Millimeter-Wave Radio Channels vs. Synthetic Beamwidth

High-gain narrow-beam antennas or beamformed antenna arrays will likely be used in millimeter-wave (mmWave) bands and 5G to mitigate the high path loss. Since many multipath components may be excluded by the narrow beam, the mmWave radio channel (consisting of the transmit antenna, the propagation channels, and the receive antenna) strongly depends on the beamwidth, orientation, and shape of the narrow beam. In this article, a procedure is proposed to measure and model the channels vs. synthetic beamwidth. Based on experimental data collected at 60 GHz in an indoor hallway/lobby scenario, the results show that the number of multipath components and the delay dispersion of the channel are significantly reduced by the narrow beams. In addition, the path loss can be decreased by more than 20 dB with an optimized beam-center orientation. The impact of the study on future 5G mmWave system design is discussed, including frequency reuse, antenna design, receiver design, equalization, and link budget.