Measurement, Evaluation, and Performance of 60 Gbps DPSK WDM Free Space Optical Link for Haze and Rain Conditions

Free space optics (FSO) is a novel wireless optical communication technique. It has proven several advantages over traditional communication techniques and overcomes the issue of last-mile connectivity. The performance measure factor bit error rate (BER) and quality (Q) factor of a free space optic link are mainly affected due to weather conditions. Ultimately, it has an impact on the data rate and the maximum range. The FSO connection is studied under different weather circumstances such as extremely heavy haze, light rain, and heavy rain, and various characteristics such as Q factor and BER maximum range are measured. This paper proposes an evaluation of four-channel WDM system with Mach-Zehnder modulator and design of 240 Gbps (60 Gbps x 4 channel) DPSK modulated WDM FSO link, working in O, E, L, U bands under heavy haze and heavy rain weather conditions for a range of 18 km and 5.8 km. The proposed four channel system is working in the operational bands O, E, L, and U. Furthermore, the system can be designed for more number of channels 8, 16, 32, and 64 Channels. The co-channel interference at such higher data rates will limit the number of channels. The measured values for the max Q factor are 7.67, and BER is 8.36 e-0(15). The proposed link has enhanced performance in terms of range and data rate for heavy rain and heavy haze condition.