Telecommunications apparatus and methods

A method of operating a terminal device for transmitting data to another terminal device in a device-to-device communication mode in a wireless telecommunications system supporting communications on a first carrier operating over a first frequency band and a second carrier operating over a second frequency band, the method comprising

• transmitting, on the first carrier, control signalling comprising an implicit indication that the terminal device intends to transmit data to the another terminal device using the device-to-device communication mode on the second carrier after a carrier switch-over time;
• and
• after the carrier switch-over time, transmitting data to the another terminal device on the second carrier using the device-to-device communication mode, wherein
• the control signalling comprises an explicit indication of the carrier switch-over time,
• the control signalling is transmitted by the terminal device in one of a plurality of control signalling time windows defined in accordance with a control signalling schedule for the terminal device,
• the explicit indication of the carrier switch-over time comprises an indication of a control signalling time window that follows the control signalling time window in which the control signalling is transmitted, and
• the carrier switch-over time is based on the time of the indicated control signalling time window.

A terminal device for receiving data from another terminal device in a device-to-device communication mode in a wireless telecommunications system supporting communications on a first carrier operating over a first frequency band and a second carrier operating over a second frequency band, the terminal device comprising:

• circuitry configured to
• receive, on the first carrier, control signalling comprising an implicit indication that the another terminal device intends to transmit data to the terminal device using the device-to-device communication mode on the second carrier after a carrier switch-over time;
• and
• after the carrier switch-over time, receive data from the another terminal device on the second carrier using the device-to-device communication mode.