This paper presents a discrete-time numerical algorithm
for computing field distributions in indoor environments by
diffuse scattering from the walls. Calculations are performed for a
rectangular room with semireflective walls. The walls are divided
into 0.5􀀀0.5 m segments, resulting in 2272 wall segments in total
and approximately 2 min running time on average computer. Frequency
independent power levels at the walls around the circumference
of the room and at four receiver locations in the middle of
the room are observed. It is demonstrated that after a finite period
of initial excitation the field intensity in all locations eventually follows
an exponential decay with the same slope and approximately
the same level for given delay. These observations are shown to be
in good agreement with theory and previous measurements—the
slopes of the decay curves for measurement, simulation and theory
are found to be 18, 19.4, and 20.2 dB per 100 ns, respectively. The
remaining differences are further discussed and an additional case
of a spherical room is used to demonstrate the influence of the room
shape on the results. It is concluded that the presented method is
valid as a simple tool for use in indoor radio coverage predictions.
Index Terms—Diffuse fields, indoor radio communication, numerical
methods, propagation.