Spatial reuse model for mmWave frequencies in ultra dense small-cells networks

With the exponential growth of demand in terms of traffic and data rates, one of the most promising potential features of the fifth generation (5G) of mobile network is the use of the millimeter-wave (mmWave) frequency bands. Although the available bandwidth in the mmWave frequency is significantly large, high frequencies pose several challenges in term of propagation loss, hence suitable models for these frequencies use are needed. Due to significant pathloss, the higher mmWave bands are better suited to the operation of short ranged small cells, while the lower frequency bands are appropriate for outdoors users. We propose in this paper, a spatial frequency reuse model for two-tier ultra-dense networks, where a dedicated band is allocated to inner and outer regions of macrocells and small-cells in order to properly exploit the advantages and limits of the mmWave frequencies. The performance of this scheme are evaluated both analytically in terms of coverage probability, and through system-simulation in terms of achieved throughput, and compared to traditional microwave systems and mmWave models with no reuse. We reach an average of 20% of coverage gain with more than 70% of the users having a throughput greater than 500 Mbps and nearly 40% greater than the target 1 Gbps.