Handling Interference in Integrated HAPS-Terrestrial Networks Through Radio Resource Management

Abstract

Located in the stratospheric layer of Earth's atmosphere, the high altitude platform station (HAPS) is a promising network infrastructure, which can bring significant advantages to sixth-generation (6G) and beyond wireless communications systems by forming vertical heterogeneous networks (vHetNets). However, if not dealt with properly, integrated networks suffer from a number of performance challenges compared to standalone networks. In harmonized integrated networks, where different tiers share the same frequency spectrum, interference is an important challenge to be addressed. This work focuses on an integrated HAPSterrestrial network, serving users in an overlapped urban geographic area, and formulates a fairness optimization problem, aiming to maximize the minimum spectral efficiency (SE) of the network. Due to the highly nonconvex nature of the formulated problem, we develop a fast converging iterative algorithm that designs the massive multiple-input multiple-output (mMIMO) beamforming weights and the user association scheme such that the propagated inter-and intra-tier interference is managed. Simulation results demonstrate the proposed algorithm's superiority over standalone terrestrial networks and baseline algorithms.

Self-Evolving Integrated Vertical Heterogeneous Networks

“…Control and management of this interference is a crucial task in enabling the self-evolving capability by supporting full integration and coordination across tiers. To avoid this interference, one approach is that all base stations can be collocated on the same tier and exploited for uplink or downlink connections [108]. This feature is supported in aerial nodes, such as HAPS, and unlike terrestrial cellular networks, can allow the exchange of information on the interference conditions within the service area between base stations with no signaling overhead.…”