A system comprising an aerial-staying type communication relay apparatus including a relay communication station that relays a radio communication of a terminal apparatus, the system comprising plural gateway stations that are time-synchronized with each other, the gateway stations configured to transmit and receive relay signals different from each other in feeder links of a same frequency between the relay communication station of the aerial-staying type communication relay apparatus and the plural gateway stations, wherein the relay communication station comprises a feeder-link communication section that is configured to transmit and receive relay signals different from each other on the same frequency in the feeder links to and from the plural gateway stations, and an interference suppression section that is configured to suppress an interference between plural feeder links formed with the plural gateway stations, wherein each of the plural gateway stations is configured to transmit a pilot signal, wherein the feeder-link communication section is configured to receive pilot signals respectively transmitted from the plural gateway stations, and to separate each of the received plural pilot signals with a filter, and wherein the interference suppression section is configured to switch between performing a first interference suppression process and performing a second interference suppression process, wherein the first interference suppression process is configured to suppress an interference signal that causes an interference by a transmission signal transmitted from the gateway station and received with a directional beam corresponding to another gateway station, by using a propagation path response estimated with one frequency in the transmission signal band as an estimation frequency based on a reception result of the pilot signal without dividing a transmission signal band of the feeder link, and wherein the second interference suppression process is configured to divide the transmission signal band of the feeder link into plural divided frequency bands and suppress the interference signal by using a propagation path response estimated with one frequency in the divided frequency band as an estimation frequency based on the reception result of the pilot signal, for each of the divided frequency bands. wherein the relay communication station comprises a feeder-link communication section that is configured to transmit and receive relay signals different from each other on the same frequency in the feeder links to and from the plural gateway stations, and an interference suppression section that is configured to suppress an interference between plural feeder links formed with the plural gateway stations, wherein each of the plural gateway stations is configured to transmit a pilot signal, wherein the feeder-link communication section is configured to receive pilot signals respectively transmitted from the plural gateway stations, and to separate each of the received plural pilot signals with a filter, and wherein the interference suppression section is configured to switch between performing a first interference suppression process and performing a second interference suppression process, wherein the first interference suppression process is configured to suppress an interference signal that causes an interference by a transmission signal transmitted from the gateway station and received with a directional beam corresponding to another gateway station, by using a propagation path response estimated with one frequency in the transmission signal band as an estimation frequency based on a reception result of the pilot signal without dividing a transmission signal band of the feeder link, and wherein the second interference suppression process is configured to divide the transmission signal band of the feeder link into plural divided frequency bands and suppress the interference signal by using a propagation path response estimated with one frequency in the divided frequency band as an estimation frequency based on the reception result of the pilot signal, for each of the divided frequency bands. wherein the first interference suppression process is configured to suppress an interference signal that causes an interference by a transmission signal transmitted from the gateway station and received with a directional beam corresponding to another gateway station, by using a propagation path response estimated with one frequency in the transmission signal band as an estimation frequency based on a reception result of the pilot signal without dividing a transmission signal band of the feeder link, and wherein the second interference suppression process is configured to divide the transmission signal band of the feeder link into plural divided frequency bands and suppress the interference signal by using a propagation path response estimated with one frequency in the divided frequency band as an estimation frequency based on the reception result of the pilot signal, for each of the divided frequency bands.