HVAC Control in the New Millennium.pdf - HVAC.Amickracing

Building Automation, Wireless Technology and the Internet100 or more. Some cable companies are using AT&T’s DWDM-basedbackbone to carry data traffic.SilkRoad has another photonics technology called RefractiveSynchronization Communication (RSC). It has demonstrated datatransfer rates of 200 gbps over 200 miles, without any signal amplification,on a single wavelength of light. The fastest fiber in use todayhas a data rate of 40 gbps. SilkRoad has been negotiating with localtelephone companies and larger carriers that could use RSC technologysoon. Expect to see local area network RSC-enabled hubs andswitches used by businesses and homes that have fiber connections.The entire Internet backbone could be using photonics in the nearfuture.Internet BottlenecksOne segment of the Internet could accelerate its data rate, butthe others must struggle to keep up. Now, the bottleneck is at thedesktop. As cable and DSL use grows, the ISPs and backbone providerswill have to speed up their segments to accommodate the newtraffic.The telecom industry is in the middle of a transition from circuitswitching to an advanced public network. Service providers are progressivelybuilding a packet-switched and cell-based infrastructurethat can handle data, video and voice. The transactional network willuse a jumble of gateways to connect legacy circuit switching withcells and packet switching.The new public network will have a packet and cell-based infrastructurethat will be equally adept at handling data, video, andvoice. When this convergence is complete, it will change everything.Instead of buying pipes for bandwidth, you will be able to signup for a new class of VPNs (virtual private networks) that will runover managed backbones. These will be tuned to deliver differenttypes of traffic. Cheaper bandwidth will be offered. The new technologyshould also allow 1-Mbit/s ADSL modems. Bandwidth will increasein the same way that memory has increased in PCs.Data traffic is growing at a remarkable rate. Today, there are about15 million fiber circuits in North America and 120 million copper lines.Creating the new public network means most of the equipment needs to©2001 by The Fairmont Press, Inc. All rights reserved.