Sounding method for beamforming transmission in wireless LAN system and apparatus therefor
When an AP (access point) performs sounding to transmit a frame to one or more STAs using a beamforming scheme in a wireless LAN (WLAN) system, the AP receives a beamforming feedback, which is generated based on measurement of a specific signal transmitted by the AP in a manner that the one or more STAs group a prescribed number of tones according to a tone grouping element (Ng). In this case, the Ng is configured by a multiple of 4.
1. A method of performing sounding by an access point (AP) with one or more stations (STAs) for a beamforming scheme in a second type wireless local area network (WLAN) system using a second subcarrier spacing, the method comprising:
transmitting a specific signal to the one or more STAs by the AP via a plurality of tones; and
receiving a beamforming feedback from the one or more STAs,
wherein the beamforming feedback is based on grouping a prescribed number of tones using a second tone grouping element (Ng) among the plurality of tones,
wherein a first Ng, used for a first type WLAN system using a first subcarrier spacing, has a value within a first group of values,
wherein the second Ng is configured by one selected from a second group of values,
wherein the first subcarrier spacing is four times larger than the second subcarrier spacing, and
wherein a minimum value of the second group of values is four times larger than a minimum value of the first group of values.
2. The method of claim 1 ,
wherein the first type WLAN system is a system supporting a IEEE 802.11ac scheme, and
wherein the second type WLAN system is a system supporting a IEEE 802.11ax scheme.
3. The method of claim 1 , wherein the second Ng is configured by one selected from 4, 8 and 16.
4. The method of claim 1 , wherein transmitting the specific signal transmitted by the AP comprises:
transmitting an NDP-A (non data packet announcement) frame to the one or more STAs by the AP; and
transmitting an NDP frame containing the specific signal to the one or more STAs by the AP.
5. The method of claim 4 , wherein the AP informs the one or more STAs of a value to be used by the one or more STAs for the second Ng via the NDP-A frame.
6. The method of claim 1 , wherein the beamforming feedback is received in a unit of 26 tones corresponding to an RU (resource unit).
7. The method of claim 6 , wherein the 26 tones correspond to a minimum resource unit of OFDMA.
8. The method of claim 1 , wherein the second Ng is configured by a different value according to a size of a resource region in which the beamforming is performed.
9. A method of transmitting a beamforming feedback by a station (STA) in a second type wireless local area network (WLAN) system using a second subcarrier spacing, the method comprising:
receiving a specific signal from an access point (AP) via a plurality of tones; and
transmitting the beamforming feedback to the AP, wherein the beamforming feedback is based on grouping a prescribed number of tones using a second tone grouping element (Ng),
wherein a first Ng, used for a first type WLAN system using a first subcarrier spacing, has a value within a first group of values,
wherein the second Ng is configured by one selected from a second group of values,
wherein the first subcarrier spacing is four times larger than the second subcarrier spacing, and
wherein a minimum value of the second group of values is four times larger than a minimum value of the first group of values.
10. The method of claim 9 ,
wherein the first type WLAN system is a system supporting a IEEE 802.11ac scheme, and
wherein the second type WLAN system is a system supporting a IEEE 802.11ax scheme.
11. The method of claim 9 , wherein the beamforming feedback is transmitted in a unit of 26 tones corresponding to an RU (resource unit).
12. An access point (AP) performing sounding with one or more STAs for a beamforming scheme in a second type wireless local area network (WLAN) system, the AP comprising:
a transceiver configured to transmit a specific signal to the one or more STAs via a plurality of tones and receive a beamforming feedback from the one or more STAs; and
a processor configured to process the beamforming feedback received by the transceiver,
wherein the beamforming feedback is based on grouping a prescribed number of tones using a second tone grouping element (Ng) among the plurality of tones,
wherein a first Ng, used for a first type WLAN system using a first subcarrier spacing, has a value within a first group of values,
wherein the second Ng is configured by one selected from a second group of values,
wherein the first subcarrier spacing is four times larger than the second subcarrier spacing, and
wherein a minimum value of the second group of values is four times larger than a minimum value of the first group of values.
13. The AP of claim 12 ,
wherein the first type WLAN system is a system supporting a IEEE 802.11ac scheme, and
wherein the second type WLAN system is a system supporting a IEEE 802.11ax scheme.
14. A station (STA) transmitting a beamforming feedback in a second type wireless local area network (WLAN) system using a second subcarrier spacing, the STA comprising:
a transceiver configured to receive a specific signal from an access point (AP) via a plurality of tones and transmit the beamforming feedback to the AP; and
a processor configured to generate the beamforming feedback based on measurement of the specific signal in a manner of grouping a prescribed number of tones using a second tone grouping element (Ng),
wherein the processor selects the second Ng as one from a second group of values,
wherein the first subcarrier spacing is four times larger than the second subcarrier spacing, and
wherein a minimum value of the second group of values is four times larger than a minimum value of the first group of values.
15. The STA of claim 14 ,
wherein the first type WLAN system is a system supporting a IEEE 802.11ac scheme, and
wherein the second type WLAN system is a system supporting a IEEE 802.11ax scheme.