Simulation study on millimeter wave 3D beamforming systems in urban outdoor multi-cell scenarios using 3D ray tracing

Urban outdoor millimeter wave communication systems will comprise of dense cell deployment and large-sized array antennas. In this paper, a millimeter wave downlink system-level simulator operating at 73 GHz, which emulates multiple base stations (BSs) and user equipments (UEs) in an outdoor street geometry, is developed. Each BS and UE are surrounded by moving obstacles (e.g., moving cars and walking pedestrians). Two-dimensional (2D) array antennas are employed at both UE and BS to form the 3-dimensional (3D) beams to combat the severe pathloss found in the spectrum. The 3D ray tracer customized to the 3D beam patterns is implemented in the simulator using the OpenGL platform. The 3D ray tracer, in our simulator, carries out the beam alignment task and produces physical channels between UE and BS. The physical channel representation characterizes useful link statistics, e.g., link blockage and co-channel interference statistics. It is shown through the simulation study that high density BS deployment with the directional 3D beamforming enhances the link quality and decreases outage probability compared to the lower density BS deployment. However, the performance degradation caused by the co-channel interference compared to the zero-interference case is still significant. Furthermore, it is observed that high density moving obstacles deteriorate both the throughput and outage performances compared to the low density case because of the increased link blockage.