Spectrum Sharing in Integrated HAPS and Terrestrial Systems Using an Interference Canceler and Coordination

High-altitude platform stations (HAPSs) have the potential to expand the coverage of sixth-generation mobile communication systems, and several international mobile telecommunications (IMT) bands below 2.7 GHz have already been identified for HAPS service links. Because of the limited frequency resources, spectrum sharing techniques are needed to ensure that HAPSs can coexist with terrestrial base stations (BSs), but this means that a HAPS may interfere with the connection of terrestrial BS users within its line of sight. This letter proposes a scheme that combines an interference canceler and enhanced inter-cell interference coordination to reduce interference in an integrated HAPS-terrestrial system. Numerical simulations demonstrated that the integrated system greatly improved the signal-to-interference-plus-noise ratio of terrestrial BSs and improved the system capacity by 26% compared to a conventional system with no interference reduction.