USING PROXIMATE ACCESS POINTS TO ENSURE FAST WI-FI NETWORK DISCOVERY AND RECONNECTION WITH REDUCED POWER CONSUMPTION

• US 20140185599A1
• Filed: 01/03/2013
• Published: 07/03/2014
• Est. Priority Date: 01/03/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Vatanapanpilas, Songkran, Chinnathambi Kailasam, Naresh Kumar
• Granted Patent: US 9,408,140 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

One embodiment of the present invention provides a portable device, which is configured to join a known Wi-Fi network. While the device is not associated with a known access point, the device scans for access points at a scanning frequency wherein information about known access points has been stored in a database in the device. During this scanning process, the device determines whether the device is proximate to a known access point and the device sets the device'"'"'s scanning frequency based on whether the device is proximate to a known access point.

Claims

1. A portable device, comprising

an antenna;

a wireless local area network (WLAN) transceiver coupled to the antenna;

an interface circuit, coupled to the WLAN transceiver, configured to communicate with other electronic devices through the WLAN transceiver;

storage hardware for storing a database in the portable device; and

control logic associated with the interface circuit, wherein the control logic is configured to perform the following operations;

while the portable device is not associated with a known access point, scanning for access points at a scanning frequency, wherein information about known access points is stored in the database;

during the scanning process, determining whether the portable device is proximate to a known access point; and

setting the scanning frequency based on whether the portable device is proximate to a known access point.

2. The portable device of claim 1, wherein the control logic is further configured to:

when the portable device associates with an access point for a WLAN, storing information for the access point in the database;

wherein the information indicates that the access point is a known access point for the WLAN; and

while the portable device is associated with the access point, scanning for other access points opportunistically.

3. The portable device of claim 2, wherein scanning for access points comprises:

broadcasting probe requests over a set of WLAN channels; and

receiving probe responses from in-range access points.

4. The portable device of claim 3, wherein determining whether the portable device is proximate to a known access point comprises:

determining whether any of the in-range access points is either a known access point or a proximate access point;

wherein information about proximate access points is stored in the database.

5. The portable device of claim 4, wherein a proximate access point either:

neighbors a known access point;

or

neighbors another access point that is less than h hops away from a known access point.

6. The portable device of claim 3, wherein the set of WLAN channels comprises WLAN channels which conform to the IEEE 802.11 standard.

7. The portable device of claim 5, wherein scanning for access points further comprises:

if the responses include a response from a known access point;

for any in-range access point that responds;

storing or updating information for the in-range access point in the database, wherein the information;

includes the known access point'"'"'s BSSID; and

indicates that the in-range access point is proximate to a known access point; and

if the responses do not include a response from a known access point but include a response from an access point that is less than h hops away from a known access point;

for any in-range access point that responds;

storing or updating information for the in-range access point in the database, wherein the information;

includes the BSSID of the access point that is less than h hops away from the known access point; and

indicates that the in-range access point is a proximate access point.

8. The portable device of claim 1, wherein setting the scanning frequency in accordance with whether the portable device is proximate to a known access point comprises:

if the portable device is proximate to a known access point;

restoring the scanning frequency to an initial scanning frequency f_initial; and

setting a counter to; and

if the portable device is not proximate to a known access point and the scanning frequency is greater than a minimum scanning frequencyfnin;

if the counter is equal to an integer c;

reducing the scanning frequency; and

setting the counter to; and

if the counter is less than c, incrementing the counter.

9. The portable device of claim 8, wherein f_initial, f_min, and d depend on h.

10. The portable device of claim 4, wherein:

information about a known access point comprises the access point'"'"'s BSSID, SSID, and channel; and

information about a proximate access point comprises the access point'"'"'s BSSID, SSID, channel, RSSI information, and a BSSID of a neighboring access point.

11. A computer-implemented method for searching for and associating with a wireless access point for a wireless local area network (WLAN), the method comprising:

while a portable device is not associated with a known access point, scanning for access points at a scanning frequency, wherein information about known access points is stored in a database in the portable device;

during the scanning process, determining whether the portable device is proximate to a known access point; and

setting the scanning frequency based on whether the portable device is proximate to a known access point.

12. The computer-implemented method of claim 11, further comprising:

when the portable device associates with an access point for a WLAN, storing information for the access point in the database;

wherein the information indicates that the access point is a known access point for the WLAN; and

while the portable device is associated with the access point, scanning for other access points opportunistically.

13. The computer-implemented method of claim 12, wherein scanning for access points comprises:

broadcasting probe requests over a set of WLAN channels; and

receiving probe responses from in-range access points.

14. The computer-implemented method of claim 13, wherein determining whether the portable device is proximate to a known access point comprises:

determining whether any of the in-range access points is either a known access point or a proximate access point;

wherein information about proximate access points is stored in the database.

15. The computer-implemented method of claim 14, wherein a proximate access point either:

neighbors a known access point;

or

neighbors another access point that is less than h hops away from a known access point.

16. The computer-implemented method of claim 13, wherein the set of WLAN channels comprises WLAN channels which conform to the IEEE 802.11 standard.

17. The computer-implemented method of claim 15, wherein scanning for access points further comprises:

if the responses include a response from a known access point;

for any in-range access point that responds;

storing or updating information for the in-range access point in the database, wherein the information;

includes the known access point'"'"'s BSSID; and

indicates that the in-range access point is proximate to a known access point; and

if the responses do not include a response from a known access point but include a response from an access point that is less than h hops away from a known access point;

for any in-range access point that responds;

storing or updating information for the in-range access point in the database, wherein the information;

includes the BSSID of the access point that is less than h hops away from the known access point; and

indicates that the in-range access point is a proximate access point.

18. The computer-implemented method of claim 11, wherein setting the scanning frequency in accordance with whether the portable device is proximate to a known access point comprises:

if the portable device is proximate to a known access point;

restoring the scanning frequency to an initial scanning frequency f_initial; and

setting a counter to; and

if the portable device is not proximate to a known access point and the scanning frequency is greater than a minimum scanning frequency f_min;

if the counter is equal to an integer c;

reducing the scanning frequency; and

setting the counter to; and

if the counter is less than c, incrementing the counter.

19. The computer-implemented method of claim 18, wherein f_initial, f_min, and d depend on h.

20. The computer-implemented method of claim 14, wherein:

information about a known access point comprises the access point'"'"'s BSSID, SSID, and channel; and

information about a proximate access point comprises the access point'"'"'s BSSID, SSID, channel, RSSI information, and a BSSID of a neighboring access point.

21. A non-transitory computer-program product for use in conjunction with a computer system, the computer-program product comprising a computer-readable storage medium and a computer-program mechanism embedded therein for configuring the computer system to search for and associate with a wireless access point for a wireless local area network (WLAN), the computer-program mechanism including:

instructions for, while the portable device is not associated with a known access point, scanning for access points at a scanning frequency, wherein information about known access points is stored in a database in the portable device;

instructions for, during the scanning process, determining whether the portable device is proximate to a known access point; and

instructions for, setting the scanning frequency based on whether the portable device is proximate to a known access point.

22. The computer-program product of claim 21, wherein the computer-program mechanism further includes:

instructions for, when the portable device associates with an access point for a WLAN, storing information for the access point in the database;

wherein the information indicates that the access point is a known access point for the WLAN; and

instructions for, while the portable device is associated with the access point, scanning for other access points opportunistically.

23. The computer-program product of claim 22, wherein scanning for access points comprises:

broadcasting probe requests over a set of WLAN channels; and

receiving probe responses from in-range access points.