Fast active scanning wireless network apparatus and method

• US 20060111103A1
• Filed: 04/02/2004
• Published: 05/25/2006
• 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: Watanabe, Fujio, Kawahara, Toshiro, Jeong, Moo Ryong
• Granted Patent: US 8,131,291 B2
• Time in Patent Office: Days
• 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

11. A wireless communications network comprising:

a collector which collects candidate access point information that differentiates between candidate access points which are most likely to provide communication with wireless stations in the network and candidate access points which are not; and

a transmitter for transmitting said candidate access point information.

12. The network of claim 11, further comprising a selector for selecting, from said candidate access point information, said candidate access points that have been differentiated as most likely to provide communication.

13. The network of claim 12, further comprising a wireless station for scanning said candidate access points that have been differentiated as most likely to provide communication.

14. The network of claim 13, wherein said scanning comprises said wireless station transmitting a probe request for a specified candidate access point chosen from among said candidate access points differentiated as most likely to provide communication with the network.

15. The network of claim 14, wherein said probe request comprises fields of information wherein a broadcast address is entered in a destination address field, an individual address of said specified candidate access point is entered in a basic service set identification field, and either of a service set identification for said specified candidate access point or a broadcast service set identification for said specified candidate access point is entered in a service set identification field.

16. The network of claim 14, wherein said specified candidate access point responds to said probe request with an acknowledgement frame prior to any other type of frame being transmitted from said specified candidate access point and immediately following an interframe space that immediately follows said probe request.

17. The network of claim 14, wherein

said specified candidate access point responds to said probe request with a probe response frame immediately following an interframe space period, said interframe space period immediately following said probe request and being shorter in time than a distributed interframe space period;

and wherein

said wireless station responds to said probe response with an acknowledgement frame.

18. The network of claim 14, wherein

said specified candidate access point responds to said probe request with a probe response frame immediately following an interframe space period, said interframe space period immediately following said probe request and being shorter in time than a distributed interframe space period;

and wherein

said probe response is neither acknowledged nor expected to be acknowledged with an acknowledgement frame from said wireless station.

19. The network of claim 14, wherein, if said specified candidate access point does not respond to said probe request with a probe response 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 begun if said distributed interframe space period had begun at the same time as said interframe space period that immediately follows said probe request.

20. The network of claim 14, wherein, if a probe request frame'"'"'s destination address field includes a broadcast destination or if the basic service set identification field includes a broadcast basic service set identification, then said scanning comprises a scanning technique selected from the group consisting of the IEEE 802.11, 802.15 and 802.16 wireless standards of interoperability.

21. A wireless telecommunications system comprising:

a plurality of access points, at least some of said access points containing candidate access point information that differentiates between candidate access points which are most likely to provide communication with wireless stations in the system and candidate access points which are not;

wherein said access points containing candidate access point information include a transmitter for transmitting said candidate access point information.

22. The system of claim 21, further comprising at least one selector for selecting, from said candidate access point information, said candidate access points that have been differentiated as most likely to provide communication.

23. The system of claim 22, wherein at least one wireless station scans said candidate access points that have been differentiated as most likely to provide communication.

24. The system of claim 23, wherein said scanning comprises said at least one wireless station transmitting a probe request for a specified candidate access point chosen from among said candidate access points differentiated as most likely to provide communication with the network.

25. The system of claim 24, wherein said probe request comprises fields of information wherein a broadcast address is entered in a destination address field, an individual address of said specified candidate access point is entered in a basic service set identification field, and either of a service set identification for said specified candidate access point or a broadcast service set identification for said specified candidate access point is entered in a service set identification field.

26. The system of claim 24, wherein said specified candidate access point responds to said probe request with an acknowledgement frame prior to any other type of frame being transmitted from said specified candidate access point and immediately following an interframe space that immediately follows said probe request.

27. The system of claim 24, wherein

said specified candidate access point responds to said probe request with a probe response frame immediately following an interframe space period, said interframe space period immediately following said probe request and being shorter in time than a distributed interframe space period;

and wherein

said wireless station responds to said probe response with an acknowledgement frame.

28. The system of claim 24, wherein

said specified candidate access point responds to said probe request with a probe response frame immediately following an interframe space period, said interframe space period immediately following said probe request and being shorter in time than a distributed interframe space period;

and wherein

said probe response is neither acknowledged nor expected to be acknowledged with an acknowledgement frame from said wireless station.

29. The system of claim 24, wherein, if said specified candidate access point does not respond to said probe request with a probe response 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 begun if, said distributed interframe space period had begun at the same time as said interframe space period that immediately follows said probe request.

30. The system of claim 24, wherein, if a probe request frame'"'"'s destination address field includes a broadcast destination or if the basic service set identification field includes a broadcast basic service set identification, then said scanning comprises a scanning technique selected from the group consisting of the IEEE 802.11, 802.15 and 802.16 wireless standards of interoperability.

31. In a wireless telecommunications system comprising a plurality of access points, the improvement wherein at least one of the access points comprises a processor which processes candidate access point information that differentiates between candidate access points which are most likely to provide communication with wireless stations in the system and candidate access points which are not.

32. The system of claim 31, further comprising a wireless station for scanning said candidate access points that have been differentiated as most likely to provide communication.

33. The system of claim 32, wherein said scanning comprises said wireless station transmitting a probe request for a specified candidate access point chosen from among said candidate access points differentiated as most likely to provide communication with the network.

34. The system of claim 33, wherein said probe request comprises fields of information wherein a broadcast address is entered in a destination address field, an individual address of said specified candidate access point is entered in a basic service set identification field, and either of a service set identification for said specified candidate access point or a broadcast service set identification for said specified candidate access point is entered in a service set identification field.

35. The system of claim 33, wherein said specified candidate access point responds to said probe request with an acknowledgement frame prior to any other type of frame being transmitted from said specified candidate access point and immediately following an interframe space that immediately follows said probe request.

36. The system of claim 33, wherein

said specified candidate access point responds to said probe request with a probe response frame immediately following an interframe space period, said interframe space period immediately following said probe request and being shorter in time than a distributed interframe space period;

and wherein

said wireless station responds to said probe response with an acknowledgement frame.

37. The system of claim 33, wherein

said specified candidate access point responds to said probe request with a probe response frame immediately following an interframe space period, said interframe space period immediately following said probe request and being shorter in time than a distributed interframe space period;

and wherein

said probe response is neither acknowledged nor expected to be acknowledged with an acknowledgement frame from said wireless station.

38. The system of claim 33, wherein, if said specified candidate access point does not respond to said probe request with a probe response 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 begun if said distributed interframe space period had begun at the same time as said interframe space period that immediately follows said probe request.

39. The system of claim 33, wherein, if a probe request frame'"'"'s destination address field includes a broadcast destination or if the basic service set identification field includes a broadcast basic service set identification, then said scanning comprises a scanning technique selected from the group consisting of the IEEE 802.11, 802.15 and

802.16 wireless standards of interoperability.

40-1. The system of claim 40, wherein at least one wireless station scans said candidate access points that have been differentiated as most likely to provide communication.