# Modeling of Downlink Interference in Massive MIMO 5G Macro-Cell +
## 1 Introduction
The second group is the so-called intentional interference (i.e., jamming) mainly used in the military or security to disrupt enemy communication systems or counteract radio systems in a protected area (i.e., electromagnetic curtain [11]), e.g., in airports, buildings, and infrastructure of strategic importance. Examples of jamming 5G systems are presented in [12; 13]. The remainder of the paper focuses on non-intentional interferences. The interference subject in communication systems, in particular in 5G systems, is widely represented in the literature. Works in this area focus on the three following topics:  
* interference cancelation, mitigation, awareness, and management methods,
* interference modeling and assessment methods,
* interference estimation and measurement methods. Software-based algorithms and hardware solutions that are implemented in BS and UE belong to the first method group. Papers focusing on this topic present novel solutions, usually based on simulation analysis, e.g., [14; 15; 16; 17; 18; 19]. The purpose of these methods is to increase the efficiency of devices and networks and make better use of radio resources. Various modeling methods are used in interference evaluation. They are usually based on energetic assessment of the received signals. However, interference level analysis may take different aspects into account. In this case, the important aspects influencing the received signal form have a crucial value in the faithful reflection of the modeled issue in relation to the real situation. These aspects include, first of all, the channel model, as well as the parameters and characteristics of antenna systems. The possibility of considering environment nature and propagation conditions, as well as the appropriate reflection of angular dispersions affecting the received signal powers, should be taken into account when choosing a channel model. On the other hand, considering the parameters and patterns of antenna systems is of crucial importance, especially in the analysis of 5G spatially multiplexing systems, including those ensuring beamforming (e.g., with the mMIMO system). Modeling methods are used to evaluate existing systems or new solutions (e.g., new mitigation algorithm) and, in particular, to evaluate inter- and intra-system electromagnetic compatibility, coexistence of 5G with other systems (e.g., fixed satellite services (FSS) [20; 21], radars [22], long term evolution (LTE) [23], etc.) or to assess 5G network/system efficiency under occurring interference [24]. For 5G systems, intra-system interference (also called self-interference) analysis concerns, i.e., inter-cell [16; 17; 18; 19] or inter-beam (or intra-cell) [17; 24] interferences. In this case, we would like to note that most of the works available in the literature focus on inter-cell rather than inter-beam interference analysis. These methods are usually used in the network design and planning stages. This paper focuses on this group method for modeling and evaluating inter-beam interference in 5G massive-MIMO systems. The last group of research and scientific works focuses on interference measurements in real environments for existing systems and networks, e.g., [23; 25; 26]. In this paper, we present a novel approach for assessing the interference level in a downlink (DL) that arises as a result of using a multi-beam antenna system in 5G BS (gNodeB), which is based on a multi-elliptical propagation model (MPM) [27]. Simulation results of the DL SIR obtained with the use of the MPM were compared with simulation results of the commonly used 3 rd Generation Partnership Project (3 GPP) channel model [28]. Simulations have been performed for realistic beam patterns of mMIMO antenna systems [29] and parameters of 5G networks determined by the 3 GPP and International Telecommunication Union (ITU) [30]. These assumptions indicate the originality of the obtained results and the MPM approach for determining the interference level from undesirable beams, i.e., interfering beams of the antenna system.