St. Lucie as well as in the county of St. Lucie in Florida. Just three years ago, the new company embarked upon its plan to build a passive optical network (PON) to link homes and businesses in its service area to the company data center. Home Town officially opened for business in September 2003 with a bundle that includes standard POTS as well as alarm and monitoring services. In addition, Home Town offers 217 channels of SDV (switched digital video) and gigabit Ethernet high-speed Internet service over the advanced IP-based network. As Home Town management drew-up its business and operating plans, it was clear that offering highly competitive pricing and operating profitably was going to require long term cost containment. In addi- tion, as a pioneer in delivering services over a fiber-to-the-premise network, it was also clear that Home Town’s PON architecture was unique. It was going to require a different approach in the outside plant and more than off-the-shelf solutions to maintain reliable service levels and speed service turn-up. Figure 1: PON Design for Home Town Cable Plus A Design Takes Shape The Home Town network was conceived as a two-fiber system—one fiber for voice and data and one for video. In addition, planners elected to aggregate drop cables in fewer points in neighborhoods, a design resulting in far fewer above ground terminals that would appeal to both builders and homeowners. The PON was designed around two major com- ponents: Neighborhood Access Points (NAP) and Local Conversion Points (LCP), each of which feeds multiple NAPs, shown in Figure 1. LCP and NAP cabinets would house splitters, splices and distribution panels. As with any PON, all active equipment is centralized in the headend and splitters deployed in the field so that PON cards in the headend are purchased and activated in unison with take rates, effectively deferring capi- tal purchases closer to revenue. Referring to Figure 1, the design calls for fiber feeder cable from the headend to be spliced to rear input ports on splitters in the LCP. Distribution cables from NAPs are terminated by splice on the rear of distribution panels in the LCP. This configuration allows cross connect- ing between input side of splitters and output side of distribution panels by use of simple jumper cables. NAPs, which are deployed deeper in the network and designed to support 32 or 64 homes, have a similar design. Distribution cable from the LCP is spliced to rear input ports of splitters and at service turn-up, drop cable is spliced to the out- put side of a distribution panel. Once fiber drop cable is blown to the premise in pre-installed conduit and spliced at the NAP, service connec- tion in the field is completed with a fiber jumper in the cross connect. The design for the outside plant was future thinking. With splitters in the PON rather than centralized in the headend, the company was able to reduce fiber count and construction costs. Upfront costs were also reduced by use of guide tubes and blown fiber for drop cables. By invest- ing an additional 1% to 2% of total project costs in a cross-connect architecture for the PON, Home Town expects to generate long-term oper- ational savings by reducing the time required for activation and troubleshooting. This small invest- ment reduces capital investment by full utilization of PON card ports in the headend, which would not be possible with an all-spliced PON. With a design in hand, the task turned to finding a ven- dor to supply LCPs and NAPs. PON Products Engineered Specifically for Home Town Bill Flanagan, Director of Operations for Home Town Cable Plus, has worked on fiber projects for over 20 years before joining the start-up Home Town. From initial investigations, it was evident there were no products existing from any vendor to meet Home Town’s needs. Yet he knew from first-hand experience of ADC’s track record for innovation and service both in the headend and the outside plant. When it came time to find products for the PON, he invited ADC to the table. After listening and discussing objectives with Home Town, ADC offered solutions for both LCPs and NAPs that combined components from existing ADC product lines. The proposal called for ACE100, ACE200 and ADCE400 outside plant cabinets retrofitted with VAM (Value- Added Modules) splitter modules as well as dis- tribution panels, splice wheels, and cable stor- age modules from the OMX ™ line of optical dis- tribution frames. In all, ADC designed five different cabinets for Home Town—all from existing products. ADC’s ability to come up with just the right cabinets for Home Town’s requirements was due to inherently modular product lines, savvy engineering support and, most important, highly flexible manufactur- ing processes. As a vertically integrated manufac- turer and provider of mass-customized products for the past 60 years, ADC was able to tailor products to Home Town’s needs. “We had several companies out to visit with us and they all had good products. But the others couldn’t produce exactly what we wanted. ADC’s manufacturing expertise impressed us enough to know they could successfully combine several off-the-shelf products into a solution for us,” said Flanagan. ADC Telecommunications, Inc., P.O. Box 1101, Minneapolis, Minnesota USA 55440-1101 Specifications published here are current as of the date of publication of this document. Because we are continuously improving our products, ADC reserves the right to change specifications without prior notice. At any time, you may verify product specifications by contacting our headquarters office in Minneapolis. ADC Telecommunications, Inc. views its patent portfolio as an important corporate asset and vigorously enforces its patents. Products or features contained herein may be covered by one or more U.S. or foreign patents. An Equal Opportunity Employer 1288842 4/04 Original © 2004 ADC Telecommunications, Inc. All Rights Reserved Web Site: www.adc.com From North America, Call Toll Free: 1-800-366-3891 • Outside of North America: +1-952-938-8080 Fax: +1-952-917-3237 For a listing of ADC’s global sales office locations, please refer to our web site. Conquering Density with Proper Cable Management For ADC engineering, NAP design posed a dual chal- lenge. On one hand, Home Town wanted small above ground cabinets in neighborhoods. On the other, cab- inets were going to be highly dense with either 32 or 64 two-fiber drops per NAP cabinet. Adding to high fiber count are splitters, splices and cross-connect panels, all of which could converge into a potentially unmanageable cabinet. In light of these challenges, making both NAPs and LCPs technician-friendly and highly reliable meant paying close attention to the details of cable manage- ment. Clamping, drop cable routing within the cabi- net, cross-connect jumper management, fiber feeder and distribution cable entrance and exit, splice stor- age, bend radius protection, choice of connector— these were all critical issues evaluated by ADC engi- neers for Home Town. The solution started with standard ACE series outside plant cabinets. Designed to meet Telcordia GR487 and NEMA 4 specifications, the cabinets offer proven durability and protection. Engineers then found that the highly modular components of the OMX optical distribution frame system were well suited for the project. To manage splices, OMX splice wheels were specified. Each splice wheel provides not only splicing but also ready storage for up to 3 meters of slack, allowing technicians to move splice wheels away from the cabinet to a proper position for effective splicing. Also brought into the solution were OMX storage modules for secure storage of cross-connect jumpers. Finally, pre-terminated OMX distribution modules ori- ented specifically for the right side of the cabinet, along with VAM splitter modules, provided the ability to cross connect in cabinets. Taken together, advanced cable management and cross-connect functionality offered Home Town the right features for operational efficiency and reliability in the PON. "Design of the cabinets addressed both density and cable management issues," said Flanagan. "We will realize lower operating costs because we’re going to take less time to activate, test and troubleshoot," he said. Connectors in the PON Add Flexibility Home Town expects to gain operational efficiency due to use of cross-connects rather than all-splices for acti- vation and rearrangements in the PON. Feeder and distribution cables are spliced behind distribution pan- els and, once spliced, are never touched again. Service turn-up and other rearrangements are conducted by placing jumpers on the front of cross-connect panels rather than pulling fibers out, breaking splices, resplic- ing, and pushing fibers back into place—an operation that risks damage to adjacent fibers, too. Given that fibers are inherently fragile, use of cross-connects in both LCPs and NAPs increases service life of fibers and minimizes risk of disruptions. The choice of connector style was an important con- sideration, too. For the harsh environment of the out- side plant, Home Town chose ADC’s LX.5 small form factor connector. From a fiber management perspec- tive, use of LX.5 supported Home Town’s two-fiber system because two LX.5 connectors are housed in the same space normally occupied by a single SC type connector. In addition, the integral shutter of the LX.5 connec- tor, which automatically closes when the connector is removed, protects ferrules from dirt and dust. This simple feature ensures high fiber performance in an environment that is subject to contaminants. Combined with thorough bend radius protection within each cabinet, the quality and consistency of pre-terminated distribution panels ensure low signal attenuation when introducing connectors in the PON. Conclusion From a capital and operating perspective, the overall network design works. Use of cross-connects rather than splices in the PON allows Home Town Cable Plus to maximize port usage on expensive PON cards while streamlining activation and troubleshooting. As an early adopter of the PON architecture for FTTP, Home Town did not have the luxury to choose from a suite of existing products. Instead, Home Town relied on experience, flexibility and manufacturing prowess of ADC to help build the PON. . case study Delivering Services over FTTP the Home Town Way Situation Home Town Cable Plus is an integrated. require long term cost containment. In addi- tion, as a pioneer in delivering services over a fiber-to-the-premise network, it was also clear that Home Town’s