Method for transmitting and receiving wake-up signal in wireless LAN system and apparatus therefor

1. A method for receiving a wake-up receiver (WUR) signal by a station (STA) in a wireless local area network (WLAN) system, the method comprising:

detecting a WUR preamble sequence comprised in a WUR physical layer protocol data unit (PPDU) through a WUR of the STA while a WLAN receiver of the STA is turned off;

obtaining WUR data comprised in the WUR PPDU based on a time synchronized through the WUR preamble sequence; and

outputting a wake-up signal to the WLAN receiver through the WUR of the STA when the WUR data is intended for the STA,

wherein the WUR preamble sequence used for synchronization is a signature sequence carrying particular information,

wherein the particular information comprises at least one of a single user (SU)/multi-user (MU) indicator indicating whether the WUR PPDU is for an SU or for an MU and information about a bandwidth for a WLAN PPDU that the WLAN receiver receives after waking up,

wherein the WUR preamble sequence is received through a narrow band narrower than the bandwidth for the WLAN PPDU,

wherein the narrow band is a portion of subcarriers comprised in a WLAN primary 20 MHz channel or a WUR-dedicated 20 MHz channel, and

wherein power for the WUR preamble is boosted according to an equation of SQRT(M/N), where SQRT denotes a square root, M denotes a total number of subcarriers comprised in the 20 MHz channel, and N denotes a total number of subcarriers comprised in the narrow band.

2. The method of claim 1 , wherein the WUR preamble sequence is repeated a plurality of times in the WUR PPDU.

3. The method of claim 2 , wherein the WUR preamble sequence is a spread sequence with a length of N for on-off keying modulation mapping of one bit of the WUR data to N subcarriers, and the spread sequence with the length of N is repeated a plurality of times in a time domain.

4. The method of claim 2 , wherein the WUR preamble sequence is mapped at a two-subcarrier or four-subcarrier interval in N subcarriers mapped to the WUR data and is repeated two or four times in a time domain.

5. The method of claim 1 , wherein the particular information further comprises at least one of an ID of the STA, a broadcast ID, and a basic service set (BSS) ID.

6. A station (STA) receiving a wake-up receiver (WUR) signal in a wireless local area network (WLAN) system, the STA comprising:

a WLAN receiver; and

a WUR configured to detect a WUR preamble sequence comprised in a WUR physical layer protocol data unit (PPDU) while the WLAN receiver is turned off, to obtain WUR data comprised in the WUR PPDU based on a time synchronized through the WUR preamble sequence, and to output a wake-up signal to the WLAN receiver when the WUR data is intended for the STA,

wherein the WUR preamble sequence used for synchronization is a signature sequence carrying particular information,

wherein the particular information comprises at least one of a single user (SU)/multi-user (MU) indicator indicating whether the WUR PPDU is for an SU or for an MU and information about a bandwidth for a WLAN PPDU that the WLAN receiver receives after waking up,

wherein the WUR preamble sequence is received through a narrow band narrower than the bandwidth for the WLAN PPDU,

wherein the narrow band is a portion of subcarriers comprised in a WLAN primary 20 MHz channel or a WUR-dedicated 20 MHz channel, and

wherein power for the WUR preamble is boosted according to an equation of SQRT(M/N), where SQRT denotes a square root, M denotes a total number of subcarriers comprised in the 20 MHz channel, and N denotes a total number of subcarriers comprised in the narrow band.

7. A method for transmitting a wake-up receiver (WUR) signal by an access point (AP) in a wireless local area network (WLAN) system, the method comprising:

generating a WUR physical layer protocol data unit (PPDU) comprising a WUR preamble sequence and WUR data;

transmitting the WUR PPDU to a WUR of a station (STA) with a WLAN receiver turned off; and

transmitting a WLAN PPDU to the STA after the WUR of the STA wakes up the WLAN receiver,

wherein the WUR preamble sequence used for synchronization between the WUR receiver of the STA and the AP is a signature sequence carrying particular information,

wherein the particular information comprises at least one of a single user (SU)/multi-user (MU) indicator indicating whether the WUR PPDU is for an SU or for an MU and information about a bandwidth for a WLAN PPDU that the WLAN receiver transmits after waking up,

wherein the WUR preamble sequence is received through a narrow band narrower than the bandwidth for the WLAN PPDU,

wherein the narrow band is a portion of subcarriers comprised in a WLAN primary 20 MHz channel or a WUR-dedicated 20 MHz channel, and

wherein power for the WUR preamble is boosted according to an equation of SQRT(M/N), where SQRT denotes a square root, M denotes a total number of subcarriers comprised in the 20 MHz channel, and N denotes a total number of subcarriers comprised in the narrow band.

8. The method of claim 7 , wherein the WUR preamble sequence is repeated a plurality of times in the WUR PPDU.

9. The method of claim 8 , wherein the WUR preamble sequence is a spread sequence with a length of N for on-off keying modulation mapping of one bit of the WUR data to N subcarriers, and the spread sequence with the length of N is repeated a plurality of times in a time domain.

10. The method of claim 8 , wherein the WUR preamble sequence is mapped at a two-subcarrier or four-subcarrier interval in N subcarriers mapped to the WUR data and is repeated two or four times in a time domain.

11. The method of claim 7 , wherein the particular information further comprises at least one of an ID of the STA, a broadcast ID, and a basic service set (BSS) ID.