Jalel Chebil

Bio: Jalel Chebil is an academic researcher from University of Sousse. The author has contributed to research in topics: Storm & Rain fade. The author has an hindex of 5, co-authored 19 publications receiving 69 citations.

Investigation of Three Dimensional Empirical Indoor Path Loss Models for Femtocell Networks

Abstract: Femtocell which is a home access point that installed by end consumers inside their houses is an important parameter and a promising technology in future wireless networks. It is proposed as a solution to the indoor propagation problems and to increase the indoor bandwidth. However, many challenges need to be addressed before deployment of femtocell. One of these challenges is the indoor propagation. Most of the available models are for long range communication like macro and micro cellular networks. Models for femtocell networks where the effects of walls and floors are appeared are necessary. In this paper eight different models of indoor propagation were studied and compared with measured data. Measurements were conducted in three story building. Four different scenarios with different numbers of penetrated walls and floors were considered. The results were statistical analysed by calculating the average error and the error standard deviation.

Comparison between path length reduction factor models based on rain attenuation measurements in Malaysia

Abstract: Attenuation due to rainfall can severely degrade the radio wave propagation at frequencies above 10 GHz. It restricts the path length of radio communication systems and limits the use of higher frequencies for line-of-sight microwave links and satellite communications. In order to predict the attenuation due to rain accurately, the reduction factor which is used to account for the inhomogeneity of rain along the propagation path need to be studied. This paper investigates reduction factor models, which have been proposed by ITU-R, Moupfouma, Lin, Assis and Dissanayake-Allnutt for the prediction of rain attenuation. A comparison was made between these models based on rain attenuation data measured at 15 GHz in two different locations in Malaysia.

Measurement of wet antenna effects on microwave propagation-an analytical approach

Abstract: Losses due to water being in or on the surface of the radomes or the parabolic reflector and on the feed window of antennas occur during rain. One minute rainfall rate and corresponding rain attenuation data at 15, 23, 26 and 38 GHz bands were collected at UTM Skudai campus for a one year period. In order to separate wet antenna loss from the propagation measurement, an analytical approach has been proposed and the results are presented.

Rain Attenuation Analysis using Synthetic Storm Technique in Malaysia

Abstract: Generated rain attenuation time series plays an important role for investigating the rain fade characteristics in the lack of real fade measurements. A suitable conversion technique can be applied to measured rain rate time series to produce rain attenuation data and be utilized to understand the rain fade characteristics. This paper focuses on applicability of synthetic storm technique (SST) to convert measured rain rate data to rain attenuation time series. Its performance is assessed for time series generation over a tropical location Kuala Lumpur, in Malaysia. From preliminary analysis, it is found that SST gives satisfactory results to estimate the rain attenuation time series from the rain rate measurements over this region.

Analysis of Time Diversity Gain for Satellite Communication Link based on Ku-Band Rain Attenuation Data Measured in Malaysia

Abstract: This paper reports a study on mitigation of propagation impairments on Earth–space communication links. The study uses time diversity as a technique for mitigating rain propagation impairment in order to rectify rain fade. Rain attenuation time series along earth-to-satellite link were measured for two years period at 12.255 GHz in Malaysia. The time diversity technique was applied on measured rain fade to investigate the level of possible improvement in system. Time diversity gain from measured one-minute rain attenuation for two years period was estimated and significant improvement was observed with different delays of time. These findings will be utilized as a useful tool for link designers to apply time diversity as a rain fade mitigation technique in Earth-satellite communications systems.

Measurement of wet antenna effects on millimetre wave propagation

Abstract: The experiment "wet antenna effects on millimetre wave propagation" is carried out at the Robert Bosch GmbH, to analyse the partial and total signal degradation of automotive radar sensors. It reveals that, the existence of water film on the surface of antenna lens or its radome is the main cause for weak performance of radar sensors, operating at high frequencies in rainy and snowy weather conditions. However, it is possible to repress the formation of water film with proper antenna lens or radome design to a certain extent, to reduce its effect on the radar performance. The results, which are discussed in this paper, show that such performance limitation has to be generally taken into account by the automotive long range radar designers. Bosch has successfully implemented appropriate technology in its new generation automotive long range radar sensor.

Real Measurement Study for Rain Rate and Rain Attenuation Conducted Over 26 GHz Microwave 5G Link System in Malaysia

Abstract: In this paper, real measurements were conducted to investigate the impact of rain on the propagation of millimeter waves at 26 GHz. The measurements were accomplished using a microwave fifth generation radio link system with 1.3 km path length implemented at Universiti Teknologi Malaysia Johor Bahru, Malaysia. The implemented system consisted of Ericsson CN500 mini E-link, radio unit, rain gauge, and data logger. The measurements were attained and logged daily for a continuous year, with 1-min time intervals. Next, the MATLAB software was used to process and analyze the annual rain rate and rain attenuation, including for the worst month. From the analyzed results, it was found that at 0.01% percentage of time, the rain rate was 120 mm/hr; while the specific rain attenuation was 26.2 dB/km and the total rain attenuation over 1.3 km was 34 dB. In addition, the statistics acquired from the measurements for the worst month were lower than what was predicted by the international telecommunication union (ITU) model; around 51% and 34% for the rain rate and rain attenuation, respectively. The average percentage of error calculated between the measurements and predicted results for the rain rate and rain attenuation were 143% and 159%, respectively. Thus, it can be concluded that the statistics for the worst month in Malaysia is lower than what was predicted by the ITU model.

Dynamic Determination of the Baseline Level in Microwave Links for Rain Monitoring From Minimum Attenuation Values

Abstract: In recent years, the use of commercial microwave links (CMLs) as tools for remote sensing of the environment has attracted special interest. However, in order to use attenuation measurements taken by microwave links for estimating the rain, one needs to determine the baseline attenuation level. Existing methods frequently use the low attenuation values that are observed during the periods prior to the onset of the rain that have been identified as dry for determining the baseline attenuation level during rainy periods. In this paper, we present a theoretical analysis that justifies the use of the lower attenuation values and propose a systematic method for estimating the baseline attenuation level on the fly that does not need a dry/wet classification. Thus, the proposed method produces a dynamic baseline, which is continuously updated. This method can be implemented on measurements taken from a single CML, in real time, without using either historic or side information. We implemented this method on actual CMLs based measurements and demonstrated its capability to estimate monthly, daily, and hourly rainfall. The resultant estimates were validated by measurements from dedicated weather sensor and rain gauges and are shown to produce accurate estimates of the hourly, daily, and monthly cumulative rain depths.

Attenuation Measurements and Propagation Modeling in the W-Band

Abstract: The frequency range that extends from 70 to 115 GHz presents low gaseous attenuation and offers the possibility of implementing radio links with capabilities of transporting more than 1 Gb/s over distances up to a few kilometers. A better knowledge of the propagation characteristics of the atmosphere at these frequencies can benefit future technological advances, providing better performance in terms of the use of radio resources. Unfortunately, the number of propagation results communicated for this band is very small. In this paper, propagation in this frequency range is analyzed on the basis of two-year experimental measurements carried out in Madrid, Spain, on a commercial link working at 75 and 85 GHz. Rain attenuation is the most relevant propagation effect in the W-band. Attenuation measurements are processed to remove wet antenna effects, leaving only the path attenuation time series. Statistics obtained from these time series are compared with a number of model predictions that use rain information of various types as input data, assessing in this way their precision and usefulness.