Associating a wireless station with an access point

• US 8,014,804 B2
• Filed: 05/04/2004
• Issued: 09/06/2011
• Est. Priority Date: 05/04/2004
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Agere Systems Incorporated (Broadcom, Inc.)
• Inventors: Banerjea, Raja
• Primary Examiner(s): Tran; Tuan A
• Application Number:
  US10/838,868
• Publication Number:
  US 20060135066A1
• Time in Patent Office: 2,681 Days
• Field of Search: 455/434, 455/445, 455/454, 455/464, 4554141- 4, 455/428, 455507-513, 4554351-4352, 455436-438, 4554521-4522, 455/453, 455/57.11, 455/67.13, 370/310, 370328-333, 370/468, 370464-465, 370/445, 370/447, 370/448, 709220-221, 709223-226
• US Class Current: 455/513
• CPC Class Codes: H04B 17/24 with feedback of measurements to the transmitter
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]
• CPC Class Codes: H04B 17/382 for resource allocation, admission control or handover
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 48/14 using user query or user detection
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A station associates with an access point in a wireless local area network conforming to, e.g., an IEEE 802.11 standard. The station measures the signal-to-noise ratio (SNR) for the downlink from each of the access points sending either a beacon or a probe response, and forms a first list of access points in decreasing order of received downlink SNR. The station transmits a link test request to each access point to query the access point for the SNR of the link test request received at the corresponding access point. Access points respond to the link test request with corresponding link test responses containing the corresponding SNR. The station i) forms a second list of access points in decreasing order of received uplink SNR and ii) compares the first and second lists to determine which access point to associate with based on overall quality of the uplink and downlink channels.

Claims

1. A method of associating a station to one of a plurality of access points in a wireless local area network (WLAN), the method comprising the steps of:

(a) measuring a downlink signal quality of a message received in a signal from each of one or more access points;

(b) transmitting a test link request to each of the one or more access points;

(c) receiving a corresponding test link response for each of one or more of the test link requests, the corresponding test link response including an uplink signal quality to the corresponding access point;

(d) identifying at least one access point having a downlink signal quality above a predetermined threshold; and

(e) associating to the access point, from among the at least one access point identified in step (d), having the highest uplink signal quality.

2. The invention as recited in claim 1, wherein the method further comprises the step of transmitting, when in an active mode, a probe request, and, for step (a), the message in the signal from each of the one or more access points is a probe response.

3. The invention as recited in claim 1, wherein the method further comprises the step of detecting, when in a passive mode, a beacon, and, for step (a), the message in the signal from each of the one or more access points is the beacon.

4. The invention as recited in claim 1, wherein, for step (a), each message conforms to a MAC layer frame format in accordance with one or more editions of an Institute of Electrical Engineers (IEEE) 802.11 standard for telecommunications and information exchange between systems.

5. The invention as recited in claim 4, wherein, for steps (b) and (c), each link test request and the corresponding link test response conform to the MAC layer frame format in accordance with one or more editions of the IEEE 802.11 standard.

6. The invention as recited in claim 1, wherein the uplink signal quality and the downlink signal quality are indicated by one or more of a signal-to-noise ratio (SNR), a bit-error rate (BER), a power level, and a burst error rate.

7. The invention as recited in claim 1, wherein the method is embodied as processing steps in a processor of an integrated circuit.

8. The invention as recited in claim 1, wherein the method is embodied as processing steps in a processor of a station operating in accordance with one or more editions of an Institute of Electrical Engineers (IEEE) 802.11 standard for telecommunications and information exchange between systems.

9. A method of associating a station to one of a plurality of access points in a wireless local area network (WLAN), the method comprising the steps of:

(a) transmitting a test link request to each of one or more access points;

(b) receiving a corresponding test link response for each of one or more of the test link requests, the corresponding test link response including an uplink signal quality to the corresponding access point;

(c) measuring a downlink signal quality of the corresponding access point for each corresponding test link response;

(e) identifying at least one access point having a downlink signal quality above a predetermined threshold; and

(f) associating to the access point, from among the at least one access point identified in step (e), having the highest uplink signal quality.

10. Apparatus for associating a station to one of a plurality of access points in a wireless local area network (WLAN), the apparatus comprising:

a detector adapted to measure a downlink signal quality of a message received in a signal from each of one or more access points;

a transmitter adapted to transmit a test link request to each of the one or more access points;

a receiver adapted to receive a corresponding test link response for each of one or more of the test link requests, the corresponding test link response including an uplink signal quality to the corresponding access point; and

a comparator adapted to;

(i) identify at least one access point having a downlink signal quality above a predetermined threshold; and

(ii) identify the access point, from among the at least one access point identified in step (i), having the highest uplink signal quality;

wherein the apparatus is adapted to associate to the access point identified in step (ii) as having the highest uplink signal quality.

11. The invention as recited in claim 10, wherein the transmitter is adapted to transmit, when in an active mode, a probe request, and the message in the signal from each of the one or more access points is a probe response.

12. The invention as recited in claim 10, wherein the detector is adapted to detect, when in a passive mode, a beacon, and the message in the signal from each of the one or more access points is the beacon.

13. The invention as recited in claim 10, wherein each message conforms to a MAC layer frame format in accordance with one or more editions of an Institute of Electrical Engineers (IEEE) 802.11 standard for telecommunications and information exchange between systems.

14. The invention as recited in claim 13, wherein each link test request and the corresponding link test response conform to the MAC layer frame format in accordance with one or more editions of the IEEE 802.11 standard.

15. The invention as recited in claim 10, wherein the uplink signal quality and the downlink signal quality are indicated by one or more of a signal-to-noise ratio (SNR), a bit-error rate (BER), a power level, and a burst error rate.

16. The invention as recited in claim 10, wherein the apparatus is embodied in a processor of an integrated circuit.

17. The invention as recited in claim 10, wherein the apparatus is embodied in the station operating in accordance with one or more editions of an Institute of Electrical Engineers (IEEE) 802.11 standard for telecommunications and information exchange between systems.

18. Apparatus for associating a station to one of a plurality of access points in a wireless local area network (WLAN), the apparatus comprising:

a transmitter adapted to transmit a test link request to each of one or more access points;

a receiver adapted to receive a corresponding test link response for each of one or more of the test link requests, the corresponding test link response including an uplink signal quality to the corresponding access point;

a detector adapted to measure a downlink signal quality of the corresponding access point for each corresponding test link response; and

a comparator adapted to;

(i) identify at least one access point having a downlink signal quality above a predetermined threshold; and

(ii) identify the access point, from among the at least one access point identified in step (i), having the highest uplink signal quality;

wherein the apparatus is adapted to associate to the access point identified in step (ii) as having the highest uplink signal quality.