On the performance of multi-tier space-air-ground integrated network exploiting mmWave and THz capabilities for 6G communication

Ubiquitous coverage and high data rate-based connectivity have become a necessity nowadays. Despite the technological advancements, reliable and efficient communication is yet dependent on infrastructure availability. In this regard, non-terrestrial networks (NTNs) have gained significant attention to complement the terrestrial communication. In addition, the millimeter wave (mmWave) and Terahertz (THz) communication are perceived as the potential solution to overcome the looming capacity crunch. Targeting the sixth generation (6G) horizon, in this paper, we propose a downlink multitier space-air-ground integrated network (SAGIN) comprising mmWave-enabled non-terrestrial entities, i.e., satellites (SATs) and high-altitude platforms (HAPs), for complementing the terrestrial THz-enabled small-cell base stations (SBSs). We analyze the performance of the proposed SAGIN architecture against association probability, network capacity, and outage probability. Our extensive simulation results validate the significance of NTNs to aid terrestrial networks to provide high data rates and uninterrupted coverage.