Three-dimensionalization of fifth generation communication

A communication system comprising:

• a radio relay station for relaying a radio communication with a terminal apparatus,
• wherein the radio relay station is provided in each of a plurality of floating objects controlled so as to be located in a floating airspace with an altitude less than or equal to 100 [km] by an autonomous control or an external control,
• wherein the radio relay station forms a three-dimensional cell in a predetermined cell-formation target airspace between a floating object and a ground level or a sea level, when the floating object is located in the floating airspace,
• wherein each of a plurality of radio relay stations forms a beam for performing a radio communication with the terminal apparatus toward the ground level or the sea level,
• wherein the communication system comprises means for controlling at least one of distances between the plurality of floating objects, an altitude of each of the floating objects and an angle of an outer edge of the beam with respect to a virtual vertical line passing through each of the radio relay stations of the floating objects, so that a plurality of beams adjacent to each other in the predetermined cell-formation target airspace partially overlap with each other and the plurality of beams of the radio relay stations cover an overall upper end surface of the predetermined cell-formation target airspace,
• wherein the plurality of floating objects includes a first floating object and a second floating object,
• wherein each beam of the radio relay stations of the first floating object and the second floating objects is formed in a conical shape, and
• wherein when a divergence angle of the beam of the radio relay station of the first floating object is defined as θ1 [rad], a divergence angle of the beam of the radio relay station of the second floating object is defined as θ2 [rad], an altitude of the radio relay station of the first floating object is defined as Hrs1 [m], an altitude of the radio relay station of the second floating object is defined as Hrs2 [m], a horizontal interval between the radio relay station of the first floating object and the radio relay station of the second floating object is defined as Drs [m] and an altitude of the overall upper end surface of the predetermined cell-formation target airspace is defined as Hcu [m], a following expression (3) is satisfied:
• (Hrs1−Hcu)×tan(θ1)+(Hrs2−Hcu)×tan(θ2)≥Drs (3).