Outage Probability of Ultra High Frequency and Millimeter Wave Based HetNets with NOMA

This paper studies the outage performance of heterogeneous network consisting of ultra high frequency base stations (UHBSs) and millimeter wave base stations (MWBSs). Offloading to MWBS is performed based on the average received power from the base stations of the two tiers, i.e., UHBS and MWBS tier. Both the UHBS and MWBS employ non-orthogonal multiple access (NOMA) to support the users. Furthermore, the impact of the channel gain difference (CGD) between the users paired at the MWBS tier is investigated in detail. The numerical results show that offloading to MWBS achieves significant improvement in the outage probability of the offloaded user. In addition, offloading to MWBS tier also improves the outage performance at the UHBS tier. Besides, it is observed that the CGD between the paired users at the MWBS tier plays a vital role in the outage performance of the offloaded user. The analytical results are verified using Monte Carlo simulations.