An improved ITU-R rain attenuation prediction model over terrestrial microwave links in tropical region

Rafiqul Md Islam,Tharek A Rahman,Yusuf A Abdulrahman

doi:10.1186/1687-1499-2012-189

Abstract

AbstractAn improved approach of predicting rain attenuation cumulative distribution (CD) over terrestrial microwave links operating in tropical regions is presented in this article. The proposed method offers a better extrapolation approach for determining the values of rain attenuation at different exceedance probability from the measured attenuation at 0.01% of the time. The experimental data consist of measured rainfall rates and rain attenuation over six geographically spread DIGI MINI-LINKs operating at 15 GHz in Malaysia. A new set of numerical coefficients was derived for improved rain attenuation CD predictions in the Malaysian tropical climate. In order to test the applicability of the proposed extrapolation method, a validation was performed using rain rate and rain attenuation measurements from five Brazilian and seven Nigerian tropical locations. When tested against measurements, the proposed method seems to provide a significant improvement over the current extrapolation method adopted by ITU-R Recommendations P.530-14, for the prediction of rain attenuation CD over tropical regions.

Highlights

Heavy traffic in the C-band has forced telecommunications service providers to migrate to higher frequency bands, which have enough band-widths to support numerous users
Even though ITU-R has provided a methodological approach for predicting the rain attenuation on any terrestrial radio link, the model does not perform well in tropical climates because it is based on data collected from temperate regions [2,3]
A modification is proposed to the extrapolation formula used in the ITU-R method, based on the results presented in Figures 1, 2, and 3

Summary

Introduction

Heavy traffic in the C-band has forced telecommunications service providers to migrate to higher frequency bands, which have enough band-widths to support numerous users. Rain-induced attenuation is the major issue at frequencies above 10 GHz, more especially in tropical regions which experience heavier rainfall intensities [1]. Rain attenuation plays significant role in the design of terrestrial and Earth-satellite radio links especially at frequencies above 10 GHz [2]. Even though ITU-R has provided a methodological approach for predicting the rain attenuation on any terrestrial radio link, the model does not perform well in tropical climates because it is based on data collected from temperate regions [2,3]. The rain attenuation A%p exceeded at %p of time is calculated as follows: A%p = γ%pdeff (1a) γ%p = kRα%P (1b) deff = dr%p (1c) where R%p (mm/h) is the rain rate exceeded at %p of the time, r%p is the path reduction factor at %p of the time, d(km) is the link path length.

Methods

Results

Conclusion