![]() Distributed antenna systems can be used in buildings, including tunnels and large structures such as sports facilities, to address coverage challenges. If allowed, tower-top amplifiers can be added to help offset the imbalance. ![]() If the design goal of the two-way radio system is portable-at-the-hip in-building coverage, and there is an imbalance of weaker uplink to stronger downlink range, then certain measures can be taken to maintain the design goals but also achieve energy savings. The mobiles, portables and fixed subscriber units have a very important role in the balancing of the link budgets and in the potential lowering of the base station power levels to save electricity. This is when the communications systems are needed most. A design engineer or maintenance technician should incorporate this feature into any critical communications system, in order to insure that the system remains operational in the event of a long-lasting primary power outage. Many of the newer radio transmitters can be set to operate with a lower transmitter power level when the unit senses that it is running on backup power due to a primary power outage. The efficiency of the base station or repeater transmitter does come into play, especially when backup power or alternative power sources are required for the system. ![]() The transmitter can be analog or digital, and is configured to repeat the signals from its receiver or receivers on separate frequencies, or is controlled by local or remote signaling. The base station consists of one or more transmitters and receivers, electrical power management, control electronics and the antenna transmission system. There are the same limitations of radiated output power from the FCC. While this practice may be appropriate for one-way paging, and television and radio over-the-air broadcast systems to maximize the coverage, there always are FCC-mandated limitations placed upon radiated output power, based on antenna height above average terrain, proximity to co-channel users and the reduction of potential interference.Ĭonsequently, designing wireless systems for two-way communications requires link-budget balancing, in order to ensure that the transmitted downlink path to the mobile or portable device’s receiver will match the transmitted uplink path from the mobile or portable device to the base station receiver. Most wireless systems attempt to maximize the transmitted power from the base station to the subscriber device in the downlink radio path. Every 1-watt decrease in transmitted power reduces electrical power by 2 watts. The efficiency ratio of the transmitted or radiated power to electrical power in most base stations is 50% or less. By using link-budget engineering, and by balancing the uplink and downlink radio paths, the base station transmit power in the downlink radio path sometimes can be lowered to match the uplink transmitters from the mobile and portable devices.Īs discussed in previous articles in this series on resource management, base stations and repeaters consume a large portion of the electrical power in a wireless communications system. ![]() Land-mobile radio systems that utilize base stations and repeaters can be engineered to save electrical power. ![]()
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