Effects of propagation between the indoor and outdoor environment

Recent years have seen the introduction of wireless local area networks linking computers in the local office environment. These WLAN services are unregulated and, depending upon the extent of attenuation of the transmitted signal, may become a source of interference for other services outside the building. One particular service which may be affected is the mobile satellite service, using feeder uplinks in the 5.150-5.250 GHz band. For this application in particular, the elevation distribution of signals emitted from buildings can have a dramatic effect on interference statistics. In addition, the introduction of high altitude platform service type applications has given a requirement for information on the typical attenuations through buildings that might be seen from the HAP to a user inside a building at other frequencies. With these and future systems in mind, it was decided to measure these effects over a rather broad bandwidth, in order to provide a resource for future planning. There is also a generic requirement for information on the mechanisms for propagation of microwave signals from indoors to the outdoors. We describe a project which was performed to provide such information, in terms of the attenuation through parts of buildings, the distribution of such transmitted signals, and how this may vary with building type.