The Extended Hata (eHata) Urban Propagation Model

This code repository contains a C++ reference version of the eHata urban propagation model. The model was developed by NTIA and used in NTIA Technical Report TR-15-517, "3.5 GHz Exclusion Zone Analyses and Methodology".

Inputs

Variable	Type	Units	Description
pfl	double[]		A terrain profile line, from the mobile to the base station. EHata uses the ITM-method of formatting terrain information, in that: pfl[0] : Number of elevation points - 1 pfl[1] : Resolution, in meters pfl[i] : Elevation above sea level, in meters
f__mhz	double	MHz	Frequency
h_m__meter	double	meter	The height of the mobile
h_b__meter	double	meter	The height of the base station
enviro_code	int		The NLCD environment code
reliability	double		The quantile percent not exceeded of the signal. Limits: 0 < reliability < 1

Outputs

Variable	Type	Units	Description
plb	double	dB	Path loss
intervalues	struct		[Optional] A data structure containing intermediate values from the eHata calculations

Intermediate Values

When calling the ExtendedHata_DBG() function, the function will populate intervalues with intermediate values from the eHata calculations. Those values are as follows:

Variable	Type	Units	Description
d_bp__km	double	km	The breakpoint distance
att_1km	double	dB	Attenuation at 1 km
att_100km	double	dB	Attenuation at 100 km
h_b_eff__meter	double	meter	Effective height of the base station
h_m_eff__meter	double	meter	Effective height of the mobile
pfl10__meter	double	meter	10% terrain quantile
pfl50__meter	double	meter	50% terrain quantile
pfl90__meter	double	meter	90% terrain quantile
deltah__meter	double	meter	Terrain irregularity parameter
d__km	double	km	Path distance
d_hzn__meter	double[2]	meter	Horizon distances
h_avg__meter	double[2]	meter	Average heights
theta_m__mrad	double	milliradian	Slope of the terrain at the at the mobile
beta	double		Percentage of path that is sea
iend_ov_sea	int		Flag specifying which end is over the sea
hedge_tilda	double	meter	Horizon correction factor
single_horizon	bool		Flag for specifying number of horizons
slope_max	double	milliradian	Intermediate value when calculating the mobile terrain slope
slope_min	double	milliradian	Intermediate value when calculating the mobile terrain slope

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_m__meter.
• Variables are named to match their corresponding mathematical variables in the underlying technical references, i.e., gamma_1.
• Most values are calculated and stored in intervalues that is passed between function calls. In general, only the correction factor functions return their result as a value.

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 eHata consists of a simple pass-through wrapper around the native DLL. It is compiled to target .NET Framework 4.7.2. Distribution and updates are provided through the published NuGet package.

References

• Drocella, E., Richards, J., Sole, R., Najmy, F., Lundy, A., McKenna, P. "3.5 GHz Exclusion Zone Analyses and Methodology", NTIA Report 15-517, June 2015.
• Hata, M. "Empirical Formula for Propagation Loss in Land Mobile Radio Services", IEEE Transactions on Vehicular Technology, Vol VT-29, Num 3. Aug 1980. pp 317-325. DOI: 10.1109/T-VT.1980.23859
• Okumura, Y., Ohmori, E., Kawano, T., Fukuda, K. "Field Strength and Its Variability in VHF and UHF Land-Mobile Radio Service", Review of the Electrical Communication Laboratory, Vol. 16, Num 9-10. Sept-Oct 1968. pp. 825-873.

Contact

For questions, contact Paul McKenna, [email protected]