# One Slope Model (Modified Free Space Model)

The one slope or modified-free-space model analyzes the building structure only regarding LOS / NLOS situation in the vertical plane between transmitter and each receiver point.

Different path loss exponents and offsets are considered for LOS / NLOS. The attenuations
of the walls are not considered during the computation. Therefore, this model computes
the path loss similar to the free space loss with adaptable exponent and offset for
line-of sight (LOS) and non-line-of-sight (NLOS) areas. Herewith it assumes that the
path loss depends only on the distance d with a specific attenuation coefficient n and
the offset l_{c}.

According to this simple approach the prediction results are fairly inaccurate and only suited for a rough estimation.

Click Computation tab.

and click theTo calibrate this model with measurement data the exponents and the offsets to be used for this model can be specified by using the Settings button. For LOS situations the values for n are in the range between 2.0 and 2.8, in NLOS scenarios values up to 4.0 are possible. The offsets are applied to field strength / power / neg. path loss results (larger offsets mean more optimistic results).