A simulation of cellular system growth and its effect on urban in-building parasitic frequency reuse

Indoor parasitic cellular systems reuse the same frequencies as outdoor cellular (macrocellular) systems to provide wireless communications inside a building or campus. This paper provides a simulation strategy to determine future channel availability that is possible between in-building and outdoor cellular systems that share the same radio spectrum. Capacity that is currently available inside an urban office building is first derived from field-strength measurements of all the channels in the macrocellular system made inside the building. We then create a simulation that determines the effect of a growing outdoor cellular system on in-building frequency reuse. Future in-building frequency reuse is predicted over a 6-yr timeline in 3-mo intervals and includes the effect of height above ground inside the building. Results show that indoor reuse is practical as long as interference levels of about -85 dBm can be tolerated from the outdoor macrocellular system.