Adaptive beamforming configuration methods and apparatus for wireless access points serving as handoff indication mechanisms in wireless local area networks

• US 7,684,370 B2
• Filed: 05/03/2007
• Issued: 03/23/2010
• Est. Priority Date: 05/03/2007
• Status: Active Grant

• Current Assignee: Malikie Innovations Limited (Key Patent Innovations Limited)
• Original Assignee: Blackberry Limited
• Inventors: Kezys, Vytautas Robertas
• Primary Examiner(s): Afshar; Kamran
• Application Number:
  US11/743,741
• Publication Number:
  US 20080273506A1
• Time in Patent Office: 1,055 Days
• Field of Search: 370/328, 370/338, 370331-334, 455436-444, 455/560, 455561-5621
• US Class Current: 370/331
• CPC Class Codes: H04W 16/18 Network planning tools
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 36/0083 Determination of parameters used for hand-off, e.g. generation or modification of neighbour cell lists
• CPC Class Codes: H04W 36/0085 Hand-off measurements

Abstract

Methods and apparatus for use in configuring a wireless access point (AP) which serves as a handoff indication mechanism (“AP tripwire”) in a wireless local area network (WLAN) for mobile device handoffs between the WLAN and a wireless wide area network (WWAN) are described. During a configuration procedure or training mode of operation of the wireless AP, radio frequency (RF) signals transmitted from a plurality of communication devices are received at the wireless AP. The plurality of communication devices include a first group of communication devices positioned at locations of undesired RF coverage of the wireless AP, outside of an RF coverage boundary of a WLAN coverage region of one or more other wireless APs of the WLAN. The plurality of communication devices also include a second group of communication devices positioned at locations of desired RF coverage of the wireless AP, around the RF coverage boundary of the WLAN coverage region and within the WWAN coverage region. Wireless transceiver parameters of the wireless AP are automatically determined and set to adjust boundaries of an RF coverage region, such that RF signal coverage of the first group of communication devices is minimized but RF signal coverage of the second group of communication devices is maximized. Preferably, the parameters of the wireless transceiver are determined through use of an adaptive beamforming technique (e.g. a minimax optimization) which is performed automatically by the wireless AP without user intervention. After the configuration procedure, the wireless AP operates with use of the configured wireless transceiver parameters in a normal, steady-state mode of operation as the AP tripwire of the WLAN.

Claims

1. A method for use in configuring a wireless access point for serving as a handoff indication mechanism in a wireless local area network (WLAN) for mobile device handoff between the WLAN and a wireless wide area network (WWAN), the method comprising the acts of:

during a configuration procedure for the wireless access point;

receiving, by the wireless access point, radio frequency (RF) signals from a plurality of communication devices;

the plurality of communication devices including a first group of communication devices positioned at locations of undesired RF coverage outside of an RF coverage boundary of a WLAN coverage region of one or more other wireless access points of the WLAN;

the plurality of communication devices including a second group of communication devices positioned at locations of desired RF coverage around the RF coverage boundary of the WLAN coverage region;

determining and setting wireless transceiver parameters of the wireless access point for adjusting boundaries of an RF coverage region of the wireless access point, such that RF signal coverage of the first group of communication devices is minimized but RF signal coverage of the second group of communication devices is maximized; and

after the configuration procedure;

providing the wireless access point with the RF coverage region to serve as part of the handoff indication mechanism in the WLAN for mobile device handoff between the WLAN and the WWAN.

2. The method of claim 1, wherein the acts of determining and setting the parameters of the wireless transceiver comprise an adaptive beamforming technique.

3. The method of claim 1, wherein the acts of determining and setting the wireless transceiver parameters comprise a minimax optimization technique.

4. The method of claim 1, further comprising:

after the configuration procedure, providing the wireless access point with the RF coverage region to serve as part of the handoff indication mechanism in the WLAN for mobile device handoff between the WLAN and the WWAN by;

identifying whether a mobile communication device is within the RF coverage region of the wireless access point; and

causing a handoff indication to be sent to at least one of the mobile communication device and the WLAN when the mobile device is identified to be within the RF coverage region of the wireless access point.

5. The method of claim 1, further comprising:

receiving a first plurality of communication device identifiers associated with the first plurality of communication devices and a second plurality of communication device identifiers associated with the second plurality of communication devices; and

wherein the acts of determining and setting parameters of the wireless transceiver are performed based on associating the first plurality of communication device identifiers with the first plurality of communication devices for which to minimize the RF signal coverage and associating the second plurality of communication device identifiers with the second plurality of mobile devices for which to maximize the RF signal coverage.

6. The method of claim 1, further comprising:

after the configuration procedure;

adjusting the RF coverage region of the wireless access point based on feedback from the WLAN.

7. The method of claim 1, wherein the wireless access point is operative in accordance with an IEEE 802.11-based standard and the WWAN is operative in accordance with a cellular telecommunications standard.

8. A wireless access point, comprising:

an antenna array;

a wireless transceiver array coupled to the antenna array;

one or more processors which are coupled to the wireless transceiver array;

the one or more processors being adapted to operate in a handoff indication mode in a wireless local area network (WLAN) for mobile device handoff between the WLAN and a wireless wide area network (WWAN);

the one or more processors being further adapted to operate in a configuration mode to;

receive, by the wireless transceiver, radio frequency (RF) signals from a plurality of communication devices, the plurality of communication devices including a first group of communication devices positioned at locations of undesired RF coverage outside of an RF coverage boundary of a WLAN coverage region of one or more other wireless access points of the WLAN, the plurality of communication devices including a second group of communication devices positioned at locations of desired RF coverage around the RF coverage boundary of the WLAN coverage region and within the WWAN coverage region;

determine and set wireless transceiver parameters of the wireless transceiver array for adjusting boundaries of an RF coverage region of the wireless access point, such that RF signal coverage of the first group of communication devices is minimized but RF signal coverage of the second group of communication devices is maximized; and

the one or more processors being further adapted to operate in the handoff indication mode after operating in the configuration mode, such that the wireless access point is set with the RF coverage region for mobile device handoff between the WLAN and the WWAN.

9. The wireless access point of claim 8, wherein the one or more processors are further adapted to determine and set the parameters of the wireless transceiver comprise an adaptive beamforming technique.

10. The wireless access point of claim 8, wherein the one or more processors are further adapted to determine and set the wireless transceiver parameters based on a mini max optimization.

11. The wireless access point of claim 8, wherein the one or more processors are further adapted to operate in the handoff indication mode by being operative to:

identify whether a mobile communication device is within the RF coverage region of the wireless access point; and

cause a handoff indication to be sent to at least one of the mobile communication device and the WLAN when the mobile device is identified to be within the RF coverage region of the wireless access point.

12. The wireless access point of claim 8, wherein the one or more processors are further adapted to operate in the configuration mode to:

receive a first plurality of communication device identifiers associated with the first plurality of communication devices and a second plurality of communication device identifiers associated with the second plurality of communication devices; and

determine and set parameters of the wireless transceiver based on associating the first plurality of communication device identifiers with the first plurality of communication devices for which to minimize the RF signal coverage and associating the second plurality of communication device identifiers with the second plurality of communication devices for which to maximize the RF signal coverage.

13. The wireless access point of claim 8, wherein the one or more processors are further adapted to operate in the handoff indication mode with use of the parameters after operating in the configuration mode.

14. The wireless access point of claim 8, wherein the wireless transceiver is operative in accordance with an IEEE 802.11 based standard.

15. A wireless local area network (WLAN) comprising:

a plurality of wireless access points which define a WLAN radio frequency (RF) coverage region for wireless communications in the WLAN;

a wireless access point which is operative to serve as a handoff indication mechanism in the WLAN for mobile device handoff between the WLAN and a wireless wide area network (WWAN);

the wireless access point having;

an antenna array;

a wireless transceiver array coupled to the antenna array, the wireless transceiver array being operative for RF communications with use of transceiver parameters;

one or more processors which are coupled to the wireless transceiver array;

the one or more processors being adapted to operate in a handoff indication mode in the WLAN for mobile device handoff between the WLAN and the WWAN;

the one or more processors being further adapted to operate in a configuration mode to;

receive, by the wireless transceiver array, RF signals from a plurality of communication devices, the plurality of communication devices including a first group of communication devices positioned at locations of undesired RF coverage outside of an RF coverage boundary of a WLAN coverage region of one or more other wireless access points of the WLAN, the plurality of communication devices including a second group of communication devices positioned at locations of desired RF coverage around the RF coverage boundary of the WLAN coverage region and within the WWAN coverage region, and

determine and set the transceiver parameters of the wireless transceiver array for adjusting boundaries of an RF coverage region of the wireless access point, such that RF signal coverage of the first group of communication devices is minimized but RF signal coverage of the second group of communication devices is maximized.

16. The WLAN of claim 15, wherein the one or more processors of the wireless access point are further adapted to determine and set the parameters of the wireless transceiver comprise an adaptive beamforming technique.

17. The WLAN of claim 15, wherein the one or more processors of the wireless access point are further adapted to operate the wireless access point with the RF coverage region in the handoff indication mode with use of the parameters of the wireless transceiver after operating in the configuration mode.

18. The WLAN of claim 15, wherein the one or more processors of the wireless access point are further adapted to operate in the handoff indication mode by being operative to:

identify whether a mobile communication device is within the RF coverage region of the wireless access point; and

cause a handoff indication to be sent to at least one of the mobile communication device and the WLAN when the mobile device is identified to be within the RF coverage, region of the wireless access point.

19. The WLAN of claim 15, wherein the one or more processors are further adapted to operate in the configuration mode to:

receive a first plurality of communication device identifiers associated with the first plurality of communication devices and a second plurality of communication device identifiers associated with the second plurality of communication devices; and

determine and set parameters of the wireless transceiver based on associating the first plurality of communication device identifiers with the first plurality of communication devices for which to minimize the RF signal coverage and associating the second plurality of communication device identifiers with the second plurality of communication devices for which to maximize the RF signal coverage.

20. The WLAN of claim 15, wherein the one or more processors of the wireless access point are further adapted to:

after the configuration procedure for the wireless access point;

provide the wireless access point with the RF coverage region to serve as part of the handoff indication mechanism in the WLAN for mobile device handoff between the WLAN and the WWAN; and

adjusting the RF coverage region of the wireless access point based on feedback from the WLAN.