Int. J. Electron. Commun. (AEÜ) 68 (2014) 33–36 Contents lists available at ScienceDirect International Journal of Electronics and Communications (AEÜ) jo ur nal ho me page: www.elsevier.com/locate/aeue Time series prediction of rain attenuation from rain rate measurement using synthetic storm technique for a tropical location Dalia Das a , Animesh Maitra b,∗ a Department of Electronics and Telecommunication Engineering, Meghnad Saha Institute of Technology, Techno Complex, Madurdaha, Kolkata 700 150, India b S.K. Mitra Centre for Research in Space Environment, Institute of Radio Physics and Electronics, University of Calcutta, Kolkata 700 009, India a r t i c l e i n f o Article history: Received 16 December 2012 Accepted 15 July 2013 Keywords: Rain attenuation Synthetic storm technique Time series prediction Tropical location a b s t r a c t A comparison of measured attenuation series with the attenuation series obtained from rain rate mea- surement by using synthetic storm technique is made for Ku band signal at a tropical location. Validity of the model is tested for the long-term statistics in terms of the cumulative distribution of attenuation occurrence and fade duration. Applicability of the model is also shown to be valid event-wise. It has been demonstrated that the long term statistics of predicted rain attenuation are insensitive to storm transla- tion speed. No significant differences are found when cumulative distributions of predicted attenuation values are compared for different data sampling intervals. It has been observed that there exists a good correlation between the predicted and measured values of attenuation for at least 80% of the events. © 2013 Elsevier GmbH. All rights reserved. 1. Introduction Frequencies above 10 GHz are of primary interest in satellite communication systems, since they provide larger transmission bandwidth and higher data rate. However, the use of these fre- quency bands is limited by different propagation effect mainly due to rain attenuation. If time series prediction of rain attenuation is possible, fade countermeasure techniques such as adaptive control of signal power, coding and data rate can be effectively imple- mented. The method of time series prediction for rain attenuation has been presented in [1]. Experimental data for rain attenuation to develop channel model are not always available and often they exist only for specific sites, frequencies and elevation. But a large set of rain rate data is available worldwide. As rain attenuation is strongly correlated with rain rate intensity, time series predictor of rain rate can be easily converted into rain attenuation predictor by using so-called synthetic storm technique (SST). SST has been proposed in [2] to convert instantaneous rain rate into attenua- tion under some assumption. So far, validity of the SST model is presented in terms of yearly cumulative distribution [2–5]. In [6,7] validation results are presented on an event by event basis, but only event duration and peak attenuation are compared for V band signals for temperate region. In this paper, measured rain rate series during a rain event is converted into attenuation series for the Ku band signal for a tropi- ∗ Corresponding author. Tel.: +91 9433733756; fax: +91 3323515828. E-mail address: animesh.maitra@gmail.com (A. Maitra). cal region. Time series prediction of attenuation is done during rain events using the method described in [1]. However, in the present case, SST converted attenuation values are considered as inputs instead of actual attenuation measurements. Validity of the syn- thetic storm technique is not only tested event-wise but also with long term statistics. Resemblance between measured and predicted event is also shown by calculating cross correlation coefficient. Storm translation speed suitable for our region is also selected from experimental results. 2. Experimental data Propagation measurements over an earth-space path have been carried out at Kolkata, India (22 ◦ 34 ′ N, 88 ◦ 29 ′ E), a tropical location by receiving a Ku band signal at frequency 11.172 GHz transmitted with horizontal polarization from satellite NSS-6 (geostationary at 95 ◦ E) at an elevation of 63 ◦ , since June 2004 [8]. The received sig- nal is down converted to an L-band frequency by the low noise block converter (LNBC) and fed to the spectrum analyzer that is used as the receiver for monitoring the satellite signal level. The signal level measurements are recorded with a data logger and stored in a PC. Further, the rain fall rates at the satellite receiver site have been measured simultaneously by an optical rain gauge (ORG). The dynamic ranges for rain rate and attenuation measurements are 500 mm/h and 20 dB respectively. The minimum detectable change in rainfall rate is 0.2 mm/h and rain attenuation is 0.1 dB. The recorded rain rate and attenuation data are passed through a raised square cosine filter with cutoff frequency 0.025 Hz to eliminate the scintillation effects and other fast fluctuations. In the present study, 1434-8411/$ – see front matter © 2013 Elsevier GmbH. All rights reserved. http://dx.doi.org/10.1016/j.aeue.2013.07.008