Method for relaying data performed by a relay station in wireless communication system based on TDD
A method of relaying data performed by a relay station in a wireless communication system based on time division duplex (TDD) is provided. The relay station receives downlink data from a base station and relays the downlink data to at least one mobile station in an uplink subframe which belongs to an unlinked subframe. Accordingly, uplink acknowledgement (ACK) collision can be avoided, and efficiency of resource allocation can be increased.
1. A method of relaying data by a relay station in a wireless communication system based on time division duplex (TDD) using a radio frame comprising a plurality of downlink subframes and a plurality of uplink subframes, the method comprising:
transmitting downlink data to a mobile station (MS) at a downlink subframe;
determining whether a first uplink subframe, to be used for transmitting uplink data to a base station (BS), is a linked uplink subframe, wherein the linked uplink subframe is an uplink subframe that is reserved to receive an acknowledgement/non-acknowledgement (ACK/NACK) for the downlink data from the MS;
changing an uplink subframe, to be used for receiving the ACK/NACK for the downlink data from the MS, from a first uplink subframe to a second uplink subframe when the first uplink subframe is the linked uplink subframe;
transmitting the uplink data to the BS at the first uplink subframe; and
receiving the ACK/NACK for the downlink data at the second uplink subframe when the first uplink subframe is the linked uplink subframe,
wherein the second uplink subframe is an uplink subframe that is positioned next to the first uplink subframe.
2. The method of claim 1 , wherein the radio frame consists of 10 subframes.
3. The method of claim 2 , wherein the radio frame has at least one uplink-downlink (UL-DL) configuration shown in the following table:
UL-DL
Configu-
Subframe number
ration
0
1
2
3
4
5
6
7
8
9
0
D
S
U
U
U
D
S
U
U
U
1
D
S
U
U
D
D
S
U
U
D
2
D
S
U
D
D
D
S
U
D
D
3
D
S
U
U
U
D
D
D
D
D
4
D
S
U
U
D
D
D
D
D
D
5
D
S
U
D
D
D
D
D
D
D
6
D
S
U
U
U
D
S
U
U
D
where D′ denotes a downlink subframe, ‘U’ denotes an uplink subframe, and ‘S’ denotes a special subframe.
4. The method of claim 1 , further comprising:
transmitting ACK/NACK timing information to the MS,
wherein the ACK/NACK timing information indicates the second uplink subframe.