scholarly journals Prediction of Rain Attenuation and Impact of Rain in Wave Propagation at Microwave Frequency for Tropical Region (Uttarakhand, India)

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Mukesh Chandra Kestwal ◽  
Sumit Joshi ◽  
Lalit Singh Garia
Keyword(s):  
Microwave Frequency ◽  
Exponential Model ◽  
Rain Attenuation ◽  
Tropical Region ◽  
Site Visit ◽  
Classical Approach ◽  
Atmospheric Attenuation ◽  
Tropical Regions ◽  
Attenuation Level ◽  
Rainfall Attenuation

The most classical approach of determining rain attenuation for radio-wave frequency has been to theoretically determine the specific attenuation. At frequency over 10 GHz, rain and precipitation can influence the attenuation a lot; the effect of atmospheric attenuation between the source and destination over wireless communication is of major concern and a proper site visit and proper method are required to control the attenuation level so that the performance can be increased. In this paper exponential model has been used to determine the attenuation level for k-region (India) which can be used for region having similar condition. The analyzed predicted attenuation data have been compared with ITU-R measured rain attenuation, and the results will provide useful estimation of rainfall attenuation on microwave links in tropical regions that have similar conditions as (Almora) Uttarakhand region.

Comparison of measured rain attenuation and ITU-R predictions on experimental microwave links in Malaysia

2011 ◽  
Vol 3 (4) ◽  
pp. 477-483 ◽  
Author(s):  
Amuda Yusuf Abdulrahman ◽  
Tharek bin Abdulrahman ◽  
Sharul Kamal bin Abdulrahim ◽  
Ulaganathen Kesavan
Keyword(s):  
Cumulative Distribution Function ◽  
Rain Rate ◽  
Rain Attenuation ◽  
Rain Gauge ◽  
Cumulative Distribution ◽  
Rain Gauge Data ◽  
Tropical Regions ◽  
International Telecommunication ◽  
Rain Rates ◽  
Rainfall Attenuation

This paper presents the results of direct rain attenuation measurements carried out on four experimental microwave links, installed at UTM, Malaysia. The links operate at frequencies of 15, 22, 26, and 38 GHz and the cumulative distribution function for different rain rates have been generated from the measured 4-year rain gauge data. The experimentally measured attenuation data have been compared with International Telecommunication Unior-R rain attenuation predictions; and it has been found that the latter have underestimated the measured values, especially at higher rain rates. The deviations have been modeled as a function of rain rate exceedances R%p. It is hoped that the study will provide useful information for estimation of rainfall attenuation on microwave links in tropical regions that have similar situation to Malaysia.

scholarly journals Rain Attenuation Predicted Model for 5G Communication in Tropical Regions

2020 ◽  
Vol 9 (3) ◽  
pp. 1151-1158
Keyword(s):  
Heavy Rainfall ◽  
Research Work ◽  
Microwave Frequency ◽  
Rain Attenuation ◽  
Frequency Variation ◽  
Communication Link ◽  
Tropical Regions ◽  
International Telecommunication ◽  
Predicted Model ◽  
Forecast Technique

The signals operating at higher microwave frequency ranges get attenuated in the tropical regions where heavy rainfall occurs. Controlling of Signal fading for establishment of efficient link plays an important role in the heavy rainfall regions. Here rain attenuation predicted model has been designed in sub- 6 GHz and mm Wave bands. This predicted model is applicable to the tropical regions where heave rainfall occurs. Frequency variation technique has been adopted to execute the research work. The estimated rain attenuation depends on International Telecommunication UnionR rain mitigation forecast technique utilizing assessment of rain in the tropical regions of South East Asia.The frequency ranges used here for variation techniques are respectively 3.6 to 4.2 GHz, 4.4 to 4.9 GHz, 27.5 to29.5 GHz, 37 to-40 GHz and 64 to71 GHz. In the previous works [1] it is observed that only lower fade margin has been considered for communication link design .As the fade margin increases, the communication link seems to be more reliable. In this paper the fade margin has been increased and it has been chosen from 12dB to 16dB. This predicted model will yield better result than that of ITU-R model.

scholarly journals Breeding Temperate Japonica Rice Varieties Adaptable to Tropical Regions: Progress and Prospects

Agronomy ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 2253
Author(s):  
Myrish Pacleb ◽  
O-Young Jeong ◽  
Jeom-Sig Lee ◽  
Thelma Padolina ◽  
Rustum Braceros ◽  
...  
Keyword(s):  
The Philippines ◽  
Tropical Region ◽  
Japonica Rice ◽  
Rice Varieties ◽  
Temperate Japonica ◽  
Tropical Regions ◽  
Tropical Environments ◽  
Increasing Demand ◽  
Northeast Asian ◽  
The Tropics

Temperate japonica rice is mainly cultivated in temperate regions. Many temperate japonica varieties have a superior grain quality that is preferred in Northeast Asian countries such as Japan, Korea, and China. The changes in consumers’ preferences in Southeast Asia and Western countries has contributed to increasing the demand for temperate japonica. Most temperate japonica varieties developed in temperate regions typically exhibit extra-early flowering under the short-day conditions in the tropics, which usually results in severely reduced yields. Since 1992, we have been developing temperate japonica varieties that can adapt to tropical environments to meet the increasing demand for temperate japonica rice, having released six varieties in the Philippines. Especially, the yield of one of the temperate japonica varieties, Japonica 7, was comparable to the yields of leading indica varieties in the Philippines. Here, we discuss the current breeding initiatives and future plans for the development of tropical-region-bred temperate japonica rice.

scholarly journals Analysis of rain fade slope for terrestrial links

2020 ◽  
Vol 18 (2) ◽  
pp. 896
Author(s):  
Jalel Chebil ◽  
Al-Hareth Zyoud ◽  
Mohamed Hadi Habaebi ◽  
Islam Md. Rafiqul ◽  
Hassan Dao
Keyword(s):  
Standard Deviation ◽  
Prediction Model ◽  
Rain Attenuation ◽  
Measured Data ◽  
Rate Of Change ◽  
Tropical Regions

<p><span>Rainfall can cause severe degradation to the operation of microwave links working with frequencies above 10 GHz. Many studies have investigated this problem, and one of the factors that attract the attention of researcher is rain fade slope which is the rate of change of rain attenuation.</span><span> The focus of this study is on rain fade slope for terrestrial links and it is </span><span>based on measurement conducted in Malaysia</span><span>.</span><span> This paper investigates the characteristics of the measured rain fade slope distribution </span><span>for various attenuation levels</span><span>. Then, </span><span>the ITU-R model for rain fade slope is compared with the corresponding statistics obtained from the measured data. Significant discrepancies have been observed since the ITU-R prediction model does not fit the measured fade slope distribution for many attenuation levels. It is recommended to modify the expression of the standard deviation in the ITU-R model when implemented in tropical regions.</span></p>

Rain attenuation of millimetre wave above 10 GHz for terrestrial links in tropical regions

2018 ◽  
Vol 29 (8) ◽  
pp. e3450 ◽  
Author(s):  
Ibraheem Shayea ◽  
Tharek Abd. Rahman ◽  
Marwan Hadri Azmi ◽  
Arsany Arsad
Keyword(s):  
Rain Attenuation ◽  
Millimetre Wave ◽  
Tropical Regions

Rain Rate and Rain Attenuation Over Millimeter Waves in Tropical Regions Based on Real Measurements

2021 ◽  
Author(s):  
Waheeb Tashan ◽  
Ibraheem Shayea ◽  
Sultan Aldirmaz-Colak ◽  
Tharek Abdul Rahman ◽  
Ayman A. El-Saleh ◽  
...  
Keyword(s):  
Millimeter Waves ◽  
Rain Rate ◽  
Rain Attenuation ◽  
Tropical Regions

The equatorial wind structure in Jupiter’s stratosphere from direct wind and temperature measurements with ALMA and IRTF/TEXES

2021 ◽  
Author(s):  
Bilal Benmahi ◽  
Thibault Cavalié ◽  
Thomas K. Greathouse ◽  
Vincent Hue ◽  
Rohini Giles ◽  
...  
Keyword(s):  
Tropical Region ◽  
Temperature Structure ◽  
Horizontal Structure ◽  
Tropical Regions ◽  
Upper Troposphere ◽  
Thermal Wind ◽  
Wind Speeds ◽  
Wind Structure ◽  
First Time ◽  
Middle Stratosphere

&lt;p&gt;Since 30 years, an equatorial oscillation of the temperature structure with a quasi-period of 4 years has been discovered in the atmosphere of Jupiter (Orton et al. 1991, Leovy et al. 1991). This phenomenon results in a complex vertical and horizontal structure of prograde and retrograde jets. However, the wind structure of the stratosphere in the equatorial zone of Jupiter has not been measured directly. It has only been inferred in the tropical region from the thermal wind balance using temperatures measured in the jovian stratosphere and the cloud-top wind speeds measured as a initial condition (e.g. Flasar et al. 2004). But temperatures are not constrained between the upper troposphere and the middle stratosphere from observations, limiting thus the accuracy of the thermal wind balance.&lt;/p&gt; &lt;p&gt;In this study, we derive self-consistently for the first time the structure of the tropical winds by utilizing wind and temperature observations all performed in the stratosphere. The wind speeds were obtained by Cavali&amp;#233; et al. (2021) at 1 mbar in Jupiter's stratosphere in both the equatorial and tropical regions in March 2017 with ALMA. The stratospheric thermal field was measured a few days before from the equator to the mid-latitudes with Gemini/TEXES (Giles et al. 2020). For the derivation of the wind, we use both the thermal wind equation (Pedlosky 1979) and the equatorial thermal wind equation (Marcus et al. 2019). In this paper, we will present and discuss our results.&lt;/p&gt;

scholarly journals RAIN ATTENUATION FOR 5G NETWORK IN TROPICAL REGION (MALAYSIA) FOR TERRESTRIAL LINK

2020 ◽  
Vol 90 ◽  
pp. 99-104
Author(s):  
Kesavan Ulaganathen ◽  
Tharek Bin Abdul Rahman ◽  
Md. Rafiqul Islam ◽  
Khaizuran Abdullah
Keyword(s):  
Rain Attenuation ◽  
Tropical Region ◽  
5G Network

Investigation of HAPs Propagation Channel for Wireless Access in a Tropical Region at Ka-Band

2017 ◽  
Vol 7 (3) ◽  
pp. 1204
Author(s):  
Felix Obite ◽  
Jafri Din ◽  
Kamaludin Mohammad Yusof ◽  
Basliza M. Noor
Keyword(s):  
Fading Channels ◽  
Channel Model ◽  
Rain Attenuation ◽  
Wireless Access ◽  
Rician Fading ◽  
Communication Link ◽  
Propagation Channel ◽  
Ka Band ◽  
Tropical Regions ◽  
Budget Analysis

<p>In the last few years, High Altitude Platforms (HAPs) have attracted considerable effort due to their ability to exploit the advantages of satellite and terrestrial-based systems. Rain attenuation is the most dominant atmospheric impairment, especially at such frequency band. This paper addresses the modelling of rain attenuation and describes a propagation channel model for HAPs at Ka-band to provide efficient and robust wireless access for tropical regions. The attenuation due to rain is modeled based on three years measured data for Johor Bahru to estimate the actual effect of rain on signals at Ka band. The radio propagation channel is usually characterized as a random multipath channel. Specifically, a statistical derivation of probability distribution function for Rayleigh and Rician fading channels are presented. The model consists of multiple path scattering effects, time dispersion, and Doppler shifts acting on the HAPs communication link. Simulation results represent the fading signal level variations. Results show perfect agreement between simulation and theoretical, thereby conforming to the multipath structures. The information obtained will be useful to system engineers for HAPs link budget analysis in order to obtain the required fade margin for optimal system performance in tropical regions.</p>

Analysis of Selected Earth-Space Rain Attenuation Models for a Tropical Station

2016 ◽  
Vol 3 (2) ◽  
pp. 383 ◽  
Author(s):  
A. I. O. Yussuff
Keyword(s):  
Prediction Models ◽  
Measurement Data ◽  
Daily Rainfall ◽  
Rain Attenuation ◽  
Propagation Path ◽  
Tropical Regions ◽  
Earth Space ◽  
Budget Analysis ◽  
Link Budget ◽  
Attenuation Models

The restrained use of millimeter bands is due to severe rain attenuation. Attenuation is caused when rain cells intersects radio wave’s propagation path; resulting in deep fades. The effect of rainfall is more severe in tropical regions characterized by heavy rainfall intensity and large raindrops; hence, rain attenuation analyses are essential to study rain fade characteristics for use in earth-space link budget analysis, for outage prediction resulting from rain attenuation. Tropical regions are particularly challenged with signal outage, necessitating the formulation and development of suitable prediction model(s) for the region. Therefore, extensive knowledge of the propagation phenomena mitigating system availability and signal quality in these bands are required. Daily rainfall data were collected from the Nigerian Meteorological Services for Lagos for spanning January to December 2010. Results showed that although, the ITU-R model out-performed the other prediction models under consideration, none of prediction models matched the measurement data.

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