Antenna steering for an access point based upon probe signals

• US 20050075141A1
• Filed: 06/17/2004
• Published: 04/07/2005
• Est. Priority Date: 06/19/2003
• Status: Active Grant

• Current Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Original Assignee: IPR Licensing Incorporated (InterDigital, Inc.)
• Inventors: Hoffmann, John E., Johnson, Kevin P., Nelson, George Rodney Jr., Regnier, John A.
• Granted Patent: US 7,047,046 B2
• Time in Patent Office: Days
• US Class Current: 455/562.100
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0602 using antenna switching H04B7/0686 takes precedence; antenna beam directivity switching H01Q3/24
• CPC Class Codes: H04B 7/0608 Antenna selection according to transmission parameters
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 88/08 Access point devices

Abstract

A method for operating an access point in a wireless local area network (WLAN) is provided. The access point includes a directional antenna for communicating with a plurality of remote stations, and the directional antenna includes an omni angle and a plurality of directional angles. The method includes selecting one of the remote stations from the plurality of remote stations, transmitting a first probe signal via the omni angle of the directional antenna to the selected remote station, and measuring a first probe response signal received via the omni angle from the selected remote station responding to the first probe signal. A respective second probe signal is transmitted via each one of the plurality of directional angles of the directional antenna to the selected remote station, and a second probe response signal received via each directional angle from the selected remote station responding to the respective second probe signal is measured. The measured first probe response signal and the respective measured second probe response signals from the selected remote station are stored in an antenna database.

Claims

1. A method for operating an access point in a wireless local area network (WLAN), the access point comprising a directional antenna for communicating with a plurality of remote stations, the directional antenna including an omni angle and a plurality of directional angles, the method comprising:

selecting one of the remote stations from the plurality of remote stations;

transmitting a first probe signal via the omni angle of the directional antenna to the selected remote station;

measuring a first probe response signal received via the omni angle from the selected remote station responding to the first probe signal;

transmitting a respective second probe signal via each one of the plurality of directional angles of the directional antenna to the selected remote station;

measuring a second probe response signal received via each directional angle from the selected remote station responding to the respective second probe signal; and

storing in an antenna database the measured first probe response signal and the respective measured second probe response signals from the selected remote station.

2. A method according to claim 1 further comprising:

selecting a preferred directional angle for the selected remote station based upon the measured second probe response signals; and

comparing the measured first probe response signal from the omni angle with the measured second probe response signal from the preferred directional angle.

3. A method according to claim 2 further comprising selecting the omni angle or the preferred directional angle based upon the comparing for continuing communications with the selected remote station.

4. A method according to claim 3 wherein the preferred directional angle is selected if the measured signal associated therewith exceeds the measured signal associated with the omni angle by a predetermined threshold.

5. A method according to claim 1 further comprising:

selecting a next remote station from the plurality of remote stations;

repeating the transmitting of the first and second probe signals to the next selected remote station, and the measuring of the first and second probe response signals received from the next selected remote station;

storing in the antenna database the measured first probe response signal and the respective measured second probe response signals from the next selected remote station; and

repeating the selecting, the transmitting and the storing for each of the remaining remote stations from the plurality of remote stations.

6. A method according to claim 1 wherein the first probe signal comprises a request-to-send (RTS) message and the first probe response signal comprises a clear-to-send (CTS) message;

and wherein the second probe signal comprises an RTS message and the second probe response signal comprises a CTS message.

7. A method according to claim 1 wherein the measuring comprises determining at least one of a received signal strength indication, a carrier-to-interference ratio, an energy-per-bit ratio and a signal-to-noise ratio.

8. A method according to claim 1 wherein selection of the omni angle and scanning through the plurality of directional angles are performed at the media access control (MAC) layer of the access point.

9. A method according to claim 1 further comprising updating the antenna database for the selected remote station if there is no communications between the access point and the selected remote station for a certain period of time, the updating comprising repeating the transmitting of the first and second probe signals to the selected remote station, and the measuring of the first and second probe response signals received from the selected remote station.

10. A method according to claim 1 wherein the access point is operating based upon at least one of an IEEE 802.11 standard and an IEEE 802.16 standard.

11. A method according to claim 1 wherein the directional antenna comprises at least one active element and a plurality of passive elements.

12. An access point for a wireless local area network (WLAN) comprising:

a directional antenna comprising an omni angle and a plurality of directional angles; and

a controller connected to said directional antenna for control thereof, said controller

selecting one of the remote stations from the plurality of remote stations,

transmitting a first probe signal via the omni angle of said directional antenna to the selected remote station,

measuring a first probe response signal received via the omni angle from the selected remote station responding to the first probe signal,

transmitting a respective second probe signal via each one of the plurality of directional angles of said directional antenna to the selected remote station,

measuring a second probe response signal received via each directional angle from the selected remote station responding to the respective second probe signal, and

storing in an antenna database the measured first probe response signal and the respective measured second probe response signals from the selected remote station.

13. An access point according to claim 12 wherein said directional antenna comprises at least one active element and a plurality of passive elements.

14. An access point according to claim 12 wherein said controller comprises a physical layer and a media access control (MAC) layer, and wherein selection of the omni angle and scanning through the plurality of directional angles are performed at the MAC layer.

15. An access point according to claim 12 wherein said controller further selects a preferred directional angle for the selected remote station based upon the measured second probe response signals;

and compares the measured first probe response signal from the omni angle with the measured second probe response signal from the preferred directional angle.

16. An access point according to claim 15 wherein said controller selects the omni angle or the preferred directional angle based upon the comparing for continuing communications with the selected remote station.

17. An access point according to claim 16 wherein the preferred directional angle is selected if the measured signal associated therewith exceeds the measured signal associated with the omni angle by a predetermined threshold.

18. An access point according to claim 12 wherein said controller further performs the following:

selecting a next remote station from the plurality of remote stations;

repeating the transmitting of the first and second probe signals to the next selected remote station, and the measuring of the first and second probe response signals received from the next selected remote station;

storing in the antenna database the measured first probe response signal and the respective measured second probe response signals from the next selected remote station; and

repeating the selecting, the transmitting and the storing for each of the remaining remote stations from the plurality of remote stations.

19. An access point according to claim 12 wherein the first probe signal comprises a request-to-send (RTS) message and the first probe response signal comprises a clear-to-send (CTS) message;

and wherein the second probe signal comprises an RTS message and the second probe response signal comprises a CTS message.

20. An access point according to claim 12 wherein said controller updates the antenna database for the selected remote station if there is no communications with the selected remote station for a certain period of time, the updating comprising repeating the transmitting of the first and second probe signals to the selected remote station, and the measuring of the first and second probe response signals received from the selected remote station.