# Distance Protection for Coexistence of 5G Base Station and Satellite Earth Station
## 1 Introduction
Besides, the interference signals generated and observed at the BSs are more significant than those at the UEs [3] because the equivalent isotopically radiated power of the UE is likely to be much lower than that of a BS, and the UE has a lower probability of line-of-sight (LOS) propagation towards the ES/SS [8]. In a system with the coexistence of FSS and cellular systems, we can restrain the transmission characteristics of the BSs to protect the FSS downlinks, e.g., by controlling the transmit power and/or beamforming. However, for 7, it is infeasible to restrain the ES. Figure 1: Korea’s 5G frequency allocations and their adjacent bands [1]. The existing work was mainly focused on the release of new frequency bands to support 5G rollout. Two methods were proposed in [10] to enable administrations to protect existing users in the 3.6-3.8 GHz band while allowing mobile/fixed communication networks to use them as new entrants. In addition, reference of [11] mainly analyzed different BS/ES deployment schemes, antenna configurations, and transmitter parameters, so as to utilize the characteristics of the millimeter wave frequency band and study the coexistence between cellular and satellite services. In the current coexistence schemes, passive interference mitigation techniques are often utilized as they do not require coordination with the incumbent systems. Space domain method is the most popular method and is adopted in most coexistence studies. It can be further divided into exclusion zones (i.e., distance isolation protection) and restriction zones. This scheme is based on the interference/noise (I/N) protection threshold technique, which involves a maximum permitted interference at the input to the FSS ES. A protection distance is set between the 5G systems and FSS to form an exclusion zone [2,7,8,10,12] where none of the BSs can be deployed in these exclusion zones. Additionally, restriction zones and BS transmit (Tx) power control schemes, in the restriction zone, are studied under the distance protection method. The advantages of this scheme are that the layout is simple, coexistence efficiency is high, and the scheme can be adapted to most environments. In this study, we investigate the limitations of the FSS protection methods. In most of the aforementioned methods, only a single-region deployment scenario is considered. Furthermore, in most of the proposed methods, the effects of the ES antenna elevation angle on the different protection methods have been overlooked. The techniques to determine the zones and power control schemes, with the restriction zones, are also not investigated in detail. In this work, we address these issues and propose a method to define both the exclusion and restriction zones for space domain protection. Inspired by the power control schemes used in the Citizens Broadband Radio Service (CBRS), we propose and study some interactive power control schemes in the restricted areas. The main contributions of this work are as follows:  
* Using various parameters, provided by the 3 GPP and ITU, we show that our proposed method covers all rural macrocell (RMa), urban macrocell (UMa), and urban microcell (UMi) deployment scenarios defined by 3 GPP. We further investigate the impact of the antenna pattern defined by the 3 GPP omnidirectional antenna and various 5G large-antenna arrays (i.e., 4 \(\times\) 4, 8 \(\times\) 8, and 16 \(\times\) 16). * We investigate the impact of the ES antenna elevation angle on different protection methods and consider the worst-case scenario for FSS ES protection. We further  
Figure 2: Coexistence of the FSS and cellular systems. incorporate the LOS and non-line-of-sight (NLOS) propagation conditions between the BS and ES using the 3 GPP LOS probability function. * We propose a new protection method, which combines the exclusion area and restricted area, where the BSs subjected to Tx power control scheme could be deployed. Moreover, we propose an iterative BS Tx power control scheme.