Method for transmitting and receiving signal in wireless LAN and apparatus therefor
A method for receiving a signal by a station (STA) in a wireless LAN system according to an embodiment of the present invention comprises the steps of: receiving a multi-user (MU) frame including a SIG-A field, a SIG-B field and a short training field (STF), and a long training field (LTF) that provides training symbols; and performing blind-decoding of the SIG-B field using a group ID assigned to the STA, wherein the SIG-B field includes information on the number of streams assigned to each of multiple stations that receive the MU frame, and the starting position of a training symbol interval for the STA in the LTF is implicitly indicated by the number of streams assigned to each of other stations in the same group, which share the group ID with the STA, and the order in which the streams are assigned to the STA in the same group.
1. A method for receiving a signal by a station (STA) in a wireless local area network (LAN) system, the method comprising:
receiving a multi-user (MU) frame including a signal-A (SIG-A) field, a signal-B (SIG-B) field which includes cyclic redundancy check (CRC) information masked with group identifiers (GIDs) different per 20MHz channel, a short training field (STF), and a long training field (LTF) that includes training symbols; and
blind decoding the SIG-B field in a unit of a 20MHz channel based on a specific GID assigned to the STA,
wherein the SIG-B field includes information on a number of streams assigned to each of multiple STAs that receive the MU frame,
wherein a starting position of a training symbol interval for the STA in the LTF is determined based on a number of streams assigned to each of the other STAs in a same group sharing the specific GID with the STA, and an order of streams assigned to the STA in the same group, and
wherein the number of the streams assigned to each of the other STAs which belong to the same group is acquired together with the number of the streams assigned to the STA as a result of the blind decoding of the SIG-B field in a unit of 20MHz channel.
2. The method according to claim 1 ,
wherein a length of the training symbol interval of the STA corresponds to a number of the streams assigned to the STA.
3. The method according to claim 1 ,
wherein the order of the streams assigned to the STA in the same group is indicated by an arrangement order of information on the number of streams assigned to the STA in the SIG-B field.
4. The method according to claim 1 ,
wherein the SIG-A field includes a frame format indicator, and
wherein in blind decoding of the SIG-B field, the specific GID is used when the frame format indicator indicates a MU multi-input multi-output (MIMO) format.
5. The method according to claim 1 ,
wherein a non-user specific part is omitted from the SIG-B field when the MU frame corresponds to a MU multi-input multi-output (MIMO) format.
6. The method according to claim 1 , further comprising:
estimating a channel for the streams assigned to the STA based on the starting position of the training symbol interval of the STA in the LTF.
7. A station (STA) in a wireless local area network (LAN) system, the STA comprising:
a receiver to receive a multi-user (MU) frame including a signal-A (SIG-A) field, a signal-B (SIG-B) field which includes cyclic redundancy check (CRC) information masked with group identifiers (GIDs) different per 20MHz channel, a short training field (STF), and a long training field (LTF) that includes training symbols; and
a processor to blind decode the SIG-B field in a unit of a 20MHz channel based on a specific GID assigned to the STA,
wherein the SIG-B field includes information on a number of streams assigned to each of multiple STAs that receive the MU frame,
wherein a starting position of a training symbol interval for the STA in the LTF is determined based on a number of streams assigned to each of the other stations in a same group sharing the specific GID with the STA, and an order of streams assigned to the STA in the same group, and
wherein the number of the streams assigned to each of the other STAs, which belong to the same group is acquired together with the number of the streams assigned to the STA as a result of the blind decoding of the SIG-B field in a unit of 20MHz channel.
8. The STA according to claim 7 ,
wherein a length of the training symbol interval of the STA corresponds to a number of the streams assigned to the STA.
9. The STA according to claim 7 ,
wherein the order of the streams assigned to the STA in the same group is indicated by an arrangement order of information on the number of streams assigned to the STA in the SIG-B field.
10. The STA according to claim 7 ,
wherein the SIG-A field includes a frame format indicator, and
wherein in blind decoding of the SIG-B field, the specific GID is used when the frame format indicator indicates a MU multi-input multi-output (MIMO) format.
11. The STA according to claim 7 ,
wherein a non-user specific part is omitted from the SIG-B field when the MU frame corresponds to a MU multi-input multi-output (MIMO) format.