Performance of On-Off Keying Modulation for Free Space Optics Communication

Abstract

One way to support the large need for information services is by building reliable network architectures such as optical networks. The challenge faced in providing an optical network is the process of deploying cables that can change the spatial layout of an area. An alternative solution of that problem is by applying the concept of optical wireless communication such as Free Space Optics. The application of optical wireless communication is affected by barriers between transmitter and receiver. This study focuses on weather factors and atmospheric turbulence factors that affect network performances of Free Space Optics measured by Bit Error Rate (BER) values using Signal-to-Noise Ratio (SNR) calculations. SNR calculation is based on the On - Off Keying modulation scheme which is divided into two, NRZ - OOK and RZ - OOK. In addition, the use of different wavelengths between 690, 780, 850, and 1550 nm will be compared to find out the factor of wavelength selection to the value of BER obtained. The results of this study indicate that the use of the RZ-OOK modulation scheme gives around 1010 lower BER value than NRZ-OOK in fog conditions. The wavelength of 1550 nm is very suitable for FSO technology because the BER value is around 1050 lower than the other wavelengths. The difference is very significant. Network implementation in accordance with the parameters used in this study can only be implemented in the range of 0 – 1.2 km to get acceptable BER which is correlated to optical communication standard