A communication system for performing a communication via a radio relay apparatus located in an upper airspace, wherein a plurality of gateway stations for forming radio sections of a plurality of feeder links with the radio relay apparatus are disposed at a plurality of locations geographically separated from each other on the ground or on the sea, wherein the communication system comprises a base station connected to the plurality of gateway stations , and wherein a feeder link is a link between the radio relay apparatus and the base station via the gateway station , and a service link is a link between the radio relay apparatus and a terminal , characterized in that the communication system comprises a management apparatus for managing current position information of each of the radio relay apparatus , the gateway stations and the base station , wherein, in each of a plurality of forward links for transmitting a signal to the radio relay apparatus via the plurality of gateway stations , each of the plurality of gateway stations is adapted to: calculate an offset according to both delay times of a transmission delay time between the base station and the gateway station and a propagation delay time between the gateway station and the radio relay apparatus , based on the current position information of each of the radio relay apparatus , the gateway stations and the base station which is acquired from the management apparatus ; and shift a transmission timing of the signal by the calculated offset. wherein a plurality of gateway stations for forming radio sections of a plurality of feeder links with the radio relay apparatus are disposed at a plurality of locations geographically separated from each other on the ground or on the sea, wherein the communication system comprises a base station connected to the plurality of gateway stations , and wherein a feeder link is a link between the radio relay apparatus and the base station via the gateway station , and a service link is a link between the radio relay apparatus and a terminal , characterized in that the communication system comprises a management apparatus for managing current position information of each of the radio relay apparatus , the gateway stations and the base station , wherein, in each of a plurality of forward links for transmitting a signal to the radio relay apparatus via the plurality of gateway stations , each of the plurality of gateway stations is adapted to: calculate an offset according to both delay times of a transmission delay time between the base station and the gateway station and a propagation delay time between the gateway station and the radio relay apparatus , based on the current position information of each of the radio relay apparatus , the gateway stations and the base station which is acquired from the management apparatus ; and shift a transmission timing of the signal by the calculated offset. calculate an offset according to both delay times of a transmission delay time between the base station and the gateway station and a propagation delay time between the gateway station and the radio relay apparatus , based on the current position information of each of the radio relay apparatus , the gateway stations and the base station which is acquired from the management apparatus ; and shift a transmission timing of the signal by the calculated offset. <EOS>