Analysis of Rain Effect in Free Space Optical Communication under NRZ Modulation in Two Regions of Tanzania
Florence Upendo Rashidi1, Senzota Kivaria Semakuwa2

1Florence Upendo Rashidi, Department of Telecommunications and Computer Networks, University of Dodoma, Dodoma, Tanzania.
2Senzota Kivaria Semakuwa, Department of Computing Science Studies, Mzumbe University, Mzumbe Tanzania.
Manuscript received on September 10, 2014. | Revised Manuscript Received on September 12, 2014. | Manuscript published on September 18, 2014. | PP: 13-16 | Volume-1 Issue-10, September 2014.
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Abstract: Free Space Optical (FSO) is an optical communication technology that uses light propagating in free space to transmit data between two points. In Tanzania now days the demand for higher and unlimited bandwidth for communication channel is highly required. For this case the communication through FSO is the best alternative solution than optical fiber. In this paper we are presenting the effects of different parameters to be used in Dodoma and Dar-es -Salaam when transmitting during the rain period. We designed a model of FSO system using OptiSystem to establish an FSO link by a range of 3 to 5 km and 5 to 15 km in Dodoma and Dar-es-Salaam respectively. In the FSO link we have used a Carbonneau model as rain attenuation model, while transmitting the data on NRZ modulation scheme, and reported analysis of various parameters like Bit Error rate (BER), transmission power and transmission length. The simulation results shows, the received signal power decrease while bit error rate increase when increasing transmission length and optical attenuation but is becoming less than 1 and less than 100 dBm respectively when transmitting within the selected range above. The analysis also found that using FSO for communication is better than optical fiber because it can avoid some challenges such as high cost of digging roads, impractical physical connection between transmitters and receivers and insecure of data.
Keywords: Rain Attenuation, Free Space Optical Communications, NRZ, BER.