Mobile communication system and user terminal

Abstract

A method for performing D2D (Device-to-Device) communication, a user terminal for supporting D2D communication, and an apparatus used in a user terminal supporting D2D communication include a user terminal in coverage of a base station broadcasting first control information using a first time radio resource, and a second user terminal being out of coverage of the base station receiving the first control information, selecting, by the second user terminal, a second time radio resource different from the first time radio resource, for transmitting second control information, and transmitting, by the second user terminal, the second control information using the second time radio resource. The second control information is determined based on the first control information, and indicates a frequency band to be used for the D2D communication. The second user terminal performs D2D communication on the basis of the first control information received from the first user terminal.

1 . A method for performing D2D (Device-to-Device) communication comprising:
 broadcasting, from a first user terminal being in coverage of a base station, first control information using a first time radio resource;   receiving, by a second user terminal being out of coverage of the base station, the first control information from the first user terminal;   selecting, by the second user terminal, a second time radio resource different from the first time radio resource, for transmitting second control information;   transmitting, by the second user terminal, the second control information using the second time radio resource, wherein the second control information is determined by the second user terminal based on the first control information, and the second control information indicates a frequency band to be used for the D2D communication; and   performing, by the second user terminal, D2D communication on the basis of the first control information received from the first user terminal.   
     
     
         2 . A user terminal supporting D2D (Device-to-Device) communication, comprising:
 a processor and a memory coupled to the processor, the processor configured to:   receive, when the user terminal is out of coverage of a base station, first control information from another user terminal being in coverage of the base station, wherein the first control information is broadcast from the another user terminal by using a first time radio resource;   select a second time radio resource different from the first time radio resource, for transmitting second control information;   transmit the second control information using the second time radio resource, wherein the second control information is determined by the user terminal based on the first control information, and the second control information indicates a frequency band to be used for the D2D communication; and   perform D2D communication on the basis of the first control information received from the another user terminal.   
     
     
         3 . An apparatus used in a user terminal supporting D2D (Device-to-Device) communication, the apparatus comprising:
 a processor and a memory coupled to the processor, the processor configured to:   receive, when the user terminal is out of coverage of a base station, first control information from another user terminal being in coverage of the base station, wherein the first control information is broadcast from the another user terminal by using a first time radio resource;   select a second time radio resource different from the first time radio resource, for transmitting second control information;   transmit the second control information using the second time radio resource, wherein the second control information is determined by the user terminal based on the first control information, and the second control information indicates a frequency band to be used for the D2D communication; and   perform D2D communication on the basis of the first control information received from the another user terminal.