Dynamic channel selection scheme for IEEE 802.11 WLANs

• US 6,985,465 B2
• Filed: 07/09/2001
• Issued: 01/10/2006
• Est. Priority Date: 07/07/2000
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Choi, Sunghyun, Soomro, Amjad Ali, Mangold, Stefan, Cervello, Gerard G
• Primary Examiner(s): Ho, Duc
• Assistant Examiner(s): Tran, Thien D.
• Application Number:
  US09/901,871
• Publication Number:
  US 20020060995A1
• Time in Patent Office: 1,646 Days
• Field of Search: 370/328, 370/329, 370/330, 370/331, 370/332, 370/333, 370/338, 370/468
• US Class Current: 370/333
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 72/02 Selection of wireless resources by user or terminal
• CPC Class Codes: H04W 72/54 based on quality criteria
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 92/10 between terminal device and access point, i.e. wireless air interface

Abstract

Disclosed is a method and system for dynamically selecting a communication channel between an access point (AP) and a plurality of stations (STAs) in an IEEE 802.11 wireless local area network (WLAN). The method includes the steps of: determining whether a new channel between the AP and STAs within a particular basic service set (BSS) is needed; requesting a channel signal quality measure to some of the plurality of stations by the AP; reporting a channel signal quality report back to the AP based on a received signal strength indication (RSSI) and a packet error rate (PER) of all channels detected by the stations within the BSS; selecting a new channel based on the channel quality report for use in communication between the AP and the plurality of stations.

Claims

1. A method for dynamically selecting a communication channel between an access point (AP) and a plurality of stations (STAs) located within the coverage area of a basic service set (BSS) in a wireless local area network (WLAN), the method comprising the steps of:

(a) determining whether a new channel to be used by said plurality of wireless stations is needed;

(b) requesting, by said AP, a channel signal quality measure to at least one of said plurality of stations;

(c) scanning a set of channels available for use by said plurality of stations to determine whether a signal from an adjacent BSS is received;

(d) if said adjacent BSS signal is detected, determining a signal quality measure of each channel of said set of channels based on a received signal strength indication (RSSI) and a packet error rate (PER) of all said channels measured by said plurality of stations to said AP; and

,

(e) selecting said new channel based on said measured RSSI and said PER information.

2. The method of claim 1, further comprising the step of communicating information about said new channel from said AP to said plurality of stations.

3. The method of claim 1, further comprising the step of establishing communication to said new channel between said AP and said plurality of stations.

4. The method of claim 1, wherein said channel signal quality report further includes an interference signal level caused by another communication device, said interference signal level is based on the absence of any 802.11 frame reception.

5. The method of claim 1, wherein said RSSI and said PER is used to determine said channel signal quality and a relative distance between the STA requested for said channel signal quality measure and a plurality of adjacent stations from said adjacent BSS.

6. The method of claim 1, further comprising the steps of:

detecting a channel signal quality from the set of said channels by said AP;

determining a candidate channel for use in communication between said AP and said plurality of stations; and

,

switching to said candidate channel if the detected channel signal quality exceeds a predetermined threshold.

7. The method of claim 6, wherein said AP measures said channel signal quality during a contention-free-period (CFP).

8. The method of claim 6, wherein said AP measures said channel signal quality after transmitting request-to-send (RTS) frame.

9. The method of claim 1, wherein it is determined that said new channel is needed in step (a) if one of the following conditions occurs:

(1) said BSS is formed by said AP;

(2) said AP or said STA experiences a bad channel condition;

(3) said BSS overlaps with an adjacent BSS; and

,

(4) no association of said STA by said AP occurs longer than a predetermined time period.

10. A method for dynamically selecting a communication channel between an access point (AP) and a plurality of stations (STAs) located within the coverage area of a basic service set (BSS) in a wireless local area network (WLAN), the method comprising the steps of:

(a) determining whether a new channel to be used by said plurality of wireless stations is needed;

(b) requesting, by said AP, a channel signal quality measure to each of said plurality of stations;

(c) scanning a set of channels available for use by said plurality of stations to determine whether a signal from an adjacent BSS is received; and

,

(c) (i) if detected, measuring a received signal strength indication (RSSI) and a packet error rate (PER) of all said channels scanned by said plurality of stations to said AP;

(c) (ii) if not detected, measuring an interference level caused by another communication system based on the absence of any 802.11 frame reception for a predetermined time period; and

,

(d) selecting said new channel representing the least interference signal level based on said measured RSSI, PER, and interference level.

11. The method of claim 10, further comprising the step of communicating information about said new channel from said AP to said plurality of stations.

12. The method of claim 10, further comprising the step of establishing communication to said new channel between said AP and said plurality of stations.

13. The method of claim 10, further comprising the steps of:

detecting a channel signal quality from the set of said channels by said AP;

determining a candidate channel for use in communication between said AP and said plurality of stations; and

,

switching to said candidate channel if the detected channel signal quality exceeds a predetermined threshold.

14. The method of claim 13, wherein said AP measures said channel signal quality during a contention-free-period (CFP).

15. The method of claim 13, wherein said AP measures said channel signal quality after transmitting request-to-send (RTS) frame.

16. The method of claim 13, wherein determining that said new channel is needed in step (a) if one of the following condition occurs:

(1) said BBS is formed by said AP;

(2) said AP or said STA experiences a bad channel condition;

(3) said BSS overlaps with an adjacent BBS; and

,

(4) no association of said STA by said AP occurs longer than a predetermined time period.