It is becoming clear that 5G wireless systems will encompass frequencies from around 500 MHz all the way to around 100 GHz. To adequately assess the performance of 5G systems in these different bands, path loss (PL) models will need to be developed across this wide frequency range. The PL models can roughly be broken into two categories, ones that have some anchor in physics, and ones that curve-match only over the data set without any physical anchor. In this paper we use both real-world measurements from 2 to 28 GHz and ray-tracing studies from 2 to 73.5 GHz, both in an urban-macro environment, to assess the prediction performance of the two PL modeling techniques. In other words, we look at how the two different PL modeling techniques perform when the PL model is applied to a prediction set which is different in distance, frequency, or environment from a measurement set where the parameters of the respective models are determined. We show that a PL model with a physical anchor point can be a better predictor of PL performance in the prediction sets while also providing a parameterization which is more stable over a substantial number of different measurement sets.

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The 5 th 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 omnidirectional 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. INDEX TERMS 5G, angular spread, beamforming, directional antenna, effective antenna pattern, millimeter wave, radio link budget.

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Abstract-Mobile communication technology has been rapidly evolving ever since its first introduction in the late 1980s. The development witnessed is not just in the refinement of the radio access techniques, but also in the progression towards offering sophisticated features and services to the mobile phone users. To fulfill this ever-growing user demand and market trends, frequency ranges in millimeter wave bands are envisioned for wireless radio transmission. To respond to this trends, the EUfunded mmMAGIC project has been launched and its main objective is to design and develop radio access techniques operating in 6 -100 GHz bands. When it comes to developing technologies for systems operating these frequency ranges, a major challenge encountered will be in terms of its radio access network integration. Unquestionably, issues at various aspects of physical layer design, channel modelling, architecture, network functions and deployment will be encountered; problems in multi-node and multi-antenna transceiver designs will surface as well. The work carried in this project will address those challenges and propose solutions; but additionally, measure its efficiency against the project specific KPIs set to meet the requirements of the operational future 5G systems. The main intention of this paper is to outline some of the challenges, more specifically to highlight the network integration challenges, and discuss some of its technical solutions. The primary purpose here is to focus towards integrated 5G technology, thereby opening further research avenues for the exploration of new and alternate frequency bands in the electromagnetic spectrum.

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The International Electrotechnical Commission (IEC) develops and validates methods for assessing radio frequency electromagnetic field (RF EMF) exposure due to base stations (BS). When the assessment is performed in-situ, it is recommended to extrapolate the maximum level of exposure from measurement of stable signals, such as broadcast signal with BS of the 5 th generation (5G) of mobile communication systems (gNodeB). A comparative statistical analysis of extrapolation methods based on nominal antenna pattern (as measured in an anechoic chamber) and effective antenna pattern (as measured in scattering environment) of gNodeB is presented in this paper. This theoretical analysis shows that extrapolation with nominal antenna pattern may lead to significant overestimation of the maximum RF EMF exposure (up to 5.4 dB) in case of scattering environment or non-line-of-sight (NLOS) conditions. This overestimation is expected to be reduced by using effective antenna pattern in order to better represent the actual propagation conditions, such as those found in urban or dense urban areas. Therefore, it is recommended to perform extrapolation of the maximum exposure based on joint modeling of antenna beam pattern and representative value of the angular spread (AS) for the targeted deployment conditions. This conclusion was obtained from the observed consistence between two different approaches for determination of effective antenna gain. The first approach assumes statistical simulations with full three-dimensional (3D) channel model, especially distribution function of AS. The second approach enables simpler calculation of the effective antenna gain in scattering environment or NLOS conditions by considering only representative values from the full range of AS distribution function. The proposed simple method, if used with representative realistic values of AS, could reduce overestimation of RF EMF exposure resulting from an extrapolation factor based on nominal antenna gains of broadcast and traffic beams.

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