Personal wireless devices communicate using RF signals. The quality and reliability of signal coverage and data capacity in many metropolitan and business places are at risk when these devices operate inside human made structures like buildings and other complexes. Obtaining reliable signals inside these places becomes a challenge when the user is located in places like underground parking lots, shopping malls, or in high rise buildings. Depending on the materials used in these structures and the outside terrain, in many cases it becomes a challenge to provide reliable signal levels. Depending on signals coverage that utilizes penetrated signals from outside base stations to propagate inside these structures, in many cases provides unreliable communications and in most cases rely on the over use of recourses such as increasing the signal level or the number of transmitting sites which creates interference to other outdoor coverage places. This problem brought the necessity of creating different approaches to RF signal coverage of in-buildings. This concept now is known as the “In-building” or “indoor” wireless communication and distribution system. In-building wireless is a means of distributing the RF signals into areas where you need them most, in many cases without relying on the signal coming from outside base stations. We introduce the basic concept of RF signal coverage inside buildings, the channel models used to analyze and design an in-building wireless system. Then we cover various interesting solutions for deploying in-building coverage in 3G, WiMax, and WLAN networks that make use of distributed radio base stations (DRS), passive and active distributed antenna systems (DAS), repeaters, extenders, and dedicated macro and pico cells. We conclude with an extensive overview of available commercial solutions for in building 3G coverage, and show several examples illustrating providing RF coverage inside a multi floor building u--sing DAS and repeaters.
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