Methods, Wireless Device, Base Station and Candidate Relay Station for Supporting D2D Communication Over Relay

A method, performed by a base station of a radio network, for supporting a Device-to-Device (D2D) communication between a first wireless device and a second wireless device over a relay, the method comprising:

• receiving, from the first wireless device, an identity of a candidate relay wireless device and a first quality metric pertaining to a first relay link between the first wireless device and the candidate relay wireless device and to a second relay link between the second wireless device and the candidate relay wireless device;
• obtaining a second quality metric pertaining to a D2D link between the first wireless device and the second wireless device;
• obtaining a third quality metric pertaining to a cellular link between the base station and the first wireless device;
• and
• when the first quality metric indicates a better link quality than both the second quality metric and the third quality metric,
• selecting a relay mode for the D2D communication with the candidate relay wireless device acting as the relay and
• instructing the first wireless device, the second wireless device and the candidate relay wireless device to communicate according to the relay mode.

A base station operable in a radio network, the base station being arranged to support a Device-to-Device (D2D) communication between a first wireless device and a second wireless device over a relay, wherein the base station comprises:

• a communication circuit configured to communicate with wireless devices;
• and
• processing circuitry operatively associated with the communication circuit and configured to:
• receive, from the first wireless device, an identity of a candidate relay wireless device and a first quality metric pertaining to a first relay link between the first wireless device and the candidate relay wireless device and to a second relay link between the second wireless device and the candidate relay wireless device;
• obtain a second quality metric pertaining to a D2D link between the first wireless device and the second wireless device;
• obtain a third quality metric pertaining to a cellular link between the base station and the first wireless device;
• and
• when the first quality metric indicates a better link quality than both the second quality metric and the third quality metric,
• select a relay mode for the D2D communication with the candidate relay wireless device acting as the relay and
• instruct the first wireless device, the second wireless device and the candidate relay wireless device to communicate according to the relay mode.

A method, performed by a first wireless device, for supporting a Device-to-Device (D2D) communication between the first wireless device and a second wireless device over a relay, the first and second wireless devices being served by a base station of a radio network, the method comprising:

• transmitting a beacon that is measurable by a candidate relay wireless device;
• receiving, from the candidate relay wireless device, an identity of the candidate relay wireless device and a first quality metric pertaining to a first relay link between the first wireless device and the candidate relay wireless device and to a second relay link between the second wireless device and the candidate relay wireless device;
• and
• sending the identity and the first quality metric of the candidate relay wireless device to the base station, thereby enabling the base station to select a relay mode for the D2D communication with the candidate relay wireless device acting as the relay, based on the first quality metric.

A first wireless device arranged to support a Device-to-Device (D2D) communication between the first wireless device and a second wireless device over a relay, the first and second wireless devices being served by a base station of a radio network, wherein the first wireless device comprises:

• communication circuitry configured for D2D communications and for communicating with the base station;
• and
• processing circuitry operatively associated with the communication circuit and configured to:
• transmit a beacon that is measurable by a candidate relay wireless device;
• receive, from the candidate relay wireless device, an identity of the candidate relay wireless device and a first quality metric pertaining to a first relay link between the first wireless device and the candidate relay wireless device and to a second relay link between the second wireless device and the candidate relay wireless device;
• and
• send the identity and the first quality metric of the candidate relay wireless device to the base station, thereby enabling the base station to select a relay mode for the D2D communication with the candidate relay wireless device acting as the relay, based on the first quality metric.

A method performed by a candidate relay wireless device for supporting a Device-to-Device (D2D) communication between a first wireless device and a second wireless device over a relay, the first and second wireless devices being served by a base station of a radio network, the method comprising:

• measuring beacons transmitted by the first wireless device and by the second wireless device;
• detecting a possibility to act as said relay between the first and second wireless devices based on the measured beacons;
• calculating, based on the measured beacons, a quality metric pertaining to a first relay link between the first wireless device and the candidate relay wireless device and to a second relay link between the second wireless device and the candidate relay wireless device;
• and
• transmitting an identity of the candidate relay wireless device and the calculated quality metric to be received by at least one of the first wireless device and the second wireless device.

A candidate relay wireless device arranged to support a Device-to-Device (D2D) communication between a first wireless device and a second wireless device over a relay, the first and second wireless devices being served by a base station of a radio network, wherein the candidate relay wireless device comprises:

• a communication circuit configured to communicate with wireless devices;
• and
• processing circuitry operatively associated with the communication circuit and configured to:
• measure beacons transmitted by the first wireless device and by the second wireless device;
• detect a possibility to act as said relay between the first and second wireless devices based on the measured beacons;
• calculate, based on the measured beacons, a quality metric pertaining to a first relay link between the first wireless device and the candidate relay wireless device and to a second relay link between the second wireless device and the candidate relay wireless device;
• and
• transmit an identity of the candidate relay wireless device and the calculated quality metric to be received by at least one of the first wireless device and the second wireless device.