International Telecommunications Union Radiocommunication Sector Research Articles

Influence of wind speed on rain-based attenuation at Ku-band for earth-satellite links in Nigeria

The peculiarity of the tropical climate shows that when the quality of service (QoS) on Satellite-Earth propagation links is to be determined, the statistics of rain-based attenuation (RbA), storm speed, and their impacts are the important parameters to be considered, especially at frequencies above 10 GHz. This paper assesses the influence of storm speed in estimating RbA at Ku-band, based on 2-year rain rate data obtained using automatic weather station (AWS) and RbA beacon measurements in Nigeria. The rain rates based on the time series were employed to deduce the time series RbA based on the synthetic storm technique (SST) algorithm. The results show a seasonal pattern of rain rate that correlates with the SST-based RbA. The RbA generated closely follows suit with the beacon measurement, especially under low wind speed, and outperforms the international telecommunications union–radiocommunication sector (ITU-R) model based on the lowest metric measures. However, at a higher storm speed, the RbA generated deviated widely from the measured RbA values by about 16%. These results are crucial for figuring out what needs to be done to protect QoS in a tropical area where wind and rain are common.

Millimeter Wave Attenuation Due to Wind and Heavy Rain in a Tropical Region.

Millimeter wave fixed wireless systems in future backhaul and access network applications can be affected by weather conditions. The losses caused by rain attenuation and antenna misalignment due to wind-induced vibrations have greater impacts on the link budget reduction at E-band frequencies and higher. The current International Telecommunications Union Radiocommunication Sector (ITU-R) recommendation has been widely used to estimate rain attenuation, and the recent Asia Pacific Telecommunity (APT) report provides the model to estimate the wind-induced attenuation. This article provides the first experimental study of the combined rain and wind effects in a tropical location using both models at a frequency in the E band (74.625 GHz) and a short distance of 150 m. In addition to using wind speeds for attenuation estimation, the setup also provides direct antenna inclination angle measurements using the accelerometer data. This solves the limitation of relying on the wind speed since the wind-induced loss is dependent on the inclination direction. The results show that the current ITU-R model can be used to estimate the attenuation of a short fixed wireless link under heavy rain, and the addition of wind attenuation via the APT model can estimate the worst-case link budget during high wind speeds.

Empirical Model of Radio Wave Propagation in the Presence of Vegetation inside Greenhouses Using Regularized Regressions.

Spain is Europe’s leading exporter of tomatoes harvested in greenhouses. The production of tomatoes should be kept and increased, supported by precision agriculture to meet food and commercial demand. The wireless sensor network (WSN) has demonstrated to be a tool to provide farmers with useful information on the state of their plantations due to its practical deployment. However, in order to measure its deployment within a crop, it is necessary to know the communication coverage of the nodes that make up the network. The multipath propagation of radio waves between the transceivers of the WSN nodes inside a greenhouse is degraded and attenuated by the intricate complex of stems, branches, leaf twigs, and fruits, all randomly oriented, that block the line of sight, consequently generating a signal power loss as the distance increases. Although the COST235 (European Cooperation in Science and Technology - COST), ITU-R (International Telecommunications Union—Radiocommunication Sector), FITU-R (Fitted ITU-R), and Weisbberger models provide an explanation of the radio wave propagation in the presence of vegetation in the 2.4 GHz ICM band, some significant discrepancies were found when they are applied to field tests with tomato greenhouses. In this paper, a novel method is proposed for determining an empirical model of radio wave attenuation for vegetation in the 2.4 GHz band, which includes the vegetation height as a parameter in addition to the distance between transceivers of WNS nodes. The empirical attenuation model was obtained applying regularized regressions with a multiparametric equation using experimental signal RSSI measurements achieved by our own RSSI measurement system for our field tests in four plantations. The evaluation parameters gave 0.948 for R2, 0.946 for R2 Adj considering fifth grade polynomial (20 parameters), and 0.942 for R2, and 0.940 for R2 Adj when a reduction of parameters was applied using the cross validation (15 parameters). These results verify the rationality and reliability of the empirical model. Finally, the model was validated considering experimental data from other plantations, reaching similar results to our proposed model.

Radio propagation measurements and modeling for standardization of the site general path loss model in International Telecommunications Union recommendations for 5G wireless networks

AbstractThe International Telecommunications Union Radiocommunication Sector (ITU‐R) Study Group 3 identified the need for a number of radio channel models in anticipation of the World Radiocommunications Conference in 2019 when the frequency allocation for 5G will be discussed. In response to the call for propagation path loss models, members of the study group carried out measurements in the frequency bands between 0.8 GHz up to 73 GHz in urban low‐rise and urban high‐rise as well as suburban environments. The data were subsequently merged to generate site general path loss models. The paper presents an overview of the radio channel measurements, the measured environments, the data analysis, and the approach for the derivation of the path loss model adopted in Recommendation ITU‐R P.1411‐10 (2019‐08).

Rain Attenuation at Millimeter Wave and Low-THz Frequencies

Wave attenuation through rain with different rainfall rates at millimeter wave ( f = 77 GHz) and low-terahertz (Low-THz) ( f = 300 GHz) frequencies is studied in this article. Rain has pronounced impacts on electromagnetic wave propagation and one of the well-known effects is attenuation of the transmitted wave. Attenuation at both frequencies and hydrometeor properties [rainfall rate and drop size distribution (DSD)] are measured simultaneously. The measured DSD is fit with gamma and Weibull distributions and is also compared to the frequently used distribution Marshall and Palmer (MP) model; Weibull is shown to be a better fit to the measured DSDs. Theoretical prediction of attenuation as a function of rainfall rate (up to about 20 mm/h) is determined using Mie scattering theory, and the fit gamma and Weibull, and MP distribution models; as well as using the International Telecommunications Union Radiocommunication Sector (ITU-R) recommendation. The calculations are evaluated by comparing them to the experiment. The measured results at 77 GHz best agree with the ITU-R recommendation whereas at 300 GHz, the calculation based on Mie scattering and the Weibull distribution exhibits the best fit to the measured data. The measured data that exceed the theoretical prediction are analyzed and interpreted based on their corresponding observed drop size properties, for the first time.

Path Loss Determination Using Linear and Cubic Regression Inside a Classic Tomato Greenhouse.

The production of tomatoes in greenhouses, in addition to its relevance in nutrition and health, is an activity of the agroindustry with high economic importance in Spain, the first exporter in Europe of this vegetable. The technological updating with precision agriculture, implemented in order to ensure adequate production, leads to a deployment planning of wireless sensors with limited coverage by the attenuation of radio waves in the presence of vegetation. The well-known propagation models FSPL (Free-Space Path Loss), two-ray, COST235, Weissberger, ITU-R (International Telecommunications Union—Radiocommunication Sector), FITU-R (Fitted ITU-R), offer values with an error percentage higher than 30% in the 2.4 GHz band in relation to those measured in field tests. As a substantial improvement, we have developed optimized propagation models, with an error estimate of less than 9% in the worst-case scenario for the later benefit of farmers, consumers and the economic chain in the production of tomatoes.

Rural Macrocell Path Loss Models for Millimeter Wave Wireless Communications

Little is known about millimeter wave (mmWave) path loss in rural areas with tall base station antennas; yet, as shown here, surprisingly long distances (greater than 10 km) can be achieved in clear weather with less than 1 W of power. This paper studies past rural macrocell (RMa) propagation models and the current third generation partnership project (3GPP) RMa path loss models for frequencies from 0.5 to 30 GHz adopted from the International Telecommunications Union-Radiocommunication Sector (ITU-R). We show that 3GPP and ITU-R RMa path loss models were derived for frequencies below 6 GHz, yet are being asserted for use up to 30 GHz. Until this paper, there has not been published data to support mmWave RMa path loss models. In this paper, 73-GHz measurements in rural Virginia are used to develop a new RMa path loss model that is more accurate and easier to apply for varying transmitter antenna heights than the existing 3GPP/ITU-R RMa path loss models, and may be used for frequencies from 0.5 to 100 GHz. The measurement system used here has a measurement range comparable to a wideband (800-MHz radio frequency bandwidth) channel sounder with 21.7-dBW effective isotropic radiated power. Measured data verify a new path loss model that uses a close-in free space reference distance with a novel height-dependent path loss exponent (CIH model). This work shows that the CIH model is accurate and stable, and is frequency-independent beyond the first meter of propagation, and effectively models the path loss dependence on base station height in rural channels.

Ultra HD Blu-ray Format Video Characteristics

The Blu-ray Disc Association recently finished a new format extension called Ultra HD Blu-ray. The new format supports next-generation video technologies and several optional enhancements. This paper provides an in-depth description of the video technologies offered by Ultra HD Blu-ray and an overview of new optional features. The Ultra HD Blu-ray format allows improvement to the video representation by increasing the pixel code value quantization to 10 bits, enabling representation of high dynamic range imagery using SMPTE ST 2084 electrooptical transfer function, enabling representation of wide color gamut imagery using International Telecommunications Union Radiocommunication Sector (ITU-R) BT.2020 color primaries, increasing spatial resolution to 3840 $\times$ 2160, and allowing increased frame rates up to 60p. Carriage of mastering display color volume metadata described by SMPTE ST 2086 and new content metadata parameters called maximum content light level (MaxCLL) and maximum frame average light level (MaxFALL) are also enabled by the new format. Additionally, the Ultra HD Blu-ray format improves compression efficiency by using the new HEVC/H.265 video compression standard.

Tentative 3GPP Timeline for 5G [Mobile Radio

The Third-Generation Partnership Project (3GPP) has endorsed a tentative timeline for the standardization of next-generation cellular technology, also known as fifth generation (5G). 3GPP is committed to submitting a candidate technology to the International Mobile Telecommunications (IMT) 2020 process triggered by International Telecommunications Union Radiocommunication Sector (ITU-R). From the perspective of IMT 2020, the key constraints are given by the following two submission deadlines: the initial technology submission by ITU-R Working Party 5D (WP5D) meeting 32 in June 2019 and the detailed specification submission by ITU-R WP5D meeting 36 in October 2020.

Design Considerations for Cinema Exhibition Using RGB Laser Illumination

Laser light sources used in digital projectors have the potential to increase quality for several image parameters, including high brightness, dynamic range, and color space. This paper discusses advantages of laser illumination for digital projection, as well as considerations for the design of future cinema parameters such as luminance standards, high dynamic range projection, and a wider color space, including the practicality of the color space of The International Telecommunications Union Radiocommunication Sector Recommendation ITU-R BT.2020 (Rec. 2020)1 as a projection gamut. Practical concerns and limits of lasers are examined in the context of near-term implementations, and suggestions for future theater and projector design are discussed.

Quantum Dots and Rec. 2020: Bringing the Color of Tomorrow Closer to Reality Today

The International Telecommunications Union Radiocommunication Sector has recommended a broadcasting standard Recommendation ITU-R BT.2020 (Rec. 2020) for ultrahigh-definition television that is aimed at providing a better visual experience. It recommends a color gamut that exceeds previous broadcasting standards and is only achievable by laser-based display technologies. Quantum dot (QD)-enabled liquid crystal displays (LCDs) provide one alternative with potential to meet Rec. 2020's standard color gamut while taking advantage of existing manufacturing capacity. We examined how existing QD and LCD technology could be optimized to meet the Rec. 2020 color standard. Our analysis revealed that up to 94% gamut coverage can be achieved.

Development of a Multilink 10 Gbit/sec Mapping Method and Interface Device for 120 Frames/sec Ultrahigh-Definition Television Signals

This paper researches a next-generation ultrahigh-definition television (UHDTV) broadcasting system. The video parameters of UHDTV systems with 120 frame/sec signals are specified in the Recommendation of the International Telecommunications Union Radiocommunication Sector, broadcasting service (television) series 2020. In this study, a new mapping method was developed to transmit various UHDTV signals, including 120 frame/sec signals. A prototype interface for connecting UHDTV video devices was also developed. The method is to transform UHDTV signals into multilink 10 Gbit/sec streams. The number of 10 Gbit/sec streams differs according to the UHDTV format (frame frequency, pixel count, and sampling lattice). To realize a compact and low-power interface, the prototype using a parallel fiber-optic transceiver with a capacity of 10 Gbit/sec per channel was implemented. Finally, the practicality and feasibility of the multilink 10 Gbit/sec mapping method and the prototype interface was verified.

ITU-R Standardization Activities on Cognitive Radio

Cognitive radio is an emerging technology to further improve the efficiency of spectrum use. Due to the nature of the technology, it has many facets, including its enabling technologies, its implementation issues and its regulatory implications. In ITU-R (International Telecommunications Union — Radiocommunication sector), cognitive radio systems are currently being studied so that ITU-R can have a clear picture on this new technology and its potential regulatory implications, from a viewpoint of global spectrum management. This paper introduces the recent results of the ITU-R studies on cognitive radio on both regulatory and technical aspects. This paper represents a personal opinion of the author, but not an official view of the ITU-R.