 installed inside ments show that long-term fluctuations can be observed the building, e.g. Digital Enhanced Cordless Tele- between signal levels received in different parts of communications (DECT), and a building. While on lower floors these fluctuations follow 2. indoor coverage from an externally installed BS a log-normal distribution, significant differences have (micro- or small macrocells deployment), where, in been observed at higher floors between LoS and NLoS most cases, propagation takes place over NLoS areas. Therefore, the relationship between the floor height conditions. and extra gain with respect to the ground floor level is not linear, depending on factors such as the radiation pattern A great deal of the radio coverage inside buildings is still of the BS antenna and the local urban clutter effect. being provided with the use of BSs located outdoors. The Additional results on indoor coverage by outdoor BSs building penetration loss is defined as the difference be- at 1.8 GHz can be found in [KüMe02], empirical factors tween the average signal strength in the local area around for building penetration and height gain from extensive a building and the average signal strength on a given measurement campaigns for the 1.8 GHz frequency building floor. For radio planning purposes, the building or band being provided. room loss factor can be used as an addition to the predicted signal loss for the surrounding local area. At higher floors, 4.7.5.4 Long-term fading the received signal strength will be higher than at the ground floor. This is important for radio planning, because In a complex propagation environment, as usually found in it may cause higher interference levels at higher floors. mobile communication systems, the received signal results Empirical penetration loss models for indoor coverage from all possible effects associated with the interactions planning and their parameters for the 1.8 GHz frequency between the propagating wave and the objects within the band, experimentally supported on a