WLAN access controller packet buffering

• US 20070097933A1
• Filed: 10/31/2005
• Published: 05/03/2007
• Est. Priority Date: 10/31/2005
• Status: Active Grant

• Current Assignee: Avaya Management L.P. (Avaya Incorporated)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Kuc, Zenon
• Granted Patent: US 8,345,645 B2
• Time in Patent Office: Days
• US Class Current: 370/338
• CPC Class Codes: H04W 28/14 using intermediate storage
• 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: Y02D 30/70 in wireless communication networks

Abstract

Traffic pending delivery to sleeping Mobile Units is buffered in an Access Controller. When a particular sleeping Mobile Unit wakes up, the Access Point with which the Mobile Unit is associated signals to the Mobile Unit indicating that traffic is buffered for that Mobile Unit. In response to signaling from the Mobile Unit via the Access Point, the Access Controller forwards the traffic buffered for that Mobile Unit. In particular, the traffic is transmitted from the Access Controller to the Access Point, and then from the Access Point to the Mobile Unit. A limit may be placed on the amount of time during which the Access Controller buffers traffic for a particular Mobile Unit.

Claims

1. Apparatus for providing network access to mobile units via wireless access points, comprising:

a port in communication with a network;

a port in communication with the access points;

a memory operable to buffer data units bound for ones of the mobile units in sleep mode, the memory being shared between a plurality of the wireless access points; and

a switch operable to forward a first one of the buffered data units, which is bound for a first mobile unit, to the wireless access point with which the first mobile unit is associated.

2. The apparatus of claim 1 further including a forwarding table including a separate sleep status field for each of a plurality of the mobile units.

3. The apparatus of claim 2 wherein each sleep status field includes a buffer interval indicative of a duration of time during which data units are buffered for the mobile unit.

4. The apparatus of claim 3, wherein the wireless access point is operable to signal an indication of which mobile unit is entering sleep mode, and a duration of time of that sleep mode (“

listen interval”

), further including control logic operable to calculate the buffer interval based at least in part on the listen interval.

5. The apparatus of claim 4 further including control logic operable, if a data unit bound for the first mobile unit is buffered within the buffer interval, to signal to the access point with which the mobile unit is associated indicating that such data unit is buffered.

6. The apparatus of claim 1 wherein the switch is operable in response to signaling from the access point to forward selected buffered data units to the access point.

7. The apparatus of claim 3 wherein data units not retrieved during the buffer interval are dropped.

8. The apparatus of claim 3 wherein data units not retrieved during the buffer interval are forwarded to the appropriate access point.

9. A method for providing network access to mobile units via wireless access points, comprising the steps of:

buffering, in a memory, data units bound for ones of the mobile units in sleep mode, the memory being shared between a plurality of the wireless access points; and

forwarding, with a switch, a first one of the buffered data units, which is bound for a first mobile unit, to the wireless access point with which the first mobile unit is associated.

10. The method of claim 9 further including the step of populating, in a forwarding table, a separate sleep status field for ones of the mobile units.

11. The method of claim 10 wherein each sleep status field includes a buffer interval indicative of a duration of time during which data units are buffered for the mobile unit.

12. The method of claim 11, wherein the wireless access point is operable to signal an indication of which mobile unit is entering sleep mode, and a duration of time of that sleep mode (“

listen interval”

), further including the step of calculating the buffer interval based at least in part on the listen interval.

13. The method of claim 12 further including the step of, if a data unit bound for the first mobile unit is buffered within the buffer interval, signaling to the access point with which the mobile unit is associated indicating that such data unit is buffered.

14. The method of claim 9 including the further step of forwarding selected buffered data units to the access point in response to signaling from the access point.

15. The method of claim 11 including the further step of dropping data units not retrieved during the buffer interval.

16. The method of claim 11 including the further step of forwarded, to the appropriate access point, data units not retrieved during the buffer interval.