Extreme Coverage Extension in 6G: Cooperative Non-terrestrial Network Architecture Integrating Terrestrial Networks

Abstract

Because communications in the future will be as commonplace as the air around us and as important a lifeline as power and water or even more so, the Fifth Generation (5G) Evolution and Sixth Generation (6G) mobile communications systems aim ultimately to expand coverage so that mobile services are available ubiquitously. Towards that goal, we present a new architecture for 5G Evolution and 6G that integrates non-terrestrial networks (NTNs) with terrestrial networks (TNs). The proposed cooperative NTN and TN architecture is promising as a means for expanding coverage in the future because it enables improved cost efficiency by sharing equipment and conservation of frequency resources through shared frequencies. In addition, by making full use of wireless technologies such as handover, carrier aggregation, and dual connectivity between NTNs and TNs, users can connect to 5G Evolution and 6G networks anywhere without being aware of the connection destination. In this paper, we propose a cooperative architecture that focuses on the link between NTNs and TNs, and a cooperative configuration with a particular focus on high-altitude platform stations (HAPSs). Furthermore, we present a HAPS performance evaluation using a 6G system-level simulator developed as a stepping stone for actualizing HAPS technology.