European Journal of Mathematics and Computer Science Vol. 2 No. 2, 2015 ISSN 2059-9951 Progressive Academic Publishing, UK Page 17 www.idpublications.org DETERMINATION OF THE DOMINANT FADING AND THE EFFECTIVE FADING FOR THE RAIN ZONES IN THE ITU-R P.838-3 RECOMMENDATION Ononiwu, Gordon Department of Electrical/Electronic Engineering Federal university Of Technology Owerri, NIGERIA Simeon Ozuomba Department of Electrical/Electronic and Computer Engineering University of Uyo, AkwaIbom NIGERIA Constance Kalu Department of Electrical/Electronic and Computer Engineering University of Uyo, AkwaIbom NIGERIA ABSTRACT The International Telecommunication Union (ITU) published well-tested models and data set for the prediction of fading (or attenuation) due to multipath and rain based on measurements on radio links across the globe. In respect of rain attenuation, ITU released ITU-R PN.837-1 recommendation in which ITU split the globe into 15 regions according to precipitation intensity. In this paper, a web application was developed to study the variation of rain attenuation, multipath attenuation, dominant attenuation and the effective fading experiencedbyterrestrial line of sight microwave links in any of the 15 ITU rain zones. The web application do generate tables and graph plots for the variation of the dominant fading and the effective fading with respect to frequency, link percentage availability, path inclination and point refractivity gradient. The web application was developed with PHP scripting language, MySQL database management system and then hosted online using apache web server. Sample computations were carried out for microwave frequencies in rain zone N which can be found in some parts of Nigeria. Rain and multipath attenuation data were obtained from ITU published data.In all, the result obtained in the paper showed that rain attenuation is the dominant fading for higher frequencies whereas, multipath fading do dominate at the lower frequencies. The frequency at which the transition from dominant multipath fading to dominant rain fading is not fixed. Rather, the turning point depends on different link parameter combinations. The results obtained in the paper showed how changes in link parameters like the link’s percentage availability, the path’s point refractivity index and the path inclination , can affect the frequency at which the dominant fading in a given rain zone transit from multipath fading to rain fading. Keywords: Microwave Communication, Communication Link, Line Of Sight Microwave Communication, Rain Attenuation, Multipath Attenuation, Dominant Attenuation, Effective Attenuation. Web Application. INTRODUCTION Over the years, microwave communication links, including terrestrial and Earth-Space satellite links, operating at frequency band of 30-300 GHz, offer the large bandwidth and high capacity required for contemporary applications such as multimedia services. Furthermore, increasing number of users and growing complexity of multimedia have driven a demand for capacity that has pressured regulators to explore higher frequency bands for larger bandwidth. However, most of the atmospheric fade mechanisms are frequency dependent, and higher frequencies are usually associated with higher losses. Studies have found that, apart from free space loss, rain attenuation and multipath fading are major impairments in terrestrial microwave communication systems. Fortunately, research findings indicate that rain attenuation and multipath fading are independent events – they are approximately mutually exclusive. The mutual relation between rain and multipath attenuation, rules out the possibility that the link could be affected by both types of