Modeling of radio link budget with beamforming antennas for evaluation of 5G systems

Development of next generation mobile communication system (5G) is progressing rapidly. Standardization and regulatory bodies like 3rd 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.