Estimation of the Propagation Impairments of Satellite Systems Design in the SHF and EHF Bands in Subtropical Region

Ojo, J. S.; Owolawi, Pius A.

doi:10.1080/08327823.2015.11689904

Cited by 3 publications

(4 citation statements)

References 14 publications

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“…These terms contributed 70% and the variability respectively to the total value of N [14], more so the wet path gives an indication of landfall and cyclone movement when it close to the coast [15]. Because radio signals refract over the whole signal path, hence the variation in any of these meteorological parameters causes significant changes in radio wave propagation [16] and temperature and liquid water content influenced attenuation due to the cloud [17]. Consequently, with respect to the lapse rate of temperature and other parameters, refractivity values decrease with increase in height.…”

Section: Radio Refractivity and Refractivity Gradientmentioning

confidence: 99%

Diurnal, Seasonal and Annual Variation of Microwave Radio Refractivity Gradient over Akure, South West Nigeria

Adediji

Dada

Ajewole

2019

PSIJ

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In this study, four years in-situ measurements of atmospheric parameters (pressure, temperature and relative humidity) were carried out. The measurement was by placing an automatic weather station at five different heights: ground surface, 50, 100, 150 and 200 m respectively on a 220 m Nigeria Television Authority TV tower in Akure, South Western Nigeria. The four years Data collected (January 2007 to December 2009 and January to December 2011) were used to compute radio refractivity and its gradient. The local effect of a location/ region cannot but looked into when designing effective radio link, hence the diurnal, seasonal and annual variations of the radio refractivity gradient were studied. Results showed that refractivity gradient steadily increases inthe hour of 8:30 and 9:30 to 18:00 during dry season throughout the years investigated, and decreases two hours in the rainy season than the dry season. The record shows that at 50 m altitude, the maximum and minimum values are 158 N-unit/km around 14:30 and - 286 N-unit/km around 13:30 to 14:00 hrs, LT during the dry and rainy season respectively. Seasonally, refractivity gradient is steeper with greater variability in the dry season months than in the wet season months.

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Section: Radio Refractivity and Refractivity Gradientmentioning

confidence: 99%

Diurnal, Seasonal and Annual Variation of Microwave Radio Refractivity Gradient over Akure, South West Nigeria

Adediji

Dada

Ajewole

2019

PSIJ

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“…The interaction of these variables leads to the variation of radio refractive index in the troposphere. Adediji and Ajewole (2008) and Ojo et al (2014) both observed that µwave systems could become unavailable due to seasonal variation of refractive index. Hence, precise information on the radio refractive index (time and space) in the troposphere is important in the planning and design of point-to-point radio links for µwave networks and other propagation applications.…”

Section: Introductionmentioning

confidence: 99%

“…Some researchers in the tropical region, particularly in Nigeria, have made attempts to model the primary radioclimatic variables. Some of the attempts are, Falodun and Ajewole (2006), Igwe and Adimula (2009), Adediji et al (2011), Oyedum (2012, Adediji et al (2014aAdediji et al ( , 2014b, Ojo et al (2014), and Falodun et al (2021a, 2021b, to mention but a few. The present study's focus is on the estimation of fade depth for various outage probabilities and the associated Geoclimatic factors based on the radioclimatological data.…”

Section: Introductionmentioning

confidence: 99%

Geo-spatial distribution of radio refractivity and the influence of fade depth on microwave propagation signals over Nigeria

Olalekan

2023

Int. J. Phys. Sci.

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The need for more bandwidth for a broad range of purposes necessitates research into how radio refractivity, multipath fading, and geoclimatic variables affect terrestrial and satellite propagation links. In this study, a geographical distribution approach to radio refractivity and fade depth over five locations in Nigeria-Akure, Enugu, Jos, Minna, and Sokoto based on five-year (2017-2021) measured data of atmospheric pressure, relative humidity, and temperature-at two levels (ground surface and 100 m heights). The results demonstrated the percentage occurrence of the dry terms dominating the radio refractivity constituent at the surface level, with a minimum and maximum contributions of about 78 and 92%, while at heights of 100 m, the percentage occurrence of the dry terms dominated the radio respectively refractivity constituent, contributing a minimum of about 79% and a maximum of about 92%. The spatial distribution reveals that, regardless of height, the tropical rainforest (TRF) and freshwater swampy mangrove (FWSM) regions reported the highest values of radio refractivity. The statistical estimate shows that fading values can differ by as much as 1.5 dB, especially near the TRF and FWSM coastlines, even during clear air conditions. The current findings will be helpful for budgeting Earth-space microwave links, particularly for the rollout 5G and future-generation microcellular networks in Nigeria.

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“…However, their performance was evaluated only through simulation and only one location was considered. The other related work by [5] did not adapt attenuation due to fog and additional effect due to atmospheric noise temperature with fibre optics. Besides, the work was performed based on subtropical data which may not apply to the tropical region.…”

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confidence: 99%

Assessment of Total Attenuation and Adaptive Scheme for Quality of Service Enhancement in Tropical Weather for Satellite Networks and 5G Applications in Nigeria

Ojo

Olurotimi

Obiyemi

2021

J. Microw. Optoelectron. Electromagn. Appl.

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The dynamic weather condition is a major concern for optimum channel utilization in recent times, especially at higher frequencies with larger bandwidth for 5G applications. Over the years, rain-induced attenuation among the hydrometeors has been linked as the major cause of signal impairment especially at the frequency, f > 10 GHz. However, when f > 18 GHz, the significant impact of other hydrometeors; cloud/fog, and scintillation increases tremendously, especially for Low Earth Orbit, LEO satellites. LEO satellites find applications in fibre optics technology, scientific research, remote sensing, surveillance, meteorology, satellite imaging, and other applications. In this paper, the assessment of combined impairments based on 5-year (2012-2016) data has been carried out and a dynamic adaptive intelligent scheme (DAIS) has been adopted to achieve a good quality of service along the satellite channels operating at Ku-V band frequencies over five stations representing different climatic regions in Nigeria namely: Port Harcourt (PH), Akure, Ilorin, Zaria, and Kano. The proposed DAIS based on fuzzy logic was able to achieve a significant reduction in the transmitting power by about 70% and SNR by 50% across the frequencies considered without altering the information content of the downlink parameters, thereby improving the QoS significantly and adhere to Customer Service Level Agreements (CSLAs) irrespective of the weather dynamics. The overall results show that the adaptive intelligent techniques can effectively fix signal links under the dynamic weather conditions for both satellite and wireless networks in this region. Information from the results is timely because it will serve as the bedrock for the newly launched transformation to the digital video broadcasting (DVB) system in Nigeria for effective service delivery.

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Estimation of the Propagation Impairments of Satellite Systems Design in the SHF and EHF Bands in Subtropical Region

Cited by 3 publications

References 14 publications

Diurnal, Seasonal and Annual Variation of Microwave Radio Refractivity Gradient over Akure, South West Nigeria

Diurnal, Seasonal and Annual Variation of Microwave Radio Refractivity Gradient over Akure, South West Nigeria

Geo-spatial distribution of radio refractivity and the influence of fade depth on microwave propagation signals over Nigeria

Assessment of Total Attenuation and Adaptive Scheme for Quality of Service Enhancement in Tropical Weather for Satellite Networks and 5G Applications in Nigeria

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