Method of adjusting a transmit power for device-to-device communication, user equipment, group head of a device-to-device communication group, and communication system

1. A method of adjusting a transmit power for a device-to-device communication, the method comprising:

detecting, by a user equipment which performs the device-to-device communication using the transmit power, that the user equipment enters a coverage area of a radio communication unit, wherein the radio communication unit is a base station of a cellular communication network, the base station defining a cell having a cell identifier, and the coverage area is the cell;

selectively decreasing the transmit power of the user equipment for the device-to-device communication in response to detecting that the user equipment enters the coverage area of the radio communication unit;

transmitting, by the user equipment, a report message to another user equipment using the device-to-device communication to indicate that the user equipment has entered the coverage area of the radio communication unit associated with the cell identifier;

receiving, from the radio communication unit, a resource allocation for the device-to-device communication; and

controlling the transmit power of the user equipment for the device-to-device communication after receiving the resource allocation.

2. The method of claim 1 ,

wherein the report message comprises an interference monitor report.

3. The method of claim 1 , further comprising:

transmitting, by the other user equipment, a command to reduce the transmit power in response to receiving the report message.

4. The method of claim 3 ,

wherein the other user equipment is a group head of a device-to-device communication group, wherein the device-to-device communication group includes the user equipment and at least one further user equipment, and

wherein the other user equipment transmits the command to reduce the transmit power to the at least one further user equipment of the device-to-device communication group.

5. The method of claim 3 ,

wherein the command to reduce the transmit power comprises an indicator for a reduced transmit power level.

6. The method of claim 1 , further comprising:

detecting, by the other user equipment, a trigger event for increasing the transmit power, and

transmitting, by the other user equipment, an other command to the user equipment to increase the transmit power of the user equipment in response to detecting the trigger event.

7. The method of claim 1 ,

wherein selectively decreasing the transmit power of the user equipment further comprises:

monitoring an interference between radio resources allocated to the user equipment for the device-to-device communication and other radio resources which are used by the radio communication unit for receiving or transmitting the radio signals.

8. A user equipment, comprising:

a wireless interface for communication with a cellular communication network; and

a processing device coupled to the wireless interface and configured to:

control the wireless interface to perform a device-to-device communication;

detect that the user equipment enters a coverage area of a radio communication unit, wherein the radio communication unit is a base station of the cellular communication network, the base station defining a cell having a cell identifier, and the coverage area is the cell;

selectively decrease a transmit power of the user equipment for the device-to-device communication when the device-to-device communication causes interference with radio signals which are transmitted or received by the radio communication unit;

control the wireless interface to transmit a report message to an other user equipment using the device-to-device communication to indicate that the user equipment has entered the coverage area of the radio communication unit associated with the cell identifier;

receive, from the radio communication unit, a resource allocation for the device-to-device communication; and

control the transmit power of the user equipment for the device-to-device communication after receiving the resource allocation.

9. A communication system, comprising:

the user equipment of claim 8 , and

a group head for a device-to-device communication group, comprising:

a wireless interface for device-to-device communication; and

a processing device coupled to the wireless interface and configured to:

receive, via the wireless interface, a report message from a user equipment of the device-to-device communication group which indicates that the user equipment has entered a coverage area of a radio communication unit; and

control the wireless interface to transmit a command to the user equipment or to at least one further user equipment of the device-to-device communication group to reduce a transmit power for the device-to-device communication in response to receiving the report message.

10. A group head for a device-to-device communication group, the group head being one user equipment of a plurality of user equipment, comprising:

a wireless interface for device-to-device communication; and

a processing device coupled to the wireless interface and configured to:

receive, via the wireless interface, a report message from a user equipment of the device-to-device communication group which indicates that the user equipment has entered a coverage area of a radio communication unit, wherein the radio communication unit is a base station of a cellular communication network the base station defining a cell having a cell identifier, and the coverage area is the cell; and

control the wireless interface to transmit a command to the user equipment or to at least one further user equipment of the device-to-device communication group to reduce a transmit power for the device-to-device communication in response to receiving the report message,

wherein the user equipment receives, from the radio communication unit, a resource allocation for the device-to-device communication, and controls the transmit power of the user equipment for the device-to-device communication after receiving the resource allocation.

11. The group head of claim 10 ,

wherein the command comprises an indicator for a reduced transmit power level of the user equipment, and

wherein the processing device is configured to decrease a transmit power of the group head for the device-to-device communication when the report message is received.

12. The group head of claim 10 ,

wherein the processing device is further configured to

detect a trigger event for increasing the transmit power, and

transmit an other command to the user equipment to increase the transmit power of the user equipment in response to detecting the trigger event.

13. The group head of claim 12 ,

wherein the trigger event is a resource allocation for the device-to-device communication.