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Seasonal and Diurnal Variability of Rain Heights at An Equatorial Station Abayomi Isiaka Yussuff; Nor Hisham Haji Khamis
International Journal of Electrical and Computer Engineering (IJECE) Vol 5, No 5: October 2015
Publisher : Institute of Advanced Engineering and Science

Seasonal and diurnal rain heights variation at Universiti Teknologi Malaysia, Johor was studied. Slant path rain attenuation prediction and modeling is crucial to satellite equipment design; a major input is the rain height. One year meteorological ground-based, S-band, 3D RAPIC precipitation radar data at 500m resolution sourced from the Malaysian Meteorological Department was complemented with two-year TRMM PR data sourced from JAXA Earth Observation Research Center. After filtering, sorting, extraction and decoding of the data, vertical reflectivity profiles were constructed; from which rain height parameters were extracted. TRMM PR processed monthly (3A25) and daily (2A23) rainfall precipitation data were similarly used to obtain rain height parameters to investigate the seasonal and diurnal variations. Results from this work suggested that rain height parameters are influenced by both seasonal and diurnal variations. Higher seasonal variability was observed during south-west and pre-southwest monsoons. Rain heights were also observed to be higher in the night than in the day time.

Underwater Channel Characterization to Design Wireless Sensor Network by Bellhop Nima Bahrami; Nor Hisham Haji Khamis; Ameruddin Baharom; Azli Yahya
TELKOMNIKA (Telecommunication Computing Electronics and Control) Vol 14, No 1: March 2016
Publisher : Universitas Ahmad Dahlan

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.12928/telkomnika.v14i1.2454

Acoustic underwater link due to low attenuation is employed for underwater sensor network (UWSN). Due to water changing physical properties and different environmental conditions, the sound propagation for every underwater channel are different. So, the most important parameters to design reliable UWSN are: the shadow zone determination, optimum nodes placement, high signal to noise ratio and more power efficiency of nodes. This paper simulates underwater channel for 7 KHz carrier frequency, with measured physical water properties and remote sensing data. Based on defined scenario, the research determines optimum nodes placement and link budget analysis based on bottom to surface acoustic link. The paper utilizes Bellhop acoustic toolbox as a simulator, GeoMapApp program to collects bathymetry data and Aviso+ database to determine wind speed on sea surface. As a result the paper based on simulation of sound propagation in channel and transmission loss determination in depth and range, finds the optimum nodes positions and link budget calculation to prove the results.

Determination of Melting Layer Boundaries and Attenuation Evaluation in Equatorial Malaysia at Ku-Band Abayomi Isiaka Yussuff; Nor Hisham Haji Khamis
Bulletin of Electrical Engineering and Informatics Vol 3, No 4: December 2014
Publisher : Institute of Advanced Engineering and Science

Upsurge in bandwidth demand in recent times for real-time data transmission have put serious constraints on satellite communication channels, leading to congestion of the lower frequency bands; necessitating migration to higher bands (Ku, Ka and V) with attendant problems such as signal fading, depolarization and attenuation due to presence of hydrometeors. There is need to separately account for attenuation due to the melting layer along the earth-space microwave links. One year data from ground-based S-band meteorological radar sourced from Kluang station of the Malaysian Meteorological Department was processed to build the vertical reflectivity of rain profile for UTM, Malaysia. Results from this work suggested that the effects of the melting layer on signal attenuation at Ku-band can be quite significant in the tropical and equatorial regions. It was estimated to be 13.36 dB and 15.44 dB at 0.01% of the time exceeded using Laws-parsons and Marshall-Palmer regression coefficients, respectively. Furthermore, it was observed that ITU-R. P.618-11 model largely under-estimated the attenuation along the slant-paths because of its failure to account for attenuation due to the melting layer in its formulation by its assumption of constant rain rate; thus rendering it unsuitable for rain attenuation predictions in the tropics.

Site Diversity Technique Application on Rain Attenuation for Lagos Abayomi Isiaka O. Yussuff; Nana Hamzat; Nor Hisham Haji Khamis
Indonesian Journal of Electrical Engineering and Informatics (IJEEI) Vol 5, No 1: March 2017
Publisher : IAES Indonesian Section

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.52549/ijeei.v5i1.262

This paper studied the impact of site diversity (SD) as a fade mitigation technique on rain attenuation at 12 GHz for Lagos. SD is one of the most effective methods to overcome such large fades due to rain attenuation that takes advantage of the usually localized nature of intense rainfall by receiving the satellite downlink signal at two or more earth stations to minimize the prospect of potential diversity stations being simultaneously subjected to significant rain attenuation. One year (January to December 2011) hourly rain gauge data was sourced from the Nigerian Meteorological Agency (NIMET) for three sites (Ikeja, Ikorodu and Marina) in Lagos, Nigeria. Significant improvement in both performance and availability was observed with the application of SD technique; again, separation distance was seen to be responsible for this observed performance improvements.

Investigating Rain Attenuation Models for Satellite Links in Tropical Nigeria Abayomi Isiaka O. Yussuff; Ibukun E Koleoso; Nor Hisham Haji Khamis
Indonesian Journal of Electrical Engineering and Informatics (IJEEI) Vol 6, No 1: March 2018
Publisher : IAES Indonesian Section

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.52549/ijeei.v6i1.263

The analyses of rain models for satellite communication links of Ku and Ka bands in Lagos, Nigeria is the focus of this paper. The choice of these frequency bands was informed by the acknowledged fact that satellite signal fading and outages are predominant at those bands. The ITU-R P. 618-12 is the globally adopted prediction model; temperate, equatorial and tropical regions, inclusive. However, there was need to review the suitability of this model especially as it concerned equatorial and tropical stations. Rainfall data spanning a period of three years were collected from Nigerian Meteorological Agency (NIMET). The ITU-R P. 618-12 model along with some renowned prediction models were analyzed and their performances with the locally recorded measurement data were compared to establish their suitability or otherwise. The results obtained suggested ITU-R P. 618-12 exhibited the overall best performance at 12 GHz while DAH showed best performance at 26 GHz, even as both models underestimated and overestimated the measurement at Ku and Ka bands respectively. Again, at both frequencies, SST presented the worst performances.

Rain attenuation models at ka band for selected stations in the southwestern region of Nigeria Abayomi Isiaka Yussuff; George Tavwo; Nor Hisham Haji Khamis
Indonesian Journal of Electrical Engineering and Informatics (IJEEI) Vol 7, No 1: March 2019
Publisher : IAES Indonesian Section

Rain is the major factor in radio propagation analyses that is responsible for outage on terrestrial point-to-point and point-to-multipoint radio communication systems at millimeter wave bands. This hampers radio wave signal transmission in the tropics. This paper investigates the performance of ITU-R P.530-16, Silver Mello, Moupfouma and Abdulrahman rain attenuation prediction models using locally-sourced data. The aim is to determine their suitability or otherwise in tropical Nigeria. Two years daily rainfall data were sourced from the Nigerian Meteorological Services (NIMET) for six different stations in southwestern Nigeria. Southern Nigeria is predominantly influenced by the southwest monsoon wind from the Atlantic Ocean due to its proximity to the coastal belt. The data were analyzed using these prediction models by comparing with measured data. The ITU-R P.530-16 rain attenuation prediction model closely matched the measurement value for p≥0.1% of the time but over-estimated it at p<0.1% while Abdulrahman and Silver Mello proposed prediction models generally over-estimated for p<0.01 of time exceeded. Overall, Abdulrahman proposed prediction model presented the best performances; it was closely followed by Silver Mello, ITU-R and Moupfouma prediction models respectively. These results further accentuate the need for urgent review of the ITU-R P.530-16 prediction model or alternatively, the development of a separate rain attenuation prediction model specifically for the stations in the tropical region.

Determination of Melting Layer Boundaries and Attenuation Evaluation in Equatorial Malaysia at Ku-Band Abayomi Isiaka Yussuff; Nor Hisham Haji Khamis
Bulletin of Electrical Engineering and Informatics Vol 3, No 4: December 2014
Publisher : Institute of Advanced Engineering and Science

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.11591/eei.v3i4.308

Upsurge in bandwidth demand in recent times for real-time data transmission have put serious constraints on satellite communication channels, leading to congestion of the lower frequency bands; necessitating migration to higher bands (Ku, Ka and V) with attendant problems such as signal fading, depolarization and attenuation due to presence of hydrometeors. There is need to separately account for attenuation due to the melting layer along the earth-space microwave links. One year data from ground-based S-band meteorological radar sourced from Kluang station of the Malaysian Meteorological Department was processed to build the vertical reflectivity of rain profile for UTM, Malaysia. Results from this work suggested that the effects of the melting layer on signal attenuation at Ku-band can be quite significant in the tropical and equatorial regions. It was estimated to be 13.36 dB and 15.44 dB at 0.01% of the time exceeded using Laws-parsons and Marshall-Palmer regression coefficients, respectively. Furthermore, it was observed that ITU-R. P.618-11 model largely under-estimated the attenuation along the slant-paths because of its failure to account for attenuation due to the melting layer in its formulation by its assumption of constant rain rate; thus rendering it unsuitable for rain attenuation predictions in the tropics.

Determination of Melting Layer Boundaries and Attenuation Evaluation in Equatorial Malaysia at Ku-Band Abayomi Isiaka Yussuff; Nor Hisham Haji Khamis
Bulletin of Electrical Engineering and Informatics Vol 3, No 4: December 2014
Publisher : Institute of Advanced Engineering and Science

Upsurge in bandwidth demand in recent times for real-time data transmission have put serious constraints on satellite communication channels, leading to congestion of the lower frequency bands; necessitating migration to higher bands (Ku, Ka and V) with attendant problems such as signal fading, depolarization and attenuation due to presence of hydrometeors. There is need to separately account for attenuation due to the melting layer along the earth-space microwave links. One year data from ground-based S-band meteorological radar sourced from Kluang station of the Malaysian Meteorological Department was processed to build the vertical reflectivity of rain profile for UTM, Malaysia. Results from this work suggested that the effects of the melting layer on signal attenuation at Ku-band can be quite significant in the tropical and equatorial regions. It was estimated to be 13.36 dB and 15.44 dB at 0.01% of the time exceeded using Laws-parsons and Marshall-Palmer regression coefficients, respectively. Furthermore, it was observed that ITU-R. P.618-11 model largely under-estimated the attenuation along the slant-paths because of its failure to account for attenuation due to the melting layer in its formulation by its assumption of constant rain rate; thus rendering it unsuitable for rain attenuation predictions in the tropics.

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