Fast active scanning wireless network apparatus and method

• US 8,131,291 B2
• Filed: 04/02/2004
• Issued: 03/06/2012
• Est. Priority Date: 04/29/2003
• Status: Active Grant

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Jeong, Moo Ryong, Watanabe, Fujio, Kawahara, Toshiro
• Primary Examiner(s): Bost, Dwayne
• Assistant Examiner(s): Wyche, Myron
• Application Number:
  US10/545,466
• Publication Number:
  US 20060111103A1
• Time in Patent Office: 2,895 Days
• Field of Search: 455/434, 455/514, 455/562.1, 455/432.1, 455/436, 455/515, 370/252, 370/349
• US Class Current: 455/434
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04W 48/14 using user query or user detection
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

In a fast active scanning wireless network apparatus and method for quick determination of available access points (20), information about a candidate set of available access points (20) is obtained, and a candidate access point is identified from the candidate set. A mobile station (10) then queries the candidate access point with a probe request that designates the candidate access point as a sole responder. The probe request prevents other access points from contending for the medium of communication between the mobile station and the designated sole responder access point by excluding the attempt by other access points (20) to transmit probe responses. The apparatus and method thus increases the probability of a fast and successful probe request from the mobile station and subsequent response from the designated access point (20). The designated access point may also respond with a probe response of high priority, preventing intervention of communication.

Claims

1. A method of enabling active channel scanning in a wireless network, said method comprising:

collecting candidate access point information that differentiates between candidate access points that are available for association;

selecting a candidate access point from said candidate access points based on said candidate access point information; and

transmitting a probe request, said probe request including an address of said selected access point that is specified in a basic service set identification field, wherein, if said selected candidate access point does not respond to said probe request within an interframe space period that immediately follows said probe request and that interframe space period is shorter than a distributed interframe space period, said wireless station resends said probe request in the time period after said interframe space period that immediately follows said probe request has ended but prior to the time period that a distributed interframe space period would have ended if said distributed interframe space period had begun at the same time as said interframe space period that immediately follows said probe request.

2. A wireless station in a wireless communications network comprising:

a collector which collects candidate access point information that differentiates between candidate access points that are available for association;

a selector that, based on the candidate access point information, selects a candidate access point from said candidate access points; and

a transmitter for transmitting a probe request, said probe request including an address of said selected candidate access point that is specified in a basic service set identification field, wherein, if said selected candidate access point does not respond to said probe request within an interframe space period that immediately follows said probe request and that interframe space period is shorter than a distributed interframe space period, said wireless station resends said probe request in the time period after said interframe space period that immediately follows said probe request has ended but prior to the time period that a distributed interframe space period would have ended if said distributed interframe space period had begun at the same time as said interframe space period that immediately follows said probe request.

3. A wireless access point among a plurality of access points in a telecommunications system that are available for association, comprising:

a receiver that receives a probe request from a wireless station, said probe request including an address of said wireless access point that is specified in a basic service set identification field; and

a transmitter for transmitting a response to said probe request, wherein, if said wireless access point does not respond to said probe request within an interframe space period that immediately follows said probe request and that is shorter than a distributed interframe space period, said wireless station resends said probe request in the time period after said interframe space period that immediately follows said probe request has ended but prior to the time period that a distributed interframe space period would have ended if, said distributed interframe space period had begun at the same time as said interframe space period that immediately follows said probe request.

4. A wireless telecommunications system comprising

a plurality of access points, wherein at least one of the access points comprises a processor which processes candidate access point information that differentiates between candidate access points that are available for association;

and

a wireless terminal which, based on said candidate access point information, selects one of said access points and transmits a probe request, said probe request including an address of said candidate access point that is specified in a basic service set identification field, wherein, if said selected access point does not respond to said probe request within an interframe space period that immediately follows said probe request and that interframe space period is shorter than a distributed interframe space period, said wireless station resends said probe request in the time period after said interframe space period that immediately follows said probe request has ended but prior to the time period that a distributed interframe space period would have begun if said distributed interframe space period had begun at the same time as said interframe space period that immediately follows said probe request.

5. A wireless telecommunications system comprising:

a plurality of wireless stations, wherein at least one of the wireless stations comprises a processor which processes candidate access point information that differentiates between candidate access points that are available for association; and

a wireless station that, based upon said candidate access point information, selects an access point and transmits a probe request, said probe request including an address of said selected access point that is specified in a basic service set identification field, wherein, if said selected access point does not respond to said probe request within an interframe space period that immediately follows said probe request and that is shorter than a distributed interframe space period, said wireless station resends said probe request in the time period after said interframe space period that immediately follows said probe request has ended but prior to the time period that a distributed interframe space period would have ended if said distributed interframe space period had begun at the same time as said interframe space period that immediately follows said probe request.