Comparative studies of the rain attenuation predictions for tropical regions

The radio waves propagating through the earth atmosphere will be attenuated due to the presence of atmosphere particles, such as water vapor, water drops and the ice particles. Meanwhile, the atmospheric gases and rain will both absorb and scatter the radio waves, and consequently degrade the performance of the link. The results of various studies conducted in temperate and tropical regions have been published in research papers. This paper presents the summary of comparative studies on different rain attenuation prediction methods for terrestrial microwave links tropical regions. Basically the models described in this paper include those of the ITU-R, revised Moupfouma, revised Silva Mello and Lin model. The objective of this study is to reveal the most suitable rain attenuation prediction model for the Malaysian tropical region. This paper will provide useful information for microwave engineers and researchers in making decision over the choice of most suitable rain attenuation prediction for terrestrial links operating in a tropical region. Even though the ITU-R model underestimates the rain attenuation at higher frequencies, the test results have clearly indicated that it is most suitable for predicting terrestrial rain attenuation in tropical Malaysia, compared to others

A statistical rain attenuation prediction model with application to the advanced communication technology satellite project. Part 2: Theoretical development of a dynamic model and application to rain fade durations and tolerable control delays for fade countermeasures

A dynamic rain attenuation prediction model is developed for use in obtaining the temporal characteristics, on time scales of minutes or hours, of satellite communication link availability. Analagous to the associated static rain attenuation model, which yields yearly attenuation predictions, this dynamic model is applicable at any location in the world that is characterized by the static rain attenuation statistics peculiar to the geometry of the satellite link and the rain statistics of the location. Such statistics are calculated by employing the formalism of Part I of this report. In fact, the dynamic model presented here is an extension of the static model and reduces to the static model in the appropriate limit. By assuming that rain attenuation is dynamically described by a first-order stochastic differential equation in time and that this random attenuation process is a Markov process, an expression for the associated transition probability is obtained by solving the related forward Kolmogorov equation. This transition probability is then used to obtain such temporal rain attenuation statistics as attenuation durations and allowable attenuation margins versus control system delay

Analisa Frekuensi Scaling Pada Redaman Hujan Terhadap Propagasi Gelombang Milimeter

In this final project, rain attenuation is predicted in PENS �ITS environment by synthetic storm technique. Wind angle and wind speed are needed as parameters to find rain attenuation beside rainfall rate. Rainfall rate data is measured by rain gauge tipping bucket. Wind data is came from Badan Meteorologi dan Geofisika Juanda Surabaya. Then that data will be processed until we get value of rain attenuation. This rain attenuation become main data to inserted in frequency scaling method, in this case use Simple Power Law Model and ITU-R. From those model we will get value of frequency scaling (n). This value is different each other beside of frequency (10 until 40 Ghz).From that frequency range we get constant n value, its mean that method is good using as rain attenuation predictor for other frequency, which rain attenuation data for that frequency still few or nothing

Performance study of automatic transmit power control (ATPC) in point to point microwave link for rain attenuation problem in Malaysia

Point-to-point microwave system is the backbone link for mobile communication industry as well as for other applications. In tropical region particularly in Malaysia, rain attenuation is the major constraint for implementing microwave system above 10GHz. The extreme of propagation channel environment due to rain has brought to the research and development of an automatic transmit power control (ATPC) in microwave transceiver. ATPC varies the transmit power level in order to maintain the receive signal level (RSL) above the threshold for biterror- rate (BER) desired. This research project will cover three main scope of study. First estimated calculation of rain attenuation on terrestrial point-to-point microwave link based on rain data captured. This will involve the understanding and computational of rain attenuation modeling equation by ITU-R recommendation using the Matlab software. Second is the basic concept and operational of ATPC applied in transceiver module of microwave link. Finally the experimental performance analysis of ATPC on actual microwave link install in Celcom microwave network. The performance will be measured on receive signal level on the actual system with ATPC option enable and disable for a certain period of time with realtime rain faded signa

Proposed Model for the Estimation of Rain Attenuation: At Ku-Band at Ota, a Tropical Location

This study proposes a model for calculating rain attenuation on earth-space path carried out in Covenant University, Ota, Nigeria, a tropical location. The beacon signals from a geostationary satellite - ASTRA 28°E (2E/2F/2G) was monitored, recorded and analysed using a spectrum analyzer operating at frequencies of 12.245 GHz. Rain rates at the station of the antenna receivers were also logged and analysed. The rainfall rate cumulative distributions and the resultant rain attenuation are obtained and presented. The results obtained showed that the cumulative distribution of the measured rainfall rate is not in agreement with ITU-R prediction. Rainfall rate at 0.001 %, 0.01 %, 0.1 % and 1 % were fed into the existing Simple Attenuation Model (SAM) and corresponding rain attenuation were obtained. The measured rain attenuation from the beacon signal was compared with sixteen existing rain attenuation models in literature only SAM model was closed to the measured result at the location. SAM model overestimated and underestimated the rain attenuation for this location at some percentage of time. Hence, a modified SAM model is proposed using newly obtained specific attenuation coefficients. The proposed modified model is found to be close to the measured rain attenuation

Systems issues in airborne Doppler radar/LIDAR certification

This report outlines: (1) thesis; (2) ground clutter challenge; (3) moving scatters (birds, bugs); (4) range ambiguities; and rain attenuation

Analysis of ITU-R Performance and Characterization of Ku Band Satellite Downlink Signals during Rainy Season over Chennai Region of India

In this paper, we present the analysis of Ku band Satellite signal reception during rainy season over Chennai region, India (Latitude: 12° 56' 60 N, Longitude: 80° 7' 60 E). We also examine the effectiveness of International Telecommunication Union – Radio communication (ITU-R) model in predicting the rainfall induced attenuation in Ku band, over this region. An improved Simulink model for Digital Video Broadcast – Satellite (DVB-S2) downlink channel incorporating rain attenuation and Cross Polarization Discrimination (XPD) effects is developed to study the rain attenuation effects, by introducing the experimental data in the ITU-R model pertaining to that region. Based on the improved model, a Monte Carlo simulation of the DVB–S2 signal link is carried out and the performance is analyzed by received constellation and Bit Error Rate (BER) parameters

Estimation of Rain Attenuation at EHF bands for Earth-to-Satellite Links in Bangladesh

Due to heavy congestion in lower frequency bands, engineers are looking for new frequency bands to support new services that require higher data rates, which in turn needs broader bandwidths. To meet this requirement, extremely high frequency (EHF), particularly Q (36 to 46 GHz) and V (46 to 56 GHz) bands, is the best viable solution because of its complete availability. The most serious challenge the EHF band poses is the attenuation caused by rain. This paper investigates the effect of the rain on Q and V bands' performances in Bangladeshi climatic conditions. The rain attenuations of the two bands are predicted for the four main regions of Bangladesh using ITU rain attenuation model. The measured rain statistics is used for this prediction. It is observed that the attenuation due to rain in the Q/V band reaches up to 150 dB which is much higher than that of the currently used Ka band. The variability of the rain attenuation is also investigated over different sessions of Bangladesh. The attenuation varies from 40 dB to 170 dB depending on the months. Finally, the amount of rain fade required to compensate the high rain attenuation is also predicted for different elevation angles.Comment: Int'l Conf. on Electrical, Computer and Communication Engineering (IEEE sponsored), Cox's Bazar, Bangladesh, February 2017, pp. 589-59

Analysis of the synthetic storm technique using rain height models to predict rain attenuation in tropical regions

This paper aims to investigate the utilization of the Synthetic Storm Technique to convert rain rate time series to rain attenuation time series using the ITU-R P.839, Stutzman and Bryant rain height models. Furthermore, the study aims to compare the actual rain attenuation with that predicted by the SST using the three above-mentioned rain height models based on rain rate and rain attenuation both measured concurrently. The reason for conducting this study is the fact that previous studies found that SST derived attenuation using the ITU-R P.839 rain height model is close to measured attenuation in low rain intensity but it is overestimated in medium rainfall and extremely overestimated in high rainfall rate. Therefore, it is vital to investigate the utilization of the SST using two additional rain height models which are the Stutzman and Bryant models. The study relies on rain rate time series and rain attenuation time series measured at University Science Malaysia (USM) campus (4.390 N, 100.980 E). The study found that the higher the rain rate, the higher is the percentage error for the SST predicated rain attenuation using the three above-mentioned rain height models as compared with measured rain attenuation. However, it is observed that when the Stutzman model applied as part of the SST model, the prediction is more accurate of the three rain height models

Reliable communications at frequencies bands above 25 GHz in the tropics

The use of frequencies in the higher bands could tap upon the large spectrum available for communication use. However, it suffers greater propagation losses, making them unsuitable for long range communication. In addition, heavy tropical rain further reduces the reliability of the link and additional link budget has to be set aside for rain fade in order to improve its reliability. Rain attenuation model that has been used widely is currently base on ITU-R model. It gives same rain rate for all places in Malaysia. However, previous study in Malaysia conducted by researchers in UTM shows that rain rate is not the same for different places in Malaysia. It is localized where some places experience heavier rainfall compared to other places. Hence, the ITU-R model does not give an accurate prediction of rain attenuation in Malaysia, where the attenuation is supposed to be localized base on the data of the rain rate. This project is aimed to develop a computer program in order to predict localized rain attenuation. The analysis of calculation to produce rain attenuation is done. The best reduction factor model is chosen to get the most accurate result. Then, the planning is done, followed by the design phase. The most challenging part, which is the development of the program, is done next. To verify the program built, it is tested by entering significant inputs and the outputs are analyzed. As a result, a computer program to predict rain attenuation in Peninsular Malaysia is successfully built. The results produced by the program are compared to the ITU-R model of rain attenuation. The differences are calculated and the outcome shows that ITU-R model is not suitable to be used as a rain attenuation method in Malaysia