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To: Frank A. Coluccio who wrote (2014)	9/7/1998 5:48:00 PM
From: Bernard Levy	Read Replies (1) \| Respond to of 12823

Hello Frank and others: The latest Data Communications Magazine has a fairly good survey article on the difficulties faced by CLECs when they try to rent space in COs and roll out DSL services: data.com Have a good Labor Day, Bernard Levy

To: Frank A. Coluccio who wrote (2014)	9/8/1998 4:10:00 PM
From: Hiram Walker	Respond to of 12823

Frank, some great articles in CED this month,all HLIT and TCOMA. You can spatially expand the network optically,and you can reuse narrowcast QAM channels. HFC has a limitless potential if the architecture is implemented correctly. cedmagazine.com The bandwidth of today's advanced networks is currently installed at 750 MHz, but recent traffic analysis studies have shown that strong arguments can be made in favor of installing 870 MHz systems. Spatial multiplexing refers to using "home run" fibers to nodes serving ever-shrinking numbers of homes passed. This allows parts of the forward spectrum to be "reused," enabling larger amounts of bandwidth to be allocated to a single user. Spectrally efficient methods of transmitting digital information such as 64 QAM and 256 QAM allow higher amounts of information to occupy each hertz of bandwidth. The use of the optical wavelength as an additional dimension to expand the performance and capacity of these advanced multi-service networks is just emerging. Such methods, referred to as optical networking, open up a wide array of possibilities, such as multi-channel transport (DWDM), passive and active optical routing, and optical cross connecting. Figure 2: Pictured is 1550 nm "blast and split," with 1310 nm WDM overlay. WDM overlay technology performs the important task of separating the broadcast and narrowcast portions of the network so they may be optimized independently. Advanced optical networking tools such as Sonet high-performance video transport, mixed format DWDM and WDM overlay technology allow operators to take full advantage of these rapidly deploying advanced services, while maintaining excellent control over equipment and operating costs. These three optical networking tools are shown schematically in Figure 1. In Sonet high-performance video transport, analog video is digitized in a 10-bit uncompressed format, which is mapped directly into a Sonet OC-3c (concatenated) frame. Sixteen of these streams are electrically multiplexed into an OC-48 rate, and eight of these optical signals can be multiplexed via 1550 DWDM into a nearly 20 Gbps data stream. Sonet high-performance video transport has advantages over DS-3-based traditional multiplexed Sonet. The OC-3c mapping allows for much higher performance and lower cost than that provided by using video codecs. Sonet high-performance video transport is also preferable to available proprietary video transport systems because full Sonet capability is needed for interfacing to other Sonet systems in the network. In addition, Sonet high-performance video transport systems have the advantages of traditional Sonet voice and data networks; namely, multiple interfaces such as DS-3, ASI, Video IF, QAM and Ethernet, add/drop capability, and cross-connect capability via time slot interchange. After amplification, the narrowcast portion of the spectrum (typically eight to 16 QAM channels plus two to three analog channels) is added via a 1550/1310 nm WDM multiplexer or a 1550/1550 nm DWDM multiplexer. Both the broadcast and narrowcast traffic are transmitted to the node, where they are received by the same photodetector. The addition of the narrowcast wavelength degrades the broadcast signal carrier-to noise ratio by less than 1 dB. Networks utilizing WDM overlay technology have an added benefit in that they allow costs to be deferred. This means that a portion of the cost of the network is deferred until the service demands on the network require the additional capacity. For the WDM overlay system, the 1310 nm overlay transmitters can be added only when the service or demographic demands require it. Each of these technologies has its own complementary place in today's HFC network configured for advanced services. Sonet high-performance video transport is used in the primary rings of the network and in regional interconnects; mixed format DWDM for the secondary interconnects; and WDM overlay technology in fiber distribution. Providing products based on these technologies, with the ability to work together in a seamless fashion, is essential for successful delivery of these advanced services. Tim