Abstract: A communication system includes a base station and a communication terminal connected to the base station. The base station transmits a result of reception of an uplink positioning signal transmitted by the communication terminal and location information of the base station to a positioning device that is a device having a positioning function of deriving a location of the communication terminal, and the communication terminal transmits a result of reception of a downlink positioning signal transmitted by the base station to the positioning device.

Abstract: A terminal device having a relay function of relaying a signal received from a first peripheral terminal among peripheral terminals, which are other terminal devices available for direct communication with the terminal device, to a second peripheral terminal among the peripheral terminals, the terminal device including: a detection unit that detects the peripheral terminals; a storage unit that holds peripheral terminal information that is information on each of the peripheral terminals detected by the detection unit; and an information notification unit that transmits a notification message for notifying the other terminal devices of information on the terminal device, the notification message including the peripheral terminal information held by the storage unit.

Abstract: In the SL communication, the QoS required for each service is maintained, and the reliability of the service is enhanced. A communication system includes a base station, and a plurality of communication terminals configured to perform communication with the base station and perform Device-to-Device communication. A first communication terminal transmits, to a third communication terminal, a scheduling request for performing the Device-to-Device communication with a second communication terminal. The third communication terminal transmits, to the base station, the scheduling request received from the first communication terminal. In response to the scheduling request received from the third communication terminal, the base station generates scheduling information on the Device-to-Device communication between the first communication terminal and the second communication terminal, and transmits the scheduling information to the third communication terminal.

Abstract: A technology that enables prompt NW connection is provided. A communication system includes: a communication terminal; and a plurality of networks configured to perform radio communication with the communication terminal. The communication terminal determines whether or not there is paging causing collision among a plurality of pagings respectively transmitted to the communication terminal from the plurality of networks. When the communication terminal detects the collision of the paging, the communication terminal notifies at least one of the plurality of networks that transmits the paging causing the collision of the paging about the collision of the paging.