Cell-Free Satellite-UAV Networks for 6G Wide-Area Internet of Things

TL;DR

This paper proposes a novel resource allocation framework for satellite-UAV networks to enhance wide-area IoT coverage in 6G, utilizing cell-free on-demand coverage and spectrum sharing.

Contribution

It introduces a process-oriented optimization framework for joint resource allocation considering UAV flight and large-scale CSI, improving efficiency and fairness.

Findings

Proposed algorithms outperform benchmarks in simulations.

Adaptive cell-free coverage effectively serves wide-area IoT.

Framework considers UAV energy and interference constraints.

Abstract

In fifth generation (5G) and beyond Internet of Things (IoT), it becomes increasingly important to serve a massive number of IoT devices outside the coverage of terrestrial cellular networks. Due to their own limitations, unmanned aerial vehicles (UAVs) and satellites need to coordinate with each other in the coverage holes of 5G, leading to a cognitive satellite-UAV network (CSUN). In this paper, we investigate multi-domain resource allocation for CSUNs consisting of a satellite and a swarm of UAVs, so as to improve the efficiency of massive access in wide areas. Particularly, the cell-free on-demand coverage is established to overcome the cost-ineffectiveness of conventional cellular architecture. Opportunistic spectrum sharing is also implemented to cope with the spectrum scarcity problem. To this end, a process-oriented optimization framework is proposed for jointly allocating subchannels, transmit power and hovering times, which considers the whole flight process of UAVs and uses only the slowly-varying large-scale channel state information (CSI). Under the on-board energy constraints of UAVs and interference temperature constraints from UAV swarm to satellite users, we present iterative multi-domain resource allocation algorithms to improve network efficiency with guaranteed user fairness. Simulation results demonstrate the superiority of the proposed algorithms. Moreover, the adaptive cell-free coverage pattern is observed, which implies a promising way to efficiently serve wide-area IoT devices in the upcoming sixth generation (6G) era.