The use of the Spherical Diffraction model for indoor-indoor propagation introduces different additional terms regard to the relative location of the transmitter and receiver.
Same-building condition
The Same-Building condition is determined in the same way as for the Modified Hata model (see section A17.3).
Transmitter and Receiver in different buildings
When transmitter and receiver are located in different buildings, the calculation mode is similar to the indoor-outdoor propagation mode but with doubled additional values for both median path loss and variation path loss.
Median path loss
The median path loss is increased by the attenuation due to external walls Lew.
(Eq. 216)
Variation in path loss
(Eq. 217)
Transmitter and Receiver in same building
The calculation is the same as for the Modified Hata Model (see section A17.3).