The Fiber to the Node (FTTN) architecture using Very High Speed Digital Subscriber Line (VDSL) transmission technology has emerged as a critical enabling technology for the Telephone companies. From a business point of view, Telephone Company entry into the full service broadband market requires a cost efficient service delivery, bundled voice, high-speed data and video services, and rapid time to market. VDSL provides all three of these crucial needs, allowing the Telephone Operating Companies to leverage their single largest capital investment: the embedded copper distribution network. From a technical point of view, Telcos require a robust transmission of high speed VDSL over existing copper loops that leverage key network assets and existing flexibility points. Video delivery requires low BER performance to ensure digital video errors are minimized, these errors impact the user's picture quality in the form of macroblocking images. Data can leverage IP retransmission and is not as susceptible to transmission error performance. As with any xDSL Technology, VDSL faces may challenges in the quest to optimize the available bandwidth-distance-product of the existing last mile of copper. This paper will present actual deployment experience with VDSL and will discuss the impact of bridged tap, split pairs, wire gauge, protector imbalance, home wiring conditions, noise ingress and the impairment caused by NEXT and FEXT (Near End and Far End Cross Talk) conditions. In addition, this paper will discuss the impact that sub loop unbundling and frequency sharing initiatives will have on VDSL deployment and proposed spectrum management plans of create a more spectrum-friendly environment.
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