Search

Site diversity is the most effective way to recover a signal lost during heavy downpours, especially in tropical regions since other mitigation techniques such as adaptive power control and code modulation may be unreliable during such. Duplicated links at diverse sites are deployed, and the least-attenuated signal of either site will be routed to the prime site for further operation. Since the deployment is costly, a diversity-gain model is used to estimate the appropriateness of selected sites. Diversity gain is known to depend on site-separation distance and elevation angle and, optionally, baseline angle and signal frequency, based on the region of research. In addition to these factors, the horizontal rain-cell span and the wind's impact on the gain are ongoing investigations, especially in tropical regions. This article presented the rain analysis from the year 2014 to mid-July 2017 at eight sites in the Gombak and Sepang districts of Malaysia to investigate the dependency relevancies. The rain rates were then used to predict the attenuation using the ITU-R P.618-13 rain-attenuation model, and the inter- and cross-district gain characteristics were evaluated. The observation of diurnal rain during the northeast seasons yielded that the northeast wind stimulates intense rain at locations along its direction, thus, extending the horizontal rain-cell span to 15 km distant from a host. Meanwhile, sites located at 5 km distant, slightly perpendicular to the wind direction, and from 90° to 180° from due north of the host, experience less rain. The baseline angle variation establishes nonimpact to the gain and lengthening the site-separation distance presented equal chances to the shorter span towards diversity-gain increment. The research outcome is necessary to formulate a more reliable diversity-gain model to be used in the industry. [ABSTRACT FROM AUTHOR]

Fifth-generation (5G) networks have been deployed alongside fourth-generation networks in high-traffic areas. The most recent 5G mobile communication access technology includes mmWave and sub-6 GHz C-bands. However, 5G signals possibly interfere with existing radio systems because they are using adjacent and co-channel frequencies. Therefore, the minimisation of the interference of 5G with other signals already deployed for other services, such as fixed-satellite service Earth stations (FSS-Ess), is urgently needed. The novelty of this paper is that it addresses issues using measurements from 5G base stations (5G-BS) and FSS-ES, simulation analysis, and prediction modelling based on artificial neural network learning models (ANN-LMs). The ANN-LMs models are used to classify interference events into two classes, namely, adjacent and co-channel interference. In particular, ANN-LMs incorporating the radial basis function neural network (RBFNN) and general regression neural network (GRNN) are implemented. Numerical results considering real measurements carried out in Malaysia show that RBFNN evidences better accuracy with respect to its GRNN counterpart. The outcomes of this work can be exploited in the future as a baseline for coexistence and/or mitigation techniques. [ABSTRACT FROM AUTHOR]

Site diversity gain prediction models were created to estimate mathematically the acquired benefits from the implementation of site diversity at place of choice. This work contributes to the comparison of existing gain prediction model to the gain of measured attenuation at Cyberjaya and Rawang, Malaysia. The experiment has been conducted for 4 years from 2014 to 2017, in Ka band using a large 7.3-m diameter antenna and a high elevation angle of 68.8°, together with the rain analysis at both places for the same duration. The average monthly rainfall and attenuation for 4 years were presented. The results revealed that prediction model Hodge performs better than other models, while X. Yeo and Panagopoulos models appear to exhibit very similar graph shape to the measured gain data. More research on gain development in tropical region should be conducted, as the existing prediction model appears to be less consistent with the current data. [ABSTRACT FROM AUTHOR]

The significance uses of Ka-Band and higher frequencies is due to high bandwidth demand from internet users, nevertheless, these high frequencies are susceptible to attenuation impairment dominantly due to rain. While the quality of received signal at consumer terminals (which is normally equipped with smaller antenna size) is important, the quality and availability of signal at earth station gateway is more important because the gateway serves the entire network of remote sites. If the signal at gateway is not available, the entire network will be affected. This paper presented the Ka-Band signal propagation data collected from MEASAT-5 satellite beacon tracking measurements for a period of 5 years. The data was collected at two gateway stations in Malaysia, Cyberjaya and Rawang, at 20.2 GHz frequency using 7.3 m diameter parabolic antenna. The antenna was located approximately 3 m above the ground with vertical polarization and with elevation angle of 68.8°. From the analysis of the rain intensity at the locations, Rawang experienced more intense rainfall which was an average of 85.2 mm/h than Cyberjaya which was 78 mm/h in average year from 2014 to 2018. The lower rain intensity, high elevation angle, vertical polarization and the high antenna gain configurations resulted in a reasonable attenuation at 0.01% of outage time which were 26 dB at Rawang and 17 dB at Cyberjaya. Therefore, it is observed that a low percentage of the Ka-band signal loss of over 0.01 percentage of time with reasonable attenuation can be achieved using the specified configuration. [ABSTRACT FROM AUTHOR]

Satellite signal propagation at Ka-Band is more prone to weather effects than those with lower frequencies. The impact is more severe in the tropics because of its natural climate with heavy rainfall throughout the year. Rain attenuation prediction models developed in this region need to be evaluated to find the optimum model that suits the experimental parameter. Therefore, the main objective of this paper is to evaluate ITU-R's variation prediction models, namely Folasade, Renuka and Xiang Yeo models, including ITU-R P.618-13 model with data collected from MEASAT Ka-Band beacon live monitoring system from 2014 to 2016 in West Peninsular Malaysia using large-size antenna. The measured attenuation for an average of 3 years was 18.2 dB and 25.0 dB at 0.01% of the time at Cyberjaya and Rawang with the rain rate of 76.7 mm/h and 86.0 mm/h at the same percentage of time, respectively. As a result, ITU-R and other models overpredicted the attenuation compared to the measured data. This is because these models were derived from smaller-size antenna, while the measured data were from large-size antenna and higher elevation angle of 68.8°, which contributes to low attenuation on both sites. Therefore, ITU-R model was probed further, using Study Group 3 (SG3) data as the anchor parameters, and from the experiment, it was suggested that the ITU-R model is inappropriate to predict attenuation at elevation angle of higher than 54°. All the resultant graph and analysis were presented to support the facts. [ABSTRACT FROM AUTHOR]