METHOD OF REDUCING INTERFERENCE BETWEEN STATIONS IN WIRELESS LAN SYSTEM, AND APPARATUS SUPPORTING THE SAME

• US 20120257574A1
• Filed: 08/18/2010
• Published: 10/11/2012
• Est. Priority Date: 12/17/2009
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Seok, Yong Ho, Noh, Yu Jin, Kim, Bong Hoe, Lee, Dae Won
• Granted Patent: US 8,995,342 B2
• Time in Patent Office: Days
• US Class Current: 370/328
• CPC Class Codes: H04W 28/04 Error control
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 72/046 the resource being in the space domain, e.g. beams
• CPC Class Codes: H04W 72/541 using the level of interference
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

An interference avoidance method performed by an Access Point (AP) in a WLAN system in an Overlapping Basic Service Set (OBSS) environment is provided. The interference avoidance method includes receiving an interference avoidance request message from the first STA, the interference avoidance request message informing that frame transmission of the AP acts as interference with a first STA; transmitting an interference avoidance response message in response to the interference avoidance request message; obtaining first channel information about a first channel between the first STA and the AP from the first STA which has received the interference avoidance response message; determining a transmitting steering matrix based on the first channel information; and transmitting data to a second STA by performing beamforming according to the transmitting steering matrix.

Claims

1. An interference avoidance method performed by an Access Point (AP) in a WLAN system in an Overlapping Basic Service Set (OBSS) environment, the interference avoidance method comprising:

receiving an interference avoidance request message from the first STA, the interference avoidance request message informing that frame transmission of the AP acts as interference with a first STA;

transmitting an interference avoidance response message in response to the interference avoidance request message;

obtaining first channel information about a first channel between the first STA and the AP from the first STA which has received the interference avoidance response message;

determining a transmitting steering matrix based on the first channel information; and

transmitting data to a second STA by performing beamforming according to the transmitting steering matrix.

2. The interference avoidance method as claimed in claim 1, wherein the first STA is an AP or non-AP STA of a neighboring BSS forming the OBSS.

3. The interference avoidance method as claimed in claim 1, wherein the step of obtaining the first channel information includes:

receiving a sounding PLOP Protocol Data Unit (PPDU) from the first STA; and

estimating the channel using the sounding PPDU.

4. The interference avoidance method as claimed in claim 3, wherein:

the sounding PPDU is a steered sounding PPDU, and

the steered sounding PPDU is precoded using a receiving matrix obtained by decomposing a channel between the first STA and a third STA, the third STA sending a frame to the first STA.

5. The interference avoidance method as claimed in claim 1, wherein the step of obtaining the first channel information includes,

receiving channel information about the first channel which is transmitted by the first STA as data.

6. The interference avoidance method as claimed in claim 1, wherein the step of obtaining the first channel information includes,

receiving a covariance value of a channel between the first STA and a third STA from the first STA, the third STA sending a frame to the first STA.

7. The interference avoidance method as claimed in claim 1, wherein the interference avoidance response message includes at least one field among:

status field indicating a reception state of the interference avoidance request message;

a capability field indicating whether interference avoidance capability exists or not; and

a training request field indicating whether a sounding frame is requested to be transmitted for estimating the first channel between the first STA and the AP.

8. An AP operating in an OBSS environment, comprising:

an Radio Frequency (RF) unit; and

a processor functionally coupled to the RF unit and configured to;

receive or overhear an interference avoidance request message from the first STA, the interference avoidance request message informing that frame transmission of the AP acts as interference with a first STA;

transmit an interference avoidance response message in response to the interference avoidance request message;

obtain first channel information about a first channel between the first STA and the AP from the first STA which has received the interference avoidance response message;

determine a transmitting steering matrix based on the first channel information; and

transmit data to a second STA by performing beamforming according to the transmitting steering matrix.

9. The AP as claimed in claim 8, wherein the first STA is an AP or non-AP STA of a neighboring BSS forming the OBSS.

10. The AP as claimed in claim 8, wherein the obtaining the first channel information includes:

receiving a sounding PLOP Protocol Data Unit (PPDU) from the first STA; and

estimating the channel using the sounding PPDU.

11. The AP as claimed in claim 10, wherein:

the sounding PPDU is a steered sounding PPDU, and

the steered sounding PPDU is precoded using a receiving matrix obtained by decomposing a channel between the first STA and a third STA, the third STA sending a frame to the first STA.

12. The AP as claimed in claim 8, wherein the obtaining the first channel information includes,

receiving channel information about the first channel which is transmitted by the first STA as data.

13. The AP as claimed in claim 8, the obtaining the first channel information includes,

receiving a covariance value of a channel between the first STA and a third STA from the first STA, the third STA sending a frame to the first STA.

14. The AP as claimed in claim 8, wherein the interference avoidance response message includes at least one field among:

status field indicating a reception state of the interference avoidance request message;

a capability field indicating whether interference avoidance capability exists or not; and

a training request field indicating whether a sounding frame is requested to be transmitted for estimating the first channel between the first STA and the AP.