Systems and Methods for Indicating Buffered Data at an Access Point with Efficient Beacon Handling

• US 20080298290A1
• Filed: 03/12/2008
• Published: 12/04/2008
• Est. Priority Date: 05/31/2007
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Wentink, Maarten Menzo
• Granted Patent: US 8,170,002 B2
• Time in Patent Office: Days
• US Class Current: 370/311
• CPC Class Codes: H04W 52/0216 using a pre-established activity schedule, e.g. traffic indication frame
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

Stations in standby mode periodically wake up to check for buffered data at the access points. Traditionally, the information is available by checking the periodic beacon frame for a traffic indication map (TIM). Unfortunately, the length of beacons has steadily increased with the progression of the various wireless standards requiring stations to wake up for longer periods to merely check for buffered data. Several approaches are disclosed which address this shortcoming, including the broadcast of TIM frames, the partial reception of beacon frames and the use of an embedded TIM frame within a beacon frame.

Claims

1. A method for indicating buffered data comprising:

broadcasting a beacon frame comprising a traffic indication map (TIM) element,

wherein the TIM element is placed near the beginning of the beacon frame;

said TIM element comprising a bitmap control field comprising an offset and a partial virtual bitmap field indicative of the stations having buffered data awaiting.

2. The method of claim 1, wherein the TIM element immediately follows a capability field in the beacon frame.

3. The method of claim 1, wherein the TIM element comprises a second bitmap control field and a second partial virtual bitmap.

4. The method of claim 1, wherein the beacon comprises a check beacon indication element.

5. The method of claim 4, wherein the check beacon indication element comprises means for indicating a critical change in the beacon frame.

6. The method of claim 4, wherein the check beacon indication element comprises a counter which is incremented after each critical change in the beacon frame.

7. The method of claim 4, wherein the check beacon indication element comprises means for indicating a significant change in the beacon frame.

8. The method of claim 4, wherein the check beacon indication element comprises a counter which is incremented after each significant change in the beacon frame.

9. The method of claim 4, wherein the beacon further comprises a partial frame check informational element.

10. A method in a station for retrieving buffered data from an access point comprising:

partially receiving a beacon frame, said partially receiving comprising receiving a TIM element comprising a partial virtual bitmap and a check beacon indication element;

if the partial virtual bitmap is indicative that the access point has buffered data for the station, receiving the buffered data; and

if the check beacon indication indicates a critical or significant change in the beacon frame, receiving the remainder of the beacon frame.

11. A station comprising a processor, a wireless network interface device and a memory comprising instructions, said instructions causing the processor and the wireless network interface device to perform the method of claim 10.

12. The method of claim 10, wherein partially receiving comprises receiving a partial frame check informational element, said method further comprises discarding the partially received beacon frame if the partial frame check informational element with the beacon frame as partially received indicates an error.

13. A station comprising a processor, a wireless network interface device and a memory comprising instructions, said instructions causing the processor and the wireless network interface device to perform the method of claim 12.

14. An access point comprising:

a processor;

a wireless network interface device; and

a memory comprising instructions;

said instructions causing the processor to cause the wireless network interface device to broadcast beacon frame comprising a TIM element,

wherein the TIM element is placed near the beginning of the beacon frame;

said TIM element comprising a bitmap control field comprising an offset and a partial virtual bitmap field indicative of the stations having buffered data awaiting.

15. The access point of claim 14, wherein the TIM element immediately follows a capability field in the beacon frame.

16. The access point of claim 14, wherein the TIM element comprises a second bitmap control field and a second partial virtual bitmap.

17. The access point of claim 14, wherein the beacon comprises a check beacon indication element.

18. The access point of claim 14, wherein the check beacon indication element comprises a means for indicating a critical change in the beacon frame, a means for indicating a significant change in the beacon frame, or both.

19. The access point of claim 14, wherein the check beacon indication element comprises a first counter which is incremented after each critical change in the beacon frame, a second counter which is incremented after each significant change in the beacon frame, or both.

20. The access point of claim 14, further comprising a partial frame check informational element.