Joint 3D Placement and Interference Management for Drone Small Cells

In this paper, considering a heterogeneous set of drone-mounted base stations (DBSs) that operate on the same frequency band, we optimize the 3D position of the DBSs to maximize the aggregate throughput with minimal power consumption. Given a minimum acceptable received power in the downlink, we formulate an optimization problem to guarantee the wireless coverage for all users. However, the interference between the adjacent cells with overlapping coverage areas can degrade the downlink transmission rate for users. In order to decrease the intercell interference, we formulate a novel and computationally-efficient beamforming method to alleviate the inter-cell interference between the overlapping DBSs. We find the closed-form Nash equilibrium for the beamforming vectors which results in maximum downlink transmission rate without requiring any coordination among the DBSs. This is particularly useful for the drone-based wireless network where implementing computationally-intensive protocols is not a viable option due to strict constraints over the battery of DBSs. Simulation results demonstrate the effectiveness of the proposed solution and provide valuable insights into the performance of the heterogeneous drone-based small cell networks.