HAPS-Enabled 6G TN-NTNs: Achieving Superior QoS-Energy Tradeoffs Compared with LEO

Abstract

Non-terrestrial networks (NTNs) can reduce terrestrial energy consumption by absorbing traffic from lightly loaded base stations (BSs), allowing them to be switched off. We study how the NTN platform shapes this quality of service (QoS) energy trade-off, comparing one low Earth orbit (LEO) satellite at 600 km with 1, 4, and 9 high-altitude platform stations (HAPS) at 20 km. Using a traffic-aware framework that jointly optimizes user association, NTN bandwidth, and terrestrial BS activation over a 24-hour traffic profile, we show that 9 HAPS reduce terrestrial energy consumption by 34.1%, versus 26.0% for LEO. At the same QoS, 9 HAPS save 20% more terrestrial energy than LEO while improving cell-edge throughput.