# Modeling of Downlink Interference in Massive MIMO 5G Macro-Cell +
## 5 Conclusions  
This paper focused on modeling the interference of radio DLs arising in multi-beam antenna systems, which helps to assess the performance of the mMIMO in 5G cells at network planning and optimization stages. Furthermore, we presented the comparison of two modeling methodologies that allow the DL intra-cell interference and SIR to be estimated. The presented methods of SIR evaluation were based on simulation studies. In this case, the MPM and 3 GPP channel model, combined with realistic beam patterns and simulation parameters of the 3 GPP/ITU, were used. The obtained results shown the effectiveness of the novel approach using the MPM in determining the minimum angular separation in multi-beam antenna arrays that provided an acceptable interference level compared with the simulation results obtained by the 3 GPP channel model. Unlike the methods of inter-beam interference assessment used so far, the MPM solution proposed in this paper considers the phenomenon of the angular dispersion of received power. The ability to adapt the MPM geometric structure to actual transmission conditions minimizes SIR evaluation errors. In this, the presented novel MPM approach's utilization for assessing the interference level at the receiving point could be considered as an efficient method for the determination of the required minimum angular separation between co-channel beams of mMIMO cells. Therefore, the MPM approach might help maximize spectral efficiency in 5G networks under deployment. This statement is justified as for 80% of simulated samples of the intra-cell SIR the difference between results obtained by the MPM and commonly used 3 GPP model was within 2 dB or less for LOS conditions of the UMa network operating in a 3.5 GHz band. In the case of NLOS, the difference between both channel models is more visible. This may result from the fact that in the MPM, the scatterer locations are limited to the defined multi-elliptical structure related to the PDP. Conversely, in the statistical 3 GPP channel model, the potential positions of the scatterers are characterized by more spatial variation. Further studies are being conducted in which the MPM effectiveness is assessed in mmWave simulation scenarios with both DL and uplink.  
Conceptualization, K.B., J.M.K. and C.Z.; methodology, K.B., J.M.K. and C.Z.; software, K.B. and J.M.K.; validation, K.B. and J.M.K.; formal analysis, C.Z.; investigation, K.B. and J.M.K.; sources, K.B. and J.M.K.; data curation, K.B. and J.M.K.; writing--original draft preparation, K.B., J.M.K., C.Z. and L.N.; writing--review and editing, K.B., J.M.K., C.Z. and L.N.; visualization, J.M.K.; supervision, C.Z.; project administration, J.M.K. and C.Z.; funding acquisition, J.M.K. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the POLISH MINISTRY OF DEFENSE, grant number GBMON/13-996/2018/WAT on \"Basic research in sensor technology field using innovative data processing methods\" and grant number UGB/22-730/2020/WAT on \"Impact of various propagation conditions on effectiveness of wireless communication and electronic warfare systems\".  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data presented in this study are available on request from the corresponding author. The data are not publicly available due to project restrictions.  
**Acknowledgments:** The authors would like to express their great appreciation to the Remote Sensing Editors and anonymous Reviewers for their valuable suggestions, which have improved the quality of the paper.  
**Conflicts of Interest:** The authors declare no conflict of interest.