Devices and methods for D2D communication

A method of operating a communication device outside a coverage area of a cellular communication network, configured to perform a device to device communication with a plurality of further communication devices using a second frequency band, wherein the method comprises:

• receiving a control message from a further communication device of the plurality of communication devices, the control message indicating that the further communication device is within the coverage area of a cellular communication network;
• and
• upon reception of the control message, starting to listen for messages from further communication devices of the plurality of communication devices using a first frequency band;
• wherein as long as the communication device does not receive the control message, communicating with the further communication devices using a communication frame having a first control channel format, the first control channel format offering only communication resources for an ad-hoc communication mode;
• and
• wherein upon reception of the control message, communicating with the further communication devices using a communication frame having a second control channel format, the second control channel format offering communication resources for an ad-hoc communication mode and a network assisted communication mode.

A non-transitory machine-readable medium having instructions stored therein, which when executed by a processor, cause a processor perform a method of operating a communication device outside a coverage area of a cellular communication network, configured to perform a device to device communication with a plurality of further communication devices using a second frequency band, the method comprising:

• receiving a control message from a further communication device of the plurality of communication devices, the control message indicating that the further communication device is within the coverage area of a cellular communication network;
• and
• upon reception of the control message, starting to listen for messages from further communication devices of the plurality of communication devices using a first frequency band;
• wherein as long as the communication device does not receive the control message, communicating with the further communication devices using a communication frame having a first control channel format, the first control channel format offering only communication resources for an ad-hoc communication mode;
• and
• wherein upon reception of the control message, communicating with the further communication devices using a communication frame having a second control channel format, the second control channel format offering communication resources for an ad-hoc communication mode and a network assisted communication mode.