Due to the prevailing impact of rain on microwave and millimetre wave propagation in tropical climates, fade margins derived from experimental campaigns would provide more practical estimates for planning In this paper, the extent of work done on the experimental assessment of the attenuation induced by rain on practical earth-space links in Nigeria is presented The cumulative rain rate distributions derived from the instantaneous precipitation indices for propagation modelling and the estimation of fade margin is presented for Ile-Ife, Akure, Ilorin, Ota, Osogbo and Ogbomoso Results reveals the spatial variability of the point rainfall rate across these stations Although the stations engaged with measurement on rain attenuation are limited in number, preliminary results from new stations are presented, while addition data from ongoing campaigns will provide a robust indices for modelling the digital DTH links and for evaluating the performance of pre-existing models over Nigeria

http://ieeexplore.ieee.org/iel7/7269215/7283733/07283813.pdf

Review of rain attenuation measurements on earth — Space links in Nigeria

The radiocommunication sector of the International Telecommunication Union (ITU R) necessitates a 1-min integration time of rainfall rate to predict attenuation at terrestrial links and earth-space links. Since time series of rainfall that satisfies this requirement is not common, the conversion into corresponding 1-min distribution is suggested as an alternative of time series with longer integration time, T (e.g., 10-,30-,60-minutes). This research reviews existing methods for the conversion of cumulative distributions of rainfall and compares the said conversion methods. Several approaches are utilized to convert the 15-minutes rainfall rate to a 1-min rainfall rate in the tropical area of Kampung Paya Jaras. It found that Segal’s method performs the best conversion procedure overall.

Conversion of 15-Minutes to 1-Minute Rainfall Distribution Derived from Tropical Rainfall Distribution Measurement

Rain attenuation is considered as one of the main factors that influence significantly the wireless communications path at frequencies above 10 GHz. There are methods of predicting rain attenuation in different frequencies and conditions, most of these methods largely dependent on the knowledge of rainfall per minute. For this reason, several studies are published to convert rainfall from different time periods to one minute rainfall rate. In this paper, we proposed a method to convert the rain attenuation from 15-minutes to 1-minute long term rain attenuation derived from tropical terrestrial rain attenuation measurement. We implemented this method on one year 15-minutes rain attenuation over microwave links operating at 15 GHz. The analysis results show that the method can convert rain attenuation from 15-minutes to 1-minute based on the degree of the correlation coefficients.

Khalid I. AlKhedhairi

Papers

Conversion of 15-minutes to 1-minute rain attenuation derived from tropical rain attenuation measurement