5G Cellular and Fixed Satellite Service Spectrum Coexistence in C-Band

The C-Band (3.4 - 4.2 GHz) is a cornerstone for many satellite services including Fixed Satellite Service (FSS), in particular above 3.6 GHz. The large geographic coverage of C-band satellite beams represents a cost-effective communication solution, while its robustness to weather impairments makes C-band the most suitable band to guarantee high service availability. On the other hand, C-band has long been a top candidate for the deployment of 5G-cellular systems because it is a mid-band spectrum, blending the signal reach of lower bands with the capacity of higher bands. The potential assignment of C-band to the 5G cellular systems is seen as a threat by the satellite operators, who are concerned about the interference that the 5G-cellular system may cause to their services, potentially leading to service interruption and causing a serious economic impact. This paper presents the interference studies of 5G cellular systems operating in the below 6 GHz band in both the adjacent channel and co-channel scenarios. We present a detailed analysis for both 5G-celullar downlink and uplink, considering the impact of out-of-band emissions, potential Low-Noise Block (LNB) saturation at the FSS Earth station receiver and the consequences of the deployment of Active Antenna Systems (AAS) in the terrestrial Base Stations (BSs). The outcomes of this paper aim to shed some light to spectrum regulators and other related stakeholders regarding the impact of the future deployment of 5G-cellular systems in the FSS Earth station receivers operating in C-band. The paper also propose and evaluates potential techniques that can be applied to facilitate the coexistence of both systems, e.g. switching off critical emitters or backing-off their transmit power.