Method and apparatus for dormant mode support with paging

• US 7,769,397 B2
• Filed: 06/04/2008
• Issued: 08/03/2010
• Est. Priority Date: 01/28/2002
• Status: Expired due to Fees

• Current Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Original Assignee: NTT Docomo Incorporated (Nippon Telegraph and Telephone Corporation)
• Inventors: Watanabe, Fujio, Miki, Toshio, Funato, Daichi
• Primary Examiner(s): Ly; Nghi H
• Application Number:
  US12/133,265
• Publication Number:
  US 20080240323A1
• Time in Patent Office: 790 Days
• Field of Search: 455/458, 455/450, 455/464, 455/509, 370/329
• US Class Current: 455/458
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information
• CPC Class Codes: H04W 48/20 Selecting an access point
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 52/0219 where the power saving management affects multiple terminals
• 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 68/00 User notification, e.g. alerting and paging, for incoming communication, change of service or the like
• CPC Class Codes: H04W 76/20 Manipulation of established connections
• CPC Class Codes: H04W 80/04 Network layer protocols, e.g. mobile IP [Internet Protocol]
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/08 Access point devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Apparatuses and methods are disclosed herein for implementing dormant mode with paging in a WLAN. Power savings in the computing device and reduction in traffic across the network are achieved by requiring a computing device to inform the WLAN of its location only when it crosses a paging area boundary or is to receive IP traffic. Dormant mode with paging is implemented in a protocol that supports dormant functionality and paging functionality but does not itself provide methods or standards for implementing such functionality, such as the IEEE 802.11. The methods and apparatuses disclosed herein provide the methods needed to implement dormant mode with paging in such a protocol. Generally, the methods and apparatuses for implementing dormant mode with paging basically include (1) establishing paging areas; (2) communicating access group information to a computing device; and (3) locating a computing device.

Claims

1. A method for synchronizing a beacon timing of a first access point with a beacon timing of a second access point wherein the first and second access points are in an access point group in a wireless local area network (WLAN), comprising:

acquiring, by a computing device, a beacon timing of the first access point when the computing device is within a range of the first access point;

acquiring, by the computing device, a beacon timing of the second access point after the computing device moves into a range of the second access point;

calculating, by the computing device, a beacon timing difference between the beacon timing of the first access point and the beacon timing of the second access point;

communicating the beacon timing difference from the computing device to the second access point; and

causing the beacon timing of either the first access point or the second access point to be adjusted to align the beacon timing of the first access point and the beacon timing of the second access point,

wherein calculating the beacon timing difference comprises;

while the computing device is within the range of the first access point, periodically shifting the computing device into an active mode to detect a first access point beacon at predetermined time instances that are spaced by a predetermined time interval, wherein the predetermined time instances correspond to the beacon timing of the first access point;

moving the computing device from within the range of the first access point to within the range of the second access point;

while the computing device is within the range of the second access point, shifting the computing device into the active mode to detect a second access point beacon at one of the predetermined time instances for a second time interval, wherein the second time interval ends when the computing device detects the second access point beacon; and

calculating the beacon timing difference based on the one of the predetermined time instances and an endpoint of the second time interval.

2. The method as claimed in claim 1, wherein communicating the beacon timing difference from the computing device to the second access point comprises:

the computing device communicating the beacon timing difference to the second access point;

the second access point identifying the first access point;

the second access point communicating the beacon timing difference to the first access point.

3. The method as claimed in claim 1, wherein adjusting the beacon timing of either the first access point or the second access point comprises:

if either the first access point or the second access point is a master of the other of the first access point or the second access point, wherein the other of the first access point or the second access point is a slave of the master access point, adjusting the beacon timing of the slave access point to the beacon timing of the master access point; and

if neither the first access point or the second access point is a master of the other of the first access point or the second access point, determining a common master access point and adjusting the beacon timing of the first access point and the beacon timing of the second access point to a beacon timing of the common master access point.

4. The method defined in claim 1 further comprising:

shifting the computing device into the active communication mode to detect the second access point beacon after calculating the beacon timing difference and before the beacon timing of the second access point is adjusted; and

shifting the computing device into the active communication mode to detect the second access point beacon after the beacon timing of the second access point is adjusted.

5. A method for synchronizing a beacon timing of a first access point with a beacon timing of a second access point wherein the first and second access points are in an access point group in a WLAN, comprising:

calculating the difference between the beacon timing of the first access point and the beacon timing of the second access point to ascertain a beacon timing difference, wherein the calculating is performed by a computing device, comprising;

while the computing device is within a range of the first access point, periodically shifting the computing device into an active mode to detect a first access point beacon at predetermined time instances that are spaced by a predetermined time interval, wherein the predetermined time instances correspond to a beacon timing of the first access point;

moving the computing device from within the range of the first access point to within a range of the second access point;

while the computing device is within the range of the second access point, shifting the computing device into the active mode to detect a second access point beacon at one of the predetermined time instances for a second time interval, wherein the second time interval ends when the second access point beacon is complete; and

calculating the beacon timing difference based on the one of the predetermined time instances and the second time interval;

communicating the beacon timing difference from the computing device to the second access point and the first access points, comprising;

the computing device communicating the beacon timing difference to the second access point;

the second access point identifying the first access point;

the second access point communicating the beacon timing difference to the first access point; and

adjusting the beacon timing of either the first access point or the second access point so that the beacon timing of either the first access point or the second access point equals the beacon timing of the other of the first access point or the second access point, comprising;

if either the first access point or the second access point is a master of the other of the first or the second access point, wherein the other of the first access point or the second access point is a slave of the master access point, adjusting the beacon timing of the slave access point to the beacon timing of the master access point; and

if neither the first access point or the second access point is a master of the other of the first access point or the second access point, determining a common master access point and adjusting the beacon timing of the first access point and the beacon timing of the second access points to a beacon timing of the common master access point.

6. A method comprising:

receiving, from a computing device that moves from within a range of a first access point into a range of a second access point, a beacon timing difference between a beacon timing of the first access point and a beacon timing of the second access point; and

adjusting the beacon timing of either the first access point or the second access point to make the beacon timing of the first access point be equal to the beacon timing of the second access point

wherein the computing device calculating the difference between beacon timings comprises;

periodically shifting into an active communication mode to detect a first access point beacon at predetermined time instances that are spaced by a first time interval while the computing device is within a range of the first access point; and

shifting into the active communication mode to detect a second access point beacon at one of the predetermined time instances for a second time interval while the computing device is within a range of the second access point, wherein the second time interval ends when the second access point beacon is complete.

7. The method defined in claim 6 further comprising:

identifying the first access point; and

communicating the beacon timing difference to the first access point.

8. The method defined in claim 6, wherein the computing device calculating the difference between beacon timings further comprises:

calculating the beacon timing difference based on the one of the predetermined time instances and an endpoint of the second time interval.

9. The method defined in claim 6, further comprising:

if either the first access point or the second access point is a master of the other of the first or the second access point, wherein the other of the first access point or the second access point is a slave of the master access point, adjusting the beacon timing of the slave access point to the beacon timing of the master access point.

10. The method defined in claim 6, further comprising:

if neither the first access point or the second access point is a master of the other of the first access point or the second access point, determining a common master access point and adjusting the beacon timing of the first access point and the beacon timing of the second access points to a beacon timing of the common master access point.

11. The method defined in claim 6 further comprising:

shifting the computing device into the active communication mode to detect the second access point beacon after calculating the beacon timing difference and before the beacon timing of the second access point is adjusted; and

shifting the computing device into the active communication mode to detect the second access point beacon after the beacon timing of the second access point is adjusted.