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Recommendation ITU-R P.1411-10 provides guidance on outdoor short-range propagation over the path lengths below about 1 km and over the frequency range 300 MHz to 100 GHz. For typical scenarios in urban and suburban areas, three closed-form algorithms for site-general models are defined in this Recommendation and implemented in SEAMCAT:

• §4.1.1: Site-general model for propagation within street canyons where both the transmitting and receiving stations are located below-rooftop, regardless of their antenna heights
• §4.2.1: Site-general model for propagation where one of the stations is located above-rooftop and the other station is located below-rooftop, regardless of their antenna heights
• §4.3.1: Site-general model for propagation between low-height terminals where both terminal antenna heights are near street level well below roof-top height, but otherwise unspecified.

All of the path loss models of this recommendation require measured empirical constants to complete the calculations. Many of the prediction methods are based on measurements at specific frequencies within the range of interest. It must be emphasised that the measurements and modelling in this Recommendation intrinsically include the effect of clutter over the full length of the path, so it would be inappropriate to add a calculation of clutter separately.

Description of the model ITU-R P.1411-10 §4.1.1

This site-general model is applicable to situations where both the transmitting and receiving stations are located below-rooftop, regardless of their antenna heights. The median basic transmission loss is given by: site-general model is provided by the following equation:
PLd

with an additive zero mean Gaussian random variable N(0,σ) with

where:
d: 3D direct distance between the transmitting and receiving stations (m)
f: operating frequency (GHz)
α: coefficient associated with the increase of the basic transmission loss with distance
β: coefficient associated with the offset value of the basic transmission loss
γ: coefficient associated with the increase of the basic transmission loss with frequency.

For NLoS urban high-rise and urban low-rise/suburban Monte Carlo simulations, the excess basic transmission loss with respect to free-space basic transmission loss, LFS, will not exceed 10log10(100.1A+1) (dB), where A is a random variable with a normal distribution N(μ,σ), μ=Lbd,f-LFS, LFS=20log10(4×109πdf/c), and c is the speed of light in metres per second.

The recommended values for LoS and NLoS situations to be used for below-rooftop propagation in urban and suburban environments are provided in Table 1.
TABLE 4

Table 1: Basic transmission loss coefficients for ITU-R P.1411-10 §4.1.1

Description of the model ITU-R P.1411-10 §4.2.

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See description of the model ITU-R P.1411-9 §4.2.1

Description of the model ITU-R P.1411-9 §4.3.

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See description of the model ITU-R P.1411-9 §4.3.1

 SEAMCAT Specific Implementation

The site-general propagation models from §4.1.1 and §4.2.1 are valid only for a given range of Tx-Rx 3D distances ,  If the Tx-Rx 3D distances in the simulation scenario are outside this range, SEAMCAT will inform the user about that in a consistency check before the simulation starts. The simulations can still be run and the values of the basic transmission loss will be computed using the formulas from Recommendation ITU-R P.1411 even for distances that are outside the range of validity.

A special care needs to be taken for distances  as they can result in non-physical values of the basic transmission loss that can be smaller than free-space loss, or even be negative. In that particular case, the median values of the basic transmission loss are capped from below by the free space loss as follows:

Compute PL=PL_1411
if d<d_min:

Compute PL_FreeSpace
PL=max⁡〖(PL,〗  PL_FreeSpace)

Input parameters

The input parameters for the three site-general propagation models from ITU-R P.1411-10 are shown in SEAMCAT GUI in Figure 2 and defined in Table 4.

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