A new path loss modeling approach for in-building wireless networks

Stochastic models for path loss are most often of the form PL = A + B log(d), where A and B are empirical constants derived from data via least-squares fitting, and d is the path distance. For in-building environments, however, many investigators have noted the added effects of transmission through interior walls and floors. Here, we represent this effect by a third term, which is exponentially related to log(d), and we model its impact on path loss. The database we use is obtained using a well-validated ray-tracing tool, which we apply to single floors of four very distinct office buildings. The context is an ad hoc wireless network, wherein both the transmit and receive locations can be anywhere on the floor. The resulting model consists of the median path loss, involving three fitting constants A, B and C; and a log-normal variation about the median, with its standard deviation being a function of distance. The structure and details of the model are shown to be remarkably similar across the four distinct buildings studied.