Recent Standardization Activities in ITU-R SG 3

2.1 Stations on the Earth’s surface

(1) Recommendation P.452: Prediction procedure for the evaluation of interference between stations on the surface of the Earth at frequencies above about 0.1 GHz

This Recommendation aims to calculate the interference between ground stations at frequencies of about 0.1 to 50 GHz. When using the clutter correction of this Recommendation as an interference evaluation, information on the distance between the radio station and nearby obstacles and the height of those obstacles is essential. If there is no information about nearby obstacles, the additional loss should be calculated using the method in Recommendation P.2108. In this Recommendation, the basic propagation-loss calculation of free space was revised at the June 2021 meeting so that the actual distance can be used instead of the great circle distance^*1 used thus far.

(2) Recommendation P.2001: A general purpose wide-range terrestrial propagation model in the frequency range 30 MHz to 50 GHz

This Recommendation provides a time-percentage calculation method for the fundamental propagation loss in the range of 30 MHz to 50 GHz. This calculation method is suitable when using Monte Carlo simulations because it can provide a full-time percentage range from 0 to 100%. This Recommendation was updated at the June 2021 meeting to revise the calculation of the total propagation loss in free space so that the actual distance can be used instead of the great circle distance.

(3) Recommendation P.1812: A path-specific propagation prediction method for point-to-area terrestrial services in the frequency range 30 MHz to 6000 MHz

This Recommendation is suitable for predicting wireless-communication systems with a frequency range of 30 MHz to 6 GHz, a distance of 0.25 km to about 3000 km, and a ground clearance of about 3 km. Power fluctuations can predict time percentages in the range of 1 to 50% and location probability in the range of 1 to 99%. This method makes detailed estimation possible on the basis of the terrain profile in which the propagation path contains clutter. This Recommendation was revised at the June 2021 meeting to extend the upper-frequency limit from 3 to 6 GHz and address the double count of clutter losses.

(4) Recommendation P.1546: Method for point-to-area predictions for terrestrial services in the frequency range 30 MHz to 4000 MHz

This Recommendation is a terrestrial-service-prediction method in the frequency range of 30 MHz to 4 GHz, intended for use on land, sea, and mixed land-sea routes up to 1000 km in length, with an effective transmit antenna height of up to 3000 m. This method builds an estimation formula on the basis of interpolation/extrapolation from the field-strength curve derived from actual measurements such as distance, antenna height, frequency, and time percentage. This method has clutter correction for the receiving terminal but cannot be combined with Recommendation P.2108.

(5) Recommendation P.1411: Propagation data and prediction methods for the planning of short-range outdoor radiocommunication systems and radio local area networks in the frequency range 300 MHz to 100 GHz

This Recommendation provides a method of predicting outdoor propagation losses on routes less than 1 km. The environments covered in this Recommendation are very high-rise/high-rise/low-rise cities as well as suburban, residential, and rural. While many prediction methods are based on specific frequencies within the target range, site-general prediction methods can be used to calculate a basic transmission loss characteristics by arbitrarily specifying the frequency, environment, and distance. It is inappropriate to add clutter loss since it inherently involves the effects of clutter. However, building-entry losses needs to be considered separately, and Recommendation P.2109 can be used.

2.2 Airborne stations and stations on the Earth’s surface

(1) Recommendation P.528: A propagation prediction method for aeronautical mobile and radionavigation services using the VHF, UHF and SHF bands

This Recommendation describes how to predict basic transmission losses in the 100 MHz to 30 GHz frequency range for air-to-air, ground-to-air, and air-to-ground propagation paths. The parameters required for the calculation are the distance between the antennas, height of the antenna from the average altitude above sea level, frequency, polarization, and time percentage. This Recommendation does not include the effects of hydrometeor^*2, scintillation^*3, and diffraction due to irregular topography. However, it can model propagation paths beyond the horizon that may be useful for interference analysis.

2.3 Stations in space and stations on the Earth’s surface

(1) Recommendation P.619: Propagation data required for the evaluation of interference between stations in space and those on the surface of the Earth

This Recommendation provides a method for calculating propagation effects, such as tropospheric refraction and beam diffusion loss, and a combination of calculations for single-entry or multi-entry interference analysis and is valid up to 100 GHz. If the terrain radio station explicitly has information on the location and dimensions of the terrain or scatter obstacles on the local path, it describes how to calculate the associated loss. This Recommendation also refers to Recommendation P.2108 on clutter loss. When using the entry loss of a building, it is necessary to calculate an additional loss using Recommendation P.2109 in accordance with the environment of the ground terminal. At the June 2021 meeting, explanations were added to help more accurate understanding of this Recommendation.

2.4 Stations within the same building

(1) Recommendation P.1238: Propagation data and prediction methods for the planning of indoor radiocommunication systems and radio local area networks in the frequency range 300 MHz to 450 GHz

This Recommendation covers the frequency range from 300 MHz to 450 GHz and provides various estimation methods for propagation paths contained in a single building. Therefore, it helps in the study of interference scenarios in which terminals are in the same building. At the June 2021 meeting, a new basic propagation-loss prediction model was established that covers the frequency range of 100 GHz or less for office, factory, and corridor environments, and the coefficients required for propagation-loss prediction at 310 and 410 GHz were added.

2.5 Propagation model related to all scenarios

(1) Recommendation P.2108: Prediction of clutter loss

This Recommendation calculates the additional loss of propagation due to clutter, such as buildings around the radio station. The height-gain model that corrects the loss for height described in Section 3.1 of this Recommendation can derive the frequency range from 30 MHz to 3 GHz of the additional loss caused by the clutter around the radio station. Diffraction is assumed to be the primary phenomenon in forest and urban environments, and reflection and scattering are considered to be the main phenomena in other environments such as water or sea area, countryside, suburban, and dense urban. When deriving the additional loss with this model, it is necessary to define a typical clutter height. At the June 2021 meeting, the applicable frequencies were expanded on the basis of the measured data to accommodate a broader range of frequencies. The additional loss in cities and suburban environments, which is essential from the viewpoint of interference evaluation, corresponds to the tilt angle of the propagation path. However, the frequency range from 10 to 100 GHz is the estimation range of the current Recommendation. For this reason, studies are underway to extend this estimation method to 10 GHz or less for the next meeting.

(2) Recommendation P.2109: Prediction of building entry loss

This Recommendation derives the additional loss when one radio station is outdoors and the other is inside a building. Coefficients are given to calculate the further loss for two types: typical buildings and thermal efficiency. Since the building-entry loss calculated in this Recommendation was examined independently of other propagation phenomena, the estimation when clutter exists around the radio station is possible by adding the building-entry loss derived in the Recommendation in units of decibels to the additional loss derived in Recommendation P.2108. However, when finding a specific probability for the loss, a mathematical convolution operation is required to find the combined probability distribution.