Proposal of Multi-Stage Interference Canceller Against Adjacent Channel Interferences in NTNs

NTNs (Non-Terrestrial Networks) for extreme coverage extension in Beyond 5G/6G have attracted satellite communications with wide coverages compared to terrestrial mobile systems. In satellite communications, ones of the NTN elements, LEO (Low Earth Orbit) systems such as satellite constellations are under investigation added to conventional GEO (Geostationary Orbit) systems. Although separate frequency bands are assigned in this time for GEO/LEO systems, it is assumed that they would use the same frequency bands in the future. If they would use the same frequency bands, they must operate under adjacent channel interference conditions, so interference compensation schemes are significantly important. In adjacent channel interference environments, the GEO receiver can use a high-power LEO signal canceller to improve the degradation due to the interference from the high-power LEO signal as same as a NOMA (Non-Orthogonal Multiple Access) canceller in terrestrial 5G mobile systems. On the other hand, in LEO receivers, conventional cancellers cannot be applied. Therefore, we propose a new multi-stage canceller that cancels low-power GEO signal in addition to the high-power LEO signal cancelation at the LEO receiver. In this paper, we clarify the performances of the proposed multi-stage canceller to expand the applicable ranges and increase frequency utilization efficiencies of both the GEO/LEO systems in against adjacent channel interference environments by computer simulations.