Cooperative V2X communication in a system wherein a network device (base station or road side unit RSU) transmits to a terminal device a signal indicating whether the network device supports cooperative V2X transmission of messages from the terminal device to a vehicle-mounted terminal device; and performs cooperative V2X communication by transmitting to the vehicle-mounted terminal device a message intended for it that is received from the terminal device; and wherein the terminal device determines whether the network device supports cooperative V2X communication based on the signal received from the network device; and, based on the determination, performs cooperative V2X communication with the vehicle-mounted terminal device with support from the network device by transmitting a message directly to the vehicle-mounted terminal device and transmitting the message intended for the vehicle-mounted terminal device to the network device.