2011 International Conference on Electrical Engineering and Informatics 17-19 July 2011, Bandung, Indonesia Analysis of the Effect of Rainfall Intensity in Jakarta and Tangerang to the Performance of Free Space Optics Communication System Riberty W.L. Bouna and Henri P. Uranus Graduate Program in Electrical Engineering, University of Pelita Harapan Plaza Semanggi, JL. Jend.Sudirman Kav 50, Jakarta 12930, Indonesia. ri_berty@yahoo.com h.p.uranus@staff.uph.edu Abstract– Free Space Optics (FSO) or optical wireless communications is an optical communication technology that uses transmission of light in free space to transmit data between two points. Similar to fiber optics, FSO communications offer enormous data capacity. This paper reports the measurement of light attenuation by typical rainfall in Jakarta area, especially in Slipi. An empirical model developed using the measurement results was then used to examine the performance of fictitious FSO systems which were assumed to be installed in buildings at Pacific Place, Jakarta and UPH Karawaci Campus, Tangerang through evaluation of loss, attenuation, and BER under typical local tropical rainy season using the data of BMKG (Indonesian Meteorology, Climatology, and Geophysics Body). The results show that from January to April 2010, the FSO system between two buildings at Pacific Place will have a BER which fluctuated between 10 -13 (without rain) and 4.4 x10 -9 (heavy rain, dated April 5, 2010). Meanwhile, the system between Building B and Building D, in UPH Karawaci Campus will have a BER which fluctuated between 10 -13 (without rain) and 4.8 x 10 -8 (heavy rain, dated March 8, 2010). Those figures indicate that typical FSO system performs very well in those area even under typical tropical rainy season. Keywords– Light absorption by the intensity of rainfall, attenuation, BER and S/N of FSO system. I. INTRODUCTION One of requirements of modern society is the availability of data networks. In the early stages of development of communication technology, the most common transmission media is copper wire. However, because the copper wire is a fixed line, in many cases it was replaced by wireless communication using radio frequency. One alternative is a wireless system that uses light as the carrier. The wavelength used is typically infrared, so that it can make use of devices developed for fiber optic systems [1]. The system is called an optical wireless communication or free space optics (FSO) systems. FSO systems offer several advantages, among others are the relatively large capacity, less expensive than radio wireless systems of the same performance, and because using light, do not require frequency licensing [1]. The biggest challenge of FSO system is the light attenuation due to weather. This paper studied the rainfall in Jakarta and Tangerang, and its effects to the data transmission between two FSO transceivers. Based on empirical model developed from measurements performed in Slipi, Jakarta and rainfall data released by BMKG (Badan Meteorologi, Klimatologi, dan Geofisika; Indonesian Meteorology, Climatology and Geophysics Body), we studied the performance of FSO systems in Jakarta and Tangerang. We believe that, the study is of importance for evaluating the performance of typical FSO in Indonesian tropical weather. Fig. 1 Photos of measurement set-up of light attenuation by rainfall I1 - 3 978-1-4577-0752-0/11/$26.00 ©2011 IEEE