Method and apparatus for transmitting/receiving control information for device to device (D2D) communication in a wireless communications system
According to an embodiment of the present invention, a method for a first terminal to receive control information from a second terminal for device to device communication includes the steps of: receiving downlink control information (DCI) format containing a link indicator; and obtaining selectively one of downlink allocation information and uplink permission information contained in the DCI format according to the link indicator, wherein the downlink allocation information indicates a resource region for receiving data from the second terminal, and the uplink permission information indicates a resource region for transmitting data to the second terminal.
1. A method for receiving control information for device-to-device (D2D) communication with a second user equipment (UE) by a first UE in a wireless communication system, the method comprising:
performing blind decoding on a search space corresponding to a link identifier configured for the first UE;
receiving, in the search space, downlink control information (DCI) comprising a link indicator indicating a link direction for the D2D communication between the first UE and the second UE, downlink allocation information, and uplink grant information;
determining the link direction based on whether the first UE is a source station or a destination station and a value of the link indicator; and
selectively acquiring any one of the downlink allocation information and the uplink grant information according to the determined link direction,
wherein DCI for the first UE is identical to DCI for the second UE and the DCI for the first UE and the second UE are transmitted at the same time from a coordination station, and the downlink allocation information indicates a resource region in which data is received from the second UE, and the uplink grant information indicates a resource region for transmitting data to the second UE, and
wherein the link identifier configured for the first UE is identical to a link identifier configured for the second UE.
2. The method according to claim 1 , wherein the DCI is scrambled with a parameter shared by the first UE and the second UE.
3. The method according to claim 2 , wherein the parameter is a link identifier of the first UE and the second UE.
4. The method according to claim 1 , wherein the DCI is scrambled with a UE-specific parameter.
5. The method according to claim 1 , wherein:
when the first UE acquires the uplink grant information, data is transmitted via the resource indicated by the uplink grant information to the second UE in a kth subframe from a subframe in which the DCI is received by the first UE and the second UE, according to the uplink grant information; and
when the first UE acquires the downlink grant information, data is received via the resource indicated by the downlink grant information from the second UE in a qth subframe from a subframe in which the DCI is received by the first UE and the second UE, according to the downlink grant information.
6. The method according to claim 1 , wherein k and q depend on an index of a subframe in which the DCI is received.
7. A first user equipment (UE) apparatus for performing device-to-device (D2D) communication with a second UE in a wireless communication system, the UE apparatus comprising:
a reception module; and
a processor, connected with the reception module, that:
performs blind decoding on a search space corresponding to a link identifier configured for the first UE,
controls the reception module to receive, in the search space, a downlink control information (DCI) comprising a link indicator indicating a link direction for the D2D communication between the first UE and the second UE, downlink allocation information, and uplink grant information,
determines the link direction based on whether the first UE is a source station or a destination station and a value of the link indicator, and
selectively acquires any one of the downlink allocation information and the uplink grant information according to the determined link direction,
wherein DCI for the first UE is identical to DCI for the second UE and the DCI for the first UE and the second UE are transmitted at the same time from a coordination station, and the downlink allocation information indicates a resource region in which data is received from the second UE, and the uplink grant information indicates a resource region for transmitting data to the second UE, and
wherein the link identifier configured for the first UE is identical to a link identifier configured for the second UE.
8. The UE apparatus according to claim 7 , wherein the DCI is scrambled with a parameter shared by the first UE and the second UE.
9. The UE apparatus according to claim 8 , wherein the parameter is a link identifier of the first UE and the second UE.
10. The UE apparatus according to claim 7 , wherein the DCI is scrambled with a UE-specific parameter.
11. The UE apparatus according to claim 7 , wherein:
when the first UE acquires the uplink grant information, data is transmitted via the resource indicated by the uplink grant information to the second UE in a kth subframe from a subframe in which the DCI is received by the first UE and the second UE, according to the uplink grant information; and
when the first UE acquires the downlink grant information, data is received via the resource indicated by the downlink grant information from the second UE in a qth subframe from a subframe in which the DCI is received by the first UE and the second UE, according to the downlink grant information.
12. The UE apparatus according to claim 7 , wherein k and q depend on an index of a subframe in which the DCI is received.