METHOD AND APPARATUS FOR SCANNING IN WIRELESS LAN

• US 20150230162A1
• Filed: 09/11/2013
• Published: 08/13/2015
• Est. Priority Date: 09/11/2012
• Status: Active Grant

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Park, Giwon, Ryu, Kiseon, Kwak, Jinsam
• Granted Patent: US 9,503,967 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 5/0055 Physical resource allocation for ACK/NACK for physical mapping arrangements in ARQ protocols H04L1/1861
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A method for scanning by a STA can comprise the steps of: the STA unicasting a probe request frame to a target AP from a first channel, the target AP having been determined in accordance with a BSSID comprised in a primitive; the STA processing an ACK transmitted via the first channel within a first ACK transmission time, and determining whether the first ACK for the probe request frame is received; if the first ACK is received within the first ACK transmission time, then the STA monitoring a probe response frame, which is a response to the probe request frame from the first channel; and if the first ACK is not received within the first ACK transmission time, then regardless of a CCA level detected during the first ACK transmission time, the STA switching the scanning channel.

Claims

1. A method for scanning by a station (STA), comprising:

unicasting, by the STA, a probe request frame to a target access point (AP) via a first channel, the target AP is determined based on a basic service identifier (BSSID) included in an MLME.SCAN.request.primitive;

determining, by the STA, whether a first acknowledgement (ACK) for the probe request frame is received by processing an ACK transmitted via the first channel within a first ACK transmission time;

monitoring, by the STA, a probe response frame as a response to the probe request frame on the first channel if the first ACK is received within the first ACK transmission time; and

switching, by the STA, a scanning channel from the first channel to a second channel regardless of a clear channel assessment (CCA) level detected during the first ACK transmission time when a timer for the first ACK transmission time expires if the first ACK is not received within the first ACK transmission time.

2. The method of claim 1, further comprising:

configuring, by the STA, a network allocation vector (NAV) to 0 if the first ACK is not received within the first ACK transmission time.

3. The method of claim 1,

wherein the first ACK transmission time is a short interframe space (SIFS).

4. The method of claim 1, wherein the determining, by the STA, whether the first ACK for the probe request frame is received by processing the ACK transmitted via the first channel within a first ACK transmission time comprises:

decoding the ACK, and

determining whether a receiver address (RA) field of the ACK acquired by decoding the ACK corresponds an identifier of the STA.

5. The method of claim 1, further comprising:

unicasting, by the STA, a short probe request frame to the target AP via the first channel; and

generating, by the STA, the probe request frame when receiving a second ACK transmitted by the target AP as a response to the short probe request frame via the first channel,

wherein the short probe request frame is transmitted before the probe request frame is transmitted via the first channel in order to determine whether the target AP exists.

6. The method of claim 5,

wherein the short probe request frame includes only a medium access control (MAC) header and a frame check sequence (FCS),

wherein the MAC header includes an address field, and

wherein the address field includes a basic service set identifier (BSSID) of the AP.

7. The method of claim 5,

wherein the short probe request frame includes a transmitter address (TA) field,

wherein the TA field includes identifier information of the STA transmitting the short probe request frame, and

wherein the second ACK includes a receiver address (RA) field determined based on the identifier information of the STA.

8. A station (STA) operating in a wireless LAN, the STA comprising:

a radio frequency (RF) unit receiving a radio signal; and

a processor operatively connected with the RF unit and configured to;

unicast a probe request frame to a target access point (AP) via a first channel, the target AP is determined based on a basic service identifier (BSSID) included in an MLME.SCAN.request.primitive;

determine whether a first acknowledgement (ACK) for the probe request frame is received by processing an ACK transmitted via the first channel within a first ACK transmission time;

monitor a probe response frame as a response to the probe request frame on the first channel if the first ACK is received within the first ACK transmission time; and

switch a scanning channel from the first channel to a second channel regardless of a clear channel assessment (CCA) level detected during the first ACK transmission time when a timer for the first ACK transmission time expires if the first ACK is not received within the first ACK transmission time.

9. The STA of claim 8,

wherein the processor is configured to set a network allocation vector (NAV) to 0 if the first ACK is not received within the first ACK transmission time.

10. The STA of claim 8,

wherein the first ACK transmission time is a short interframe space (SIFS).

11. The STA of claim 8,

wherein the processor is configured to:

decode the ACK and

determine whether a receiver address (RA) field of the ACK acquired by decoding the ACK corresponds to an identifier of the STA.

12. The STA of claim 8,

wherein the processor configured to:

unicast a short probe request frame to the target AP via the first channel, and

generates the probe request frame when receiving a second ACK transmitted by the target AP as a response to the short probe request frame via the first channel, and

wherein the short probe request frame is transmitted before the probe request frame is transmitted via the first channel in order to determine whether the target AP exists.

13. The STA of claim 12,

wherein the short probe request frame includes only a medium access control (MAC) header and a frame check sequence (FCS),

wherein the MAC header includes an address field, and

wherein the address field includes a basic service set identifier (BSSID) of the AP.

14. The STA of claim 12,

wherein the short probe request frame includes a transmitter address (TA) field,

wherein the TA field includes identifier information of the STA transmiting the short probe request frame, and

wherein the second ACK includes a receiver address (RA) field determined based on the identifier information of the STA.