Recommendation ITU-R P.2108-1 - U.S. Reference Implementation

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This code repository contains the U.S. Reference Software Implementation of Recommendation ITU-R P.2108. This Recommendation contains three methods for the prediction of clutter loss: Height Gain Terminal Correction Model, Terrestrial Statistical Model, Aeronautical Statistical Model. The software implements Section 3 of Annex 1 of the Recommendation.

Height Gain Terminal Correction Model

The height gain terminal correction model is described in Section 3.1. This end-point clutter method gives the median loss due to different terminal surroundings for terrestrial paths for frequencies between 0.3 to 3 GHz. This model can be applied to both transmitting and receiving ends of the path.

Inputs (Height Gain Terminal Correction Model)

Variable	Type	Units	Limits	Description
f__ghz	double	GHz	0.3 <= f__ghz <= 3	Frequency
h__meter	double	meter	0 <= h__meter	Antenna height
w_s__meter	double	meter	0 < w_s__meter	Street width
R__meter	double	meter	0 < R__meter	Representative clutter height
clutter_type	int			Clutter type 1 = Water/sea 2 = Open/rural 3 = Suburban 4 = Urban 5 = Trees/forest 6 = Dense urban

Where site-specific values for the representative clutter height are not available, the following default values are recommended.

Clutter Type	R__meter
Water/sea	10
Open/rural	10
Suburban	10
Urban	15
Trees/forest	15
Dense urban	20

Outputs (Height Gain Terminal Correction Model)

Variable	Type	Units	Description
A_h__db	double	dB	Additional loss (clutter loss)

Return Codes (Height Gain Terminal Correction Model)

Possible return codes, including the corresponding defined constant name as defined in Errors.h:

Value	Const Name	Description
0	SUCCESS	Successful execution
3100	ERROR31__FREQUENCY	Frequency must be between 0.3 and 3 GHz, inclusive
3101	ERROR31__ANTENNA_HEIGHT	Antenna height must be >= 0 meters
3102	ERROR31__STREET_WIDTH	Street width must be > 0 meters
3103	ERROR31__CLUTTER_HEIGHT	Representative clutter height must be > 0 meters
3104	ERROR31__CLUTTER_TYPE	Invalid value for clutter type

Terrestrial Statistical Model

The statistical clutter loss model for terrestrial paths as described in Section 3.2. This model is valid for urban and suburban clutter environments. For paths between 0.25 and 1 km, this model can only be applied to one end of the path. For paths greater than 1 km, the model can be applied to both terminals, if desired.

Inputs (Terrestrial Statistical Model)

Variable	Type	Units	Limits	Description
f__ghz	double	GHz	2 <= f__ghz <= 67	Frequency
d__km	double	km	0.25 <= d__km	Path distance
p	double	%	0 < p < 100	Percentage of locations clutter loss not exceeded

Outputs (Terrestrial Statistical Model)

Variable	Type	Units	Description
L_ctt__db	double	dB	Clutter loss

Return Codes (Terrestrial Statistical Model)

Possible return codes, including the corresponding defined constant name as defined in Errors.h:

Value	Const Name	Description
0	SUCCESS	Successful execution
3200	ERROR32__FREQUENCY	Frequency must be between 2 and 67 GHz, inclusive
3201	ERROR32__DISTANCE	Path distance must be >= 0.25 km
3202	ERROR32__PERCENTAGE	Percentage must be between 0 and 100

Aeronautical Statistical Model

The Earth-space and aeronautical statistical clutter loss model as described in Section 3.3. This model is applicable when one end of the path is within man-made clutter and the other end is a satellite, aeroplane, or other platform above the Earth. This model is valid for urban and suburban clutter environments.

Inputs (Aeronautical Statistical Model)

Variable	Type	Units	Limits	Description
f__ghz	double	GHz	10 <= f__ghz <= 100	Frequency
theta__deg	double	deg	0 <= theta__deg <= 90	Elevation angle
p	double	%	0 < p < 100	Percentage of locations clutter loss not exceeded

Outputs (Aeronautical Statistical Model)

Variable	Type	Units	Description
L_ces__db	double	dB	Clutter loss

Return Codes (Aeronautical Statistical Model)

Possible return codes, including the corresponding defined constant name as defined in Errors.h:

Value	Const Name	Description
0	SUCCESS	Successful execution
3300	ERROR33__FREQUENCY	Frequency must be between 10 and 100 GHz, inclusive
3301	ERROR33__THETA	Elevation angle must be between 0 and 100 GHz, inclusive
3302	ERROR33__PERCENTAGE	Percentage must be between 0 and 100, inclusive

Example Values

The Study Group Clutter Excel Workbook contains an extensive set of validation example values.

Notes on Code Style

• In general, variables follow the naming convention in which a single underscore denotes a subscript (pseudo-LaTeX format), where a double underscore is followed by the units, i.e. h_1__meter.
• Variables are named to match their corresponding mathematical variables in the underlying Recommendation text.
• Wherever possible, equation numbers are provided. It is assumed that a user reviewing this source code would have a copy of the Recommendation's text available as a primary reference.

Configure and Build

C++ Software

The software is designed to be built into a DLL (or corresponding library for non-Windows systems). The source code can be built for any OS that supports the standard C++ libraries. A Visual Studio 2019 project file is provided for Windows users to support the build process and configuration.

C#/.NET Wrapper Software

The .NET support of P.2108 consists of a simple pass-through wrapper around the native DLL. It is compiled to target .NET Framework 4.8.1. Distribution and updates are provided through the published NuGet package.

References

• Recommendation ITU-R P.2108
• Report ITU-R P.2402

Contact

For questions, contact Billy Kozma, wkozma@ntia.gov