Performance analysis of rain attenuation at Ku-band in Malaysia

Due to the lack of reliable analysis in Malaysia as tropical region, this study presents an analysis of experimental data compared against existing rain attenuation prediction models, namely the Dissanayake Allnut Haidara (DAH), and International Telecommunication Union rain ITU-R models, which have been used previously in satellite communication systems. Experimental data was measured at Universiti Putra Malaysia, Selangor, by retrieving signals from the MEASAT-3 satellite, which is geostationary at 91.5°E; at 11.096 GHz. Serdang Selangor is the southern-most state of the Kuala Lumpur region of Malaysia. Data analysis was conducted in two ways. Firstly, by performing statistical analysis on rain attenuation prediction models; and secondly, by making a comparison between measured data and the existing rain attenuation prediction model. Of all, the ITU-R model gave the lowest real mean square value of (2.2) for the three chosen states in Malaysia

Extracted atmospheric impairments on earth-sky signal quality in tropical regions at Ku-band

Atmospheric condition variations were shown to have a major effect on the earth sky signal quality at Ku band. Moreover, such variations increased in the tropical regions as compared to temperate areas due to their different weather parameters. With the increase of recent satellite communication technology applications throughout the tropical countries and lack of information regarding the atmospheric impairments analysis, simulation and mitigation techniques, there is an ever increasing need for extracting a unique and accurate performance of the signal quality effects during highly natural tropical weather impairments. This paper presents a new method developed for proper analysis with distinctive and highly realistic performance evaluation for signal quality during the atmospheric conditions variations in 14 tropical areas from the four continents analyzed based on actual measured parameters. The method implementation includes signal attenuation, carrier to noise ratio, symbol energy to noise ratio, and symbol error rate at different areas and different modulation schemes. Furthermore, for improvement in analysis in terms of covering more remarkable regions in tropics, the paper provides new measurements data with analysis for certain region in tropics used as a test bed and to add measurement data of such area to the world's data base for future researchers. The results show a significant investigation and performance observation in terms of weather impairments in tropical regions in general and each region in that area in particular regarding the signal attenuation and error rates accompanied for several transmission schemes

Energy-driven scheduling for Digital Video Broadcasting - Satellite Second Generation (DVB-S2)

The continuous growth in wireless data traffic results in the increase in total energy consumption of wireless networks. Therefore, energy-efficient solutions are extremely required to minimize the energy consumption over the entire network. In this paper, an energy-driven scheduling algorithm with optimized throughput, termed as Energy Efficiency Fair (EEF) queuing algorithm, is proposed. Based on energy efficiency of each modulation and coding scheme (MODCOD) available in Digital Video Broadcasting - Satellite Second Generation (DVB-S2), the EEF algorithm improves a scheduling mechanism of a two-step scheduler by selecting frames to be transmitted next according to “energy efficiency” policy developed. The EEF is compared with Round Robin (RR) algorithm, and a gain in energy efficiency of 47% is obtained when different modulation schemes with common code rate are implemented. Furthermore, EEF outperforms RR by 264% concerning the useful transmitted bits when QPSK modulation scheme with different coding rates is used

Channel characterization and modeling for GEO satellite-to-land terminals at ku-band with tropical weather awareness

Severe tropical weather dynamic impairments on the earth-sky signal quality at Ku-band compared to temperate weather have increased the demand for channel characterization and modeling for satellite-to-land terminals in tropical regions. Consequently, this will achieve improvement in identifying the type and the performance of the Fade Mitigation Technique (FMT), managing the available communication resources, and enhancing the reliability and efficiency of the communication link. The variation in weather dynamics decreases the accuracy of the existing Land Mobile Satellite (LMS) channel models when applied in tropical regions which may negatively impact the performance of the satellite networks in the tropical regions. This may also attributed to the lack of reliable investigations and studies on channel performance characterization, experiments, and analysis of the LMS channel in tropical regions under atmospheric impairments. Moreover, the existing LMS channel models do not consider several other essential issues in channel modeling. Therefore, it is necessary to design a comprehensive, reliable, and more accurate LMS channel model that considers these issues. To overcome such drawbacks: Firstly, we developed a signal attenuation prediction method for extracting the atmospheric impairments out of other impairments affecting signal quality for multi-regions in tropics, update the world’s database with the first measured data of some regions in the tropics, design and validate a new satellite-to-land mobile channel model at Ku-band with features that enhance accuracy, comprehensiveness, and reliability. Finally, the study proposed a tropical weather-aware LMS channel model that can be applied under different atmospheric (rain, clouds, and tropospheric scintillation) and mobility impairments. Furthermore, the resultant signal quality was evaluated for different modulation and coding schemes using an improved Quality Indicator Module (QIM) that is included in the proposed channel model. The results obtained show that the proposed method provides reliable multiregion channel performance analysis in the tropical regions. The method enables the system designer to accurately predict the atmospheric impairments on satellite link and signal quality performance with error rates during dynamic weather conditions in various tropical regions. Moreover, the proposed extended LMS channel (ELMSC) model during non-rainy and -cloudy environments, and the comprehensive satellite to tropical LMS channel (STROC) model that incorporates atmospheric dynamics, were proven to have lower Root Mean Square Error (RMSE), and higher reliability than the conventional models. The measured data were provided, and a significant agreement was observed between the proposed model and the measured data. The comparison of the performances of the proposed model with the measured channel performances confirms the reliability and the accuracy of the proposed ELMSC model with lower RMSE (reaches 0.0543 dB) than the conventional model (0.187 dB). Moreover, the proposed STROC model is shown to have lower RMSE (reaches 0.0072 dB) than the existing model with 0.0297 dB RMSE. The proposed channel models are suitable for analytical and numerical performance prediction and evaluation of various realistic atmospheric conditions and channel states, for narrow- and wide-band LMS systems, at various modulation and uncoded/coded schemes, and different satellite terminal speeds. The model and its associated modules can be used to study the signal performance, availability, and error rates of different services, including communications, broadcast, and navigation, as well as to develop a FMT for channel-aware strategies

The effect of the strategy of the quintuple learning cycle (5E) in learning some basic basketball skills for female students

In order to achieve the learning goals as quickly and as little as possible, as well as to achieve the best results in various activities and skills, many interested people have been studying technical means to organise the subject matter in physical education by focusing on the main learning methods for controlling and kinetic sports skills and how to invest These methods, as choosing the most appropriate methods, methods and strategies and the most economical in time and effort, is an important matter and a major aspect of the teaching process when teaching activities and sports motor skills in the field of physical education lessons, and from this objective understanding devoted effort through the use of modern strategies and their effective role sports activities and the development of events, especially for students, to raise the scientific aspect After presenting, analyzing, and discussing the results, the researcher reached the following conclusions ,The strategy of the five-year learning cycle (5E) has a positive effect on learning some basic skills of basketball in the research sample

Establishing standards to evaluate the performance of sports education teachers by consideration of quality requirements in education

The study aims to propose standards that can be relied upon to assess the physical education teacher's performance in the light of the requirements for quality in education, and the most important indicators that can bring of these measures. The researchers used a descriptive and analytical approach, the appropriateness of the nature of research. This was through a literature review of the quality of teaching in physical education .As well as the importance of setting standards in the assessment and performance tuning, and then use a researchers approach "Delphi". In order to determine a list of criteria that can be relied upon to assess physical education teachers performance considering of the quality and accreditation requirements in education . As well as 58 of the administrators and supervisors of educational supervision and competence in physical education in the provinces of central and southern Iraq. The researchers used the appropriate statistical ways to make a statistical analysis of the tours (Delphi) three that led to reach a list of criteria that can be relied upon to assess the performance of the physical education teachers in consideration of the quality of education and the requirements of the most important indicators that can brin

Analysis and modeling of the cloud impairments of satellite-to-land mobile channel at Ku and Ka bands

Cloud impairments have significant effect on signal propagated in the satellite to land stationary terminals channel at frequencies above 10 GHz. With the recent satellite to land mobile terminals network technologies and services that use these frequencies, there is a lack of channel impairments modeling and analysis for such type of link. This study presents a reliable channel model of satellite-to-land mobile terminals that consider dynamic cloudy weather impairments. The cloud’s dynamic parameters and their effect on the Rician factor are modeled. The model involves modules that design multipath signals, direct clear line-of-sight (LOS) normalized signals, and cloud impairments. Results show that a considerable change occurs in the performance of the signal propagated through the cloud. The change appears as deviations in the fade depth and the variance of the propagated signal in the link between the satellite and the land mobile terminals. The channel model is a realistic approach to the link characteristics, which satellite systems designers should consider when designing high data rate satellite systems

Tracking- and scintillation-aware channel model for GEO satellite to land mobile terminals at Ku-band

Recent advances in satellite to land mobile terminal services and technologies, which utilize high frequencies with directional antennas, have made the design of an appropriate model for land mobile satellite (LMS) channels a necessity. This paper presents LMS channel model at Ku-band with features that enhance accuracy, comprehensiveness, and reliability. The effect of satellite tracking loss at different mobile terminal speeds is considered for directional mobile antenna systems, a reliable tropospheric scintillation model for an LMS scenario at tropical and temperate regions is presented, and finally a new quality indicator module for different modulation and coding schemes is included. The proposed extended LMS channel (ELMSC) model is designed based on actual experimental measurements and can be applied to narrow- and wide-band signals at different regions and at different speeds and multichannel states. The proposed model exhibits lower root mean square error (RMSE) and significant performance observation compared with the conventional model in terms of the signal fluctuations, fade depth, signal-to-noise ratio (SNR), and quality indicators accompanied for several transmission schemes

Promising Outcomes of Modified ALPPS for Staged Hepatectomy in Cholangiocarcinoma

Associating liver partition and portal vein ligation for staged hepatectomy (ALPPS) is a two-stage procedure that can potentially cure patients with large cholangiocarcinoma. The current study evaluates the impact of modifications on the outcomes of ALPPS in patients with cholangiocarcinoma. In this single-center study, a series of 30 consecutive patients with cholangiocarcinoma (22 extrahepatic and 8 intrahepatic) who underwent ALPPS between 2011 and 2021 was evaluated. The ALPPS procedure in our center was modified in 2016 by minimizing the first stage of the surgical procedure through biliary externalization after the first stage, antibiotic administration during the interstage phase, and performing biliary reconstructions during the second stage. The rate of postoperative major morbidity and 90-day mortality, as well as the one- and three-year disease-free and overall survival rates were calculated and compared between patients operated before and after 2016. The ALPPS risk score before the second stage of the procedure was lower in patients who were operated on after 2016 (before 2016: median 6.4; after 2016: median 4.4; p = 0.010). Major morbidity decreased from 42.9% before 2016 to 31.3% after 2016, and the 90-day mortality rate decreased from 35.7% before 2016 to 12.5% after 2016. The three-year survival rate increased from 40.8% before 2016 to 73.4% after 2016. Our modified ALPPS procedure improved perioperative and postoperative outcomes in patients with extrahepatic and intrahepatic cholangiocarcinoma. Minimizing the first step of the ALPPS procedure was key to these improvements