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42 | BROADBAND COMMUNITIES | www.broadbandcommunities.com | MAY/JUNE 2016 TECHNOLOGY Wireless Coverage in Elevators Car-mounted distributed antenna systems promise to end the nagging problem of dropped calls in elevators. By John Spindler / Zinwave E levator coverage for mobile services is becoming a mandatory requirement for buildings and is rapidly becoming a requirement in lease agreements between tenants and building owners. In addition, in- elevator coverage is required for public safety wireless applications. Unfortunately, traditional solutions for wireless coverage inside elevators leave much to be desired: Antennas mounted within elevator shafts don't provide consistent coverage throughout tall buildings, and lobby-mounted antennas cause constant handofs for elevator passengers with mobile devices, degrading call performance and leading to call drops. However, a new solution promises to overcome the shortcomings of these legacy solutions. DEMAND FOR WIRELESS COVERAGE IN ELEVATORS With the evolution of mobile telecommunications, user demand for continuous, high-quality wireless voice and data performance throughout buildings has become a major issue for building owners. Increasingly, tenants demand ubiquitous coverage within buildings. Tey want to be able to continue calls or mobile sessions as they enter and ride inside elevator cars, and they have little tolerance for service disruptions due to elevators. Providing seamless coverage inside elevators is one of the biggest challenges in in-building wireless. Wireless signals cannot easily pass through nonporous materials, so elevator cars, which are metal, can block wireless service from the outside, leading to poor connectivity within. In addition, as an elevator travels from the bottom of a building to the top, it can pass through diferent zones of wireless coverage, depending on the placement of remote antennas within the structure; this can lead to poor service or dropped calls. Te challenge of providing wireless service inside elevators is a function of building height, the strength of construction materials required for elevator cars and car mobility. Because of building height, antennas within an elevator shaft may not provide adequate signal strength (especially in taller buildings) to cover the entire shaft, and the metal construction of the cars blocks outside wireless signals. As a car moves up and down an elevator shaft, the signals from external antennas grow and fade as the car nears and then moves away from antennas on each foor. Traditionally, there are two ways to provide wireless coverage inside elevators: • Place distributed antennas in each elevator lobby on every foor • Place a high-power distributed antenna at the top or bottom of each elevator shaft. COVERAGE FROM THE ELEVATOR LOBBY Traditionally, antennas have been located in elevator lobbies as close as possible to the elevator doors so that leakage through the