ACTIVE SEARCH METHOD IN WIRELESS LAN SYSTEM

• US 20150223154A1
• Filed: 09/17/2013
• Published: 08/06/2015
• Est. Priority Date: 09/20/2012
• Status: Active Grant

• Current Assignee: Red Hat, Inc. (International Business Machines Corporation)
• Original Assignee: KT Corporation
• Inventors: Jeong, Yang Seok, Kim, Joo Young
• Granted Patent: US 9,781,661 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04L 1/1671 the supervisory signal being transmitted together with control information
• 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 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/23 in the downlink direction of a wireless link, i.e. towards a terminal
• CPC Class Codes: H04W 74/004 in the uplink, i.e. towards network
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

An active search method in a wireless LAN system is disclosed. The active search method comprises the steps of: transmitting, through an arbitrary channel, a preceding probe request frame for confirming the existence of an access point; acquiring, from at least one access point, a probe ACK frame that is a response to the preceding probe request frame; setting a maximum waiting time on the basis of the number of probe ACK frames; and performing an active search for an access point in the arbitrary channel for the maximum waiting time. Therefore, the waiting time for receiving a probe response frame can be reduced.

Claims

1-18. -18. (canceled)

19. A method of performing active scanning by a terminal, the method comprising:

transmitting a prior probe request frame through a wireless channel;

receiving probe acknowledgement (ACK) frame in response to the prior probe request frame, from at least one access point; and

when receiving the probe ACK frame, transmitting a probe request frame through the wireless channel to an access point which has transmitted the probe ACK frame.

20. The method of claim 19, wherein the prior probe request frame is a null data packet (NDP) frame.

21. The method of claim 19, wherein the prior probe request frame includes a Compressed Service Set Identifier (SSID) information of an access point.

22. The method of claim 19, wherein the probe ACK frame includes identifier information of an access point.

23. The method of claim 19, wherein the receiving the probe ACK frame comprises receiving a probe ACK frame that has a signal strength greater than or equal to a predetermined signal strength.

24. The method of claim 19, further comprising waiting for the probe ACK frame on the wireless channel during a waiting time shorter than a Max Waiting Time.

25. The method of claim 24, further comprising performing scanning on a next channel when no probe ACK frame is received on the wireless channel during the waiting time shorter than a Max Waiting Time.

26. The method of claim 19, wherein the probe ACK frame includes information on a next beacon transmission time of the access point which has transmitted the probe ACK frame.

27. The method of claim 26, further comprising receiving a beacon from the access point which has transmitted the probe ACK frame at a time determined based on the information on the next beacon transmission time.

28. The method of claim 26, acquiring additional information on the access point which has transmitted the probe ACK frame using a beacon transmitted from the access point which has transmitted the probe ACK frame at a time determined based on the information on the next beacon transmission time.

29. A method of responding to active scanning by an access point, the method comprising:

receiving a prior probe request frame from a terminal through a wireless channel;

transmitting a probe acknowledgement (ACK) frame in response to the prior probe request frame; and

receiving a probe request frame which is transmitted from the terminal through the wireless channel, when the probe ACK frame is received by the terminal.

30. The method of claim 29, wherein the prior probe request frame is a null data packet (NDP) frame.

31. The method of claim 29, wherein the prior probe request frame includes a Compressed Service Set Identifier (SSID) information of the access point.

32. The method of claim 29, wherein the probe ACK frame includes identifier information of the access point.

33. The method of claim 29, wherein the probe ACK frame information on a next beacon transmission time of the access point.

34. A terminal for performing active scanning, the terminal comprising:

a transceiver; and

a processor,

wherein the processor is configured to;

transmit, using the transceiver, a prior probe request frame through a wireless channel;

receive, using the transceiver, probe acknowledgement (ACK) frame in response to the prior probe request frame, from at least one access point;

when receiving the probe ACK frame, transmit, using the transceiver, a probe request frame through the wireless channel to an access point which has transmitted the probe ACK frame.

35. An access point for responding to active scanning, the access point comprising:

a transceiver; and

a processor,

wherein the processor is configured to;

receive, using the transceiver, a prior probe request frame from a terminal through a wireless channel;

transmit, using the transceiver, a probe acknowledgement (ACK) frame in response to the prior probe request frame;

receive, using the transceiver, a probe request frame which is transmitted from the terminal through the wireless channel, when the probe ACK frame is received by the terminal.