Through the Air

June 1, 2000
Air-blown fiber-optic cabling is a flexible and cost-effective alternative.
The convergence of computer, telephony, audio, video, and Internet applications have made high-speed data transmission imperative for today’s local area networks (LANs). Communication systems designers and integrators need innovative strategies to cope with constantly changing landscapes within office buildings, corporate campuses, and other commercial facilities where continuous moves, adds, and changes are a fact of life. In these dynamic environments, air-blown fiber-optic (ABF) cabling technology can provide a cost-effective solution. ABF offers all of the benefits of conventional fiber-optic transmission — high speed, high bandwidth, and superior performance — but without the high infrastructure and reconfiguration costs.How ABF Works
The heart of the ABF system is a highway of tube cable installed in place of conventional inner duct to define the network topology. Once the infrastructure is in place, lightweight bundles of single-mode or multi-mode fiber are blown, at speeds up to 150 feet per minute, through a predefined route, using specially designed equipment. Installation is fast and easy, typically requiring only two trained technicians. Cable runs may exceed 6,000 feet and the fiber path may traverse outdoor, riser, and plenum tubes in a single run. Since the fibers are not pulled, installation damage ceases to be an issue. Moreover, point-to-point connectivity eliminates splices — the most common site of network failure. In most ABF installations, tube cable is installed with more cells than are currently required to ensure room for expansion. Unused cells are capped until needed. Network expansion or reconfiguration is accomplished by extending tube cables from the nearest tube distribution unit. Fiber bundles can be upgraded or replaced by blowing cable through unused cells, or by blowing out old fiber (which can be reused) and blowing in new — all without disrupting the existing network. A World of Applications
Because of its inherent flexibility, ABF cabling systems are ideally suited to LANs deployed in healthcare complexes, universities, manufacturing sites, resort hotels, corporate office buildings, and campuses. The renowned Getty Center in Los Angeles is a prime example. With construction costs of about $1 billion, the Getty Center is as enormous in scope as it is stunning in setting and architecture. The Getty Center is one of the nation’s largest fiber-to-the-desk installations, with more than 3 million feet of air-blown optical fiber. Typical of corporate environments, the Getty Center network had to be designed for computers, printers, and other devices, as well as Internet access and videoconferencing. At the sprawling campus, the state-of-the-art ABF cabling system paid for itself almost immediately. Huge savings stemmed from the selection of ABF technology and adoption of a centralized network architecture (CNA) that eliminates costly communications closets. The CNA design model takes advantage of the longer transmission distances possible over optical fiber to eliminate the floor-by-floor electronics required in telecommunications closets served by copper wire installations. At the Getty Center, most or all network electronic equipment is housed in a single computer room, making TC closets unnecessary. The fiber-optic cabling systems are fully compliant with industry standards TIA/EIA-568A for telecommunications cabling and ICEA-S-83-596 for fiber-optic premises cabling. For the Getty Center, these choices delivered a cost-savings bonanza. Total cost savings in floor space saved and related construction costs avoided totaled more than $5 million — more than enough to pay for the entire telecommunications cabling system. Additional system maintenance and administration savings were gained through centralized network electronics and a sophisticated cable management system.Jim Allen is product marketing manager at Research Triangle Park, NC-based Sumitomo Electric Lightwave Corp., a leading supplier of conventional fiber-optic cabling and FutureFLEX® Air-Blown Fiber-Optic Cabling systems.

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