Method and apparatus for scanning in wireless LAN

• US 9,503,967 B2
• Filed: 09/11/2013
• Issued: 11/22/2016
• Est. Priority Date: 09/11/2012
• Status: Expired due to Fees

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Park, Giwon, Ryu, Kiseon, Kwak, Jinsam
• Primary Examiner(s): MEW, KEVIN D
• Application Number:
  US14/424,921
• Publication Number:
  US 20150230162A1
• Time in Patent Office: 1,168 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 short probe request frame to a target access point (AP) via a first channel,

wherein the target AP is determined based on a basic service identifier (BSSID) included in an MAC Layer Management Entity (MLME).SCAN.request.primitive;

unicasting, by the STA, a probe request frame to a the target AP via the first channel when receiving a first acknowledgement (ACK) transmitted by the target AP as a response to the short probe request frame,

wherein the short probe request frame is transmitted before the probe request frame is transmitted via the first channel;

determining, by the STA, whether a second ACK for the probe request frame is received via the first channel within a second ACK transmission time;

monitoring, by the STA, for a probe response frame, as a response to the probe request frame, on the first channel if the second ACK is received within the second 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 second ACK transmission time when a timer for the second ACK transmission time expires if the second ACK is not received within the second ACK transmission time.

2. The method of claim 1, further comprising:

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

3. The method of claim 1,

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

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

decoding the second ACK, and

determining whether a receiver address (RA) field of the decoded second ACK corresponds an identifier of the STA.

5. The method of claim 1,

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.

6. The method of claim 1,

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

7. 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 short probe request frame to a target access point (AP) via a first channel,

wherein the target AP is determined based on a basic service identifier (BSSID) included in an MAC Layer Management Entity (MLME).SCAN.request.primitive;

unicast a probe request frame to a the target AP via the first channel when receiving a first acknowledgement (ACK) transmitted by the target AP as a response to the short probe request frame,

wherein the short probe request frame is transmitted before the probe request frame is transmitted via the first channel;

determine whether a second ACK for the probe request frame is received via the first channel within a second ACK transmission time;

monitor for a probe response frame, as a response to the probe request frame, on the first channel if the second ACK is received within the second 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 second ACK transmission time when a timer for the second ACK transmission time expires if the second ACK is not received within the second ACK transmission time.

8. The STA of claim 7,

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

9. The STA of claim 7,

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

10. The STA of claim 7, wherein the processor is configured to:

decode the second ACK and

determine whether a receiver address (RA) field of the decoded second ACK corresponds to an identifier of the STA.

11. The STA of claim 7,

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.

12. The STA of claim 7,

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