Cooperative Strategies for {UAV}-Enabled Small Cell Networks Sharing Unlicensed Spectrum

TL;DR

This paper proposes a cooperative drone-assisted cellular network that optimizes 3D drone placement and resource allocation to improve terminal throughput while managing interference in unlicensed spectrum.

Contribution

It introduces a novel cooperative decode-forward protocol for DBSs and formulates an optimization framework for joint 3D placement and resource management.

Findings

The proposed algorithm effectively improves terminal throughput.

Utilizing DBSs provides significant performance gains.

The method maintains interference levels within acceptable bounds.

Abstract

In this paper, we study an aerial drone base station (DBS) assisted cellular network that consists of a single ground macro base station (MBS), multiple DBSs, and multiple ground terminals (GT). We assume that the MBS transmits to the DBSs and the GTs in the licensed band while the DBSs use a separate unlicensed band (e.g. Wi-Fi) to transmit to the GTs. For the utilization of the DBSs, we propose a cooperative decode--forward (DF) protocol in which multiple DBSs assist the terminals simultaneously while maintaining a predetermined interference level on the coexisting unlicensed band users. For our network setup, we formulate a joint optimization problem for minimizing the aggregate gap between the target rates and the throughputs of terminals by optimizing over the 3D positions of the DBSs and the resources (power, time, bandwidth) of the network. To solve the optimization problem, we propose an efficient nested structured algorithm based on particle swarm optimization and convex optimization methods. Extensive numerical evaluations of the proposed algorithm is performed considering various aspects to demonstrate the performance of our algorithm and the gain for utilizing DBSs.