Rework the Radio Link Budget for 5G and Beyond

5th generation of mobile communication system (5G) enables utilization of millimeter wave frequency bands and beamforming with narrow-beam directional antennas for personal mobile communication. One of the most challenging problems in 5G network planning is accurate estimation of radio link budget, which allows direct assessment of achievable cell range or maximum throughput and facilitates network parametrization before deployment. 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, 5G adopts in millimeter wave bands directional antennas whose beam-width is comparable 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 beam 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 the power in interfering links of real networks, which in consequence gives erroneous estimation of network performance and leads to unsatisfactory deployment. On the other hand, once the effective antenna pattern is determined according to propagation conditions, it can be further optimized by matching its effective half-power beam-widths to the angular spread in the radio channel. Such optimization of effective antenna pattern increases the effective gain of the antenna, which leads to improvement of overall 5G network performance. We demonstrate via simulations how to rework the radio link budget for accurate estimation of system performance in high bands for 5G and Beyond and the benefit of effective antenna pattern optimization.