A novel method for estimation of rainfall attenuation using coarse rainfall data and proposal of modified ITU-R rain model for India

Abstract

Rain attenuation becomes the prime reason for link failure at frequencies above 10 GHz. C band and Ku band are already exhausted for Indian region satellite communication and time has come to shift to next higher Ka-band. But the attenuation due to rain is very large for this band, especially for tropical country like India. This has led to the development of many rain attenuation prediction models. But to apply rainfall data in these models, fine rainfall data is required which is not available for most locations, and if available, are not for longer durations. In this paper, a novel method is described that can be used for rainfall attenuation prediction for India using coarse rainfall data, that is available from Indian Meteorological Department. Many models are available to predict the 1 min integration rainfall distribution around the world. But for Indian subcontinent, most models show large variations from actual rainfall attenuation. This paper presents estimation of rainfall attenuation for Ka-band for five different regions covering almost whole India using ITU-R model, Crane-Global model and Moupfouma model. These estimations are compared with actual measured results of previous works. The calculated rainfall rates suggest significant variances in the mean rainfall intensity or rate in mm/h. The analysis shows that the ITU-R model overestimates the rainfall intensity rates when empirical model is developed using data from Indian Meteorological Department. It is observed that ITU-R model is best suited for Indian region, but needs modifications to obtain accurate estimation for rain attenuation. Hence a new empirical model named Dafda-Maradia model for rain attenuation for India is proposed. This model is based on ITU-R model and is basically a modified ITU-R model. Here the prediction of rainfall attenuation is done from coarse rain data of 64 years (1951-2014). It is observed that there is a large decrease in the average rainfall intensity as compared to the ITU-R model. Keywords Coarse rainfall data • Dafda-Maradia model • India Meteorological Department (IMD) • Ka-band satellite • Kothyari and Garde equation • Novel method of estimation of rain attenuation

International Telecommunication Union-Radiocommunication Sector P.837-6 and P.837-7 performance to estimate Indonesian rainfall

“…Furthermore, for 1% of time exceeded, the maximum rainfall rates obtained by ITU-R P.837-6 as shown in Figure 4 Figure 4 (l) were 10, 11, 23, 25, 12 and 12, respectively. Therefore, one-minute rainfall rate from ITU-R P.837-7 was slightly larger than that of ITU-R P. 837-6, as found in mainland China [26] and India [27], consistent with Figure 1, but it was smaller than that obtained by TRMM 3A25+3B43.…”

On the Quasi-Moment-Method as a Rain Attenuation Prediction Modeling Algorithm

“…The set of functions appearing in (4) serve as basis and weighting functions as described for example, in [4]. And the problem then reduces to that of determining a set of coefficients , such that (5) satisfies (3).…”

“…AIN ATTENUATION represents a key consideration in the design of wireless terrestrial and Earth-space radiocommunication links, whose performances degrade significantly on account of severe signal scattering and absorption associated with rainfall events, when operating frequencies are greater than 10GHz; [1] - [4]. Design procedures for these links, including signal fade mitigation strategies [5], [6], routinely utilize prediction models, typically developed with the use of field measurements.…”

“…Design procedures for these links, including signal fade mitigation strategies [5], [6], routinely utilize prediction models, typically developed with the use of field measurements. Easily the most popular of such models are the ITU-R models (exemplified by [7]- [9]), which are continuously being updated, and which have been put to extensive use by the global community of researchers, [4], [10]. The ITU-R models have however, been reported in the literature, to give inaccurate attenuation prediction outcomes, especially when utilized for rain attenuation in tropical climatic zones: underestimating in some cases, [11], [12]; over-estimating in some others [4], [13]; though yielding predictions comparable with measurements in a few other cases, [10], [14].…”

A Survey of Rain Fade Models for Earth–Space Telecommunication Links—Taxonomy, Methods, and Comparative Study

“…The proper scaling mechanism regarding these parameters is yet to be devised. The ITU-R model is the most significant model that has been moderated for tropical regions by many researchers [29,[142][143][144][145][146]. However, these models do not support the scaling properties.…”