International Islamic University Malaysia Engineering Journal (Jul 2024)
Area-Based Rainfall Rate Model for Specific Attenuation in the Equatorial Region
Abstract
The advent of new telecommunication systems with large bandwidths like 5G/6G and satellites operating at higher frequency bands such as Ku, Ka-band, and even Q/V bands, has brought to the forefront the issue of rain attenuation, particularly in equatorial and tropical regions. Many existing models developed to address these inaccuracies in the rainfall rate prediction rely on a single rain gauge measurement, which still can lead to inaccuracy when the model is generalized for a larger area. This research, therefore, is of utmost importance as it aims to develop an area-based rainfall rate model using multiple rain gauges spread across many locations in a specific area. The area of focus for this research is the Klang Valley area, a crucial economic territory that includes the capital city, Kuala Lumpur, in Malaysia. Five rain gauges distributed in Klang Valley were chosen to measure the rainfall rate. The rainfall rate model was then developed based on the data from these five rain gauges. The results indicate that each rain gauge's rainfall rate at R0.01% exceedance level varied greatly from 102 mm/hr to 138 mm/hr and exceeded Malaysia's recommended ITU-R at 100 mm/hr. The new model, presented herein, accounts for the variation of rainfall rate across a larger area, which can provide accurate modeling of specific attenuation and rain attenuation in the equatorial regions, thereby enhancing the reliability of communication systems. ABSTRAK: Kemunculan sistem telekomunikasi jalur lebar baru seperti 5G/6G dan satelit yang beroperasi pada jalur frekuensi tinggi seperti Ku, Ka-band, dan jalur Q/V, menyebabkan penurunan ketara amplitud gelombang akibat hujan, terutamanya di kawasan khatulistiwa dan tropika. Kebanyakan model sedia ada yang dibangunkan bagi menangani ketidak tepatan ramalan kadar hujan hanya berdasarkan pengukuran dari satu tolok hujan, ini menyebabkan ketidaktepatan model itu apabila digeneralisasikan bagi kawasan lebih luas. Oleh itu, kajian ini adalah amat penting kerana ia bertujuan bagi membangunkan model kadar hujan berasaskan kawasan menggunakan beberapa tolok hujan yang tersebar di pelbagai lokasi pada satu kawasan tertentu. Kawasan tumpuan kajian ini adalah kawasan Lembah Klang, sebuah wilayah ekonomi penting yang melingkupi ibu negara, Kuala Lumpur, Malaysia. Lima tolok hujan yang tersebar di Lembah Klang dipilih bagi mengukur kadar hujan. Model kadar hujan kemudiannya dibangunkan berdasarkan data dari kelima-lima tolok hujan ini. Dapatan menunjukkan kadar hujan R0.01% bagi lima tolok hujan adalah antara 102 mm/jam hingga 138 mm/jam dan melebihi kadar cadangan ITU-R Malaysia iaitu pada 100 mm/jam. Model baru yang mengambil kira variasi kadar hujan pada suatu kawasan lebih luas menggunakan banyak tolok hujan, di mana dapat memberikan pemodelan amplitud gelombang yang lebih tepat bagi hujan di kawasan khatulistiwa, dengan itu meningkatkan kebolehpercayaan sistem komunikasi.
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