Free space optics/millimeter-wave based vertical and horizontal terrestrial backhaul network for 5G

The exponential increase of mobile users and high-speed data driven applications, along with the demand for IoT based services have resulted in a significant congestions in cellular backhaul network. An essential feature requirement for 5G backhaul networks is their ultimate capacity to handle not only human centric traffic, but also machine centric traffic including interconnected vehicles, machines and networks. The hybrid concept of Free Space Optics/Millimeter-Wave technology emerges as a suitable complementary solution platform for next-generation communication networks. In this paper, we have investigated the feasibility of ground station backhaul network. In this approach, a flying network platforms passage the backhaul traffic between the access and the core networks via point-to-point RF/FSO links. We use numerical and analytical results to analyze the performance of the proposed free space optics/millimeter-wave based vertical and horizontal terrestrial backhaul network under different adverse weather conditions, such as the atmospheric turbulence and attenuation. The detrimental effects such as longitudinal pulse broadening of the signal (which is a major reason behind group velocity dispersion (GVD)) and misalignment between the transmitter and the receiver (which is the reason behind pointing errors) are also included in this study. Taking into account these effects, based on Meijer G-function a closed-form analytical expression is derived. The performance is analyzed in terms of probability of fade, threshold and outage probability using receiver diversity over gamma-gamma channel model. These results are useful in designing and deploying a RF/FSO vertical and horizontal backhaul link for 5G communication system.