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

Building Automation, Wireless Technology and the Internetoff allows subscriber units to be simultaneously connected to multiplesectors. This results in an increase in the total average transmit powerper subscriber, which wastes valuable resources.Excessive hand-off activity can also result in dropped calls due tohand-off failures in areas where there is no dominant server. Smart antennasmake it possible to synthesize radiation patterns that reducehand-off problems and maintain coverage.Varying interference levels across the network mean that coverage,quality and capacity change based on geography and time of day. Duringnetwork installation and network maintenance, a significant amountof time and effort is used to fine-tune interference levels. Operatorsadjust transmit powers, change antenna patterns and tweak networkparameters to eliminate interference in problem areas. Smart antennasprovide exceptional flexibility in tuning the RF footprint of each sector.Transmit power can be turned up in certain directions to enhance inbuildingcoverage. In other directions, transmit power can be reduced tominimize interference, control handoffs and reduce coverage overshoot.The flexibility of smart antennas allows service providers to customizeRF coverage footprints to precisely manage interference, hand-off levelsand traffic load balancing. Sensing the radio environment and providinga flexible way of responding to changes allows smart antennas to playa leading role in building communications management.ISDNThe Integrated Services Digital Network (ISDN) is based onswitched digital technology. It can be used to upgrade analog telephonesystems to an all-digital end-to-end network. ISDN can be used forvoice, data, video, fax, and image transmission. ISDN fills a gap betweenslower switched analog (modem) connections and dedicated digital(leased-line) connections. ISDN is both switched and digital. A switchedconnection lets anyone on a network make an on-demand connectionfrom one site to another.ISDN is all digital, so with computer-generated information alreadyin digital form, you do not have to convert computer data fromdigital to analog form and convert it back to digital on the other end.ISDN has a low bit-error rate compared with modem transmissions andyou also have the advantage of virtual connections. With a virtual con-©2001 by The Fairmont Press, Inc. All rights reserved.