Statistical investigation of refractivity and path delay in a semi temperate region

Abstract

Of the many impairments that affect quality of signals propagated at frequencies above 10 GHz, attenuation of electromagnetic waves by rain is the major impediment system engineers and designers have to overcome. Path delay and refractivity are two major factors to be considered alongside rain attenuation. Hence, this paper investigates the relationship between refractivity and path delay, and the results are used to predict path delay in Jos (09°57’N, 08°58’E, 1192m), a semi temperate region of Nigeria. In this research, daily meteorological data, collected from October 2013 to September 2014, was statistically analysed for refractivity and path delay. The values of the refractivity index was estimated with ITU-R prediction model, and path delay was computed afterwards. The statistical analysis of the least square regression model revealed that the month of July to September experienced variation as envisaged with respect to R2 and adjusted R. This variation took place in at the peak of raining season and this is attributed to rain attenuation. There was no variation observed between the variables from the month of October to June which appears to be dry season. Pearson correlation showed a strong correlation between the variable under study as all the correlation coefficient value stood above 0.99. There was correlation between refractivity and path delay as increase in refractivity led to increase in path delay and path delay is more prominent in the wet season due to impairments such rain attenuation. The result obtained in this research could be used to plan and deploy fade mitigation techniques for microwave links in the region.