Throughput Performance of Multiband HetNets using Sectorized Picocells with 3D Beamforming at 28 GHz Band

Heterogeneous networks (HetNets) which combine with macrocells and picocells in the same coverage are key technology to increase the system capacity. The use of millimeter wave (mmWave) bands is also expected to achieve higher data rates because it promises a vast amount of signal bandwidth. Therefore, multiband HetNets with picocells operating at mmWave band have attracted a lot of attention to increase the system capacity and/or achieve higher data rate in fifth-generation (5G) mobile systems and beyond. To compensate for the path-loss on mmWave, we propose sectorized picocells with three-dimensional beamforming (3D-BF) in multiband HetNets, however conventional picocell is formed by omnicell. We investigate the average and 5-percentile user throughput of the HetNet using the three-sector picocells with 3D-BF operating at 28 GHz band, whose bandwidth is 10 times wider than that of the macrocell operating at 2 GHz. Using system-level computer simulations, we confirmed that the HetNet using three-sector picocells can improve the average and 5-percentile user throughput by approximately 2.1 and 1.8 times compared with that using conventional omni picocells, respectively. We also clarified that the HetNet using three-sector picocells with 3D-BF can increase the use rate of high-order modulation scheme in the downlink modulation and coding scheme, compared with that using conventional omni picocells.