ABSTRACK
Free Space Optic (FSO) is an alternative communication technology that utilizes light as a transmission medium through free space, without requiring cables or radio frequencies. This technology offers advantages such as high bandwidth, immunity to electromagnetic interference, no need for spectrum licensing, and relatively low implementation costs since it does not require complex civil infrastructure. The International Telecommunication Union (ITU) regulates the electromagnetic spectrum up to 3 THz, which includes standards for FSO devices used and traded in Indonesia. Although FSO provides an effective solution for communication networks, its implementation in Indonesia still faces various challenges, particularly in terms of regulations and environmental conditions. Factors such as atmospheric conditions (rain, fog, and air pollution) can affect the performance of optical signal transmission. Therefore, this study examines the technical and regulatory aspects of implementing FSO as a backup link in Indonesia. This research analyzes the reliability of FSO systems by evaluating technical parameters such as Bit Error Rate (BER) and assessing the effectiveness of coherent detection SNR in improving signal quality. In addition, a regulatory review is conducted by comparing national and international standards to ensure the compatibility of FSO implementation with Indonesia’s telecommunications policies. The results of this study are expected to provide recommendations for the government and communication service providers in adopting FSO technology optimally, thereby supporting the development of a more efficient and widespread telecommunications infrastructure. The study evaluates the reliability of the FSO system by analyzing technical parameters such as Bit Error Rate (BER) and testing the effectiveness of coherent detection SNR in enhancing signal quality. Simulation results indicate that before vii applying coherent detection, under clear atmospheric conditions, BER for QPSK reaches 1.8x10?9 with an SNR of 29 dB. However, under dense fog conditions, BER increases drastically to 10?2 with an SNR of 5 dB. In certain distances, under foggy, heavy rain, and light rain conditions, BER becomes unreadable (NaN - Not a Number) due to extremely low SNR values, reaching -89 dB. After implementing coherent detection SNR, significant improvements were observed. Under clear conditions, BER improved to 10?12 with SNR increasing to 53 dB. Meanwhile, in dense fog conditions, BER improved to 10?9with SNR reaching 35 dB, along with improvements in other weather conditions. This technique has proven to enhance system reliability by improving signal detection and mitigating atmospheric disturbances affecting communication quality. Besides the technical analysis, a regulatory review was conducted by comparing national and international standards to ensure the alignment of FSO implementation with Indonesia’s telecommunications policies. The findings of this study are expected to provide recommendations for the government and communication service providers in adopting FSO technology optimally, thereby supporting the development of a more efficient and widespread telecommunications infrastructure.
Keywords: Free Space Optic (FSO), International Telecommunication Union (ITU), Bit Error Rate (BER), Coherent Detection SNR, Telecommunications Infrastructure