Utilization of aerial heterogeneous cellular networks: Signal-to-interference ratio analysis

As a component of future communication networks, aerial telecommunication platforms are a promising solution to meet surging traffic demands. These platforms can be used as aerial base stations (ABSs) to build an aerial heterogeneous network architecture. In this study, we explore the promising utilization of high- and low-altitude platforms (HAPs and LAPs) working on the same network as macrocells and femtocells, respectively. First, using stochastic geometry, we determine the probability of each user being associated with either a HAP or a LAP. The association probability is used for deriving the cell load of ABSs. Next, we derive the outage probability of a typical user in a certain tier that is equivalent to the downlink signal-to-interference ratio cumulative distribution function in aerial heterogeneous cellular networks. Moreover, we propose a dynamic placement and sizing algorithm for cells established by LAPs to achieve load balancing and enhance the overall quality of service for users inside the coverage of a HAP. Our simulation results show that the algorithm provides considerable gains over static aerial cellular networks. Furthermore, we derive the coverage probability of a target receiver when the downlink paths are correlated or uncorrelated. The results demonstrate the impact of the difference in elevation angles between HAPs and LAPs on the coverage probability of the target receiver.