System-Level Performance Evaluation for 5G mmWave Cellular Network

Cellular networks with hyper-dense deployment of small cells have been identified as the performance-optimizing architecture for fifth-generation (5G) mobile systems. A thousandfold capacity increase is projected when such networks benefit from aggressive spatial multiplexing and huge bandwidth, realizable with massive antenna arrays and millimeter-wave (mmWave) spectrum, respectively. As a precursor to the 5G projections, we show in this paper that network performance (cell capacity, user throughputs and spectral efficiency) can be significantly increased by overlaying mmWave small cells on microwave macrocells, due to the elimination of crosstier interference. This is without any increase in bandwidth or antenna configuration of legacy dense networks. Dramatic performance gains can further be achieved by employing more antenna arrays and larger bandwidth. In addition, we demonstrate that such networks are density-limited. Increasing the number of small cells per macrocell beyond the optimal cell density threshold leads to performance degradation. Adequate consideration should, therefore, be given to this limit in the design, planning and operation of cellular networks.