Method and Apparatus for Reducing Channel Scanning Time by Sharing Channel Information in Wireless Local Area Network (wlan)

1. A method for scanning a channel in a wireless local area network (WLAN) system, the method comprising: extracting at least one target channel from among a plurality of channels present in at least one frequency band, based on channel scanning record information; generating a basic service set (BSS) existing channel information element (IE) including at least one BSS existing channel bitmap indicating information on a channel in which at least one access point (AP) exists, based on channel information received from at least one neighboring station (STA); determining a scanning rank of at least one target channel, using the BSS existing channel IE; and identifying a target AP from among the at least one AP through scanning the at least one target channel, based on the scanning rank.

2. The method of claim 1 , wherein the channel scanning record information comprises information on at least one channel that performed scanning from among the plurality of channels.

3. The method of claim 1 , wherein the at least one BBS existing channel bitmap comprises: at least one band indication bit indicating information on the at least one frequency band and at least one channel indication bit indicating information on a presence of a BSS in the at least one channel.

4. The method of claim 1 , wherein a size of the at least one BSS existing channel bitmap corresponds to a number of the plurality of channels present in the at least one frequency band.

5. The method of claim 1 , wherein the determining of the scanning rank of the at least one target channel, using the BSS existing channel IE comprises: identifying at least one BSS existing channel from among the at least one target channel, using the BSS existing channel IE; and generating the scanning rank, based on a priority of the at least one BSS existing channel.

6. The method of claim 5 , wherein the determining of the scanning rank of the at least one target channel, using the BSS existing channel IE further comprises: generating the scanning rank of the at least one target channel, using a predetermined rule when the at least one BSS existing channel is unidentifiable among the at least one target channel.

7. The method of claim 1 , wherein the identifying of the target AP further comprises: determining whether scanning channel information obtained by scanning the at least one target channel corresponds to the at least one BSS existing channel bitmap; and updating the at least one BSS existing channel bitmap, based on the scanning channel information when the scanning channel information does not correspond to the at least one BSS existing channel bitmap as a result of the determination.

8. The method of claim 1 , wherein the BSS existing channel IE further comprises: an identifier (ID) field indicating an ID of the BSS existing channel IE, and a length field indicating a length of the BSS existing channel IE.

9. The method of claim 1 , further comprising: providing information on a channel in which the at least one AP exists in the at least one neighboring STA.

10. The method of claim 9 , wherein the providing of the information on the channel in which the AP exists to the at least one neighboring STA comprises: setting a receiver address of a probe request frame to be an address of the at least one neighboring STA; and transmitting the probe request frame including the BSS existing channel IE to the at least one AP.

11. An apparatus for scanning a channel in a wireless local area network (WLAN) system, the apparatus comprising: a target channel extractor configured to extract at least one target channel from among a plurality of channels present in at least one frequency band, based on channel scanning record information; a basic service set (BSS) existing channel information element (IE) generator configured to generate a BSS existing channel IE including at least one BSS channel bitmap indicating information on a channel in which at least one access point (AP) exists, based on channel information received from at least one neighboring station (STA); a scanning rank determiner configured to determine a scanning rank of the at least one target channel, using the BSS existing channel IE; and a target AP identifier configured to scan the at least one target channel, based on the scanning rank, and identify a target AP from among the at least one AP.

12. The apparatus of claim 11 , wherein the scanning rank determiner is configured to identify at least one BSS existing channel from among the at least one target channel, using the BSS existing channel IE, and generate the scanning rank, based on a priority of the at least one BSS existing channel.

13. The apparatus of claim 11 , wherein the target AP identifier is configured to determine whether scanning channel information obtained by scanning the at least one target channel corresponds to the at least one BSS existing channel bitmap, and update the at least one BSS existing channel bitmap, based on the scanning channel information when the scanning channel information does not correspond to the at least one BSS existing channel bitmap as a result of the determination.

14. The apparatus of claim 11 , wherein the at least one neighboring STA is provided channel information in which the at least one AP exists.

15. The apparatus of claim 14 , wherein the channel information provider is configured to set a receiver address of the probe request frame to be an address of the at least one neighboring STA, and transmit a probe request frame including the BSS existing channel IE to the at least one AP.

16. A system, comprising: a plurality of access points (APs) including a first AP configured to perform a method, the method including: receiving a probe request frame from a first station, the probe request frame including a basic service set (BSS) existing channel information element (IE), the BSS existing channel information element including a BSS existing channel bitmap indicating information on a channel in which the first AP exists; and transmitting a probe response frame to a second station performing channel scanning, the probe response frame including the BSS existing channel IE, wherein the second station determines a scanning rank using the BSS existing channel IE and identifies a target AP among the plurality of access points based on the scanning rank.