Mobile communication system, user terminal, base station, processor, and communication control method

A user terminal, comprising:

• a controller including a processor, which performs D2D communication under management of a base station, the D2D communication indicating direct device to device communication, wherein
• the controller transmits data to a plurality of D2D communication partner terminals in the D2D communication, and
• the controller transmits a D2D buffer status report to the base station, the D2D buffer status report including:
• an amount of non-transmitted data to each D2D communication partner terminal;
• and
• a plurality of identifiers corresponding to the plurality of D2D communication partner terminals, wherein the plurality of identifiers corresponding to the plurality of D2D communication partner terminals does not include the identifier of the base station to which the D2D buffer status report is transmitted.

A device comprising a processor, which is to be provided in a user terminal, wherein

• the processor performs D2D communication under management of a base station, the D2D communication indicating direct device to device communication, the processor further performing:
• a process of transmitting, by the user terminal, data to a plurality of D2D communication partner terminals in the D2D communication;
• and
• a process of transmitting, by the user terminal, a D2D buffer status report to the base station, the D2D buffer status report including:
• an amount of non-transmitted data to each D2D communication partner terminal;
• and
• a plurality of identifiers corresponding to the plurality of D2D communication partner terminals, wherein the plurality of identifiers corresponding to the plurality of D2D communication partner terminals does not include the identifier of the base station to which the D2D buffer status report is transmitted.

A base station, comprising:

• a controller including a processor, which manages D2D communication that is direct device to device communication, by a user terminal, wherein
• the controller receives a D2D buffer status report from the user terminal, the user terminal transmitting data to a plurality of D2D communication partner terminals in the D2D communication, and the D2D buffer status report including:
• an amount of non-transmitted data to each D2D communication partner terminal in the D2D communication;
• and
• a plurality of identifiers corresponding to the plurality of D2D communication partner terminals, wherein the plurality of identifiers corresponding to the plurality of D2D communication partner terminals does not include the identifier of the base station to which the D2D buffer status report is transmitted.

A device comprising a processor, which is to be provided in a base station, wherein

• the processor manages D2D communication that is direct device to device communication, by a user terminal,
• the processor performs a process of receiving, by the base station, a D2D buffer status report from the user terminal, the user terminal transmitting data to a plurality of D2D communication partner terminals in the D2D communication, and the D2D buffer status report including:
• an amount of non-transmitted data to each D2D communication partner terminal in the D2D communication;
• and
• a plurality of identifiers corresponding to the plurality of D2D communication partner terminals, wherein the plurality of identifiers corresponding to the plurality of D2D communication partner terminals does not include the identifier of the base station to which the D2D buffer status report is transmitted.

A communication control method in a mobile communication system, which includes a user terminal that performs D2D communication under management of a base station, the D2D communication indicating direct device to device communication, comprising:

• transmitting, by the user terminal, data to a plurality of D2D communication partner terminals in the D2D communication;
• and
• transmitting, by the user terminal, a D2D buffer status report to the base station, the D2D buffer status report including:
• an amount of non-transmitted data to each D2D communication partner terminal in the D2D communication;
• and
• a plurality of identifiers corresponding to the plurality of D2D communication partner terminals, wherein the plurality of identifiers corresponding to the plurality of D2D communication partner terminals does not include the identifier of the base station to which the D2D buffer status report is transmitted.