Channel sounding method in wireless lan system and device for supporting same

Patent metadata

Field	Value
Publication number	US-2016119902-A1
Application number	US-201414890303-A
Country	US
Kind code	A1
Filing date	May 12, 2014
Priority date	May 10, 2013
Publication date	Apr 28, 2016
Grant date	—

Abstract

A method for channel sounding in a wireless local area network (WLAN) system and apparatus for the same is disclosed. An access point (AP) to perform the method for channel sounding broadcasts information on a restricted access window (RAW) for channel sounding included in a beacon, and transmits null data packets (NDP) for channel estimation in the RAW to a station (STA). The STA estimates channel information based on the NDPs, and transmits the estimated channel information to the AP.

First claim

1 . A method for channel sounding in a wireless local area network (WLAN) system performed by an access point (AP), the method comprising:
broadcasting a beacon comprising information on a restricted access window (RAW) for channel sounding; and transmitting a plurality of null data packets (NDP) in the RAW to a station (STA).

2 . (canceled)

3 . The method of claim 21 , wherein the AP controls the data transmission by the STA to be prohibited over the RAW duration for the channel sounding.

4 . The method of claim wherein the AP controls transmission of the channel information to the AP to be allowed, and other transmission to be prohibited, subsequent to the transmission of the NDPs in the RAW duration for the channel sounding.

5 . The method of claim 1 , wherein the beacon comprises at least one of:
a bit value indicating whether the channel sounding is performed through the RAW, a bit value to control the transmission by the STA in the RAW duration, and a bit value indicating a communication type to be performed by the AP.

6 . The method of claim 1 , wherein the transmitting comprises:
transmitting the NDPs for a plurality of sectors set by the AP in the RAW duration for the channel sounding.

7 . The method of claim 1 , wherein the transmitting comprises:
transmitting the NDPs for a plurality of frequencies used in sub-channel selective transmission (SST) in the RAW duration for the channel sounding.

8 . The method of claim 1 , wherein the transmitting comprises:
transmitting the NDPs successively at predetermined time intervals.

9 . The method of claim 1 , further comprising:
receiving, from the STA, channel information estimated based on the NDPs.

10 . The method of claim 9 , wherein the receiving comprises:
receiving the channel information through an RAW for a feedback report, wherein the RAW for the feedback report is allocated subsequent to the RAW for the channel sounding.

11 . The method of claim 1 , wherein the transmitting comprises:
transmitting the NDPs at predetermined time intervals of a short inter-frame space (SIFS) or a point inter-frame space (PIFS).

12 . The method of claim 1 , wherein the STA wakes up at a beginning of the RAW for the channel sounding, and remains awake until the RAW for the channel sounding terminates or the transmission of the NDPs ends.

13 . A method for channel sounding in a wireless local area network (WLAN) system performed by a station (STA), the method comprising:
receiving, from an access point (AP), a beacon comprising information on a restricted access window (RAW) for channel sounding; estimating channel information based on a null data packet (NDP) received from the AP; and transmitting the estimated channel information to the AP, wherein the NDP is transmitted to the STA in the RAW.

14 . The method of claim 13 , wherein the STA is prohibited from transmitting data over a duration of the RAW for the channel sounding.

15 . The method of claim 13 , wherein the STA is allowed to transmit the channel information to the AP, and prohibited from performing other transmissions, subsequent to the transmission of the NDP over the RAW duration for the channel sounding.

16 . The method of claim 13 , wherein the estimating comprises:
identifying a communication type to be performed by the AP based on the received beacon; receiving the NDP from the AP in the RAW when the STA supports the communication type; and estimating channel information based on the received NDP and the identified communication type.

17 . The method of claim 13 , wherein the estimating comprises:
searching for a frequency channel that satisfies a predetermined reference from among frequency channels used in communication with the AP, and determining information on the found frequency channel to be channel information.

18 . The method of claim 13 , wherein the estimating comprises:
searching for a sector to which the STA belongs from among a plurality of sectors set by the AP, and determining identification information on the found sector to be channel information.

19 . The method of claim 13 , wherein when the estimated channel information is transmitted to the AP, transmission by other STAs aside from the STA that transmits the channel information is prohibited.

20 . The method of claim 13 , wherein the estimating comprises:
determining a frequency channel that satisfies a predetermined reference from among a plurality of frequency channels based on the NDP, and the transmitting comprises: transmitting the channel information to the AP using the determined frequency channel.

21 . (canceled)

22 . A wireless apparatus comprising:
a transceiver to transmit and receive a frame; and a processor functionally associated with the transceiver, wherein the processor receives, from an access point (AP), a beacon comprising information on a restricted access window (RAW) for channel sounding, estimates channel information based on a null data packet (NDP) received from the AP, and transmits the estimated channel information to the AP.

Assignees

• Korea Electronics Telecomm

Inventors

• Cheong Min Ho
• Kwon Hyoung Jin
• Lee Jae Seung
• Lee Sok Kyu

Classifications

• H04W72/21

  in the uplink direction of a wireless link, i.e. towards the network · CPC title

• H04W72/23 Primary

  in the downlink direction of a wireless link, i.e. towards a terminal · CPC title

• H04W74/006

  in the downlink, i.e. towards the terminal · CPC title

• H04W48/12 Primary

  using downlink control channel · CPC title

• H04W84/12

  WLAN [Wireless Local Area Networks] · CPC title