A Seamless Gbps Hybrid FSO/THz Communication System with Intelligent Switching: Experiment and Analysis

Abstract The advancement of hybrid free-space optical/radio frequency (FSO/RF) communication holds promise in improving link reliability and resilience against diverse weather conditions. However, the limited data rates of conventional RF bands, typically in the range of several Mbps, restrict the performance of high-speed wireless systems. To address this challenge, we replace the low-rate RF link with a Gbps-level Terahertz (THz) communication link, resulting in a hybrid FSO/THz (140GHz/1550nm) communication system. Specifically, in the experiment with a 1m*1m*1m fog chamber with variable visibility, a seamless data transmission of 10Gbps(FSO)/1.6Gbps(THz) over a 20m distance with no outage is demonstrated. Moreover, to facilitate efficient decision-making between FSO and THz links, we propose an intelligent switching strategy based on a deep neural network, implemented on a field-programmable gate arrays (FPGAs) using the PYNQ framework. FPGAs offer a compact and energy-efficient solution, making them suitable for deploying machine learning models in resource-constrained environments. This approach ensures efficient link selection and maintains continuous connectivity without any outage.