A radio communication system comprising: a plurality of communication devices (11-1 - 11-n), wherein a first communication device (11-1) among the plurality of communication devices transmits a signal addressed to a second communication device (11-5) among the plurality of communication devices to a third communication device (11-2) of one or more third communication devices among the plurality of communication devices; the third communication device (11-2) relays the radio communication between the first communication device (11-1) and the second communication device (11-5) by transferring the signal to a next hop third communication device (11-3, 11-4) in a relay order among the one or more third communication devices or to the second communication device (11-5); each of the plurality of communication devices stores a common set of resource pools including a plurality of resources each of which specifies frequency and time usable by each of the plurality of communication devices for direct radio communication with a next hop communication device among the plurality of communication devices; the first communication device (11-1) selects a resource pool from the set of resource pools, and transmits the signal to the third communication device (11-2) by the use of a resource included in the selected resource pool; and in response to receiving the signal, each of the one or more third communication devices selects a resource pool from the set of resource pools based on a hop count at the respective third communication device indicating the number of transmission hops from the first communication device (11-1), and the resource pool selected by the first communication device (11-1), and transfers the signal to the next hop third communication device (11-3, 11-4) or to the second communication device (11-5) by the use of a resource included in the selected resource pool. a plurality of communication devices (11-1 - 11-n), wherein a first communication device (11-1) among the plurality of communication devices transmits a signal addressed to a second communication device (11-5) among the plurality of communication devices to a third communication device (11-2) of one or more third communication devices among the plurality of communication devices; the third communication device (11-2) relays the radio communication between the first communication device (11-1) and the second communication device (11-5) by transferring the signal to a next hop third communication device (11-3, 11-4) in a relay order among the one or more third communication devices or to the second communication device (11-5); each of the plurality of communication devices stores a common set of resource pools including a plurality of resources each of which specifies frequency and time usable by each of the plurality of communication devices for direct radio communication with a next hop communication device among the plurality of communication devices; the first communication device (11-1) selects a resource pool from the set of resource pools, and transmits the signal to the third communication device (11-2) by the use of a resource included in the selected resource pool; and in response to receiving the signal, each of the one or more third communication devices selects a resource pool from the set of resource pools based on a hop count at the respective third communication device indicating the number of transmission hops from the first communication device (11-1), and the resource pool selected by the first communication device (11-1), and transfers the signal to the next hop third communication device (11-3, 11-4) or to the second communication device (11-5) by the use of a resource included in the selected resource pool. <EOS>