A promising way of realizing the 5th generation (5G) wireless systems is to operate 5G deployments in higher frequency bands, specifically in the millimeter wave (mmW) spectrum (30- 300 gigahertz, GHz). Access to such spectrum bands will enable future 5G wireless systems to meet the 5G requirements of peak rate greater than 10 Gbps, and cell edge rate of up to 1 Gbps. However, the emerging 5G systems will need to coexist with a number of incumbent systems in these bands. This paper provides an extensive study of co-channel coexistence of 5G in two critical mmW bands, 27.5-28.35 GHz (28 GHz) and 71-76 GHz (70 GHz) bands, where Fixed Satellite Service (FSS) and Fixed Service (FS) such as Wireless Backhaul (WB) are the predominant incumbent users. In the 28 GHz study, we show that interference from 5G into the FSS Space Stations (SSs) can be kept below the FSS interference protection criterion. We also characterize the minimum separation distance between the FSS Earth Stations (ESs) and 5G in order to protect the 5G system from interference due to the ESs transmissions. In the 70 GHz study, we show that the 5G-to-FS interference could be a potential issue in certain scenarios, but we introduce techniques to significantly suppress this interference, while maintaining acceptable performance of the 5G systems. For each study, we suggest appropriate deployment strategies for a 5G system based on our results.

This paper presents a methodology for assessing co-channel interference that arises in multi-beam transmitting and receiving antennas used in fifth-generation (5G) systems. This evaluation is essential for minimizing spectral resources, which allows for using the same frequency bands in angularly separated antenna beams of a 5G-based station (gNodeB). In the developed methodology, a multi-ellipsoidal propagation model (MPM) provides a mapping of the multipath propagation phenomenon and considers the directivity of antenna beams. To demonstrate the designation procedure of interference level we use simulation tests. For exemplary scenarios in downlink and uplink, we showed changes in a signal-to-interference ratio versus a separation angle between the serving (useful) and interfering beams and the distance between the gNodeB and user equipment. This evaluation is the basis for determining the minimum separation angle for which an acceptable interference level is ensured. The analysis was carried out for the lower millimeter-wave band, which is planned to use in 5G micro-cells base stations.

Multi-beam antenna systems are the basic technology used in developing fifth-generation (5G) mobile communication systems. In practical implementations of 5G networks, different approaches are used to enable a massive multiple-input-multiple-output (mMIMO) technique, including a grid of beams, zero-forcing, or eigen-based beamforming. All of these methods aim to ensure sufficient angular separation between multiple beams that serve different users. Therefore, ensuring the accurate performance evaluation of a realistic 5G network is essential. It is particularly crucial from the perspective of mMIMO implementation feasibility in given radio channel conditions at the stage of network planning and optimization before commercial deployment begins. This paper presents a novel approach to assessing the impact of a multi-beam antenna system on an intra-cell interference level in a downlink, which is important for the accurate modeling and efficient usage of mMIMO in 5G cells. The presented analysis is based on geometric channel models that allow the trajectories of propagation paths to be mapped and, as a result, the angular power distribution of received signals. A multi-elliptical propagation model (MPM) is used and compared with simulation results obtained for a statistical channel model developed by the 3rd Generation Partnership Project (3GPP). Transmission characteristics of propagation environments such as power delay profile and antenna beam patterns define the geometric structure of the MPM. These characteristics were adopted based on the 3GPP standard. The obtained results show the possibility of using the presented novel MPM-based approach to model the required minimum separation angle between co-channel beams under line-of-sight (LOS) and non-LOS conditions, which allows mMIMO performance in 5G cells to be assessed. This statement is justified because for 80% of simulated samples of intra-cell signal-to-interference ratio (SIR), the difference between results obtained by the MPM and commonly used 3GPP channel model was within 2 dB or less for LOS conditions. Additionally, the MPM only needs a single instance of simulation, whereas the 3GPP channel model requires a time-consuming and computational power-consuming Monte Carlo simulation method. Simulation results of intra-cell SIR obtained this way by the MPM approach can be the basis for spectral efficiency maximization in mMIMO cells in 5G systems.

Base stations equipped with large multi-antenna systems and associated beamforming schemes provide large capacity and coverage. Massive multiple-input-multiple-output (MIMO) with beamforming was introduced as one of the enablers of 5G system performance, and this technology is evolving with the introduction of more advanced algorithms for spatial multiplexing. One of the most relevant conditions to support deployment of 5G base stations with massive MIMO is to assess realistic RF electromagnetic field exposure compliance distances leveraging the actual maximum approach introduced in IEC 62232:2022. This evaluation method takes into account the variability of traffic load and beam patterns used by the beamforming algorithm. This work investigates the impact of various beamforming schemes, like grid-of-beams, eigen-beamforming and zero-forcing, as well as various array antenna configurations on the evaluation of the power reduction factor used when implementing the actual maximum approach for RF electromagnetic field compliance assessment of massive MIMO base stations. The modelling results show that lower power reduction factors can be considered for eigen-beamforming and zero-forcing beamforming algorithms compared to grid-of-beam. The power reduction factor drop can be up to -4 dB when 8 user equipment’s are connected simultaneously.

The 5th generation of mobile communication system (5G) enables the use of millimeter wave frequency bands and beamforming with narrow-beam directional antennas for mobile communication. Accurate estimation of radio link budget which enables direct assessment of achievable cell range or maximum throughput and facilitates network parametrization before deployment is one of the most challenging problems in radio network planning. In contrast to traditional cellular systems, where omni-directional or sectoral antennas are deployed with half-power beam-width much larger than angular spread of the radio channel, the beam-width of antenna arrays assumed for 5G in sub-6GHz and millimeter wave bands can be comparable to or smaller than channel angular spread in scattering environment. Since the effective antenna pattern is determined jointly by the nominal antenna pattern and channel angular spread, it is no longer appropriate to use nominal pattern in radio link budget analysis or system level simulations. Simplified approach, where nominal pattern is assumed for all typical propagation conditions, results in overestimation of the signal power in serving links and underestimation of interference, which in consequence gives erroneous estimation of link budget and leads to unsatisfactory network design and deployment. To avoid inaccurate calculation of link budget while maintaining simplicity it is proposed to modify the simplified approach by using effective antenna patterns. On the other hand, effective antenna pattern can be further optimized by matching its half-power beam-width to the angular spread of the radio channel. It is demonstrated via simulations how to rework the radio link budget for accurate estimation of system performance in high bands for 5G and beyond, along with benefits of effective antenna pattern optimization.

Development of next generation mobile communication system (5G) is progressing rapidly. Standardization and regulatory bodies like 3 ^rd Generation Partnership Project (3GPP) or International Telecommunication Union (ITU) are working on definition of requirements which will enable global usage of 5G and ensure sufficient co-existence with previous generations of mobile communication systems like Universal Mobile Telecommunication System (UMTS) or Long Term Evolution (LTE), as well as with other users of radio spectrum like satellite or radars. One of the key factors which distinguish 5G from previous technologies is the ability to operate in radio bands not accessible for LTE, i.e. higher than 6GHz. However, worse radio propagation conditions on higher frequencies require the usage of more directional antennas with higher maximum gains to compensate higher path loss in radio link budget. Particularly important in system evaluation and coexistence studies is correct modeling of power budget of radio link with directional antennas, both serving link and interfering link, as it impacts final signal to interference and noise ratio (SINR), which is the basis of 5G requirements evaluation. In this paper authors are concentrated on the methods of system level simulation modeling of serving link and interfering link with directional antennas on both sides of the link. For assumed simulation scenarios it is shown that use of idealized antenna gain, that neglects the angle spread, leads to an overestimation of received power of serving link by around 15dB. A simple approximate evaluation method is shown to be within less than 2dB of the detailed 3D channel simulation.